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Table of Content

15 February 2018, Volume 39 Issue 3
Basic Research
Effect of Heating Treatment on Physical and Oxidative Stability of Seed Oil Bodies from Diverse Oilseed Crops
CUI Chunli, ZHANG Hongchao, WANG Qiuling, JIANG Shanshan, ZHOU Xin, JIANG Lianzhou, HOU Juncai
2018, 39(3):  1-6.  doi:10.7506/spkx1002-6630-201803001
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The objective of this study was to determine the effect of heating treatment on physical and oxidative stability of oil bodies (OBs) from mature seeds of soybean, peanut and sunflower. The chemical compositions of seeds and OBs were analyzed, and the ζ-potentials, mean particle diameters, emulsifying properties, and lipid hydroperoxides of OBs at different temperatures were measured. The data we obtained demonstrated that there were significant differences in the chemical compositions of seeds, OBs and extracts among diverse oilseed crops (P < 0.05). The ζ-potential of soybean OBs was significantly higher than that of sunflower and peanut OBs (P < 0.05), while the mean particle diameter was significantly smaller (P < 0.05). There was no significant effect of thermal processing on the mean particle diameter of soybean or peanut OBs. The emulsifying activity indexes (EAI) of soybean and peanut OBs reduced from (61.32 ± 1.19) to (51.99 ± 0.90) m2/g, and from (57.50 ± 0.30) to (40.13 ± 1.51) m2/g, respectively, with increasing temperature from 30 to 80 ℃. However, the EAI of sunflower OBs at 50–70 ℃ was significantly higher than that at 30–40 ℃ and 80–90 ℃ (P < 0.05). These OBs were stable against oxidation at 4 and 25 ℃. When stored at elevated temperature, hydroperoxide formation in the oil from peanut OBs was significantly more than that in the oil from soybean and sunflower OBs (P < 0.05). These results suggested that OBs from diverse species had good emulsifying stability at certain temperatures, but were different from each other in physicochemical properties.
Spoilage Potential of Dominant Spoilage Bacteria from Chilled Tuna (Thunnus obesus)
LIU Aifang, XIE Jing, QIAN Yunfang
2018, 39(3):  7-14.  doi:10.7506/spkx1002-6630-201803002
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Pseudomonas spp., Acinetobacter spp. and Brochothrix thermosphacta isolated from chilled raw tuna (Thunnus obesus) at the end of shelf life were explored for their spoilage potential. Bacterial counts and growth kinetic parameters, sensory quality, total volatile basic nitrogen (TVB-N) and biogenic amine contents and the yield factor of metabolic products, YTVB-N/CFU, were assayed on sterile T. obesus inoculated separately with each of the three isolates during chilled storage. It was found that the modified Gompertz, Baranyi-Roberts, and Logisitic models could describe the dynamic growth of Pseudomonas spp., Acinetobacter spp. and Brochothrix thermosphacta at cold temperature. The Lag phase of the 3 bacterial strains were 10.85, 83.93 and 79.11 h, respectively, and the relative maximum growth rates were 0.045 7, 0.182 9 and 0.111 1 h-1, respectively. The shelf life of inoculated tuna was 96, 108 and 105 h, respectively. The TVB-N contents of sterile T. obesus inoculated with Pseudomonas spp., Acinetobacter spp. and B. thermosphacta were 27.32, 22.80 and 24.85 mg/100 g, respectively. The changes in biogenic amines contents of T. obesus during chilled storage revealed that the capability of Pseudomonas spp. to produce biogenic amines was stronger than that of Acinetobacter spp. and B. thermosphacta. The biogenic amine index of tuna inoculated with Pseudomonas spp. was 155.84 after 96 h storage, which was higher than the threshold value of 100. This study also showed that YTVB-N/CFU values for the 3 strains were 7.36 × 10-8, 1.85 × 10-8 and 5.07 × 10-8 mg TVB-N/CFU, respectively, indicating that Pseudomonas spp. played the most important role in spoilage of chilled raw T. obesus, followed by B. thermosphacta and Acinetobacter spp..
Effect of High-Temperature Heating on Fatty Acid Composition and Physicochemical Properties of Peony Seed Oil
WEI Xiaobao, WEI Yingying, XUE Jingqi, ZHANG Xiuxin, SHAO Xingfeng
2018, 39(3):  15-20.  doi:10.7506/spkx1002-6630-201803003
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In order to explore the effect of heating temperature on its quality, peony seed oil was heated at 90, 120, 150, 180, 210 or 240 ℃ for 30 min and changes in fatty acid composition and physicochemical properties were monitored. The results indicated that fatty acid isomers, cyclic fatty acids, and short and medium chain fatty acids were generated after heating, depending on temperature. Physicochemical indicators of peony seed oil were in line with quality standards for edible oil after high-temperature heating, but the unsaturated fatty acid content decreased with the increase of temperature; the α-linolenic acid content, making it a nutritional product, steeply declined when temperature exceeded 180 ℃. In conclusion, peony seed oil has good thermal stability with respect to physicochemical properties but from a nutritional perspective, it is not suit for frying at temperatures higher than 180 ℃.
Isolation and Anti-Diabetic Activity in Vitro of Flavonoids from Buckwheat Hull
ZHAO Ziying, PIAO Chunhong, WANG Yuhua, LIU Junmei, YU Hansong, DAI Weichang, TANG Yufang, WANG Jing, LIU Dailin
2018, 39(3):  21-27.  doi:10.7506/spkx1002-6630-201803004
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The purpose of this investigation was to evaluate the in vitro bioactivity of buckwheat hull extract (BHE). BHE was purified and separated into 5 fractions: BHE-M1, BHE-M2, BHE-M3, BHE-M4 and BHE-M5 by sequential chromatography on macroporous resins. The inhibitory activity against α-glycosidase and advanced glycosylation end products (AGEs) formation of these fractions was assessed. The results indicated that the purity of BHE was increased from 30.8 to 65.3 g/100 g after purification and BHE-M4 had the highest purity of 89.2 g/100 g among the five fractions. The percentage inhibition of α-glycosidase by BHE, purified BHE, BHE-M2, BHE-M3, BHE-M4 and BHE-M5 at a concentration of 1.000 mg/mL were 16.03%, 24.39%, 18.04%, 25.46%, 28.23% and 26.24%, respectively, which were significantly higher than that of the positive control arabinose. In glucose-bovine serum albumin (G-BSA) and fructose-bovine serum albumin (F-BSA) systems, all samples except BHE-M1 had a stronger inhibitory effect on AGEs formation than amino guanidine with BHE-M4 being the mwost effective. High performonce liquid chromatography-mass spectrometry (HPLC-MS) results indicated that flavonoids identified in BHE-M4 were kaempferol-3-O-β-D-glucoside or kaempferol-3-O-β-D-galactosidase, vitexin, rutin, isoquercitrin or hyperoside and quercitrin. Conclusively, flavonoid-rich extracts from buckwheat hull possessed a stronger inhibitory effect on α-glycosidase activity and AGEs formation, implying that flavonoids are the major antidiabetic components in buckwheat hull.
Synergistic Improvement of Myofibrillar Protein Gel Properties by Combination of Rosemary Extract and NaCl
JIA Na, XIE Zhenfeng, LI Ruren, SHAO Junhua, LIU Dengyong, LIU Yuhui
2018, 39(3):  28-33.  doi:10.7506/spkx1002-6630-201803005
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The synergistic effect of combinations of rosemary extract (0.01 g/g pro) and NaCl at different concentrations on the structure and gel properties of myofibrillar proteins from pork Longissimus dorsi muscle was investigated by determining intrinsic fluorescence intensity, sulfhydryl group content, gel strength, water-holding capacity and rheological properties. The results indicated that addition of rosemary extract did not benefit the formation of stable gel network structure and decreased the water-holding capacity of myofibrillar proteins at NaCl concentration below 0.45 mol/L. However, the combination of rosemary extract and NaCl at 0.45 mol/L could significantly improve the gel strength, storage modulus and water-holding capacity and result in a remarkable decrease in the intrinsic fluorescence intensity of myofibrillar proteins as manifested by a 2 nm red shift. The tertiary structure of myofibrillar proteins changed favorably at lower NaCl concentrations so that the water-holding capacity did not decrease markedly. These results may be expected to provide new insights for the development of salt substitutes.
