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Table of Content

25 October 2019, Volume 40 Issue 20
Food Chemistry
JIA Na, ZHANG Fengxue, SUN Jia, SONG Li, LIU Dengyong
JIA Na, ZHANG Fengxue, SUN Jia, SONG Li, LIU Dengyong
2019, 40(20):  1-7.  doi:10.7506/spkx1002-6630-20181019-211
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This study examined the effect of adding different amounts (0.1%–0.4%) of flaxseed gum to catechins-myofibrillar protein systems on the gel strength, water-holding capacity, hydration characteristics, rheological properties and protein secondary structure. The results showed that the highest gel strength was obtained with addition of 0.1% flaxseed gum. The gel with 0.4% flaxseed gum and 100 μmol/g catechins had the highest water-holding capacity. Flaxseed gum increased the water-binding capacity of the gel. The storage modulus G’ increased with increased content of flaxseed gum in the formed gel. The addition of flaxseed gum increased the α-helix content in the gel, but decreased the contents of β-sheet, β-turn and randon coil. In summary, flaxseed gum could mitigate the adverse effects of catechins on the gel properties of myofibrillar protein.
JU Mengnan, ZHU Gang, LIU Yingjie, DONG Yabo, LAN Tian, JIANG Lianzhou, SUI Xiaonan
JU Mengnan, ZHU Gang, LIU Yingjie, DONG Yabo, LAN Tian, JIANG Lianzhou, SUI Xiaonan
2019, 40(20):  8-13.  doi:10.7506/spkx1002-6630-20180823-250
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In this paper, soybean protein isolate (SPI)-anthocyanin (ACN) covalent composite nanoparticles were successfully constructed and used to fabricate Pickering emulsions. The particle size, zeta potential, free radical scavenging ability, and optical microscopy of nanoparticles and Pickering emulsions were evaluated. The results showed that the particle size distribution and potential values of nanoparticles and Pickering emulsions were changed by adding anthocyanins. The comparisons showed that the nanoparticles and the emulsion systems became more stable after the addition of anthocyanins. In addition, the particle size distribution of the nanoparticles with 0.15% anthocyanins was uniform with the highest relative volume of particles; the absolute value of zeta potential was the largest and the abilities to scavenge free radicals were relatively strong. Microscopic observation showed that the droplet distribution of the Pickering emulsion with 0.15% anthocyanins was relatively uniform, and it was not easy to aggregate and relatively stable.
QI Chuang, QIN Lerong, LI Zhichao, HAN Lijuan, HE Junbo, ZHANG Weinong
QI Chuang, QIN Lerong, LI Zhichao, HAN Lijuan, HE Junbo, ZHANG Weinong
2019, 40(20):  14-20.  doi:10.7506/spkx1002-6630-20180808-078
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Oleogel-based margarine was prepared from sunflower oil with 0.5%–2.5% fully hydrogenated palm oil (FHPO) added as a high-melting-point fat source. Our aim was to investigate the effect of high-melting-point fat on the fatty acid composition, stability, melting point, texture, rheological properties, microstructure and crystalline characteristics of oleogel-based margarine. The results showed that margarine with less than 1.5% FHPO had lower melting point and poorer plasticity. Margarine with more than 1.5% FHPO had an instability index over 1.5 and deteriorated severely. Margarine with 1.5% FHPO had the best overall performance, and its hardness, plasticity and viscosity were more approximate to those of commercial margarine.
CAO Yungang, MA Wenhui, AI Nasi, YAN Linlin, ZHAO Qianqian, MIN Hongwei, BAI Xue, HUANG Junrong
CAO Yungang, MA Wenhui, AI Nasi, YAN Linlin, ZHAO Qianqian, MIN Hongwei, BAI Xue, HUANG Junrong
2019, 40(20):  21-27.  doi:10.7506/spkx1002-6630-20181105-059
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In this research, porcine myofibrillar protein (MP) was artificially oxidized in simulated oxidation systems (containing 10 μmol/L FeCl3, 100 μmol/L ascorbic acid, and 0, 0.5, 1, 3, 5 or 10 mmol/L H2O2) with a view to investigating the effects of different oxidation degrees on the structural characteristics and gel properties of myofibrillar protein. The results showed that the protein carbonyl content increased, while the contents of sulfhydryl groups and free amino groups and the endogenous fluorescence intensity decreased with the increase of H2O2 concentration. SDS-PAGE indicated that oxidative disulfide bond formation resulted in protein cross-linking and aggregation, and consequently a decrease of protein surface hydrophobicity and solubility. When the concentration of H2O2 was lower than 1.0 mmol/L, no significant change was observed in the heat-induced gel properties of MP. However, when the H2O2 concentration was higher than 1.0 mmol/L, the cooking loss increased significantly (P < 0.05) and the gel strength decreased obviously (P < 0.05), while the whiteness changed barely. Overall, H2O2 concentration was positively correlated with protein oxidation degree, but negatively correlated with gel strength.
ZHANG Guangjie, GU Lingbiao, ZHOU Minsheng, YUAN Chao, LIU Jinzhou
ZHANG Guangjie, GU Lingbiao, ZHOU Minsheng, YUAN Chao, LIU Jinzhou
2019, 40(20):  28-33.  doi:10.7506/spkx1002-6630-20181102-026
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A squalene/γ-cyclodextrin inclusion complex was prepared by aqueous solution method combined with freeze-drying. The inclusion complex was characterized by phase solubility method, Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance (1H NMR), and its molecular structure was simulated. The results showed that when excess squalene was available, the molar ratio of the host to the guest in the inclusion complex was mostly 1:1. When excess γ-cyclodextrin was available, an inclusion complex with an average molar ratio of the host to the guest of 3.45:1 was formed. The molecular structure of the inclusion complex was organized by uniform linear connection of the cyclic γ-cyclodextrin molecules to each other via the chain-like squalene molecules and its tended to be stable as the molar ratio of the host to the guest increased. Because the molecular chain length of squalene is limited, the optimum host-to-guest mole ratio is theoretically 4:1. The inclusion constant increased with increasing temperature, and could reach a maximum of 1 778.086 L/mol at 55 ℃; the maximum water solubility of squalene could be increased by 309 times at this temperature. It is inferred from the change in energy that entropy increase is the main driving force for squalene molecules to enter the γ-cyclodextrin cavity.
WANG Yuhuan, CHEN Jiwang, ZHAI Jinling, WANG Haibin, LIAO E, XIA Wenshui, XIONG Youling
WANG Yuhuan, CHEN Jiwang, ZHAI Jinling, WANG Haibin, LIAO E, XIA Wenshui, XIONG Youling
2019, 40(20):  34-40.  doi:10.7506/spkx1002-6630-20181101-006
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Battered and breaded fish nuggets (BBFNs) were prepared with batters with nothing (control), 0.4% xanthan gum, 2% soybean fiber or 4% whey protein added, and fried at 180 ℃ for 50 s. The loss modulus (G”) and storage modulus (G’) of the batter and the microstructure characteristics, Sudan red-dyed level and fat distribution of fried BBFNs were evaluated. The effects of the ingredients added to the batter on its rheological properties and oil penetration of BBFNs during deep-fat frying were investigated. The results showed that G” and G’ values of the four batters decreased, then increased, and finally remained stable with an increase of frying temperature. The highest G” and G’ values were observed by addition of xanthan gum among the batters. Furthermore, the crust structure of fried BBFNs with xanthan gum was compact, there were fewer small pores in it, and much higher moisture content and much lower fat content were found compared to the other groups. The control fried BBFNs had the highest Sudan red-dyed level among the batters and showed oil penetration into the core through the crust. However, the lowest Sudan red-dyed level was observed in the xanthan gum group. Oil was mainly distributed around the pores in the crust of fried BBFNs. Of all fried BBFNs, xanthan gum gave the lowest fluorescence intensity, followed by whey protein and soybean fiber, and the highest fluorescence intensity was found in the control. The results highlighted the impact of the ingredients on rheological properties of the batter, resulting in inhibition of oil penetration of BBFNs during deep-fat frying.
