Table of Content

15 April 2019, Volume 40 Issue 7
Basic Research
Prediction of Pseudomonas aeruginosa Growth in Milk
ZHU Lei, ZHANG Aijing, WANG Pengjie, XIA Fan, DONG Yue, GAO Yulong
2019, 40(7):  1-8.  doi:10.7506/spkx1002-6630-20180316-217
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The relationship between the parameters of growth models for foodborne pathogenic Pseudomonas aeruginosa ATCC27853 in milk and temperature was investigated. P. aeruginosa ATCC27853 was inoculated into fresh sterilized milk samples and incubated at 6, 10, 16, 22, 28, 36, 42, 45, 48 and 50 ℃, respectively. The Gompertz equation was used as primary model to fit the growth data of P. aeruginosa by Matlab software. Maximum specific growth rate (μmax) and lag phase duration (λ) obtained from the Gompertz model were fitted to secondary models, modified Ratkowsky and Hyperbola models, respectively. The primary model and secondary models were evaluated and validated with respect to determination coefficient, root mean square error, accuracy factor and bias factor. The results showed that the Gompertz model was fitted well to the experimental data and could well predict the growth of P. aeruginosa ATCC27853 in milk at different temperatures. Both secondary models had excellent goodness of fit to the experimental data. The initial physiological state parameter (h0) of P. aeruginosa ATCC27853 at 6, 10 and 48 ℃ were significantly higher than at 16–45 ℃. The models, indicating the effects of growth temperatures on μmax, λ and h0, can predict the growth of P. aeruginosa ATCC27853 in milk during its processing, transportation, storage and distribution, and therefore provide a theoretical basis for microbial safety control of milk.
Kinetic Analysis and Modelling of Changes in the Texture of Pear Fruit during Postharvest Storage
ZHANG Wen, LIANG Yilei, WU Chenyang, YANG Yuanping, XIONG Shuangli
2019, 40(7):  9-14.  doi:10.7506/spkx1002-6630-20180731-385
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Three pear varieties (Pyrus pyrifolia cv. ‘Whangkeumbae’, ‘Yuguan’, and ‘Hosui’) were used to investigate the textural changes of pear fruit during storage and evaluate their storage lives. Magness-Taylor (MT) firmness, flesh firmness and stiffness were measured by puncture test, and overall acceptability was measured by sensory evaluation. Kinetic models were established for texture parameters of pear fruit. The results showed that MT firmness, flesh firmness and stiffness generally decreased with storage time, and stiffness was more sensitive to storage time than MT firmness and flesh firmness. In addition, stiffness had better correlation with overall acceptability than MT firmness and flesh firmness. The zero-order and first order kinetic models, logistic model and Weibull model were established for each texture parameter. The best results were obtained by the Weibull model. Based on the Weibull model and sensory evaluation,‘Whangkeumbae’, ‘Yuguan’ and ‘Hosui’ lost commodity value and should not be eaten when their MT firmness were lower than 14.762, 10.411 and 7.255 N, flesh firmness were lower than 8.215, 7.438 and 5.181 N, and stiffness were lower than 4.571, 5.572 and 3.609 N/mm, respectively. These results can provide useful guidance for pear storage and consumption.
Structural Changes of Myoglobin during Beef Storage as Analyzed by Raman Spectroscopy
ZHANG Tonggang, LUO Ruiming, LI Yalei, MA Mengbin, ZHOU Yaling
2019, 40(7):  15-19.  doi:10.7506/spkx1002-6630-20180408-083
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The effect of storage time on the structure of myoglobin in beef was studied by Raman spectroscopy. The results showed that the α-helix content of myoglobin gradually decreased, the β-sheet content initially increased followed by a decrease, the β-turn content showed the opposite trend to β-sheet, and the random coil content increased progressively with increasing storage time. Furthermore, increasing storage time of beef resulted in configurational transformation of disulfide bonds in myoglobin from gauche-gauche-trans and trans-gauche-trans to gauche-gauche-gauche. Disulfide bonds were partially damaged and the intermolecular force of myoglobin reduced. The oxidation status of myoglobin had a strong correlation with the secondary structure and the amount of exposed tyrosine and tryptophan residues, respectively. The structure of myoglobin became disorderly scattered and the microenvironment of amino acid residues changed during storage. These results could explain the molecular mechanism of the effect of storage time on the color change of beef.