Kinetic Modeling for Mass Transfer of Breaded and Battered Fish Nuggets (BBFNs) with Soybean Fiber, Xanthan Gum and Whey Protein during Deep-Fat Frying
YUAN Zijun, CHEN Jiwang, ZENG Heng, XIA Wenshui, XU Wei, XIONG Youling
2018, 39(3):  34-40.  doi:10.7506/spkx1002-6630-201803006
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In the present study, xanthan gum (0.4%), soybean fiber (2%), and whey protein (4%) were separately added to the batter made up of medium-gluten wheat flour, corn starch, baking powder, salt, and water. Breaded and battered fish nuggets (BBFNs) were fried at 170 ℃ for 30 to 180 s (30, 60, 90, 120, 150, and 180 s) in fresh soybean oil to measure moisture and fat content. Kinetic modeling for mass transfer during deep-fat frying was performed by Fick’s second law and first order kinetic model. Furthermore, surface oil and penetrated surface oil content were measured and oil absorption was simulated using frying experiments in Sudan red dyed oil to investigate the mass transfer mechanism of BBFNs during deep-fat frying. The results showed that moisture content of the crust of three fried BBFNs decreased with the increase of frying time, while moisture content of the core firstly decreased, then increased, and finally decreased. Fat content of the crust increased from 0 to 120 s of frying, and then decreased from 120 to 180 s. For BBFNs with soybean fiber, xanthan gum, and whey protein, the mass transfer coefficient of moisture evaporation (0.003 8, 0.003 3, and 0.003 9 s-1, respectively) was fitted to Fick’s second law, while the mass transfer coefficient of oil absorption (0.062, 0.059, and 0.061 s-1, respectively) was fitted to a first order kinetic model. The oil penetration levels for the three fried BBFNs were not significantly different from 30 to 60 s of frying, while the highest level for BBFNs with whey protein and the lowest level for BBFNs with xanthan gum were separately presented from 90 to 180 s. These findings indicated that moisture evaporation and oil absorption in BBFNs during deep-fat frying were affected by separate addition of soybean fiber, xanthan gum, and whey protein in the batter, resulting in a significant difference in mass transfer coefficient among the BBFNs.
Correlation of Antioxidant Properties with Contents of Total Polyphenols and Total Flavonoids in Successive Solvent Extracts of Abandoned Hop Branches and Leaves
BAI Shanshan, ZHANG Yingying, ZHAO Qiang, LIU Yumei
2018, 39(3):  41-48.  doi:10.7506/spkx1002-6630-201803007
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The ethanol extracts of abandoned hop branches and leaves of SA-1 and Marco Polo hop varieties grown in Xinjiang were separated by using different polar solvents. The antioxidant activities of the resulting extracts were studied by four in vitro assays: hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl radical, β-carotene-linoleic acid and phosphomolybdenum model systems and were correlated with the contents of polyphenols and flavonoids. The results showed that all samples displayed antioxidant activity. Ethyl acetate extracts from hop main stems, side stems, and leaves had the highest contents of phenols and flavonoids, which were 5.80–34.20 and 2.00–18.00 mg/g, respectively. On the contrary, water extracts had the lowest contents of phenols and flavonoids, which were 0.73–11.05 and 0.06–5.74 mg/g, respectively. The correlation analysis showed that hop main stems, side stems and leaves exhibited significant relationship between antioxidant activity and the contents of phenols and flavonoids (P < 0.05).
Effect of Sun-Drying on Potential Allergenicity of Peanut Allergens
CHANG Xuejiao, LI Kun, ZHANG Ying, CHEN Hongbing, WU Zhihua
2018, 39(3):  49-54.  doi:10.7506/spkx1002-6630-201803008
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Peanut is one of the eight major food allergens, and its allergic reaction is usually life-long. The drying is an essential step of peanut processing. In the present study, peanut allergens were extracted and studied after drying in the sun with or without shells. The amounts and compositions of peanut allergens were measured by the Kjeldahl method, bicinchoninic acid method and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Besides, the structural change of peanut proteins was characterized by circular dichroism, ultraviolet scanning spectroscopy, and the potential allergenicity of allergens was quantified by serum immunoglobulin E (IgE) binding capacity. The results showed that after sun-drying, IgE binding capacity of peanut proteins increased significantly. The secondary structure of peanut proteins dried with shells was more orderly than that of peanut proteins dried without shells, with the tertiary structure being more compact. The peanut proteins dried with shells had higher potential allergenicity, which may be due to their loose structure.
Effect of Protein Oxidation on the Structure-Activity Relationship of Myofibrillar Protein Gels
ZHAO Bing, LI Su, ZHANG Shunliang, ZHOU Huimin, PAN Xiaoqian, REN Shuang, LI Jiapeng, CHEN Wenhua, ZHAO Yan, WANG Shouwei
2018, 39(3):  55-61.  doi:10.7506/spkx1002-6630-201803009
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The effects of different concentrations of H2O2 on the degree of oxidation and gelation properties of myofibrillar proteins were studied, and we also examined changes in the secondary structure and spatial structure of myofibrillar protein gels after H2O2 oxidation. The results showed that hydroxyl radicals derived from H2O2 could promote the oxidation of myofibrillar proteins, and that the degree of oxidation increased with increasing H2O2 concentration. The gelation properties of myofibrillar proteins regularly changed with the degree of oxidation. The gel strength, water retention, storage modulus and loss modulus decreased, whereas the surface hydrophobicity showed an increasing trend. Furthermore, the secondary structures of α-helix and β -sheet were partially destroyed and became unstable as H2O2 concentration increased. By observing the network structure of the protein gels by scanning electron microscopy, it was confirmed that protein oxidation hindered protein gels from forming a spatial structure.
Effect of Oak Extracts on the Quality of Chardonnay and Cabernet Sauvignon (Vitis vinifera L.) Grape Berries
JU Yanlun, YU Hang, LIU Min, ZHAO Xianfang, YUE Xiaofeng, FANG Yulin
2018, 39(3):  62-68.  doi:10.7506/spkx1002-6630-201803010
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In this paper, the effects of oak extracts on grape berry quality were studied, with the aim to make full use of oak waste. Cabernet Sauvignon and Chardonnay grapes were used as research materials. Oak extracts were sprayed onto grape berries at the early stage of veraison and the contents of tannins and polyphenols and anthocyanins in ripe grapes were determined with a spectrophotometer. Besides, the contents of monosaccharides and organic acid monomers were determined by high performance liquid chromatography (HPLC) and volatile aroma compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that oak extracts had no significant effect on physical and chemical properties but increased the total phenols and tannin contents of Chardonnay berries. Among the extracts evaluated, 25% American oak extract could result in a 33.2% increase in tannin content when compared with the control group. The oak extract could increase the contents of tannin and total anthocyanin of Cabernet Sauvignon berris, 25% American oak extract could result in a 40.7% increase in tannin content when compared with the control group, and pure American oak extract increased the anthocyanin content by 10.7%. Pure oak extracts elevated the fructose content in both varieties. Moreover, oak extracts resulted in increased glucose contents in the two varieties. Oak extracts had a significant impact on fruit aroma components in Chardonnay and Cabernet Sauvignon. The contents and types of aroma components especially esters, aldehydes and alcohols were increased after treatment. For instance, 25% American oak extract increased the concentration of 6-methoxy eugenol by 9 folds. In conclusion, exogenous oak extract could improve grape fruit quality. These results will provide a theoretical basis for the development and utilization of grape industrial processing wastes.
Effect of Different Cooking Methods on the Quality of Pre-Cooked Abalone (Haliotis discus hanai)
WANG Yang, LIU Wentao, PAN Jinfeng, JIANG Pengfei, ZHANG Xiaofang, QIN Lei, DONG Xiuping
2018, 39(3):  69-75.  doi:10.7506/spkx1002-6630-201803011
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The purpose of the experiment was to explore the quality change of abalone with four cooking methods, namely boiling-water cooking (BWC), steam cooking (SC), microwave cooking (MC) and vacuum-sealed bag cooking (VSBC). The quality indicators of cooked abalone including mass loss percentage, water-holding capacity (WHC), nutrient composition, texture characteristics, color properties and water distribution were investigated. The results revealed that the cooking loss percentages of SC, MC and VSBC samples were significantly lower than that of BWC samples. SC samples had the highest WHC, followed by VSBC and MC samples. SC samples possessed the highest protein (76.54%) and moisture content (78.90%). BWC and SC samples maintained better amino acid composition when compared with fresh abalone. Texture analysis showed that the tenderness and springiness of SC, MC and VSBC samples were significantly better than those of BWC samples. Low field nuclear magnetic resonance (NMR) transverse relaxation time (T2) measurement showed that immobile water (A22) accounted for higher than 90% of the total area, and the changing trend of immobile water (A22) of SC, MC and VSBC samples was consistent with WHC. Sensory evaluation showed the same trend to the measured indicators. Thus, SC could be a more suitable cooking method for abalone.
Physical Characteristics of Camellia chrysantha (Hu) Tuyama Flower Powder with Different Particle Sizes
HUANG Meihua, WU Ruhua, HE Quanguang, YANG Quanguang, PAN Hong, ZHANG Ezhen, HUANG Ruibin, YANG Haijuan, ZHANG Hong, PAN Zilai
2018, 39(3):  76-82.  doi:10.7506/spkx1002-6630-201803012
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The flowability, solubility, saponin dissolution rate and other physical properties of Camellia chrysantha (Hu) Tuyama flower powder in 3 different particle size ranges were determined, and the particle size and microstructure were measured with a particle size analyzer and a scanning electron microscope. The results showed that the particle size of ordinary, submicron and nanometer powder decreased sequentially with mean diameter of 133.90, 15.76 μm and 201.50 nm, respectively, and consequently the degree of cell disruption and the degree of irregularity increased with significant differences being observed among the three powders. Flowability, bulk density, wettability and expansibility decreased first and then increased with the decrease of particle size and the highest values of these parameters were recorded for the ordinary powder. The ordinary powder also had the highest water-holding capacity, followed by the submicron powder. Water solubility and saponin dissolution rate initially increased followed by a slight decrease. These findings suggested that the physical characteristics of Camellia chrysantha (Hu) Tuyama powder with different particle sizes were diverse. Overall, the submicron powder had high water solubility and saponin dissolution rate, and could be readily absorbed with high bioavailability in the body and conveniently processed, presenting good application prospects.