CAO Jiarui, WANG Bing, LI Fangwei, ZHANG Yan
CAO Jiarui, WANG Bing, LI Fangwei, ZHANG Yan
2019, 40(20):  41-46.  doi:10.7506/spkx1002-6630-20181107-087
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We examined the effects of different pH values on the stability of thylakoid membrane in spinach and oilseed rape after heat treatment in terms of color value, polypeptide composition, soluble protein content, absorption spectrum and inverted fluorescence imaging of chlorophyll. The results showed that the color values (?a*) of spinach and oilseed rape thylakoid membrane solution were significantly decreased at low pH (3.6 and 4.6), the polypeptide components of chlorophyll protein complex were obviously degraded, the soluble protein content was significantly decreased, and the fluorescence distribution was aggregated (P < 0.05). It was confirmed that low pH could destroy the structural and functional stability of thylakoid membrane and chlorophyll protein complex, thus releasing more free chlorophyll and accelerating the degradation of chlorophyll; under the same pH condition, the stability of spinach thylakoid membrane was lower than that of oilseed rape thylakoid membrane. The chlorophyll protein complex of photosystem I was more sensitive to low pH than that of photosystem II.
WANG Xiaopeng, ZHAO Xinhuai
WANG Xiaopeng, ZHAO Xinhuai
2019, 40(20):  47-53.  doi:10.7506/spkx1002-6630-20180730-361
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Transglutaminase (TGase) was employed to catalyze the preparation of glycosylated casein with chitosan (1 kDa). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reverse phase-high performance liquid chromatography (RP-HPLC) analysis confirmed the occurrence of glycosylation. In vitro digestion with pepsin plus trypsin was used to evaluate the effect of the glycosylation modification on casein digestibility. The results showed TGase catalyzed the acyl-transfer reaction between casein and chitosan and the amount of glucosamine bound to modified casein was 6.86 g/kg protein. After in vitro digestion, the degree of hydrolysis and trichloroacetic acid-soluble nitrogen (TCA-SN) of glycosylated casein were lower than those of native casein, and more macromolecular peptides were found in the glycosylated casein digest. This study showed glycosylation modification with TGase reduced the digestibility of casein.
DENG Jiao, LIU Xin, CHENG Wenhao, LIU Tiantian, ZHOU Jun, LI Xiangzhou
DENG Jiao, LIU Xin, CHENG Wenhao, LIU Tiantian, ZHOU Jun, LI Xiangzhou
2019, 40(20):  54-59.  doi:10.7506/spkx1002-6630-20181022-236
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Objective: Shellac resin ammonium salt (SRAS) was used to prepare the SRAS/resveratrol (RES) microcapsules with pH response and antioxidant activity in order to improve the bioavailability of RES. Methods: SRAS was used as wall material for RES microencapsulation by spraying drying, and the properties of SRAS/RES microcapsules were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC), and antioxidant activities and release behaviors under different pH conditions were studied as well. Results: The microencapsulation efficiency was 82.70%, and the load rate was 8.27% when 2 g of SRAS, 0.278 g of RES and 0.5 g of Tween 80 were used in the formulation. SRAS/RES microcapsules were microspheres with smooth surfaces, and had good thermodynamic stability. The antioxidant capacity of RES was increased after microencapsulation, and the microcapsules had pH responsiveness and could slowly release RES in simulated human gastric fluid but rapidly in simulated human intestinal fluid. Conclusion: SRAS, modified shellac with ammonia water, can be used for RES microencapsulation. SRAS/RES microcapsules can facilitate the absorption and utilization of RES in the intestinal liquid and show great promise in delivery systems for functional foods and drugs.
WANG Chen, XIE Yanli, FAN Tingting
WANG Chen, XIE Yanli, FAN Tingting
2019, 40(20):  60-66.  doi:10.7506/spkx1002-6630-20180725-308
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The interactions between cyanidin-3-O-glucoside (C3G) and wheat gluten (gliadin and glutenin) under neutral conditions were studied by fluorescence spectroscopy and Fourier transform infrared spectroscopy. The results showed that C3G had strong quenching effects on both proteins, and the fluorescence quenching mechanism of glutenin was static quenching, while the fluorescence of gliadin was quenched through the combination of dynamic quenching and static quenching mechanism. The binding constant (KA) and the number of binding sites (n) for the interaction between C3G and gliadin were larger, indicating stronger interaction with gliadin. Thermodynamic data indicated that the interaction between C3G and gliadin was mainly hydrophobic, while the interaction between C3G and glutein was mainly driven by van der Waals force and hydrogen bond. Synchronous fluorescence spectroscopy indicated that the binding site of C3G to gliadin was closer to the tryptophan residue, while the binding site of C3G to glutein was closer to the tyrosine residue. Fourier transform infrared spectroscopic data showed that C3G interacted with gliadin and glutein, altering the protein conformation.
WEI Youbing, WU Xiang, ZHOU Hui, LI Xinfu, LI Cong, XU Baocai
WEI Youbing, WU Xiang, ZHOU Hui, LI Xinfu, LI Cong, XU Baocai
2019, 40(20):  67-73.  doi:10.7506/spkx1002-6630-20181101-008
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In this paper, the hydrolysis and oxidation of protein and lipid during the processing of salami were studied. The results showed that during the fermentation and ripening process of salami, the proteolysis index increased continuously and proteolysis and free amino acid accumulation mainly took place during the first (from day 0 to 7, at 23–17 ℃) and second (from day 8 to 15, at 17–15 ℃) stages of fermentation. The total content of free amino acids slightly, but?not?statistically significantly, decreased during the third stage (from day 15 to 45, at 13–14 ℃). In addition, the relative contents of neutral lipids and free fatty acids increased significantly (P < 0.05), while the relative content of phospholipids decreased continuously. The contents of all unsaturated fatty acids except oleic acid and oleic acid increased first and then reduced during fermentation, and this trend was the same as that of lipid oxidation. It was indicated that lipid hydrolysis and oxidation simultaneously occurred during the fermentation of salami.
ZHANG Hui, JIANG Yan, WU Shaofu, TU Yonggang, YANG Lingling, XU Mingsheng
ZHANG Hui, JIANG Yan, WU Shaofu, TU Yonggang, YANG Lingling, XU Mingsheng
2019, 40(20):  74-80.  doi:10.7506/spkx1002-6630-20181124-281
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The purpose of this research was to investigate the feasibility of using egg white-xanthan gum (EW-XG) complex as a fat substitute to reduce the fat content in high-fat ice cream and thus obtain low-fat ice cream. The effect of lipid replacement in ice cream was analyzed on its physicochemical properties, sensory evaluation and microstructure. The results showed that overrun was increased from 54.9% to 72.6% and melting rate was decreased from 48.32% to 24.3% when 15% fat substitute was added. Besides, the amount of bubbles and fat aggregation were increased. However, the taste and acceptance were reduced when 25%–30% fat substitute was added. Therefore, ice cream was best accepted with addition of 15% fat substitute.
LIU Weilin, KONG Youyu, XU Xiankang, ZHENG Lingyi, LIU Yefei, HAN Jianzhong
LIU Weilin, KONG Youyu, XU Xiankang, ZHENG Lingyi, LIU Yefei, HAN Jianzhong
2019, 40(20):  81-86.  doi:10.7506/spkx1002-6630-20180815-152
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In this study, interpenetrating polymer network (IPN) hydrogels based on chitosan and gelatin using microbial transglutaminase (mTG) as the cross-linker were prepared and characterized. The formation of hydrogels was confirmed by intrinsic viscosity measurement. The structure and cross-linking mechanism of liposome immobilized IPN hydrogels (lips-in-gels) were examined. The results showed that lips-in-gels formulated from a mixture of gelatin and chitosan (4:1, m/m) and 10 mg/mL mTG had the best texture (18.68 g hardness). Moreover, swelling test, Fourier transform infrared spectroscopy, differential scanning calorimetry and cross-linking degree measurement suggested that the cross-linking of liposome immobilized hydrogels may be achieved through chemical linkages together with hydrogen bonding, and the liposome was located inside of the gel network. Hydrogels are attractive for a diverse range of applications in the protection, delivery and controlled release of liposomes; however, limited studies have been focused on the structure and cross-linking of lip-in-gels. It is expected that this liposome immobilized hydrogel will have potential as a new nutrient delivery system for application in biomedical and food industries.