Effects of Different Thawing Methods on Quality of Frozen Pork as Investigated Using Low Field-Nuclear Magnetic Resonance
CHENG Tianfu, JIANG Yi, ZHANG Yifei, ZHAO Monan, YU Longhao
2019, 40(7):  20-26.  doi:10.7506/spkx1002-6630-20171127-333
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The purpose of this study was to investigate the effects of different thawing methods on the quality of frozen pork by low field-nuclear magnetic resonance (LF-NMR) T2 transverse relaxation measurements. Chilled meat (semitendinosus muscle, at postmortem 27 h) was used as the control to measure the quality characteristics of refrigerated thawed meat, microwave-thawed meat samples 1 and 2 including thawing loss, cooking loss, water holding capacity (WHC), pH, color, water-soluble and salt-soluble protein content, water content correlated with T2 relaxation and sensory attributes. The results showed that the second microwave thawing process took the shortest time of 5 min. Compared with refrigerated thawing, microwave thawing exhibited lower thawing loss (P < 0.01), with the lowest value (5.31%) being observed for microwavethawed sample 2. Compared with fresh meat, microwave-thawed sample 2 had higher WHC (30.99%) and lower shear force value (19.49 N). All three thawing methods had no significant effect on meat pH (P > 0.05). The effect of microwave thawing on L*, a* and b* values and water-soluble and salt-soluble protein contents was better than that of refrigerated thawing, and the values of these parameters in microwave-thawed meat were closer to those in chilled meat. The moisture distribution as observed by NMR T2 relaxation imaging method showed that refrigerated thawing resulted in the transformation of immobilized water to free water, while microwave thawing 1 caused the opposite effect and microwave thawing 2 tended to transform immobilized water to bound water, which may explain the differences in the above quality characteristics. The sensory evaluation score of microwave-thawed meat samples was closer to that of fresh meat. Thus, microwave-thawing can better preserve the eating quality of pork.
Relationship between Changes of Phenolic Substances and Browning during Drying of Thompson Seedless Grapes
LI Xiaoli, CHEN Jiluan, FAN Yingying, HE Weizhong, WANG Zhi, LIU Fengjuan
2019, 40(7):  27-32.  doi:10.7506/spkx1002-6630-20180315-198
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The objective of this study was to investigate the changes of phenols and their relationship with browning during shade drying of Thompson seedless grapes. We determined total phenolic content, phenolic composition and browning degree, and identifyied substrates for enzymatic browning. The results showed that total phenolic content in Thompson seedless grapes decreased during the drying process and that browning degree increased progressively. Totally 14 phenolic compounds were detected in Thompson seedless grapes, six of which such as proanthocyanidin B2, p-hydroxycinnamic acid, catechin, trans-caffeic acid, cis-resveratrol and ferulic acid were substrates for enzymatic browning. The most important substrate was catechin. The browning degree of Thompson seedless grapes was significantly correlated with the contents of total phenols, procyanidin B2, p-hydroxycinnamic acid, catechin, trans-caffeic acid and cis-resveratrol (P < 0.05, P < 0.01). The results of thisse studyies provide a theoretical basis for improving the quality of seedless raisins.
Raman Spectral Analysis of the Structure of Soybean Meal Protein from Aqueous Enzymatic Extraction of Soybean Oil as Affected by Ultrafine Grinding at Low Temperature
WU Changling, XUN Chongrong, LIU Baohua, WANG Zhongjiang, TENG Fei, JIANG Lianzhou, LI Yang
2019, 40(7):  33-39.  doi:10.7506/spkx1002-6630-20180109-104
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The purpose of the present study was to determine the effect of ultrafine grinding at low temperature on the structure of soybean meal protein from aqueous enzymatic oil extraction. Soybean meal was oven dried and ground into ultrafine powders with different particle sizes (100, 200 and 300 mesh) at room temperature or low temperature. Raman spectroscopy was used to analyze the structural changes of soybean meal protein. The results showed that ultrafine grinding at low temperature increased the contents of α-helix and β-sheet and decreased the content of β-turn. Trp and tyr and aliphatic amino acid residues were exposed on the protein surface. Ultrafine grinding at low temperature significantly increased the disulfide bond mode t-g-t. The disordered structure of soybean meal protein turned into an ordered one after ultrafine grinding at low temperature.
Preparation of Antioxidant Peptide from Moringa oleifera Seeds and Its Protective Effects on Oxidatively Damaged Erythrocytes
LIN Lianzhu, ZHU Qiyuan, ZHAO Mouming
2019, 40(7):  40-46.  doi:10.7506/spkx1002-6630-20180319-241
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An antioxidant peptide was purified from enzymatic hydrolysate of Moringa oleifera seed proteins by antioxidant activity-guided separation using fractional precipitation with 20%, 40% and 60% ethanol and macroporous resin column chromatography. Simulated gastrointestinal digest of the antioxidant peptide was evaluated for oxygen radical absorbance capacity (ORAC). The peptide profile and structure of the digest was identified by ultra performance liquid chromatographyquadrupole time of flight-tandem mass spectrometry (UPLC-QTOF-MS/MS). The anti-hemolysis activity and protective effect of the digest against 2,2’-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage in erythrocytes were studied. The 60% ethanol precipitate was harvested and purified using column chromatography by sequential elution with pure water, 20%, 40% and 60% ethanol, yielding an antioxidant peptide rich in antioxidant and hydrophobic amino acids (which contained 92.84% protein and exhibited 1,1-diphenyl-2-picrylhydrazyl scavenging capacity and ORAC value of 39.95 and 1 454.57 μmol/g, respectively). The antioxidant activity of the peptide was enhanced after gastrointestinal digestion, and short-chain peptides including 11 dipeptides and 5 tripeptides were released. The resulting digest, Gln-Met and Leu-Phe could effectively inhibit oxidative stress-induced hemolysis through scavenging intracellular reactive oxygen species (ROS), down-regulating malondialdehyde (MDA) level and superoxide dismutase (SOD) activity, and inhibiting AAPH-induced oxidative stress.