Composition Analysis and in Vitro Anti-Lipid Peroxidation Activity of Red Raspberry Polyphenols
KUANG Hui, FENG Jianwen, FAN Qian, WANG Ping, WANG Jinling
2018, 39(3):  83-89.  doi:10.7506/spkx1002-6630-201803013
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Ultraviolet-visible spectroscopy, infrared spectroscopy and high performance liquid chromatography were applied to explore the compositions of crude and purified polyphenols from “Fertod Zamatos” red raspberry, and the antilipid peroxidation activity of red raspberry polyphenols was evaluated by three in vitro assays. The composition analysis showed the presence of flavonoids, anthocyanins and glycosides in red raspberry polyphenols. Proanthocyanidins B2, rutin, salicylic acid and ellagic acid were detected in red raspberry polyphenols, and there were some differences in the phenolic profile between the crude and purified polyphenols. Red raspberry polyphenols in a certain concentration range had inhibitory effects on Fe2+-induced lipid peroxidation in yolk lipoprotein, H2O2-induced hemolysis of rat red blood cells and spontaneous lipid peroxidation in rat liver tissue homogenate in a concentration-dependent manner. But crude red raspberry polyphenols showed stronger anti-lipid peroxidation activity than the purified one. Therefore, the polyphenol extracts from red raspberry have anti-lipid peroxidation activity; however, further studies are needed to investigate the underlying mechanism and pathways.
Antioxidant Capacity of Probiotic Cheese after Simulated Gastrointestinal Digestion
QU Xiuwei, LIU Lu, WANG Haixia, LI Xiaodong, ZHANG Xiuxiu, CHEN Ping, SHEN Qi
2018, 39(3):  90-96.  doi:10.7506/spkx1002-6630-201803014
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The aim of this work was to explore the effect of digestion on the antioxidant activity of probiotic cheese. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, reducing power and 2,2’-azino-bis(3- ethylbenzthiozoline-6)-sulphonic acid (ABTS) radical scavenging capacity were analyzed to investigate the antioxidant activity of probiotic Cheddar cheese after simulated gastrointestinal digestion, and the viable count of probiotics and polypeptide content were examined. The results showed that the antioxidant activity of cheese increased significantly after simulated gastrointestinal digestion (P < 0.05), and the antioxidant activity of cheese containing both B. bifidum 07-300B and L. acidophilus 1.0357 were significantly higher than that of any other group (P < 0.05). Moreover, the DPPH radical scavenging capacity, reducing power and ABTS+· scavenging capacity ((82.76 ± 3.19)%, 0.828 ± 0.021 and (44.84 ± 1.36)%) were increased by 71.42%, 62.35% and 51.69%, respectively, and the polypeptide content ((2.80 ± 0.02) mg/mL) was also significantly increased by 39.30% (P < 0.05) when compared with that before digestion, with the polypeptides with molecular weight < 3 kDa presenting the highest antioxidant activity. The number of viable probiotic bacteria in cheese decreased significantly by 16.93% after digestion. Therefore, the antioxidant activity of cheese could be improved by generating small molecule polypeptides with antioxidant activity after simulated gastrointestinal digestion.
L-Lysine-Induced Solubilization and Mechanism of Tilapia Myosin under Low Ionic Strength Conditions
ZHU Panhong, ZHOU Chunxia, FU Weiya, QI Huihong, LI Ting, HONG Pengzhi
2018, 39(3):  97-103.  doi:10.7506/spkx1002-6630-201803015
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Myosin was extracted from tilapia muscle, and the effect of 5 mmol/L L-lysine on the turbidity, solubility, molecular structure and shape of myosin (2.0 mg/mL) was studied in low ionic strength (0–150 mmol/L KCl) solutions. The L-lysine-induced solubilization behavior and mechanism of myosin were analyzed. Results showed that myosin molecules were assembled into filaments with low solubility under low ionic strength conditions. L-Lysine could significantly decrease the turbidity of myosin dispersion (P < 0.05), and inhibit the aggregation of protein molecules, thereby having an obvious solubilizing effect on L-lysine. Surface hydrophobicity of soluble myosin was increased, and α-helix content was decreased (P < 0.05). Compared with the pH shifting group, the solubilization of myosin by L-lysine was more remarkable in 1–40 mmol/L KCl solution. The absolute zeta potential of myosin treated with L-lysine was increased, leading to the dissociation of myosin filaments.
Wheat Protein Fining of Cherry Wine
LI Juanjuan, ZHANG Lizhen, Lü Guotao, ZHAO Yuying, ZHANG Jinsong, WANG Chu, NIU Yu
2018, 39(3):  104-109.  doi:10.7506/spkx1002-6630-201803016
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Gliadin-free wheat protein isolate (GFWPI) was prepared from wheat flour and its efficacy in fining cherry wine was analyzed by measuring changes in physical and chemical properties and stability before and after clarification. The results indicated that the turbidity of fined cherry wine treated with 50 mg/L GFWPI was significantly declined by 71.64% when compared with unfined cherry wine. On the other hand, the contents of total phenols and flavonoids in cherry wine did not obviously differ between the two samples (P > 0.05). GFWPI provided the minimum turbidity of 2.07 NTU at 139 h prior to other three clarifying agents such as gelatin, polyvinylpyrrolidone and carboxymethyl cellulose, which remained stable later. The maximum reduction of total phenols of 35.37 mg/L was obtained by gelatin treatment. PVPP treatment resulted in the maximum loss of color value of 0.30. The maximum reduction of total phenols of 0.49 mg/L was observed for anthocyanins-treated wine. The optimal fining conditions with GFWPI were determined as GFWPI concentration of 50 mg/L, stirring rate of 800 r/min, and stirring time of 120 min. GFWPI had the advantages of good efficiency, high clarification rate, safety without toxicity and low cost. In conclusion, it is of great significance for the industrial production and shelf life prolongation cherry wine.
Antibacterial Activity and Mechanism of Hawthorn Pectin Oligosaccharides
WANG Wei, MOU Dehua, LI Dandan
2018, 39(3):  110-116.  doi:10.7506/spkx1002-6630-201803017
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In this study we conducted experiments to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of hawthorn pectin oligosaccharides with different polymerization degrees, and to draw the growth curves of five test strains in order to explore the antibacterial activity of pectin oligosaccharides. The underlying mechanism was elucidated by evaluating the changes in cell morphology, cell membrane permeability and integrity. The results showed that pectin oligosaccharides with average polymerization degree of 3 had the strongest antibacterial effect, especially against Escherichia coli, Bacillus subtilis and Staphylococcus aureus, with MICs of 1.250, 0.625 and 0.625 g/L, respectively. The relative conductivity of bacterial cell suspensions increased with increasing addition of pectin oligosaccharides, accompanied by a simultaneous increase in nucleic acid and protein concentrations, implying that pectin oligosaccharides exerted antibacterial activity presumably by damaging the cell membrane permeability and integrity and consequently resulting in leakage of cell contents, thereby causing an adverse effect on the metabolic activity and consequently inhibiting bacterial growth. Therefore, hawthorn pectin oligosaccharides can be used as natural preservatives to inhibit the growth of spoilage bacteria and pathogens in foods and thus prolong their shelf life.
Composition and Functional Properties of Proteins in Radish Seed Meal
ZHAO Gongling, LIANG Xinhong, GUO Yancheng, KONG Jin, LI Keke, KANG Chaodi, SHI Cuiping
2018, 39(3):  117-122.  doi:10.7506/spkx1002-6630-201803018
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This study aimed at the extraction, fractionation and functional characterization of proteins from radish seed meal. According to their solubility, albumin, globulin, glutelin and prolamin were separated from radish seed meal. The amino acid composition of the protein isolate extracted from radish seed meal was determined with an automatic amino acid analyzer and its functional properties and 1,1-diphenyl-2-picrylhydrazyl free radicals, ·OH, NO2 - and H2O2 scavenging capacity of in vitro were analyzed by physical and chemical methods. Results showed that globulin, glutelin, albumin and prolamin accounted for 44%, 33%, 21% and 2% of the total proteins in radish seed meal. Eighteen amino acids were detected in the protein isolate, and the first limiting amino acid was methionine with an amino acid score of 57. From this study, we concluded that radish seed meal proteins have good functional properties and antioxidant capacity and thus can be regarded as a potentially valuable resource that can be developed into high-value products.