SUN Qian, ZHANG Aiqin, XUE Yufei, CAO Wenli, XI Fengling, WANG Ronghao, LI Fang, KONG Lingming
SUN Qian, ZHANG Aiqin, XUE Yufei, CAO Wenli, XI Fengling, WANG Ronghao, LI Fang, KONG Lingming
2019, 40(20):  87-93.  doi:10.7506/spkx1002-6630-20180831-367
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Walnut glutenin, constituting up to more than 70% of the total proteins in walnut, was modified chemically (acylated or phosphorylated). After acylation or phosphorylation, the solubility of the glutenin was increased by 4.61 and 5.49 times, and the water-holding capacity by 2.97 and 2.55 times, respectively. The oil-holding capacity was slightly reduced, and the emulsifying capacity and foaming capacity were not changed substantially. Spectroscopic analyses showed that both the secondary and tertiary structures of the protein were changed, leading to changes in the functional properties of the protein. This study provides useful information for further analysis of the changes in functional properties of walnut glutenin.
WANG Ran
WANG Ran
2019, 40(20):  94-99.  doi:10.7506/spkx1002-6630-20190316-204
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In this study, starch ester nanoparticles which could stabilize food-grade Pickering emulsions were successfully prepared by the combined use of alcohol sedimentation and octenyl succinic anhydride (OSA) esterification. The particle size, zeta potential, optical microscopy, and fluorescence microscopy were used as indicators to study the stability of Pickering emulsions versus nanoparticle content, pH and ionic strength. The results showed that the zeta potential of nanoparticles were changed to some extent with pH and ionic strength. The lowest absolute value of zeta potential was observed at extreme pH or low ionic strength. This study showed that the Pickering emulsion was more stable with 2.0 g/100 mL starch ester nanoparticles. In addition, stable Pickering emulsions could be obtained with a KCl concentration of 0.005 mol/L at pH 6.0. In this system the diameters of the oil droplets were the smallest of all emulsions and the oil droplets were not prone to aggregation, making the Pickering emulsion the most stable.
ZENG Ming, CUI Cuicui, WANG Dong, LIU Chuanbei, LI Kai, SONG Hao
ZENG Ming, CUI Cuicui, WANG Dong, LIU Chuanbei, LI Kai, SONG Hao
2019, 40(20):  100-105.  doi:10.7506/spkx1002-6630-20181102-021
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The flavor changes of red orange juice concentrate (Citrus reticulate Blanco ‘Dahongpao’) during storage were analyzed by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Five pathways for flavor change were summarized: 1) degradation of precursors of terpene and carotenoid, producing isopentenyl alcohol and methylbutenol; 2) degradation of typical citrus aromas, such as limonene, producing terpineol and carveol; 3) degradation of carbohydrates, producing furfural, 2-acetylfuran among others; 4) degradation of carotenoids, producing isophorone, safranal among others; and 5) degradation of ferulic acid, producing 4-vinyl guaiacol. Principal component analysis showed that the first principal component (PC1, accounting for 64.015% of the total variation) could represent the collection of typical aromas (factor loading > 0.8) and odors (factor loading < ?0.8). The PC1 score kept decreasing during storage, and the Pearson correlation coefficient between PC1 score and color difference ΔE was ?0.973 (P < 0.01), indicating that the flavor change of red orange juice concentration was significantly correlated with the color change, and it could effectively reflect the quality change.
Bioengineering
CAO Chenchen, FENG Meiqin, SUN Jian, XU Xinglian, ZHOU Guanghong
CAO Chenchen, FENG Meiqin, SUN Jian, XU Xinglian, ZHOU Guanghong
2019, 40(20):  106-113.  doi:10.7506/spkx1002-6630-20190513-129
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Fermented sausages were manufactured with a mixed functional starter culture of Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201, and a commercial starter culture and natural fermentation were used as the controls. We aimed to study the effect of the functional starter culture on fat and protein oxidation and flavor profile in fermented sausages by determining peroxide value (POV), thiobarbituric reactive substances (TBARS) value, protein carbonyl and sulfhydryl content and volatile flavor compounds. The results indicated that during the processing and storage of sausages, the POV, TBARS value and protein carbonyl content in each group increased generally, while protein sulfhydryl content showed a downward trend. Inoculation of the functional starter culture could inhibit lipid oxidation and protein oxidation in fermented sausages, and significantly increase the varieties of volatile compounds (P < 0.05). Its ability to inhibit lipid oxidation was significantly stronger than that of the commercial product (P < 0.05), and its ability to inhibit protein oxidation was comparable to that of the commercial product.
FU Linglin, HUANG Jianjian, XIE Menghua, WANG Chong, WANG Yanbo
FU Linglin, HUANG Jianjian, XIE Menghua, WANG Chong, WANG Yanbo
2019, 40(20):  114-121.  doi:10.7506/spkx1002-6630-20190308-104
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In the present study, maltose-binding protein/cholera toxin B subunit/enhanced green fluorescent protein (MBP-CTB-EGFP) complex was constructed by the recombination of MBP, CTB and EGFP, expressed by E. coli and purified. To assess the viability of the recombinant protein as a novel mucosal adjuvant, a cell model was used to explore the ability of MBP-CTB-EGFP to penetrate the cell membrane. Further, the shrimp allergen tropomyosin (TM) was used to produce the recombinant fusion protein MBP-CTB-TM, and we investigated whether it could reduce allergen usage and improve modeling efficiency in food allergy studies. Therefore, MBP-CTB-TM was applied to sensitize Balb/c mice to investigate the allergenicity of the fusion protein, and to evaluate its influence on the food allergy-related immune reactions. The results showed that MBP-CTB-EGFP was able to act as a mucosal adjuvant in promoting the transportation of foreign proteins into cells, and the efficiency was higher than that of transfection. Furthermore, sensitization of mice with the fusion protein MBP-CTB-TM resulted in an OD450 nm of 0.4 for TM specific IgE in ELISA, while the OD450 nm for natural TM sensitization group was only 0.05. In addition, fusion protein sensitization also promoted TM specific IgG1 and IgG2a production. This study shows that the fusion protein MBP-CTB-TM has a better sensitization effect and thus may reduce the requirement for allergens, therefore providing a powerful tool for further allergy studies.
HE Hehe, LIN Houmin, KOU Lidan, QIN Fenglan, WEI Yutuo, HUANG Ribo, DU Liqin
HE Hehe, LIN Houmin, KOU Lidan, QIN Fenglan, WEI Yutuo, HUANG Ribo, DU Liqin
2019, 40(20):  122-129.  doi:10.7506/spkx1002-6630-20181024-279
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A recombinant expression plasmid named pQE-lmsp was constructed based on the sequence of the sucrose phosphorylase gene from Leuconostoc mesenteroides ATCC 12291 published in the GenBank database. The plasmid pQE-lmsp was expressed in Escherichia coli M15/pREP4. The recombinant protein LMsp was purified by NI-NTA affinity chromatography. The enzymatic properties, especially transglycoside activity of LMsp were studied. Using sucrose as substrate, the optimum temperature and pH were 40 ℃ and 6.5, respectively. The Km and Vmax values were (34.16 ± 1.219) mmol/L and (370.5 ± 6.049) μmol/(mg·min), respectively. When glucose-1-phosphate was used as donor, it had transglycoside activity on most monosaccharides, especially L-arabinose, which had 75% conversion efficiency. Then, molecular modification of LMsp was performed by homology modeling and amino acid sequence alignment analysis. A total of 7 single- and multiple-point mutants were obtained, including T180A, T219V, P236S, T180A-T219V, T180A-P236S, T219V-P236S, and T180A-T219V-P236S, and the transglycoside activities of T180A and P236S on L-sorbose were increased by 13.7% and 15%, respectively compared to that of LMsp. In this study, we found the sucrose phosphorylase LMsp had good pH stability and high transglycoside activity on L-arabinose. Further, the mutants with improved transglycoside activity on L-sorbose were obtained. This study enriches the properties of sucrose phosphorylase and provides a basis for molecular modification.