Effect of Freshness of Monopterus albus on Protein Changes during Heating
TANG Mi, ZHENG Hong, MA Liang, DAI Hongjie, GUO Ting, ZHOU Hongyuan, YU Yong, ZHANG Yuhao
2019, 40(7):  47-53.  doi:10.7506/spkx1002-6630-20180901-005
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Monopterus albus with different freshness (stored for 1, 2, 3, 4 and 5 days at 4 ℃) was used to investigate the changes of moisture loss, chemical forces and protein structure during heating and to explore the mechanism of quality deterioration during storage. The results indicated that protein degradation took place in low-freshness Monopterus albus, resulting in a higher rate of moisture loss during heating. During heating, ionic bonds and hydrogen bonds in Monopterus albus proteins were gradually destroyed, and hydrophobic interaction and disulfide bonds gradually became the major forces. When heating Monopterus albus stored for 1–2 days, hydrophobic interaction gradually increased, while disulfide bonds gradually increased at the early stage of heating and then did not change significantly at the late stage. Hydrophobic interaction and disulfide bonds in Monopterus albus stored for 3–5 days were reduced significantly at the late heating stage. The analysis of protein structure showed that the degree of protein unfolding in low-freshness Monopterus albus increased during heating, and hydrophobic groups were more likely to be buried inside, which was consistent with the trend of hydrophobic interaction. In conclusion, Monopterus albus with a longer storage time was more prone to protein degradation with a greater degree of protein unfolding and greater burying depth of hydrophobic groups, resulting in a reduction in hydrophobic interaction and disulfide bonds, consequently a higher rate of moisture loss and texture deterioration. This study provides preliminary theoretical support for the clarification of the mechanism of quality deterioration of Monopterus albus with different freshness after cooking.
Polyphenolic Content and Antioxidant Capacity of Whole Plants and Different Parts of Heraclenm dissectum
WANG Ju, ZHANG Xiuling, GAO Ning, WANG Yunyi
2019, 40(7):  54-59.  doi:10.7506/spkx1002-6630-20180320-256
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In this study, the total phenolic content (TPC) and total flavonoid content (TFC) and antioxidant activities of methanol extracts from whole plants and different parts of Heraclenm dissectum were compared. In order to study the difference in antioxidant activity in vitro, total antioxidant capacity was estimated by ferric reducing antioxidant power, superoxide anion, hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2’-azino-bis (3-ehtylbenzothiazoline-6- sulfonic acid) (ABTS) radical scavenging methods. The results showed that TPC in tender leaves was 30.51 mg/g, which was 1.25 and 1.78 times higher than whole plants and tender stems, respectively. TFC in tender leaves was 28.92 mg/g, which was 1.34 and 4.00 folds increased relative to whole plants and tender stems. The ferric reducing antioxidant power and superoxide anion and hydroxyl radical scavenging capacity of different parts of H. dissectum were in the decreasing order: tender leaves > whole plants > tender stems > control group (VC). The ABTS radical scavenging capacity was ranked in a descending order as follows: tender leaves > whole plants > control group (Trolox) > tender stems. The DPPH radical scavenging capacity followed the decreasing order: tender leaves > tender stems > control group (VC) > whole plants. In summary, the extracts of H. dissectum had strong scavenging capacity against superoxide anion and hydroxyl, followed by DPPH and ABTS radicals, but weak ferric reducing ability.
Quality Analysis and Evaluation of Commercial Roast Mutton Based on Fuzzy Comprehensive Sensory Evaluation and Value Engineering Evaluation
XI Jiapei, ZHAN Ping, TIAN Honglei, WANG Peng, WEI Zhisheng
2019, 40(7):  60-67.  doi:10.7506/spkx1002-6630-20180108-082
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The quality of five different groups of commercial roast mutton samples (SS1, SS2, SS3, SS4 and SS5) was evaluated by fuzzy comprehensive sensory evaluation (FSE) and value engineering evaluation (VEE). The differences in the contribution rates of the volatile organic compounds (VOCs) in roast mutton to its sensory attributes were analyzed by gas chromatography-mass spectrometry (GC-MS) and sensory evaluation. Principal component analysis (PCA) was used to compare the differences between the results from both evaluation methods and to explore the correlation between fuzzy sensory indicators and value function scores so as to rank five groups of roast mutton. The experimental results showed that a total of 42 VOCs were identified in roast mutton by GC-MS and all VOCs could be divided into four value functional components with different attributes, terpenes and alcohols (Z1), aldehydes and sulfur-containing compounds (Z2), ethers and ketones (Z3), and aromatic and others (Z4). Function index ranked in the decreasing order: SS4 (26.18%) > SS1 (22.53%) > SS2 (19.59%) > SS3 (17.26%) > SS5 (14.43%). The result of ranking by FSE was only slightly different, SS4 > SS1 > SS2 > SS5 > SS3. PCA indicated that the results from FSE were consistent with VEE. Moreover, VEE made up for the flaw caused by boundary fuzziness in FSE, and therefore could serve as evaluation criterion in food quality monitoring. The combination of the two models can allow improved comprehensive quality evaluation of roast mutton.