Inhibitory Kinetics of Acrylamide by Procyanidins
ZHOU Mengzhou, DING Cheng, GUAN Yafei , WU Qian
2018, 39(3):  123-128.  doi:10.7506/spkx1002-6630-201803019
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The effect of procyanidins on the formation and elimination kinetics of acrylamide was investigated. The concentrations of litchi pericarp procyanidin (LPPC) and lotus seedpod procyanidin (LSPC) for the maximum percentage inhibition of acrylamide were determined, and then the kinetic process of acrylamide formation and elimination was described by the Logistic-growth curve, Logistic-Fermi and Logistic-exponential kinetic models. The Logistic-exponential kinetic model was found to be the best among these models. The experimental results showed that both LPPC and LSPC had a significant impact on the formation of acrylamide, especially LSPC; however, they had no significant inhibitory effect at the later stage of reaction.
Variation Analysis and Comprehensive Evaluation of Nut Quality of Torreya grandis ‘Merrilli’ from Shaoxing
SUN Xiaohong, WANG Guofu, DU Yijun, HU Shaoquan, GE Jian
2018, 39(3):  129-134.  doi:10.7506/spkx1002-6630-201803020
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The objective of this investigation was to explore the nutritional quality of Torreya grandis ‘Merrilli’ nuts. Variations in 21 internal and external quality attributes of 12 nut samples from the core growing area of Shaoxing, Zhejiang province were measured and analyzed by principal component analysis (PCA) and cluster analysis (CA). Furthermore, a comprehensive evaluation was carried out on the quality of T. grandis ‘Merrilli’ nuts. The results showed that significant differences in both internal and external quality characteristics were observed among 12 samples. The oil and protein contents of T. grandis ‘Merrilli’ nut kernels significantly varied among geographical areas (P < 0.05), with average values of 50.28% and 12.70 g/100 g, respectively. The proportion of unsaturated fatty acids in the kernel oil was in the range of 60.08%–75.77%, oleic acid and linoleic acid being the predominant ones. Comprehensive evaluation and PCA analysis demonstrated that the comprehensive score of T. grandis ‘Merrilli’ from Shengzhou was the highest, followed by those from Zhuji and Shaoxing’s Jidong. The seed length, total fat content, seed weight, and average protein content, oleic acid and linoleic acid were considered as the most important quality indicators. In summary, PCA and CA could simplify the evaluation of T. grandis ‘Merrilli’ quality.
Food Engineering
Flow Cytometric Assessment of Sublethal Injury of Escherichia coli O157:H7 Cells Caused by High Hydrostatic Pressure
KONG Xiaoxue, HAN Yanqing, FU Yong, JI Saisai, WANG Xianjing, YU Jinlong, JIANG Yun
2018, 39(3):  135-141.  doi:10.7506/spkx1002-6630-201803021
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As a widely used non-thermal decontamination technology in the food processing industry, high hydrostatic pressure processing has a significant lethal effect on foodborne Escherichia coli O157:H7. However, effective methods for detecting viable cells after high hydrostatic pressure treatment are still lacking, and the inactivation mechanism of pressurized Escherichia coli O157:H7 needs to be confirmed. In this study, the living state of high hydrostatic pressuretreated Escherichia coli O157:H7 cells was evaluated by flow cytometric analysis and the conventional culture technique. The microstructure of pressurized bacterial cells was observed by scanning and transmission electron microscopy. The inactivation mechanism of high-pressure-treated cells was further explored. Results showed that double-staining flow cytometry was a rapid and effective method to sort Escherichia coli O157:H7 cells in different physiological states with high sensitivity and accuracy. Significant damage and sub-lethal injury of Escherichia coli O157:H7 cells were observed after treatment at 400 MPa, and the bacterial cells were seriously deformed with partial rupture of the cell membrane at this pressure level. When the pressure was increased up to 500 MPa, the bacterial cell wall and membrane were separated severely from each other with lots of radial filaments appearing in the light transparent area. It is worth noting that there is a large part of sub-lethally injured pathogenic cells surviving even after high hydrostatic pressure treatment at 500 MPa, which may be a potential risk factor for food-borne disease outbreaks.
Drying Characteristics and Kinetic Model of Liquid Whole Egg during Ultrasound-Reinforced Vacuum Drying
MA Yitong, ZHU Wenxue, BAI Xiting, LUO Lei, HUANG Jing, YU Bin, LI Ning
2018, 39(3):  142-149.  doi:10.7506/spkx1002-6630-201803022
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A new ultrasound-reinforced vacuum drying device was built to investigate the enhancing effect of ultrasound on the vacuum drying of viscous food. Ultrasound-reinforced vacuum drying of liquid whole egg was carried out to explore the influence of drying temperature, ultrasound energy density and irradiation time on the drying characteristics and microstructure. Furthermore, a kinetic model was established. The results showed that the internal mass transfer process could be enhanced by applying ultrasound to vacuum drying. Meanwhile, the drying rate was improved with the increase of ultrasound energy density. The drying process of liquid egg at 50 ℃ was no longer affected by ultrasound treatment at an energy density of 2.0 W/g after 2.5 h. The results of scanning electron microscopy (SEM) showed that many microtunnels were observed in the microstructure of powdered eggs, which was beneficial to enhancing the connectivity and consequently reducing water migration resistance. Nine different thin layer drying models were fitted nonlinearly with the experimental data. Comparison of correlation coefficient (R2), root mean square error (RMSE) and reduced chisquare (χ2) and verification experiments showed that R2 of the Page model was greater than 0.99, RMSE and χ2 were less than 0.01. Then, the Page model was the most suitable to describe the relationship between liquid egg moisture and drying time. The effective moisture diffusivity (Deff) was calculated according to Fick’s second law to range from 1.645 6 × 10-9 to 6.549 7 × 10-9 m2/s, which was increased with the increase of ultrasonic energy density. The linear relationship between the natural logarithm of effective moisture diffusivity and the reciprocal temperature was described by the Arrhenius empirical formula. The activation energy (Ea) was 16.151 2 kJ/mol. These results can provide a valuable basis for optimizing and controlling ultrasound-reinforced vacuum drying of liquid whole egg.
Effect of Electron Beam Dose Rate on Myofibrillar Protein Structure and Physicochemical Characteristics of Chilled Beef
CHENG Shuzhen, WANG Xiaotuo, ZHANG Jie, XIE Xinfang, WANG Zhidong
2018, 39(3):  150-156.  doi:10.7506/spkx1002-6630-201803023
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This study was performed to determine the effect of electron beam dose rate on myofibrillar protein structure and physicochemical properties of chilled nitrogen-packaged beef. Longissimus dorsi muscles from Chinese yellow cattle were irradiated by a high-energy electron accelerator at 2.5 kGy at dose rates of 30, 150 and 300 kGy/min and then stored at 4 ℃ for up to 25 days. Changes in the secondary structure and physicochemical properties of myofibrillar proteins and the thermal stability of muscles were examined at five-day intervals during storage. Compared with the control group, the sulfhydryl group content in the three irradiated groups declined significantly (P < 0.05) by 19.05%, 22.00% and 22.60% at day 0 of storage, respectively. The surface hydrophobicity and solubility of myofibrillar proteins decreased in irradiated samples. In addition, the contents of α-helix and β-sheet decreased along with a simultaneous increase in β-turn and random coil; the protein structure became more disordered. Myosin was oxidized and degraded after electron beam treatment, and the thermal stability declined. To conclude, the irradiation treatment could result in changes in the structure and consequently some physicochemical properties of myofibrillar proteins in beef muscles, thereby affecting beef quality. However, the structure of myofibrillar proteins and meat quality were comparatively less affected at a dose rate of 150 kGy/min.
Effect of Electrostatic Field-Assisted Freezing-Thawing on Water-Holding Capacity and Physicochemical Characteristics of Beef Muscle Proteins
SHANG Ke, YANG Fangwei, LI Xia, ZHANG Chunhui, QIAN Shuyi, SUN Zhen
2018, 39(3):  157-162.  doi:10.7506/spkx1002-6630-201803024
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In order to provide a theoretical basis for the quality control of beef muscle during freezing-thawing process, the effect of electrostatic field-assisted freezing and thawing on the water-holding capacity and physicochemical characteristics of myofibrillar proteins from beef Longissimus dorsi muscle was investigated. Four different freezing-thawing processes including electrostatic field-assisted freezing and thawing (EFF-EFT), conventional freezing and thawing (control), conventional freezing and electrostatic field-assisted thawing, and electrostatic field-assisted freezing and conventional thawing were used. The thermal stability of myofibrillar proteins and water migration in beef muscle during thawing process were measured by different scanning calorimetry and proton nuclear magnetic resonance, respectively. The surface hydrophobicity, freezing and thawing rate, and thawing loss were also measured. Compared to the control, the freezing and thawing time of muscles in the EFF-EFT group was reduced respectively by 16.290 and 8.920 h and the time required to pass through the zone of maximum ice crystal formation for EFF-EFT-treated samples was shortened by 3.41 h. Moreover, a significant decrease in the thawing loss of 4.19% was recorded (P < 0.05). The surface hydrophobicity of myofibrillar proteins in EFF frozen muscle (16.16 μg) was significantly lower than that of the control, while that of EFT thawed muscle (9.45 μg) demonstrated a significant increase compared with the control (P < 0.05). The degree of protein denaturation in EFF-EFT-treated samples with denaturation temperatures of 55.130, 63.940 and 78.350 ℃ was lower than that in the control group. In conclusion, electrostatic field-assisted freezing and thawing can effectively improve the freezing and thawing rate of beef muscle, reduce the extent of myofibrillar protein denaturation, and decrease the thawing loss of beef muscle.