XUE Hui, FU Ling, LI Hongbo, WANG Shumei, LIU Ning, ZHANG Lili
XUE Hui, FU Ling, LI Hongbo, WANG Shumei, LIU Ning, ZHANG Lili
2019, 40(20):  130-135.  doi:10.7506/spkx1002-6630-20181026-301
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The purposes of the present study were to clarify the relationship between the morphological differentiation and transglutaminase (TGase) production Streptomyces mobaraensis, and to explore the physiological role of TGase in S. mobaraensis development. EDTA was added into the fermentation medium to inhibit the activities of the key proteases for TGase biosynthesis, and then the viability and morphological differentiation of the pellets were investigated using a confocal laser scanning microscope (CLSM) and a scanning electron microscope (SEM). The viability of S. mobaraensis pellets in the control group increased initially and decreased afterwards as the TGase activity increased, and the mycelia showed complex morphological changes. In the experimental group, a significant inhibition effect of EDTA was observed on TGase production, and the viability of S. mobaraensis pellets was decreased upon the addition of EDTA. In addition, mycelial morphological differentiation was delayed. These results suggest that TGase biosynthesis affects the viability of pellets and mycelial morphological differentiation of S. mobaraensis.
LIU Gang, LIANG Qi, SONG Xuemei, ZHANG Yan
LIU Gang, LIANG Qi, SONG Xuemei, ZHANG Yan
2019, 40(20):  136-143.  doi:10.7506/spkx1002-6630-20181008-028
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Streptococcus thermophilus Q4F8 is a mutant strain producing extracellular polysaccharide, which was obtained through mutagenesis screening. In order to realize industrial application, its fermentation process was optimized to improve the yield of extracellular polysaccharide. In this study, GM17 was taken as the basic medium and the medium components and culture conditions were optimized through the combined use of one-factor-at-a-time method, Plackett-Burman design (PBD) and response surface methodology based on Box-Behnken design (BBD). The results showed that the influence of pH, culture temperature and lactose concentration on the synthesis of exopolysaccharides by S. thermophilus decreased in that order. The optimum process parameters were as follows: pH 6.90, 42 ℃, and 1.51% lactose. Under the optimized conditions, the yield of extracellular polysaccharide was 191.47 mg/L, a 2.3-fold increase compared to that of the original strain (P < 0.01). The extracellular polysaccharide of mutant Q4F8 had good antimicrobial activity. This strain holds a great potential as a functional starter culture.
ZENG Jing, GUO Jianjun, TU Yikun, WEI Guowen, YUAN Lin
ZENG Jing, GUO Jianjun, TU Yikun, WEI Guowen, YUAN Lin
2019, 40(20):  144-151.  doi:10.7506/spkx1002-6630-20190419-256
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In order to determine the effect of domain C of thermoacidiphilic raw starch-degrading α-amylase Gt-amy on its catalytic properties, circulation permutation based on protein molecular structure was used to construct circularly permutated mutants of Gt-amy. The abilities of Gt-amy and the mutants to adsorb onto and hydrolyze raw corn starch were investigated. Moreover, the specific activities and kinetic constants were also measured. Compared with Gt-amy, the mutants with higher raw corn starch-binding capacity had higher raw corn starch degradation capacity, and those with lower raw corn starch binding capacity had lower raw corn starch degradation capacity, i.e, there was a positive correlation between Gt-amy’s capacity to bind to and degrade raw corn starch. The raw corn starch binding and degradation rates of mutant Gt-amy-S498 were 93.14% and 90.93%, respectively, which were higher than those of Gt-amy (78.86% and 65.80%). This study confirms that circulation permutation can be used as an engineering method to change the structure and function of proteins, and provides a new way to improve the catalytic performance of enzymes.
YAN Fenfen, SHI Jialu, LI Na, YUE Yingxue, LI Huizhen, SONG Yue, HUO Guicheng
YAN Fenfen, SHI Jialu, LI Na, YUE Yingxue, LI Huizhen, SONG Yue, HUO Guicheng
2019, 40(20):  152-158.  doi:10.7506/spkx1002-6630-20181106-069
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In this study, the cell-free excretory supernatants (CFS) and cell-free extracts (CFE) of 13 Lactobacillus strains deposited in the laboratory were evaluated for α-glucosidase and dipeptidyl peptidase IV inhibitory activities. Then probiotic characteristics of the strains with higher enzyme inhibitory activities were assessed. The results showed that the CFS of the 13 strains had different α-glucosidase inhibitory activities, with inhibition rates of 0%–12.13%, while none of the CFE possessed α-glucosidase inhibitory activities. The inhibition rates of DPP-IV with the CFS and CFE of all strains were 0%–7.13% and 0%–55.42%, respectively. L. acidophilus KLDS1.1003, KLDS1.0901 and KLDS1.0902, with higher enzyme inhibitory activities, were selected to determine their probiotic properties. Among them, L. acidophilus KLDS1.0901 showed the highest acid tolerance, and L. acidophilus KLDS1.1003 showed the highest bile salt tolerance and hydrophobicity. Principal component analysis (PCA) showed that L. acidophilus KLDS1.1003 had the best comprehensive performance: its α-glucosidase inhibitory activity was 10.29%; DPP-IV inhibitory activity was 7.13% and 50.14% for its CFS and CFE, respectively; the survival rate was 51.55% after incubation for 1 h at pH 2.0; under 0.3% bile salt conditions, the lag time was 2.26 h; the hydrophobicity rates in xylene, ethyl acetate and chloroform were 134.33%, 20.51% and 344.08% respectively. Overall, L. acidophilus KLDS1.1003 had high enzyme inhibitory activity and good probiotic properties.
HUANG Xiang, TAO Lei, YANG Ran, HUANG Qun, AN Fengping, HUANG Xi, MA Meihu
HUANG Xiang, TAO Lei, YANG Ran, HUANG Qun, AN Fengping, HUANG Xi, MA Meihu
2019, 40(20):  159-165.  doi:10.7506/spkx1002-6630-20190427-360
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This paper reports on the optimization of the mixed culture fermentation of eggshell for enhanced production of calcium carbonate by the combined use of one-factor-at-a-time method and Box-Behnken experimental design. The results showed that a mixture of Enterococcus mundtii, Streptococcus thermophilus, Lactobacillus casei and Lactobacillus bulgaricus (1:1:2:1, V/V) was found to be the optimum starter culture. The optimum fermentation parameters were determined as follows: temperature 37 ℃, time 72 h, initial medium pH 6.5, and inoculum amount 8.0%. Under these conditions, the yield of calcium lactate was (40.01 ± 0.035) g/L, and the purity was 92.65%. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) confirmed the fermentation product to be calcium lactate. The results provide a feasible way and theoretical basis for the efficient biotransformation of eggshell calcium into calcium lactate.
DANG Qiao, KONG Lingcong, LIU Jie, LIU Shuming, WEI Xing, MA Hongxia, MIN Weihong
DANG Qiao, KONG Lingcong, LIU Jie, LIU Shuming, WEI Xing, MA Hongxia,, MIN Weihong
2019, 40(20):  166-170.  doi:10.7506/spkx1002-6630-20181109-093
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The aims of this study were to isolate and identify Lactobacillus from kimchi produced in Jilin, China, and to analyze the antimicrobial resistance of the strains, for the purpose of paving a foundation for subsequent risk assessment. The species and quantity of Lactobacillus in kimchi samples collected from many different regions of Jilin were analyzed by bacterial isolation using MRS medium and 16S rDNA sequencing. Further, the susceptibilities of the isolates to 10 commonly used antibiotics were tested by agar plate dilution method. The results showed that a total of 34 strains of Lactobacillus were isolated from 15 kimchi from different manufacturers, including 12 strains of Lactobacillus plantarum, 5 strains of Lactobacillus brevis, 3 strains of Lactobacillus rhamnosus, 2 strains of Lactobacillus casei, 2 strains of Lactobacillus sake, 2 strains of Leuconostoc mesenteroides, 2 strains of Streptococcus thermophilus, 1 strain of Weissella cibaria, 1 strain of Lactobacillus curvatus, 1 strain of Lactobacillus coryniformis, 1 strain of Lactobacillus acidophilus, 1 strain of Enterococci durans, and 1 strain of Lactobacillus namurensis. All the strains were susceptible to ampicillin and chloramphenicol, and had different degrees of resistance to other antibiotics. The prevalence of resistance to ciprofloxacin was the highest of all antibiotics tested.