Use of Macroporous Resin LP-8 for Preparing Tea Polyphenols Rich in Esterified Catechins
CHEN Lin, Lü Yangjun, ZHANG Haihua, ZHU Yuejin, WANG Yuefei, ZHANG Shikang
2019, 40(7):  68-73.  doi:10.7506/spkx1002-6630-20180125-318
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In the light of the current great interest in esterified catechins in tea science and the demand for diverse industrial products of tea polyphenols, macroporous resin LP-8 was chosen to separate tea polyphenols with high proportion of esterified catechins in this study. In static adsorption and desorption experiments, resin LP-8 was proven to have differential selectivity for tea polyphenols (containing esterified catechins) and caffeine. Ideal recovery of tea polyphenols could be subsequently obtained by elution with 70% ethanol. As a result, resin LP-8 is promising to prepare tea polyphenols with high proportion of esterified catechins. Furthermore, static adsorption kinetics and isothermal adsorption experiments were conducted, and the saturated adsorption capacity of resin LP-8 at 25 ℃ was calculated to be 70.9 mg/g by fitting the data obtained to the Langmuir equation. The optimal dynamic adsorption conditions were determined as 1 BV/h of loading flow rate and 30 mg/mL of sample concentration. Different concentrations of ethanol were used in gradient dynamic desorption, and the tea polyphenols in the pooled sample of 40%–60% ethanol eluates contained 78.0% esterified catechins (61.0% epigallocatechin gallate (EGCG)). In conclusion, tea polyphenols with high proportion of esterified catechins were successfully obtained by the application of macroporous resin LP-8.
Structural Characterization and Functional Properties of Ultrafine Dietary Fiber from Phyllostachys praecox
LI Lu, HUANG Liang, SU Yu, FU Xiaokang
2019, 40(7):  74-81.  doi:10.7506/spkx1002-6630-20180306-069
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In order to improve the coarse taste of dietary fiber and enhance its characteristics, in the present study, Phyllostachys praecox dietary fiber (PPDF) from bamboo shoots was treated by heavy pressure grinding, jet milling and ordinary grinding, yielding three powders: Z-PPDF, M-PPDF and C-PPDF, respectively. Our aim was to explore the effects of different ultrafine grinding treatments on the structure, physicochemical properties of dietary fiber and on its ability to bind cholesterol, sodium cholate and nitrite. The results showed that compared with C-PPDF, the particle size of Z-PPDF and M-PPDF was significantly (P < 0 .05), reduced by 84.82% and 94.81%, respectively, and the specific surface area was increased by 5.92 and 8.38 folds, respectively. Fourier transform infrared spectra showed that the position of hydroxyl groups in Z-PPDF and M-PPDF moved in a small range with increased peak width and absorption intensity. The surface of Z-PPDF and M-PPDF was rough, and the thermal stability was enhanced. Nevertheless, there was no significant change in the composition or structure of PPDF. Compared with C-PPDF, the contents of soluble dietary fiber in Z-PPDF and M-PPDF increased by 25.23% and 38.59% (P < 0.05), respectively, resulting in an improvement in hydration properties. Z-PPDF and M-PPDF, especially the latter, had a significantly enhanced ability to bind cholesterol, sodium cholate and nitrite. This study indicated that jet milling could enhance functional properties of PPDF to the maximum extent.
Physicochemical Changes of Sturgeon Surimi during Gelation
TANG Shuwei, GAO Ruichang, ZENG Mingyong, FENG Qiufeng, CHEN Yiping, ZHAO Yuanhui
2019, 40(7):  82-87.  doi:10.7506/spkx1002-6630-20180320-253
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The physicochemical changes of sturgeon surimi during its gelation were studied by protein composition, water distribution, Fourier transform infrared spectroscopy, rheological analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that during sturgeon surimi gelation, the proportion of salt-soluble protein and water-soluble protein decreased, and the proportion of insoluble protein increased. Myosin heavy chain and actin content decreased. The absorption peak of surimi protein was red-shifted near 1 100 cm-1. The T2 relaxation time of sturgeon surimi was distributed in four regions. Surimi gelation resulted in greater water binding force and higher viscoelasticity, which indicates that after rinsing, chopping and gelation, a dense gel network structure can be formed. This study provides a theoretical basis for further improving the quality of sturgeon surimi gel.
Degradation Characteristics of Anthocyanins from Purple Sweet Potato during Storage
JIANG Tian, LI Jia, YANG Ning, HE Yi, ZHU Zhenzhou, LI Shuyi, YANG Xinsun, HE Jingren
2019, 40(7):  88-94.  doi:10.7506/spkx1002-6630-20180110-126
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In this study, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to identify anthocyanins in tubers of the purple sweet potato cultivar ‘Eshu 12’. Changes in the contents of total and monomeric anthocyanins in purple sweet potato extract over 98 days of storage at 4, 20 and 35 ℃ were determined using the pH-differential method and HPLC. Additionally, the degradation kinetics of anthocyanins, and as well as the browning index and polymeric color index was investigated. Thirteen anthocyanins were identified majorinly including cyanidin and peonidin 3-sophoroside-5-glucosides acylated with p-hydroxybenzoic acid, ferulic acid, or caffeic acid. The contents of total and monomeric anthocyanins progressively decreased during storage, following first-order reaction kinetics. The half-life time of total anthocyanins were 228.8, 48.1 and 32.6 d at 4, 20 and 35 ℃, respectively. Moreover, the half-life of cyanidin glycosides was shorter than that of peonidin counterparts. The half-life of acylated anthocyanins was longer than that of non-acylated counterparts, and the half-life of diacyl anthocyanins was longer than that of monoacyl ones. Furthermore, the browning index and polymeric color index increased storage time and temperature. Our results suggested a strong negative exponential correlation between anthocyanin content and polymeric color index in purple sweet potatoas.