Effect of Ultra-High Pressure Treatment on the Quality of Persimmon Pulp
LIANG Zhihong, LI Xiaoping, RU Huiling, Lü Yingzhong
2018, 39(3):  163-168.  doi:10.7506/spkx1002-6630-201803025
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This paper explored the effect of ultra-high pressure (UHP) treatment at different pressures and durations on the quality of persimmon pulp. The results showed that the total number of bacteria in the pulp decreased with increasing pressure and time and treatment at 400 MPa for 15 min could meet the requirement of commercial sterility. After treatment, the color and the contents of soluble sugar, soluble solid and titratable acids were not changed significantly (P > 0.05) when compared with the control group. However, vitamin C content gradually declined with the increase in pressure and time, with the maximum loss of 8.06% being observed at 600 MPa and 20 min. Peroxidase (POD) activity also declined with increasing pressure and time, and polyphenol oxidase (PPO) activity similarly showed a gradual decrease with increasing treatment time; however it initially rose and then fell with increasing pressure. Polyphenol content also showed an initial increase followed by a decrease with pressure, but it showed a general increasing trend with treatment time, with the maximum value being attained at 400 MPa and 20 min. The antioxidant capacity was much higher when compared with the control group, but no significant differences were observed among the treatment groups (P > 0.05). Compared with the control samples, soluble tannin content was increased after UHP treatment to a level below the critical value for astringency (2 mg/g). In conclusion, UHP treatment has only a slight effect on the sensory quality and can maintain the nutritional quality to a large extent and improve the antioxidant activity of persimmon pulp. Moreover, this treatment can lead to elimination of astringency.
Effect of Ultrasonic Wave and Ultra High Pressure Treatment on Conformation and Enzyme Activity of Lipoxygenase in Silver Carp Muscle
WANG Bangguo, YU Zhenyu, LIN Lin, PAN Lijun, JIANG Shaotong
2018, 39(3):  169-175.  doi:10.7506/spkx1002-6630-201803026
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Ultrasonic wave (UW) and ultra-high pressure (UHP) were used for the treatment of lipoxygenase (LOX) from silver carp muscle. Our present work was undertaken to evaluate the effects of UW and UHP treatment on the conformation and enzyme activity of LOX using circular dichroism and fluorescence spectroscopy. The results showed that as the UW power and irradiation time increased, the contents of α-helix and β-sheet in LOX decreased and fluorescence intensity increased, indicating that the secondary and tertiary structures of LOX were greatly changed, leading to a gradual reduction in LOX activity. The optimal UW conditions were 300 W and 3 h, resulting in a decrease in LOX activity of 66.07% when compared with the untreated sample. Moreover, as the UHP processing pressure and time increased, the contents of α-helix and β-sheet decreased and fluorescence intensity steeply declined, suggesting that the secondary and tertiary structures of LOX were greatly changed and consequently LOX activity rapidly dropped. Under the optimum UHP conditions of 300 MPa and 20 min, LOX activity was decreased by 93.10% when compared with the untreated sample.
Nutrition & Hygiene
Protective Mechanism of Grape Seed Proanthocyanidin Extract against Oxidative Damage Induced by Arsenic in HL-7702 Cells
XU Mengchuan, LI Shugang, DING Yusong, NIU Qiang, FENG Gangling, SHEN Hui, GUO Fangming
2018, 39(3):  176-181.  doi:10.7506/spkx1002-6630-201803027
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Objective: To explore the protective mechanism of grape seed proanthocyanidin extract (GSPE) against oxidative damage induced by arsenic for the purpose of providing a theoretical foundation for the prevention and treatment of arsenic poisoning and for the evaluation of the antioxidant activity of GSPE. Methods: HL-7702 cells were randomly divided into seven groups: control, arsenic poisoning (25 μmol/L), GSPE intervention (5, 10, 25 and 50 mg/L), and single GSPE treatment (50 mg/L) groups. After treatment for 24 and 48 h, the levels of aspartate transaminase (AST), alanine aminotransferase (ALT), glutathione (GSH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) were determined by commercial kits. Cell viability was tested by 3-(4,5)-dimethylthiahiazo(-z-yl)- 3,5-di-phenytetrazoliumromide (MTT). We used polymerase chain reaction (PCR) and Western blot to detect the mRNA and protein expression levels of nuclear factor erythroid-2 related factor 2 (Nrf2), glutathione S-transferase (GST), heme oxygenase 1 (HO-1), and quinone oxidoreductase 1 (NQO1). Results: The cell viability in the high-concentration arsenic groups (≥ 25 μmol/L) was significantly lower than that in the control group (P < 0.05). The levels of ALT, AST and MDA in the GSPE intervention group were significantly lower than those in the arsenic poisoning group (P < 0.05), while a significant elevation was observed for GSH, T-AOC and SOD (P < 0.05). The mRNA and protein expression levels of Nrf2, GST, HO-1 and NQO1 in the GSPE intervention group were significantly elevated when compared with the arsenic poisoning group (P < 0.05). Conclusion: GSPE has an antagonistic action against arsenic poisoning in a dose-dependent manner by activating the Nrf2-mediated signaling pathway to improve the antioxidant capacity of cells and consequently reduce arsenic-induced liver oxidative injury.
Antioxidant Effect of Soluble Dietary Fiber from Mung Bean (Phaseolus radiates L.) Hull
LUO Lei, WANG Yaqi, MA Liping, ZHU Wenxue, ZHANG Kuan, JI Qinghua, GUAN Ningning, XUE Yihan
2018, 39(3):  182-187.  doi:10.7506/spkx1002-6630-201803028
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The in vivo and in vitro antioxidant effects of soluble dietary fiber (SDF) from mung bean (Phaseolus radiates L.) hull were studied. The results showed that the reducing power of SDF at a concentration of 4 mg/mL was 1.526, which could scavenge 82.65% 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 85.16% hydroxyl radical. Animal experiments showed that total antioxidant capacity (T-AOC), catalase, total superoxide dismutase, glutathione peroxidase activity in the serum and liver tissue of D-Galactose-induced aging mice decreased, while malondialdehyde (MDA) content increased with significant differences being observed for most parameters (P < 0.05 or P < 0.01) when compared with the normal control group, indicating that the animal model of D-galactose-induced aging was constructed successfully. Compared with the model group, MDA content in the serum and liver tissue of mice administrated with SDF from all dose groups significantly decreased. High-dose SDF could significantly improve T-AOC and total superoxide dismutase, catalase, glutathione peroxidase activity in the serum and liver tissue of mice (P < 0.05). Therefore, SDF from mung bean hull has an excellent antioxidant activity.
Effect of Tartary Buckwheat on Blood Lipid Metabolism and Tissue Redox Status in Mice Fed High-Fat Diet
ZHOU Xiaoli, WANG Yue, ZHAO Shen, ZHOU Yiming, WANG Hong, SHI Ronghua, XIAO Ying
2018, 39(3):  188-192.  doi:10.7506/spkx1002-6630-201803029
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With the improvement of people’s living standard, huge changes in the dietary structure have taken place. Increasing proportion of fats in the diet is harmful for human health by inducing blood lipid metabolism disorder and oxidative stress and impairing the intestinal flora balance. In the present study, a mouse model of diet-induced lipid metabolism disorder was established to explore the effects of macronutritional components (protein, starch and flavonoids) of tartary buckwheat on blood lipids, liver lipids and redox capacity in mice and to investigate the relationship between physio-biochemical indexes and antioxidant activity in liver tissue. The results showed that compared with the high-fat control group, the major nutrient components of tartary buckwheat could decrease fasting blood-glucose level, increase insulin sensitivity index, significantly reduce plasma total cholesterol, triglyceride, low density lipoprotein cholesterol, and arteriosclerosis index (P < 0.05). improve total antioxidant capacity and the activity of catalase and superoxide dismutase (SOD), and decrease the content of malondialdehyde (MDA) in lipid peroxidation products. In summary, the major nutritional components of buckwheat have multiple functions including regulating blood lipids, reducing hepatomegaly, improving antioxidant capacity and preventing lipid metabolism disorder, thereby restraining blood lipid disorder and oxidative stress in tissues.