XIA Ji, FANG Yong, WANG Mengmeng, ZHANG Yixiang, YANG Wenjian, MA Ning, HU Qiuhui, PEI Fei
XIA Ji, FANG Yong, WANG Mengmeng, ZHANG Yixiang, YANG Wenjian, MA Ning, HU Qiuhui, PEI Fei
2019, 40(20):  171-177.  doi:10.7506/spkx1002-6630-20190416-208
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To improve the quality of Lentinus edodes kimchi, the effect of low temperature blanching conditions, nitrite control and fermentation methods on the texture and flavor characteristics of L. edodes kimchi were investigated. The results showed that the optimal conditions for blanching pre-treatment were 55 ℃ and 20 min, and the L value, hardness and elasticity of the resulting kimchi were 30.64, 43.49 N and 0.59 mJ, respectively. Moreover, the nitrite content in kimchi was decreased from 6.16 to 3.11 mg/kg by addition of 0.5‰ VC before fermentation. Meanwhile, the process of pure culture fermentation lasted for 7 days, which was shorter than natural fermentation (11 days). Additionally, the pure culture fermentation increased the amounts of total free amino acids as well as the flavor-active compounds acids, alcohols, aldehydes and alkanes by 49.7%, 2.17%, 5.88%, 1.07% and 4.37%, respectively compared to natural fermentation. In summary, this study provides a theoretical basis for the industrialization and standardization of L. edodes kimchi.
LAN Weiqing, CHE Xu, GONG Taoshuo, ZHANG Moyan, SUN Xiaohong, XIAO Lei, XIE Jing
LAN Weiqing, CHE Xu, GONG Taoshuo, ZHANG Moyan, SUN Xiaohong, XIAO Lei, XIE Jing
2019, 40(20):  178-184.  doi:10.7506/spkx1002-6630-20180819-190
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The changes in the quality and microbial population structure of big-eye tuna during cold chain (CK) or logistic process (L1) were analyzed comprehensively, aiming to provide a theoretical basis for the circulation and preservation of aquatic products. The temperature fluctuations under the CK and L1 modes were simulated in this paper. Physicochemical parameters including pH and total volatile base nitrogen (TVB-N) and microbial parameters like total viable count (TVC) and Psychrobacter count (PC) were measured during the two processes, and the microbial diversity was studied by high-throughput sequencing analysis. The results showed that the quality and microbial diversity of the CK group at ?55 ℃ were stable, but the microbial indexes increased considerably at 4 ℃. The pH value of the L1 group decreased first and then increased. TVB-N, TVC and PC of L1 were higher than those of CK, which exceeded the safety limit because of temperature fluctuations after 168 h. The results of high-throughput sequencing showed that the dominant bacteria in the CK group at the end of circulation (SM-HR) were mainly Brochothrix thermosphacta, Endophytes, Ralstonia solanacearum, Acinetobacter spp., Bacillus spp. and Pseudomonas spp., and the main bacteria in the L1 group at the end of circulation (R-FT) were B. thermosphacta, Endophytes, R. solanacearum, Acinetobacter spp., Lysobacter, Pseudoalteromonas spp., Psychrobacter spp. and Shewanella spp..
ZHENG Li, LI Da, NIU Honghong, MIAO Xinyu, WANG Jinghui, SU Ying
ZHENG Li, LI Da, NIU Honghong, MIAO Xinyu, WANG Jinghui, SU Ying
2019, 40(20):  185-191.  doi:10.7506/spkx1002-6630-20180808-073
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In this study, we screened out a strain with high protease activity and evaluated its effect on soybean meal. The strain, coded as JL8, was an aerobic spore-forming Bacillus isolated from pig feed in Jilin province, which could produce (519.1 ± 4.7) U/g protease. This isolate was identified as Bacillus siamensis by physiological and biochemical tests and 16S rDNA sequence analysis. The optimal fermentation time was determined based on the spore quantity of JL8, and soluble reducing sugar content, total protein content, the ratio of soluble to total protein and the degradation degree of allergenic proteins in soybean meal. Then, the microstructure of soybean meal protein was investigated by scanning electron microscopy (SEM) and X-ray diffraction before and after fermentation. Results showed the optimal fermentation time was 24 h at 37 ℃ and at a water content of 50%. Moreover, the SEM images revealed that fermentation significantly changed the microstructure of soybean meal protein, making it looser. The X-ray diffraction patterns showed that the backbone of soybean meal protein was changed and the content of β-sheet was significantly increased by Bacillus fermentation, which may improve the solubility of soybean meal protein.
ZHANG Xin, CHEN Shuman, WU Nan, WANG Tong, PEI Xingwu, JIANG Lianzhou, HAN Cuiping, YU Dianyu
ZHANG Xin, CHEN Shuman, WU Nan, WANG Tong, PEI Xingwu, JIANG Lianzhou, HAN Cuiping, YU Dianyu
2019, 40(20):  192-199.  doi:10.7506/spkx1002-6630-20190104-052
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Candida antarctica lipase B (CALB) was docked with trilinolein to obtain the active site composition of CALB. The free ε-NH2 residues of CALB were located far from the active site and a small part of –COOH was located at the active site. Given the distribution characteristics of the CALB reactive groups, MCM-41 was modified into G-MCM-41 having aldehyde groups or NH2-MCM-41 having amino groups. CALB was immobilized with G-MCM-41 by binding the aldehyde group to ε-NH2 with a loading capacity of 87.4 mg/g, and the activity of the immobilized enzyme was as high as 1 176 U/g. CALB was immobilized with NH2-MCM-41 by binding the amino group to –COOH with a loading capacity of 89.6 mg/g, and the activity the immobilized enzyme was only 672 U/g. The results confirmed the distribution of amino acid residues in the CALB molecule. Using first-grade soybean oil and phytosterol as substrates, the transesterification rate of the immobilized lipase was 87.4% under the optimum conditions established using response surface methodology.
CHANG Chen, LIU Weifeng, GUO Yang, BAO Yihong
CHANG Chen, LIU Weifeng, GUO Yang, BAO Yihong
2019, 40(20):  200-207.  doi:10.7506/spkx1002-6630-20181106-073
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In this study, comparative transcriptomic analysis of Yarrowia lipolytica grown with glucose (control group) and oleic acid (experimental group) as the carbon source was conducted using Illumina high-throughput sequencing and the data were analyzed by various bioinformatics methods. A total of 17 923 921 clean reads were obtained from the sequencing results of the control group, and 22 656 852 clean reads from the sequencing results of the experimental group. A total of 536 significantly differentially expressed genes were obtained between the two samples, of which 376 genes were up-regulated whereas the remaining 160 genes were down-regulated. GO and KEGG enrichment analysis showed these differential genes participated in the regulation of various biological processes. This study provides an important basis for subsequent molecular biology research.
Component Analysis
WU Qianrong, ZHOU Huimin, LI Su, ZHU Ning, ZHANG Shunliang, ZHAO Bing, PAN Xiaoqian, QIAO Xiaoling, CHEN Wenhua, QU Chao
WU Qianrong, ZHOU Huimin, LI Su, ZHU Ning, ZHANG Shunliang, ZHAO Bing, PAN Xiaoqian, QIAO Xiaoling, CHEN Wenhua, QU Chao
2019, 40(20):  208-216.  doi:10.7506/spkx1002-6630-20190217-078
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The volatile flavour compounds of air-dried sausages stored for different times (0, 7, 14, 21, 35, 49 or 77 days) were investigated and analyzed by dynamic headspace sampling combined with gas chromatography-olfactometry-mass spectrometry (DHS-GC-O-MS). Odor activity value (OAV) and sensory evaluation results were used to analyze the changes in volatile flavour compounds and the source of off-flavour. The results showed that a total of 59, 56, 63, 58, 73, 68 and 71 volatile flavour compounds, mainly esters, were detected in the samples stored for different times. With the increase of storage time, the color of the samples became darker and less glossy, the off-flavour intensity increased, and the acceptability decreased. A total of 21, 21, and 17 flavor active substances were significantly correlated with the color, flavor, and acceptability scores in sensory evaluation, respectively. By OAV analysis and GC-O identification, ethyl octanoate, oct-1-en-3-ol, n-hexanal, heptanal, n-octanal, nonanal and trans,trans-2,4-decadienal may be the main source of sausage off-flavour.