Effect of Alkaline Electrolyzed Water on Extraction of Seed Kernel Protein from Citrullus lanatus var. megalaspermus
LI Zhihao, ZHOU Bin, WANG Ping, YU Xiongwei, FU Qinli, LI Shugang
2019, 40(7):  95-100.  doi:10.7506/spkx1002-6630-20180315-197
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Traditionally, alkali dissolution and acid precipitation is used for protein extraction. The structure and function of proteins are damaged due to the use of a strong acid or alkali to adjust the pH during the extraction process and, at the same time, the aqueous environment is deterioratedapplication. In order to develop a new extraction method, in the present study, electrolyzed water was used as a solvent to extract seed kernel protein from Citrullus lanatus var. megalaspermus and the extraction efficiency was compared with that of the alkali dissolution and acid precipitation method (using ultrapure water as extraction solvent). The results revealed that at pH 9.5, the yield, solubility, and emulsifying and foaming properties of electrolyzed water extracted seed kernel protein (EWP) were significantly superior to those of ultrapure water extracted seed kernel protein (UWP) (P < 0.05). In the case of essential amino acid composition, cysteine, proline, isoleucine and leucine in EWP were significantly more abundant than in UWP (P < 0.05). Moreover, andwith the secondary structure of EWP was more ordered; the relative contents α-helix and β-sheet (ordered) were 60.2% and 2.3%, and the relative contents of β-turn and random coil (disordered) were 35.8% and 1.7%. In conclusion, compared with ultrapure water extraction, electrolyzed water extraction could not only increase the extraction yield of protein from seed kernels of Citrullus lanatus var. megalaspermus, but also cause less damage to protein structure and function and was an efficient and environmentally friendly extraction method.
Food Engineering
Influence of Ultra High Pressure Treatment on the Effect of Flaxseed Gum on the Properties of Pork Myofibrillar Protein Gel
LIU Wang, FENG Meiqin, SUN Jian, XU Xinglian, ZHOU Guanghong
2019, 40(7):  101-107.  doi:10.7506/spkx1002-6630-20181130-348
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In order to explore the optimal ultra high pressure (UHP) treatment for enhancing the effect of flaxseed gum in improving myofibrillar protein gel properties, myofibrillar protein gels with flaxseed gum treated under different pressure conditions (0.1–400 MPa, 10 min) were evaluated for rheological properties, water distribution as analyzed by low-field nuclear magnetic resonance (NMR), intermolecular forces and microstructure. The influence of UHP on the effect of flaxseed gum on the water-holding capacity (WHC) and strength of myofibrillar protein gel was elucidated. The results showed that upon exposure to pressure ranging between 0.1 and 100 MPa, flaxseed gum significantly increased the WHC, and decreased the storage modulus (G’), loss modulus (G’’) and gel strength (P < 0.05); at a pressure of up to 200 MPa, flaxseed gum further enhanced the WHC and increased G’, G’’ and the peak area of bound water of myofibrillar protein gel, promoting the formation of a compact cross-linked gel network structure and consequently increasing the gel strength (P < 0.05); the effect of flaxseed gum on the WHC and gel strength was mitigated with increasing pressure from 300 to 400 MPa. Hydrophobicity and reactive sulfhydryl group content increased significantly in both the control and treatment groups with increasing pressure from 0.1 to 400 MPa (P < 0.05) and were not affected by the presence or absence of flaxseed gum. In conclusion, flaxseed gum can improve the gel properties of myofibrillar protein to the maximum extent at 200 MPa, and this pressure is optimal for improved gel properties of myofibrillar protein with flaxseed gum.
Effect of Reverse Micellar Extraction on Structure and Physicochemical Properties of Soybean Protein Isolate
ZHANG Qian, CHEN Fusheng
2019, 40(7):  108-113.  doi:10.7506/spkx1002-6630-20180312-154
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More intensive research on the extraction of soybean protein isolate (SPI) may provide new possibilities for developing and utilizing plant proteins. In this study we made a comprehensive comparison between traditional alkali dissolution and acid precipitation method and reverse micellar extraction (RME) for soybean protein extraction and we investigated the unique properties of the reverse micellar environment. For this purpose, the structure, thermodynamic properties and rheological properties of SPI extracted from full-fat soybean powder by the two methods were studied. The results demonstrated that the SPI extracted by RME contained less β-sheet but more β-turn structure, representing a higher degree of unfolding, and therefore had a lower surface hydrophobicity. The reverse micelle environment could protect the protein from denaturation by organic solvents. The SPI extracted by RME had poor thermostability and was more prone to gelation, but the gel strength was lower when compared with the SPI extracted by the traditional method. Finally, we came to the conclusion that the unique water core structure of the reverse micelle could help to preserve the native structure of SPI.