Quality Evaluation of Sacha Inchi Seeds and Oil
LIU Yulan, AN Kejing, HU Aipeng, MA Yuxiang
2018, 39(3):  193-199.  doi:10.7506/spkx1002-6630-201803030
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To explore the nutritional quality and safety of sacha inchi seeds and oil, the major micronutrients, phthalates and polycyclic aromatic hydrocarbons in both samples were analyzed, and physicochemical properties and fatty acid composition of the oil were determined. The results showed that the contents of plasticizers and polycyclic aromatic hydrocarbons in sacha inchi seeds from 8 different geographical areas were 0.543–1.695 mg/kg and 111.65–282.21 μg/kg, respectively; the contents of crude fat in sacha inchi seeds from Puwen town and Lvchun county, Yunnan province were 44.70% and 48.00%, and the contents of crude protein were 31.50% and 29.46%, respectively. The concentrations of phytosterol and vitamin E in sacha inchi oil were in the range of 190.16–225.51 and 177.99–208.14 mg/100 g, and the concentrations of plasticizers and polycyclic aromatic hydrocarbons were 0.94–130.97 mg/kg and 207.92–1 139.47 μg/kg, respectively. Results of the physicochemical properties showed that acid value, peroxide value, iodine value, saponification value and phospholipids were 0.45–2.70 mg KOH/100 g, 0.57–3.05 mmol/kg, 189.98–193.39 g/100 g, 189.71–195.10 mg KOH/g and 0.00%–0.10%, respectively. Six major fatty acids were detected in sacha inchi oil, with linolenic acid being the most abundant one (44.28%–46.45%) followed by linoleic acid (37.88%–40.19%), and unsaturated fatty acids accounted for more than 92% of the total fatty acids. Overall, sacha inchi oil had a high nutritional value and good quality, but a wide difference in the contents of polycyclic aromatic hydrocarbons and plasticizers was observed among different production batches; furthermore, plasticizer contents of only a few oil samples plasticizers greatly exceeded the national standard limit. Therefore, it is necessary for vegetable oil factories to monitor plasticizers in different production batches.
Isolation, Purification and Structural Identification of Immunoactive Peptides Derived from Hazelnut (Corylus heterophylla Fisch.) Protein
WANG Peng, WANG Mingshuang, LIU Chunlei, FANG Li, WANG Ji, LIU Xiuqi, MIN Weihong
2018, 39(3):  200-205.  doi:10.7506/spkx1002-6630-201803031
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Hazelnut protein isolate hydrolysate was ultrafiltrated to obtain peptides with molecular weight less than 3 kDa. Further purification and structural identification were carried out using gel filtration chromatography and reversedphase high-performance liquid chromatography (RP-HPLC). The results showed that fraction B1, separated on a column of Sephadex G-15, could significantly decrease the production of TNF-α and IL-6 (P < 0.01) in RAW264.7 cells. The peptide Pro-Glu-Asp-Glu-Phe-Arg (PEDEFR) as identified by mass spectrometry (MS) had no cytotoxicity on cells. PEDEFR at a high concentration (> 50 μmol/L) could enhance the phagocytosis of RAW264.7 cells. When the concentration was up to 100.0 μmol/L, the proliferation rate of spleen lymphocytes was 44.21% and reached up to 53.22% in the presence of concanavalin A. PEDEFR had an immunomodulatory effect on RAW264.7 cells. This study can provide an experimental basis for the development and utilization of immunoactive peptides derived from hazelnut protein.
Immunomodulatory Activity of Docosahexaenoic Acid
HAN Lirong, WEI Shuoming, WANG Xufeng, WANG Chunling
2018, 39(3):  206-212.  doi:10.7506/spkx1002-6630-201803032
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In this study, the immunomodulatory activity of docosahexaenoic acid (DHA) in mouse macrophage RAW264.7 cells was detected by MTT, cell staining, related enzyme activities and Western blot. The MTT assay showed that cell proliferation index reached the maximum level of 73.03% after 48 h of incubation at DHA concentration of 800 ng/mL. The neutral red phagocytosis of RAW264.7 cells was significantly enhanced by DHA. The activation of RAW264.7 cells could be promoted by DHA as observed under scanning electron microscopy. Acrine orange (AO) staining showed that the nucleic acid metabolism of RAW264.7 cell was enhanced by DHA. Periodic acid-Schiff (PAS) staining indicated that DHA promoted the glycogen metabolism and accelerated the differentiation of RAW264.7 cells. Besides, the activities of acid phosphatase, lysozyme and superoxide dismutase were increased by DHA. DHA could increase the phosphorylation of ERK1/2, p38 mitogen-activated protein kinases (MAPKs) and JNK in the MAPKs pathway, indicating that DHA-induced macrophage activation in part depends on the MAPKs pathway. Our results confirmed that DHA had immunomodulatory activity, which will provide a scientific basis for the application of DHA.
Preventive Effect and Mechanisms of Glucosamine Combined with Rhizoma Drynariae on Chronic Osteoarthritis Rats
ZHOU Yanli, CHEN Shijie, LAO Wenyan, ZHU Yangxiong, ZHAO Xiaohong
2018, 39(3):  213-221.  doi:10.7506/spkx1002-6630-201803033
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Objective: To investigate the preventive effect and mechanisms of glucosamine (GLU) combined with drynariae rhizome (DR) on osteoarthritis (OA) of rats. Methods: A rat model of chronic arthritis was established by injection of kaolin and carrageen-λ into the articular cavity to induce acute osteoarticular injury combined with run, which was preceded by intragastric administration of GLU (750 mg/kg), DR (150 mg/kg), low-, medium- and high-dose GLU + DR (125 mg/kg GLU + 25 mg/kg DR, 250 mg/kg GLU + 50 mg/kg DR, and 750 mg/kg GLU + 150 mg/kg DR), diclofenac sodium (DS, 2 mg/kg, positive control), and sterile distilled water (10 mL/kg, for control and model groups) until the end of a 6 week run on a threadmill. Arthroncus in rats was measured. Tissue sections of knee joints were prepared by paraffin embedding and staining with hematoxylin eosin and saffron-O-solid green to observe the pathological changes of articular cartilage. The levels of matrix metalloproteinase-3 (MMP-3), tissue inhibitor of metalloproteinase-1 (TIMP-1), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in serum were detected with enzyme-linked immunosorbent assay (ELISA) kits. Superoxide dismutase (SOD) activity and nitric oxide (NO) content in serum were measured by xanthine oxidase and nitrate reductase methods, respectively. The expression of type Ⅱ collagen was detected by immunohistochemistry. Results: Compared with the control group, arthroncus in rats in the model group was increased and the cartilage was destroyed. Moreover, MMP-3 and TIMP-1 concentrations and MMP-3/TIMP-1 ratio were significantly increased as well as iNOS activity and of IL-1β, NO and TNF-α concentrations(P < 0.05), while SOD activity and type Ⅱ collagen expression were significantly declined (P < 0.05). Compared with the model group, GLU and DR alone as well as their combination at medium and high doses could reduce arthroncus, improve pathological abnormality in knee joint tissue, significantly inhibit the increase in MMP-3, TIMP-1, IL-1β, NO and TNF-α contents and iNOS activity, and significantly suppress the decrease in SOD activity and type II collagen content (P < 0.05), and the best effect was observed with highdose GLU + DR followed by GLU, DR, and GLU + DR at medium and low doses. Conclusion: Separate and combined GLU and RD can attenuate osteoarticular injury, but an effective dose is required for the combined treatment. The potential mechanism of action may be related to the regulation of MMP-3/TIMP-1 balance, resulting in increased SOD activity and type Ⅱ collagen content as well as decreased iNOS activity and IL-1β, TNF-α and NO contents. This study can provide a theoretical basis for the development of functional foods for the prevention and treatment of OA.
Protective Mechanism of Polysaccharides from Dolichos Bean Seeds (Dolichos lablab L.) on Hypoxia-Induced Neuronal Apoptosis
ZHANG Xianyi, LI Wenjuan, ZHONG Liang, PAN Meng,TANG Xiaofang, YAO Yufei
2018, 39(3):  222-228.  doi:10.7506/spkx1002-6630-201803034
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Objective: The aim of this study was to explore the protective effect of dolichos bean seed polysaccharides (DBSP) against anoxia/reoxygenation (A/R) injury and its potential mechanism of action in neurons. Methods: Primary cultured cerebral cortical neurons were randomly divided into four groups including control group, A/R group, DBSP + A/R group and DBSP + LY294002 + A/R group. Cell survival rate and lactate dehydrogenase (LDH) release were determined. Apoptosis, mitochondrial membrane potential and Ca2+ concentration were determined by flow cytometry analysis. The expression of T-Akt and p-Akt protein was evaluated by Western blot. Results: Compared with the control group, cell survival rate of the A/R group was decreased (P < 0.01) and LDH release, Ca2+ concentration and apoptotic rate were significantly increased (P < 0.01). Compared with the A/R group, cell survival rate of the DBSP + A/R group was increased, and LDH release, Ca2+ concentration and apoptotic rate were significantly decreased (P < 0.01), suggesting that DBSP could protect neurons against A/R injury. Mitochondrial membrane potential and the expression of p-Akt protein increased significantly in the DBSP + A/R group when compared with the A/R group (P < 0.01). The expression of p-Akt protein after treatment with LY294002 (a potent inhibitor of the PI3K-Akt signaling pathway) + DBSP + A/R was attenuated in neurons when compared with A/R + DBSP treatment (P < 0.05). Further experimental results showed that the treatment of cells with LY294002 completely blocked the expression of p-Akt protein, and significantly attenuated the protective effect of DBSP on neurons subjected to A/R. Conclusion: The protective mechanism of polysaccharides from dolichos bean seeds on neuronal cells is closely related to the PI3K-Akt signaling pathway.