ZHANG Hongrui, ZHANG Jiukai, HAN Jianxun, XING Ranran, ZHENG Lei, CHEN Ying
ZHANG Hongrui, ZHANG Jiukai, HAN Jianxun, XING Ranran, ZHENG Lei, CHEN Ying
2019, 40(20):  217-226.  doi:10.7506/spkx1002-6630-20181102-024
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A metabolomics method was proposed for identifying the geographical origin of Maca and the differences in metabolites among geographical origins were analyzed by ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Five origins of Maca were successfully distinguished by orthogonal partial least squares discriminant analysis and then the target and non-target metabolites of Maca from each geographical origin were analyzed. A total of 28 metabolites, including macaamide, macaene, glucosinolate, alkaloids, sterols, polyphenols and flavonoids, were identified by target metabolomics analysis. The markers from Maca geographical origin discrimination were identified by non-target metabolomics analysis. It is concluded that the metabolomics method can be used for the discrimination of Maca origin and the identification of the whole component.
JIA Shijie, ZHANG Haihua, ZHANG Huan, LIU Chang, CHEN Sirui, TANG Linlin, WANG Jinling
JIA Shijie, ZHANG Haihua, ZHANG Huan, LIU Chang, CHEN Sirui, TANG Linlin, WANG Jinling
2019, 40(20):  227-233.  doi:10.7506/spkx1002-6630-20181114-162
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The contents of total phenolics, total flavonoids and proanthocyanidins in six different varieties of red raspberry leaves growing in northeast China were investigated by spectrophotometry. Their phenolic compositions were investigated by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). In addition, their antioxidant activity was evaluated by three different assays. The results showed that all cultivars were richer in total phenolics than total flavonoids and proanthocyanidins. The cultivar European red possessed the highest total phenol content (5.56 ± 0.06) mg/g and total flavonoid content (3.77 ± 0.06) mg/g. Heritage possessed the highest proanthocyanidins content (3.06 ± 0.04) mg/g. There was a significantly positive correlation between the 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonic) acid (ABTS) cation radical scavenging capacity and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of red raspberry leaf extracts, with a correlation coefficient of 0.992 (P < 0.01); ABTS cation and DPPH radical scavenging capacity showed significantly positive correlations with the total content of polyphenols with correlation coefficients of 0.886 and 0.891, respectively. Thirteen phenolic compounds, including six phenolic acids and seven flavonoids, were identified by UPLC-MS/MS from the red raspberry leaf extracts. Ellagic acid, chlorogenic acid, gallic acid were the dominant phenolic acids, and rutin, catechin, epicatechin, and hyperoside were the dominant flavonoids in the extracts.
ZHANG Ling, SHI Caiwen, XIAO Kaijun, LI Chunhai, MO Junquan, ZHANG Zhong, SHI Yuyu
ZHANG Ling, SHI Caiwen, XIAO Kaijun, LI Chunhai, MO Junquan, ZHANG Zhong, SHI Yuyu
2019, 40(20):  234-240.  doi:10.7506/spkx1002-6630-20181118-206
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To develop a rapid method for the determination of tilapia collagen peptide content, the colorimetric biuret method was improved using tilapia skin collagen peptide as a reference material. We determined the maximum absorption wavelength of the chromogenic complex and the concentration ranges of peptide and trichloroacetic acid (TCA) and pH for high linearity. The repeatability, precision and recovery of the improved method were tested under optimized conditions. The applicability of this method to the detection of collagen peptides from the skin and scales of tilapia with different molecular masses was also studied. The results showed that the absorbance was linearly fitted with peptide concentration ranging from 0.3 to 1.5 mg/mL under the following conditions: 13% TCA, adjustment of the system pH to 12.5, and detection wavelength 545?nm, and the following equation was obtained: y = 0.144 9 x + 0.001 5 (R2 = 0.999). The relative standard deviation (RSD) for repeatability and precision were 1.86% and 1.84%, respectively. The average spiked recoveries with and without the addition of gelatin were 113.9% and 109.7%, with RSD of 1.39% and 1.00%, respectively. The method had wide linear range, good repeatability and high accuracy. Its application to different tilapia collagen peptides showed little differences in spiked recoveries and RSD. The improved biuret method proved to be simple, rapid and suitable for the determination of peptides derived from tilapia.
MA Yu, HUANG Yongguang
MA Yu, HUANG Yongguang
2019, 40(20):  241-248.  doi:10.7506/spkx1002-6630-20180730-363
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In this paper, the volatile flavor components of base and finished Fen-Maotai-flavored liquors were studied. The main aroma compounds were analyzed by headspace solid phase microextraction (HS-SPME) or liquid-liquid microextraction (LLME) coupled to gas chromatography-mass spectrometry (GC-MS). The results showed that Fen-Maotai-flavored liquor contained abundant amounts of esters, imparting a floral and fruity aroma that was elegant and comfortable to the liquor. The liquor contained a very low amount of fusel oil, only 7.3% as compared to the total alcohols; the total acid content was moderate, which balanced the taste and enrich the aftertaste. The important flavor components identified included ethyl octanoate, ethyl 2-methylbutyrate, ethyl propionate, isoamyl acetate (3-methylbutyl acetate), dimethyl trisulfide, ethyl valerate, ethyl heptanoate, 2-methylbutanol, ethyl isovalerate (ethyl 3-methylbutanoate), 4-ethyl guaiacol, isovaleraldehyde (3-methylbutanal), ethyl hexanoate, ethyl butyrate, ethyl decanoate, ethyl phenylacetate, ethyl decanoate, ethyl laurate, and 2-phenylethyl acetate. The liquor integrated the essence of Fen and Maotai style, making it easier for consumers to accept.
XIN Xi, CHEN Dejing, CHEN Xiaohua, JIA Shaojie
XIN Xi, CHEN Dejing, CHEN Xiaohua, JIA Shaojie
2019, 40(20):  249-254.  doi:10.7506/spkx1002-6630-20181116-188
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In this paper, the main volatile components and characteristic odors of giant salamander were studied. The volatile components in its meat, claws and skin were extracted and analyzed by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 57, 69 and 49 volatile constituents were identified from the meat, claw and skin of giant salamander, respectively. A total of 15 volatile constituents were detected in all of them, including aldehydes, ketones, alcohols, acids, hydrocarbons, esters, and amines. Nonanal and heptaldehyde contributed to the fishy odor, while 1-octene-3-alcohol and 1-octanol were responsible for the earthy odor of giant salamander.
Processing Technology
YU Hong, PENG Zhen, HUANG Tao, LI Junyi, XIONG Tao
YU Hong, PENG Zhen, HUANG Tao, LI Junyi, XIONG Tao
2019, 40(20):  255-260.  doi:10.7506/spkx1002-6630-20181022-243
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This study aimed to develop a vacuum freeze drying method for preparing fermented goji berry powder with active Lactobacillus plantarum. Differential scanning calorimetry (DSC) and freeze drying microscopy were used to analyze the physical properties of fermented goji berry pulp. The type and concentration of lyoprotectant were optimized by orthogonal array design, meanwhile, and freeze-drying curves were obtained. By using DSC with continuous scanning after annealing at ?5 ℃ with a heating rate of 5 ℃/min, the physical parameters of the fermented goji berry pulp were determined as follows: co-melting point ?5.28 ℃, eutectic point ?19.59 ℃, glass transition temperature ?31.82 ℃, and disintegration temperature ?36 ℃. On this basis, the pre-freezing temperature was ?40 ℃, pre-freezing time 4 h, and sublimation drying temperature ?45 ℃. The optimal lyoprotectant combination was 20% maltodextrin, 14% lactose and 6% trehalose, and the resulting sublimation drying temperature was ?30 ℃. The viable cell count of the fermented goji berry powder, with good color and rehydration characteristics, was 9.6 (lg (CFU/g)), and the water content was lower than 3%, indicating high quality of the product.
YANG Hongji, HAN Ling, KONG Xiangying, MA Junyi, ZHANG Wenhua, YU Qunli
YANG Hongji, HAN Ling, KONG Xiangying, MA Junyi, ZHANG Wenhua, YU Qunli
2019, 40(20):  261-268.  doi:10.7506/spkx1002-6630-20181018-198
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The purpose of this paper was to develop a new process for the tenderization of yak steak. By using response surface methodology, the optimal operating conditions were determined as follows: calcium chloride concentration 10.19 mg/mL, papaya activity 14.94 U/g, sodium bicarbonate concentration 20.95 mg/mL, and treatment time 12.32 h. The shear force value and sensory score of yak steak treated under these conditions were 1.801 kg and 4.61 points, which was 62.13% lower and 147.84% higher than the control group, respectively. Meanwhile, the use of calcium chloride and papain decreased by 74.53% and 70.12%, respectively. The results can provide a basis for quality control and standardized production of yak steak.