Effect of Ultrasonic Pulping Process on the Preparation and Quality of Freeze-Dried Tofu
LIU Baohua, TONG Xiaohong, WU Changling, QI Yuman, LIU Zongzheng, ZHANG Wankun, LI Yang, JIANG Lianzhou, CHEN Fusheng, MA Chuanguo, WANG Zhongjiang
2019, 40(7):  114-119.  doi:10.7506/spkx1002-6630-20171129-361
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Ultrasonic treatments at different powers (0, 100, 200, 300, 400 and 500 W) were applied on soybean milk to evaluate their effects on the preparation and quality of freeze-dried tofu. The particle size distribution results showed that the average particle size of soybean milk gradually decreased with increasing ultrasonic power up to 300 W and then increased, which indicated that appropriate ultrasonic treatment could reduce the aggregation of soybean milk. Texture profile analysis showed that hardness, springiness, cohesiveness and chewiness of freeze-dried tofu after rehydration were significantly increased when compared with fresh tofu (P < 0.05), which indicated that protein denaturation occurred during the freezing process. Scanning electron microscope and rehydration rate demonstrated that appropriate ultrasonic treatment could result in uniform hole distribution of freeze-dried tofu with a simultaneous reduction in aperture. Therefore, freeze-dried tofu with good texture characteristics and high rehydration rate could be prepared by 10 min ultrasonic treatment at 300 W.
Effect of Barrel Temperature and Chicken Powder Addition on the Quality of Extruded Products
YANG Zhen, GONG Hui, LIU Meng, WANG Shouwei, QIAO Xiaoling, SHI Zhijia
2019, 40(7):  120-126.  doi:10.7506/spkx1002-6630-20180821-214
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Most existing extruded products are made from pure grain, with low protein content and relatively poor nutritional value. In order to improve the quality of extruded products by addition of poultry meat protein, the effects of barrel temperature and the amount of chicken powder on physical and chemical properties of extruded products were studied. The results showed that increased amount of chicken powder could significantly improve the protein content, water retention, hardness, brittleness, volume density and water absorption, and reduce the degree of gelatinization and swelling (P < 0.05). The hardness increased from 3 558 to 6 775 g, while the swelling degree decreased from 3.69 to 1.27 and the gelatinization degree decreased from 96.1% to 92.0%. However, the effect on color, water solubility index and other indicators was not significant (P > 0.05). In addition, increased barrel temperature could significantly improve the hardness (from 2 703 to 5 081 g), brittleness, chewiness and gelatinization degree (from 93.1% to 96.8%), and reduce the water absorption index, water content and swelling degree (from 2.78 to 2.41) (P < 0.05). However, no significant effect was noticed on the color or protein content (P > 0.05). Taken together, the optimal addition level of chicken powder was 30%, and the optimal barrel temperature was 155 ℃.
Effects of Different Thawing Methods on Processing Characteristics of Raspberry Juice
LIU Lu, Lü Chunmao, MENG Xianjun, XIN Guang, LI Bin, ZHANG Liting
2019, 40(7):  127-134.  doi:10.7506/spkx1002-6630-20180424-319
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In order to identify the best thawing method to produce raspberry juice, five thawing methods were used to treat frozen raspberry, namely water bath thawing, microwave thawing, ultrasonic thawing, room temperature thawing and refrigerator thawing. This study intended to investigate if different thawing techniques could have different impacts on the thawing efficiency and drip loss. Besides, the effects of different thawing methods on 16 processing characteristics of raspberry juice were examined. Finally, we used principal component analysis, cluster analysis and grey correlation degree analysis to classify and screen the 16 indicators, and we comprehensively evaluate the 5 thawing methods. The results showed that the thawing efficiency and drip loss were highly significantly different among thawing methods (P < 0.01). The thawing efficiency followed the descending order: microwave thawing > ultrasonic thawing > water bath thawing > room temperature thawing > refrigerator thawing. The drip loss followed the ascending order: microwave thawing < room temperature thawing < refrigerator thawing < ultrasonic thawing < water bath thawing. The juice yield, sugar-acid ratio, browning degree and viscosity were representative indexes and their weight coefficients were 0.239, 0.196, 0.250 and 0.315, respectively. According to grey correlation degree analysis, the best thawing method to produce raspberry juice was microwave thawing.
Improved Thermostablity of Liquid Whole Egg by Octenyl Succinic Anhydride Modification Combined with Ultrasound Treatment
CAO Wenhui, XU Lina, LI Tong, ZHANG Huajiang, CHI Yujie, LIU Yuanyuan, JIANG Xuehan
2019, 40(7):  135-143.  doi:10.7506/spkx1002-6630-20180115-193
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The phenomenon of thermal denaturation and coagulation occurs when liquid whole egg is heated at 64.5 ℃ or above, limiting its application in food processing. In this study, liquid whole egg was modified by sequential preheating, octenyl succinic anhydride (OSA) modification and ultrasonic treatment. Polymer dispersity index (PDI), particle size, turbidity, rheological properties, solubility and differential scanning calorimetric (DSC) analysis were used as indicators to investigate the variation in the thermal stability of liquid whole egg as a function of OSA dosage. The results showed that when 10% OSA was added, the apparent viscosity, G’ and G’’ of liquid whole egg were the lowest, which indicates that protein aggregation was minimized. The decrease in PDI value, average particle size, turbidity and the increase in solubility reflected improved thermal stability of liquid whole egg. At the same time, the results of DSC proved that when the amount of OSA addition was 10%, the thermal denaturation temperature was up to 95.91 ℃. This modification method could improve the thermal stability of liquid whole egg and therefore could provide an effective method for its intensive processing and sterilization.