Packaging & Storage
Characteristics of Cell Wall Metabolism of Harvested Chinese Olive Fruits with Different Maturities in Response to Chilling Injury During Cold Storage
KONG Xiangjia, REN Siqi, LIN Hetong, LI Ni, LIN Yixiong, ZHUO Siqi
2018, 39(3):  229-235.  doi:10.7506/spkx1002-6630-201803035
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Changes in the cell wall metabolism of Chinese olive fruits during cold storage were examined to explore the relationships between chilling injury and cell wall components and cell wall-degrading enzyme activities in four maturities of Chinese olive fruits. ‘Tanxiang’ Chinese olive (Canarium album (Lour.) Raeusch cv. Tanxiang) fruits harvested at the solar terms of White Dews, Cold Dews, Winter Begins and Heavy Snow were stored at (2 ± 1) ℃ and 85%–90% relative humidity. During storage, chilling injury index, cell wall component contents and cell wall-degrading enzyme activities in the fruit pulp were periodically determined. The results showed that the chilling injury symptoms were closely related to the degradation of cell wall components, and that the chilling injury index of fruits with different maturities was negatively correlated with the contents of ionic-soluble pectin (ISP), covalent-soluble pectin (CSP), semicellulose and cellulose. Cell wall structure disintegration, cell wall metabolism abnormality and chilling injury occurrence were in large part due to the imbalance of pectin methylesterase (PME) and polygalacturonase (PG) activities, as well as the increase of β-galactosidase (β-Gal) and cellulase (CEL) activities. Meanwhile, compared with maturities Ⅰ, Ⅲ, and Ⅶ, maturity Ⅴ could maintain lower chilling injury index during the entire storage and lower activities of PME, PG, β-Gal and CEL in pulp during the middle and late storage stages while retarding the decline in water-soluble pectin, ISP, CSP, semicellulose and cellulose. From these results, it can be concluded that maturity Ⅴ could maintain the integrity of cell wall structure and alleviate chilling injury symptoms in Chinese olive fruits during cold storage.
Effects of Different Thawing Methods on Fruit Quality and Antioxidant Compound Contents of ‘Ruan’er’ Pear
ZHANG Zhong, MA Chaoling, DING Ruojun, BI Yang, WANG Yi, WEI Yongbo
2018, 39(3):  236-244.  doi:10.7506/spkx1002-6630-201803036
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Freezing and thawing are two essential steps for the traditional way of ‘Ruan’er’ pear consumption. Ethephon is widely used in the acceleration of climacteric fruit ripening. This study investigated the effects of two thawing methods (room temperature air and water bath) on fruit quality and the contents of phenolic compounds in naturally ripened and ethephontreated ‘Ruan’er’ pear. The results showed that room temperature air thawing could significantly improve titratable acidity (TA), total soluble solids (TSS) content and TSS/TA ratio in naturally ripened fruit compared with water bath thawing. In addition, the fruit maintained higher VC and showed lower stone cell content during room temperature air thawing. Furthermore, room temperature air thawing reduced the TA and TSS content in ethephon-treated fruit compared with water bath thawing but had no effect on TSS/TA ratio, VC content or stone cell content. Both thawing methods had no significant effect on the total phenolic content in naturally ripened fruit but increased the total phenolic content in ethephontreated fruit. Different thawing methods had different effects on the major individual phenolic compounds with ferulic acid and chlorogenic acid being undetectable in two thawed samples. Similarly, different thawing methods had different effects on the antioxidant properties of the fruit. The antioxidant potency composite (APC) index of water bath-thawed fruit was the highest, followed in decreasing order by air thawed fruit and naturally ripened fruit. The APC index of ethephon-treated fruit was higher than that of naturally ripened fruit and the same result was observed when frozen fruits were thawed by each method.
Effect of Different Plasticizers on Mechanical Stability of Soybean Protein Packaging Films
ZHI Yawen, ZHANG Huajiang, WANG Xiaoqi, WU Yongqing, LIU Yuanyuan, CAO Wenhui
2018, 39(3):  245-251.  doi:10.7506/spkx1002-6630-201803037
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Soybean protein packaging film was prepared from soybean protein isolate (SPI) with a proper amount added plasticizer. However, its practical application was limited primarily by its poor mechanical stability. In this experiment, we prepared SPI films with three different plasticizers: glycerin, sorbitol and oleic acid. Changes in the mechanical properties of SPI films during storage were evaluated by measuring tensile strength, elongation at break, water vapor permeability, and water soluble loss rate. Results showed that the combination of glycerol, sorbitol and oleic acid (2:1:1, m/m) could result in the best mechanical stability of SPI film. Compared with the control group (with glycerin alone), the combination of plasticizers increased the stability of tensile strength, breaking elongation, water vapor permeability, and water soluble loss rate by 64%, 65%, 27%, and 20%, respectively. In conclusion, this study will provide a theoretical basis for extensive application of SPI packaging film.
Effect of Allyl Isothiocyanate Treatment on Physiological Metabolism of Fresh-Cut Purple Cabbage
JIANG Aili, HU Wenzhong, ZHANG Weina, CHEN Chen, LIU Chenghui, ZHOU Fuhui
2018, 39(3):  252-258.  doi:10.7506/spkx1002-6630-201803038
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In order to explore the effect of allyl isothiocyanate (AITC) on its physiological metabolism, fresh-cut purple cabbage was fumigated with 0, 5 and 10 μL/L AITC, respectively, then put in 19 cm × 14 cm plastic trays and sealed with plastic wrap, and stored at 4 ℃. After 0, 2, 4, 6 and 8 days, the physiological parameters, resistance-related enzyme activity, antioxidant contents and other indicators were determined. The results showed that compared with the control, 5 μL/L AITC treatment inhibited the respiration rate of fresh-cut purple cabbage and increased the activity of resistancerelated enzymes and antioxidant contents, suggesting increased antioxidant capacity; however, 10 μL/L AITC treatment accelerated the senescence process in fresh-cut purple cabbage, as manifested by accelerated rate of respiratory metabolism. In summary, 5 μL/L AITC treatment can effectively reduce the respiration rate and weight loss percentage and maintain the quality and nutritional value of fresh-cut purple cabbage, thereby benefiting the preservation of fresh-cut purple cabbage. But 10 μL/L AITC treatment can stimulate the occurrence of oxidation reaction during short periods of storage and thus have a detrimental effect on the quality of fresh-cut purple cabbage.
Effect of Trichothecium roseum Inoculation and Benzothiadiazole Treatment on the Lipoxygenase Pathway and Characteristic Aroma Compounds in Muskmelon
HU Yanyun, LI Jixin, WANG Yu, WANG Bo, CHEN Jihua, ZHANG Guoxiang, JIANG Yumei
2018, 39(3):  259-267.  doi:10.7506/spkx1002-6630-201803039
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Volatile C6 and C9 alcohols and aldehydes are the characteristic aroma compounds of muskmelon, which are derived from the lipoxygenase (LOX) pathway of unsaturated fatty acids. The effect of postharvest Trichothecium roseum inoculation and benzothiadizaole (BTH) treatment on the enzyme activities involved in the LOX pathway and the release of characteristic aroma compounds from muskmelon (Cucumis melo L. cv. Yujinxiang) was investigated and the correlation between the independent variables was evaluated. The results showed that T. roseum inoculation increased the enzyme activities involved in the LOX pathway compared with control and BHT-treated fruit and the peak occurred earlier in inoculated fruit than in uninoculated one. The peak values of LOX and alcohol dehydrogenase (ADH) activity in the peel and pulp of BTH-treated fruit were higher than those of the control group by 3.49%, 3.93% and 5.13%, 7.21%, respectively; alcohol acyltransferase (AAT) activity was inhibited by BTH in peel and pulp tissues by 19.03% and 14.79%, respectively. The release of C6 and C9 aroma compounds was motivated by T. roseum inoculation, which had a positive correlation with the changes in the LOX pathway enzyme activities. The emission of C6 and C9 aroma compounds from BTH-treated fruit was lower than that from control fruit, which had no significant correlation with the changes in the LOX pathway enzyme activities. BTH treatment could improve disease resistance, and inhibit aroma emission from postharvest muskmelon.
Effect of Cutting Styles on Quality and Antioxidant Activity of Fresh-Cut Lettuce
LI Jing, JI Yue, LI Meilin, WANG Lei, JIN Peng, ZHENG Yonghua
2018, 39(3):  268-273.  doi:10.7506/spkx1002-6630-201803040
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The effects of different cutting styles on the quality and antioxidant activity of fresh-cut lettuce were investigated. The lettuce was cut into slices, quarter slices and shreds and then stored at 5 ℃ for 48 h. The results showed that cutting styles had no significant effect on total bacterial count, color values, chlorophyll or vitamin C contents. However, the freshcut processing significantly induced the activity of phenylalanine ammonia-lyase and enhanced total phenolic content and DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging activity during the initial 24 h of storage, with the shreds having the highest total phenolic content and DPPH free radical scavenging activity. These results demonstrated that cutting styles did not have much effect on the quality, but significantly induced the synthesis of phenolic compounds, thereby improving the antioxidant activity of fresh-cut lettuce.