YANG Daqiao, WANG Jinxu, LI Laihao, YANG Xianqing, MA Haixia, CEN Jianwei, WANG Yueqi
YANG Daqiao, WANG Jinxu, LI Laihao, YANG Xianqing, MA Haixia, CEN Jianwei, WANG Yueqi
2019, 40(20):  269-278.  doi:10.7506/spkx1002-6630-20181009-070
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To simultaneously produce polysaccharides and polypeptides with a higher yield, the enzymatic hydrolysis of Alectryonella plicatula Gmelin was optimized using one-factor-at-a-time (OFAT) method and response surface methodology. Firstly, OFAT experiments were conducted to evaluate the effect of enzyme dosage, hydrolysis time and solid-to-water ratio on the concentrations of polypeptides, total sugar and glycosaminoglycan and the degree of hydrolysis. Then further experiments were designed?by using Design-Expert 8.0.5.0 considering three independent variables each at three levels. Four mathematical models were built using the concentrations of polypeptides, total sugar and glycosaminoglycan and the degree of hydrolysis as responses, respectively. The results showed that the optimal conditions were found to be hydrolysis with 0.2% trypsase (≥ 250 U/mg) for 80 min at a solid-to-water ratio of 1:3 (g/mL). Experiments carried out under these conditions led to a polypeptide concentration of (85.14 ± 1.67)%, total sugar concentration of (28.35 ± 2.72)%, glycosaminoglycan concentration of (1.60 ± 0.10)%, and degree of hydrolysis of (11.12 ± 0.61)%. Good agreement between these values and the model predictions was found, suggesting that the optimized process was feasible. The yields of polypeptides and polysaccharides on a dry basis were (29.39 ± 0.41)% and (36.81 ± 0.47)%, respectively. This study provides a theoretical basis for simultaneous production of polysaccharides and polypeptides from A. plicatula, which will create greater economic benefits for enterprises by comprehensive utilization of A. plicatula.
SHAN Yuanyuan, LIU Yehongxuan, DAI Yurou, ZHOU Yuan, YI Yanglei, WANG Xin, LIU Bianfang, Lü Xin
SHAN Yuanyuan, LIU Yehongxuan, DAI Yurou, ZHOU Yuan, YI Yanglei, WANG Xin, LIU Bianfang, Lü Xin
2019, 40(20):  279-285.  doi:10.7506/spkx1002-6630-20181018-197
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In order to make full use of calcium resources in bovine bone, bovine bone waste was chosen as starting material to prepare calcium citrate by an ultrasonic-assisted direct neutralization method and the process conditions were optimized by the combined use of one-factor-at-a-time method and response surface methodology based on the yield of calcium citrate. The new preparation method was evaluated in comparison to the routine calcium dissolution method. Results showed that the optimum process conditions were determined as follows: solid-to-solvent ratio 1:15 (g/mL), solid-to-citric acid ratio 1:2, ultrasonic power 320 W, temperature 39 ℃, and sonication time 21 min, giving a calcium citrate yield of 71.21%. The purity of the product prepared using the optimized conditions was 94.38%. The amount of dissolved calcium after 21 min reaction in the new method was 85, 5.5 and 4 times as high as that obtained by 60 min standing, stirring or cooking without ultrasonic treatment, respectively. The amount of dissolved calcium was as high as 96.18% after three cycles of ultrasonic treatment. These results confirmed the ultrasonic-assisted method to be an effective method for preparing dissolved organic calcium from bovine bone, which can provide a basis for the industrial production of calcium products from waste bovine bone.
YU Shuqi, BAO Xiaoqing, LIANG Mingtsai, JIN Chenzhong, TIAN Wei
YU Shuqi, BAO Xiaoqing, LIANG Mingtsai, JIN Chenzhong, TIAN Wei
2019, 40(20):  286-292.  doi:10.7506/spkx1002-6630-20181022-228
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Triterpenoids from the fruiting bodies of Ganoderma lucidum were extracted by supercritical fluid extraction (SFE) and simulated moving bed (SMB) chromatography was then applied to remove impurities from the crude extract. The contents of ganoderic acid A (GAA), ganoderic acid F (GAF) and ganoderol B (GB) were monitored during the process. The extraction conditions were optimized. Using the optimal SMB columns and mobile phases, hydrophilic and lyophilic impurities were effectively removed from the crude extract to increase the total content of triterpenoids. The results showed that the extraction yield of triterpenoids could be substantially improved by adding ethanol as co-solvent. Triterpenoids could be thoroughly extracted in two hours and the crude extract contained 4.50% GAA, 3.39% GAF and 0.29% GB. It was observed that hydrophilic impurities could be effectively removed by SMB separation with 1-1-3/3 column configuration, increasing the contents of GAA, GAF and GB to 19.34%, 15.51%, and 0.74%, respectively. In contrast, lyophilic impurities could be removed by SMB separation with 2/3/3 column configuration, increasing the contents of GAA, GAF and GB to 5.70%, 4.17%, and 0.85%, respectively. Therefore, the removal of hydrophilic impurities from the crude extract should be the main task to increase the content of triterpenoids in the product.
Safety Detection
XU Wei, JIANG Yihe, TIAN Shuanghong, ZHU Qi
XU Wei, JIANG Yihe, TIAN Shuanghong, ZHU Qi
2019, 40(20):  293-298.  doi:10.7506/spkx1002-6630-20181106-064
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In order to understand the changes of quality components and mycotoxins residues in mildewed raw tea with high humidity, the changes in the contents of various quality components and three mycotoxins in raw dark tea during its incubation at a high relative humidity. The results showed that the contents of polyphenols, catechins (mainly EGCG and EGC), and amino acids (mainly theanine) decreased with increasing degree of mildew, while the total content of purine alkaloids remained substantially stable. In contrast, the content of theophylline slightly increased. The contents of ochratoxin A (OTA), deoxynivalenol (DON) and aflatoxin B1 (AFB1) were undetectable in mildewed raw dark tea, implying that mycotoxins did not occur widely in mildewed dark tea, and contaminating molds may be the main cause of mycotoxins residues in raw dark tea.
WANG Lijuan, HU Zhihe, WANG Xingxuan, LI Zhiqing, LUO Mengjuan, PAN Zimeng, YANG Yujuan, LIU Lifeng, LIU Li
WANG Lijuan, HU Zhihe, WANG Xingxuan, LI Zhiqing, LUO Mengjuan, PAN Zimeng, YANG Yujuan, LIU Lifeng, LIU Li
2019, 40(20):  299-304.  doi:10.7506/spkx1002-6630-20180817-178
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Three low-allergenic shrimp products, shrimp protein, crushed shelled shrimp and whole shelled shrimp were prepared by combined high pressure and enzymatic treatment. The allergenicity of these products was measured in vitro by enzyme linked immunosorbent assay (ELISA), and by systemic anaphylaxis test in guinea pigs and Schultz-Dale test. A comparative analysis was made between the in vitro and in vivo results. The results showed that the three untreated shrimp samples had extremely high allergenicity, which was reduced by 97.0%, 94.1% and 94.5%, respectively after the combined treatment. In the animal tests using phosphate buffer saline as the negative control and untreated shrimp protein as the positive control, both the incidence of anaphylaxis and mortality in the untreated shrimp protein group were 100%. The incidence of anaphylaxis in the three low-allergenic shrimp products was likewise 100%, and the mortality of shrimp protein product, mashed shrimp product and shrimp meat product were 16.7%, 50% and 83.3%, respectively. The contractility of sensitized isolated ileum challenged by low-allergenic shrimp protein, mashed shrimp and shrimp meat products were increased by 376.9%, 766.2% and 1 004.4%, respectively compared with their untreated counterparts. According to these results, there were differences between in vitro experiments and animal experiments for allergenicity evaluation of low-allergenic shrimp products prepared by combined high-pressure and enzymatic treatment.