Effect of Low-Water-Consuming Pipeline Grinding Technology on the Quality and Stability of Soybean Milk
ZHANG Qing, ZHANG Xiaofei, PENG Yijiao, BAI Jie, LI Yumei, JIN Yang, GUO Hong, TIAN Xu, LIU Lisha
2019, 40(7):  144-149.  doi:10.7506/spkx1002-6630-20180815-159
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The effect of low-water and pipeline grinding technology on the quality attributes (composition, particle size, centrifugal sedimentation rate, stability, color difference and sensory evaluation) of soybean milk obtained from different pulping processes were investigated. The results showed that compared with other treatments, a new low-water consuming immersion technique combined with colloidal grinding provided the highest extraction rate of protein. The protein content of the soybean milk was 3.89 g/100 g. In addition, the average particle size was smaller (2.55 μm); the particle size distribution was more uniform with a greater peak height and narrower peak width. The centrifugal sedimentation rate (1.81%) and turbiscan stability index were lowest. The stability of the system was significantly higher than that of soybean milk prepared by traditional soaking and grinding process (P < 0.05). Furthermore, the soybean milk had a significantly higher sensory score (96.20 points) with a brighter color and more delicate taste than other treatments (P < 0.05). The current work indicated that low-water consuming immersion combined with colloidal grinding significantly increased the extraction rate of soybean protein, reduced the particle size, and improved the stability and sensory quality of soybean milk.
Effect of Screw Rotation Speed on Structure and Volatile Component Retention Rate of Flavored Meat Analogues Produced by an Extruder
XUN Chongrong, XUE Hongfei, JIANG Lianzhou, TENG Fei, LI Yang, SUI Xiaonan, XIE Fengying, WANG Zhongjiang
2019, 40(7):  150-155.  doi:10.7506/spkx1002-6630-20180120-278
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In this study, we prepared flavored meat analogues using soybean protein isolate and wheat gluten as major ingredients and natural flavor-active oil powder as a flavoring agent by high moisture extrusion. Solid phase microextraction coupled with gas chromatography-mass spectrometry, scanning electron microscopy, nuclear magnetic resonance and infrared spectroscopy were used to determine the effect of screw rotation speed on flavor retention, microstructure, water distribution and protein structure of flavored meat analogues. The results showed that flavor retention increased with increasing screw rotation speed up to 300 r/min and then decreased. In addition, dense microstructure of meat analogues, smaller freedom of motion of water molecules and unfolding of protein secondary structures were beneficial to the preservation of flavor substances.
Nutrition & Hygiene
Nattokinase Alleviates Alcoholic Liver Injury and Modulates Immune Function in Rats
ZHUO Yiyun, Lü Jing, LIU Ying, WANG Zilong, LIU Man, LIANG Hui
2019, 40(7):  156-162.  doi:10.7506/spkx1002-6630-20180326-340
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Objective: In order to investigate the effect of nattokinase on the alleviation of alcoholic liver injury and its immunomodulatory effect in rats. Methods: Male Wistar rats were randomly divided into five groups: normal control (intragastrically administered with normal saline), model (gavaged with Erguotou liquor (56% alcohol, V/V) at 6 mL/(kg·d mb) for the first week, at 8 mL/(kg·d mb) for the second week, at 10 mL/(kg·d mb) for the third week, and at 11 mL/(kg·d mb) for the fourth to the tenth week), nattokinase control (orally administered with 530.39 FU/(kg·d mb) nattokinase), nattokinase intervention (administered with 530.39 FU/(kg·d mb) nattokinase and alcohol), and diammonium glycyrrhizinate intervention (administered with 200 mg/(kg·d mb) diammonium glycyrrhizinate and alcohol). The same dose of alcohol was given to the latter two groups as that for the model group. The experiment lasted for 10 weeks. Morphological examination of liver tissue was performed by hematoxylin and eosin (H&E) staining, and the ultrastructure of liver cells was observed by transmission electron microscopy. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamyl transpeptidase (GGT), and cholinesterase (CHE) activities were determined. The spleen index was calculated and the number of CD4+ and CD8+ T lymphocyte subsets and natural killer (NK) cells in the peripheral blood of rats was determined by flow cytometry. Results: The morphological structure of liver tissue and the ultrastructure of liver cells in the model group showed obvious pathological changes and damage, which were improved significantly after nattokinase and diammonium glycyrrihizinate intervention. Compared with the model group, the levels of serum ALT, AST and GGT decreased significantly (P < 0.05) whereas CHE increased in the nattokinase intervention and diammonium glycyrrhizinate intervention groups. Moreover, the spleen index and the percentage of CD3+CD4+ T cells and CD3+CD8+ T cells increased significantly (P < 0.05), and the percentage of TCRαβ+CD161a+ NK cell also rose in different degrees in the nattokinase intervention and diammonium glycyrrhizinate intervention groups. Conclusion: Nattokinase attenuates alcoholic liver injury in rats, likely by regulating the proportion of immune effector cells such as CD4+, CD8+ T and NK cells and enhancing immune function.