Migration Behavior of Thymol from Polylactic Acid Packaging Material to Food Stimulant
QIAN Haojie, MU Honglei, GAO Haiyan, CHEN Hangjun, WU Weijie
2018, 39(3):  274-281.  doi:10.7506/spkx1002-6630-201803041
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The migration behavior of thymol from polylactic acid (PLA) film to different food stimulants was studied by soaking the film in distilled water, 4% acetic acid (V/V), n-hexane and 10% ethanol (V/V) at 4, 10, 20 and 30 ℃, respectively. The migration amount of thymol to food simulants was determined by UV spectrophotometry. The effects of temperature and food simulants on the migration of thymol were analyzed. Based on the obtained experimental data, a model for thymol migration was established by the Piringer equation and its rationality was analyzed. Results showed that the thymol content increased gradually until reaching equilibrium with increasing migration temperature and time in both simulants. The migration of thymol to four food simulants was in the decreasing order of n-hexane > 10% ethanol > 4% acetic acid > distilled water. According to the power law model, the mechanism of thymol diffusion through PLA films was in line with Fick’s law. The diffusion coefficient increased with migration temperature while the opposite was observed for the partition coefficient. Thus, the Piringer equation could describe the migration behavior of thymol. The mathematical equation developed in this study can provide a useful tool for prediction of the migration of thymol from PLA food packaging materials to foodstuffs.
Physiological Mechanism for Browning Inhibition in Fresh-Cut Apple by Cysteine
CHEN Chen, HU Wenzhong, JIANG Aili, LIU Chenghui, ZHAO Lei
2018, 39(3):  282-288.  doi:10.7506/spkx1002-6630-201803042
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The purpose of this study was to explore the physiological mechanism for browning inhibition in fresh-cut apple by cysteine. Fresh-cut apples were dipped in 0.5 g/L cysteine solution for 1 min. The effect of cysteine treatment on browning index (BI), the activities of polyphenol oxidase (PPO) and antioxidant enzymes, the contents of antioxidant substances and malondialdehyde (MDA) and non-enzymatic antioxidant capacities was evaluated. The results showed that cysteine treatment significantly inhibited surface browning in fresh-cut apples during storage and resulted in lower PPO activity at the early stage of storage. Furthermore, cysteine treatment enhanced the activities of antioxidant enzymes, improved antioxidant capacity and the contents of antioxidant substances, and inhibited the accumulation of MDA at the same time. Statistical analysis indicated that BI was significantly negatively correlated with ascorbic acid content, catalase (CAT) activity, and antioxidant activity (P < 0.01), while there was a positive correlation between BI and MDA content (P < 0.01). Collectively, these finds suggest that cysteine treatment can inhibit PPO activity and enhance antioxidant capacity, thereby retarding the browning of fresh-cut apples during storage.
Effect of Postharvest Polyamine Treatment on Black Spot Disease Control and Storage Quality of Apricot Fruits
MA Yueyue, LI Yongcai, HU Peifang, BI Yang
2018, 39(3):  289-294.  doi:10.7506/spkx1002-6630-201803043
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The effect of postharvest exogenous polyamine treatment on black spot disease control and storage quality of apricot (cv. Dajiexing) fruits was studied. The results showed that this treatment significantly inhibited black spot development and increased disease resistance in apricot fruits and the effect was dependent on the type and concentration of polyamine. Moreover, the treatment with 1.5 mmol/L spermine, 1.5 mmol/L spermidine or 10 mmol/L putrescine was the most effective, resulting in a decrease in lesion diameter of 38.0%, 26.6% and 34.2%, respectively when compared with the control. At the same time, polyamine treatment reduced weight loss percentage, inhibited the increase of respiration intensity and ethylene release, and retarded the decline of fruit firmness, soluble solid content and color change. In a word, the findings suggested that polyamines may be promising for application in disease control and preservation of apricot fruits.
Reviews
Progress in Molecular Mechanism of Salt Tolerance in Lactic Acid Bacteria
LIN Songyang, HAO Limin, LIU Xin, LU Laizheng, KANG Qiaozhen1, LU Jike
2018, 39(3):  295-301.  doi:10.7506/spkx1002-6630-201803044
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Lactic acid bacteria (LAB) are widely used in food and fermentation industries. Bacterial growth is often affected by high salt concentration during the production of fermented foods such as soy sauce, bacon and pickles. The change in osmotic pressure induced by salt stress can cause damage to cell structure, leading to cell physiological and metabolic disorders or even death. Therefore, the survival, growth and metabolic capacity of LAB under salt stress are very important during food fermentation. In this article, the mechanism of salt tolerance in LAB is reviewed, which will provide a theoretical basis for scientific research of lactic acid bacteria and their industrial application in food fermentation.
A Review of the Role of Intestinal Mucosal Immune Cells in Food Sensitization
YANG Fan, MA Xin, WU Yong, CHEN Hongbing, LI Xin
2018, 39(3):  302-308.  doi:10.7506/spkx1002-6630-201803045
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Food allergy is one of the most important problems in food safety, and most food allergy events occur in the gastrointestinal tract. A series of immune responses are initiated in the gut, since some digested peptides pass through the barrier of intestinal epithelial cells and enter the intestinal mucosa, where they are presented to relevant immune cells. In this review, the roles of intestinal epithelial cells, dendritic cells, B lymphocytes and CD4+ T lymphocytes in the sensitization of digested peptides at the intestinal mucosa are discussed, which will provide valuable information to explore the underlying mechanisms of gastrointestinal immunity during food allergy development.
Progress in Edible Films Prepared with Polysaccharides
LI Shuai, ZHONG Genghui, LIU Yumei
2018, 39(3):  309-316.  doi:10.7506/spkx1002-6630-201803046
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Edible films represent an important research direction in food packaging. In particular, those prepared with polysaccharides are highly favored because of their good uniformity and transparency. Today, research efforts are focused on endowing edible films with a wider range of biological activities such as antioxidant and antimicrobial in addition to improving their applicability, thus presenting promising application prospects. The main components, properties, filmforming mechanisms and biological activities of edible films prepared with polysaccharides are reviewed in this paper. Furthermore, future application prospects are also discussed.
Progress in Packaging Technologies for Vegetables
ZHENG Qiuli, WANG Qing, GAO Lipu, WANG Yunxiang, SHI Junyan, ZUO Jinhua
2018, 39(3):  317-323.  doi:10.7506/spkx1002-6630-201803047
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Vegetables are perishable agricultural products. During storage, transportation and marketing, under the influence of the surrounding environment and mechanical damage, vegetables are vulnerable to senescence and decay, leading to quality deterioration and difficulties in their storage and transportation. Suitable packaging methods can not only maintain the quality of vegetables, but also facilitate their storage and circulation. Studying vegetable packaging is of great importance to extend the shelf life of vegetables. This paper reviews the existing packaging technologies for fresh vegetables including modified atmosphere, modified humidity, antimicrobial, temperature controlled, and intelligent packaging. The existing problems and future trends are discussed.
Advances in Understanding Oxalate-Degrading Activity of Lactic Acid Bacteria and Underlying Mechanism
GUO Lidong, WANG Liqun, YU Chunmiao, LIU Xiaoyan, JIAO Yuehua, HAN Hua
2018, 39(3):  324-329.  doi:10.7506/spkx1002-6630-201803048
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Hyperoxaluria is a chronic disease that is characterized by extremely high levels of urinary oxalate, which can lead to urolithiasis. Urolithiasis is closely associated with the gut microbiome. More recently, particular attention has been paid to lactic acid bacteria for their potential to degrade oxalate, improve urinary oxalate excretion and inhibit stone formation. Strains of lactic acid bacteria with oxalate-degrading activity mainly belong to the genera Lactobacillus, Bifidobacterium, and Enterococcus. The degradation of oxalate by lactic acid bacteria may be achieved through a mechanism involving the transportation of oxalate by permease into the cells where it is converted into oxalyl-CoA by formyl-CoA transferase and further into formate and carbon dioxide by oxalyl-CoA decarboxylase. The purpose of this paper is to provide a comprehensive overview on the oxalate-degrading activity of lactic acid bacteria and the underlying mechanism, aiming to provide a useful guidance for the development of fermented products containing lactic acid bacteria.
Metagenomic and Metatranscriptomic Analysis of Microbiota in Fermented Foods: Review of Recent Advances
LEI Zhonghua, CHEN Congcong, CHEN Gu
2018, 39(3):  330-337.  doi:10.7506/spkx1002-6630-201803049
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Exploring the microbial community structure, succession and functional genes in traditional fermented foods has been the focus of common concern for academic and industrial researchers in the field of food for many years. Because of its high efficiency and relatively low cost, high-throughput sequencing has become one of the most important tools for exploring the microbiota of fermented foods. Based on high-throughput sequencing, metagenomics and metatranscriptomics have greatly advanced our knowledge about microbial succession, interaction and functional genes in various fermented foods. Here, we review the progress that has been made over the past eight years in the metagenomic and metatranscriptomic analysis of the microbiota in fermented foods. We also discuss the limitations and prospects of metagenomics and metatranscriptomics. We hope that this review will provide useful information for future research and industrial production of fermented foods.