QIAN Shasha, YANG Yang, ZHANG Yuping, ZHUANG Yan, JI Hanxu, LI Ning, WU Xiaoxiao, ZHANG Chi
QIAN Shasha, YANG Yang, ZHANG Yuping, ZHUANG Yan, JI Hanxu, LI Ning, WU Xiaoxiao, ZHANG Chi
2019, 40(20):  305-310.  doi:10.7506/spkx1002-6630-20180807-059
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In this paper, a solid phase extraction-gas chromatography (SPE-GC) method and a comprehensive two dimensional gas chromatography (GC × GC) method were established and compared for the determination of MOSH migration from food contact paper-based products. The results showed that both methods could achieve effective separation and detection of MOSH in the migration solution with a relative standard deviation of 4.3%. Compared with SPE-GC, GC × GC required simpler sample pretreatment and had lower limit of detection (LOD) (1.0 mg/L) and higher recoveries (94.4%–102.4%). The deviation between the quantitative results from the two method was 8.6% for 17 batches of actual samples. It was further found that GC × GC had wider applicability and could be used to detect and quantify the samples which could not be detected by SPE-GC. This study provides important methodological data support for the formulation of new standards.
YU Gaiwen, LIU Ye, WANG Mingming, LI Yunyan, LIU Dachuan
YU Gaiwen, LIU Ye, WANG Mingming, LI Yunyan, LIU Dachuan
2019, 40(20):  311-317.  doi:10.7506/spkx1002-6630-20180723-278
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To develop a rapid and reliable method for the identification of waste cooking oil (WCO), this study investigated the effects of heat treatments during oil processing, use and repetitive refining on the ultraviolet (UV) spectrum of rapeseed oil. UV spectra of oil samples were collected using a thin film chamber with an optical lenghth of 0.05 mm and two characteristic parameters from the UV spectra, i.e. D245 nm and R272 nm, were selected to evaluate the contents of di- and tri-conjugates. The results showed that the maximum values of D245 nm and R272 nm for refined rapeseed oil (RO) were no more than 4.8 and 12.9, respectively. High-temperature oxidation could lead to a significant increase in both D245 nm and R272 nm, while repetitive refining of oxidized RO could not decrease R272 nm. Therefore, a branch discrimination process based on D245 nm and R272 nm could be used for discrimination of oxidized or repeatedly refined oil from normal RO. The detectable threshold of deodorized WCO adulterized in normal RO was 2.3%.
NIE Jiyu, LI Rong, WANG Ying, TANG Shuhua, TAN Jin, BAO Rong, JIANG Zitao
NIE Jiyu, LI Rong, WANG Ying, TANG Shuhua, TAN Jin, BAO Rong, JIANG Zitao
2019, 40(20):  318-324.  doi:10.7506/spkx1002-6630-20181120-227
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A rapid method for simultaneous determination of the contents of theobromine, theophylline and caffeine in beverages by high performance liquid chromatography (HPLC) with a titania-based reverse-phase column was developed. The proposed method presented good linearity (R2 > 0.999 0) for theobromine, theophylline and caffeine in the range of 5–500, 5–1 000 and 6–1 200 mg/mL, respectively, under the optimum?conditions, and the limits of detection (LODs) for them were 0.04, 0.08 and 0.03 mg/mL, respectively. The recoveries of spiked samples were 99.0%–102.0%, 96.7%–106.7% and 99.4%–102.3%, respectively. The relative standard deviations (RSDs) of the precision for 9 replicate detections were less than 0.23%. This method was simple in operation and fast in analysis. Both the precision and accuracy could meet the requirements of quantitative analysis.?The method could be used for simultaneous determination of theobromine, theophylline and theobromine in food, giving satisfactory results. In addition, the thermodynamic parameters, entropy, enthalpy and Gibbs free energy, were calculated for the retention of the analytes. The retention behaviors of the three alkaloids were driven by enthalpy change ΔH0, and the retention sequence of theobromine, theophylline and theobromine was consistent with the experimental results.
GUO Jianping, WAN Jiajia, LU Zhaoxin, Lü Fengxia, ZHANG Chong, ZHAO Haizhen, BIE Xiaomei
GUO Jianping, WAN Jiajia, LU Zhaoxin, Lü Fengxia, ZHANG Chong, ZHAO Haizhen, BIE Xiaomei
2019, 40(20):  325-331.  doi:10.7506/spkx1002-6630-20180830-332
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In this paper, a simple, rapid and sensitive method for the detection of Staphylococcus aureus based on color determination was established by using loop-mediated isothermal amplification (LAMP). LAMP primers were designed based on the specific target gene SAR0395 of S. aureus, and a visualized LAMP reaction system was built. The optimized conditions were determined as follows: inner primers (FIP and BIP), 1.6 μmol/L; outer primers (F3 and B3), 0.2 μmol/L; MgSO4, 4.0 mmol/L; dNTPs, 1.0 mmol/L, Bst 2.0 WarmStart? DNA polymerase, 0.4 U/μL; hydroxynaphthol blue, 120 μmol/L; and amplification at 60 ℃ for 60 min. Two loop primers (LF and LB) added to the LAMP system could reduce the reaction time to 20 min. After 60 minutes of reaction, the sensitivity of the LAMP assay was 0.010 3 fg/μL for genomic DNA and 1.9 CFU/mL for colonies. The specificity and reliability were confirmed by using 46 S. aureus and 24 non-S. aureus strains. The LAMP assay established in this study provides a new technique for rapid and visual detection of S. aureus.
YANG Jinquan, HE Xiaomin, SHI Minfang, CHEN Hao, LI Yongrong, ZHU Youlin
YANG Jinquan, HE Xiaomin, SHI Minfang, CHEN Hao, LI Yongrong, ZHU Youlin
2019, 40(20):  332-337.  doi:10.7506/spkx1002-6630-20180827-295
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An analytical method was established for the determination of bisphenol A (BPA) and bisphenol S (BPS) in drinking water by solid-phase extraction and ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). BPA and BPS from samples were enriched by an Oasis HLB SPE cartridge, eluted with methanol and concentrated with nitrogen. The analytes were separated on an C18 column with 1 mmol/L NH4F aqueous-acetonitrile as the mobile phase, and then analyzed by UPLC-MS/MS using multiple reaction monitoring (MRM) under the negative-ion mode. The limits of detection (LODs) of the method for BPA and BPS were 1.0 and 0.2 ng/L, respectively. The mean recoveries at three spiked levels of BPA ranged from 88.3% to 114.8%, with relative standard deviations (RSDs) of 10.0%–16.2%. The recoveries of BPS were 83.7%–98.2%, with RSDs of 5.9%–12.3%. The method was proved to be sensitive, accurate and efficient, and it was suitable for qualitative and quantitative analysis of BPA and BPS in drinking water.
ZHANG Kaijie, QIN Sinan, ZHAO Chunjuan, GAO Wenhui
ZHANG Kaijie, QIN Sinan, ZHAO Chunjuan, GAO Wenhui
2019, 40(20):  338-345.  doi:10.7506/spkx1002-6630-20180806-051
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Molecularly imprinted polymer microspheres (MIPMs) were prepared by precipitation polymerization with atrazine as the template molecule, methacrylic acid (MAA) as the functional monomer, and acetonitrile as the porogen. The preparation process was optimized, and the best adsorption performance was observed for MIPMs prepared under the following conditions: atrazine-to-MAA molar ratio 1:4, addition of 50 mL of acetonitrile, and polymerization temperature 60 ℃. The adsorption properties of the MIPMs toward target compounds were investigated through adsorption experiments and Scatchard analysis. It was found that there were two types of adsorption sites for atrazine in the MIPMs, and the maximum apparent binding capacity was 282.69 μmol/g. A molecularly imprinted solid phase extraction (MISPE) column was prepared with the MIPMs as a sorbent for sample pretreatment, and an atrazine-MISPE-high performance liquid chromatography (HPLC) method was established for determining residues of four triazine pesticides, simazine, ametryn, atrazine and prometryn, in foods. The results showed that the MISPE column had specific selectivity to the four triazine pesticides with linear correlation coefficients of 0.999 1–0.999 7. The detection limits of the method were 0.5–5 ng/mL. The average recoveries were between 86.2% and 95.7%, and the relative standard deviations (RSDs) were 1.98%–4.51% (n = 5). This method can easily, accurately and selectively detect triazine herbicide residues in foods.