Protective Effect of Zeaxanthin on SH-SY5Y Cell Injury Induced by Tunicamycin
WEI Jun, ZHAO Fanfan, LIU Xinjun, LAO Fengxue, HUANG Hanchang, SHANG Yinghui
2019, 40(7):  163-168.  doi:10.7506/spkx1002-6630-20171124-303
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This study was designed to evaluate the protective effect of zeaxanthin on SH-SY5Y cell injury induced by tunicamycin (TM) in vitro. The experiment was divided into control group, model group and treatment groups with different doses of zeaxanthin. Cell viability was measured by methyl thiazolyl tetrazolium (MTT) assay, and lactate dehydrogenase (LDH) in cells and cell culture were determined by a commercial kit. The results showed that TM at concentrations over 2 μg/mL could significantly decrease cell viability (P < 0.01). In contrast to the model group, the pretreatment of zeaxanthin in the concentration range of 2–10 μmol/L could increase cell viability (P < 0.05) and suppress TM-induced LDH release in SH-SY5Y cells. The same results were obtained with the reverse sequence. TM caused cell injury by inducing endoplasmic reticulum stress. This effect was reduced or even abrogated by zeaxanthin.
Construction of Tropomyosin-Sensitized Mouse Model and Effect of Lactic Acid Bacteria-Induced Intestinal Mucosal Immunity on Allergenicity
FU Linglin, FU Shujie, HUANG Jianjian, QIAN Yi, WANG Chong, WANG Yanbo
2019, 40(7):  169-176.  doi:10.7506/spkx1002-6630-20180710-131
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This study was devised to elucidate the role of intestinal mucosal immunity in the sensitization of mice by tropomyosin (TM) and in the alleviation of allergy symptoms by probiotics. Female and male BALB/c mice were sensitized and challenged by intraperitoneal (IP) injection of TM and were treated by oral administration of Bifidobacterium longum subsp. 1.2202 or Bacillus coagulans 09.712 for 20 consecutive days starting from Day 14. Anaphylaxis and diarrhea were evaluated, serum immunoglobulin(Ig)E and histamine (HIS) levels were determined. Intestinal mucosal mast cells and goblet cells were detected by histological analysis. Eosinophils and CD4+ T cells were identified by immunohistochemistry. The results showed that female mice were more suitable for building TM-induced mouse model and probiotics could alleviate the allergy symptoms by downregulating intestinal mucosal immune response as manifested by decreased levels of HIS and TM-specific IgE. These results provide a theoretical basis for the mechanistic study of TM-induced food allergy and for understanding the therapeutic effect of probiotics on food allergy.
Eating Quality Evaluation of Dry Cocoon Silk Reeling Pupa
LONG Xia, DING Xiaowen, HUANG Xianzhi
2019, 40(7):  177-184.  doi:10.7506/spkx1002-6630-20180125-325
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Objective: To evaluate the sensory, nutritional and hygienic characteristics of commercial dry cocoon silk reeling pupa from different regions in order to provide evidence for developing and utilizing dry cocoon silk reeling pupa. Methods: The sensory quality was assessed by sensory evaluation and color measurement using a colorimeter. The nutritional and hygienic characteristics were determined by chemical methods. Results: Of 22 samples investigated, samples 2, 14, 18 and 20 had better sensory quality. Dry cocoon silk reeling pupa contained 3.95%–11.41% water, 51.18%–58.40% total protein, 28.13–42.28 g/100 g total fat, and 237.37–459.87 mg/100 g cholesterol. The contents of minerals were in the range of 270.40– 632.29, 34.44–215.92 and 115.67–151.40 mg/100 g for calcium, iron and zinc, respectively. The contents of harmful substances were in the range of 7.21–78.79, 5.08–32.04 and 21.97–127.15 mg/kg for total volatile basic nitrogen, trimethylamine and nitrite, respectively. Acid values ranged from 7.35 to 73.06 mg/g, and malondialdehyde (MDA) levels from 0.87 to 5.86 mg/kg. The contents of harmful elements were in the range of 0.004–0.108, 0.65–3.89 and 2.42–12.61 mg/kg for mercury, chromium and lead, respectively. Cadmium was at an undetectable level. Conclusion: Cocoon silk reeling pupa was rich in nutrients. However, the majority of the samples tested had the drawbacks of poor sensory quality, protein breakdown, severe lipid oxidation, nitrite levels exceeding the maximum residue limit, and hazardous element contamination. Hence, strict quality control during the processing of cocoon silk reeling pupa is needed for its use as a food ingredient.
Immunomodulatory Effects of Peptides from Enzymatic Hydrolysate of Cyclina sinensis on RAW264.7 Macrophages
YE Shengwang, YANG Zuisu, LI Wei, TANG Yunping, HUANG Fangfang, ZHANG Xiaojun, YU Fangmiao, DING Guofang
2019, 40(7):  185-191.  doi:10.7506/spkx1002-6630-20171214-163
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An enzymatic protein hydrolysate from Cyclina sinensis was prepared by treatment with pepsin. The hydrolysate was fractionated by ultrafiltration into five fractions (CSP-1–CSP-5). CSP-5 was found to be most effective in promoting cell proliferation as determined by methyl thiazolyltetrazolium (MTT) assay. To further evaluate its immunomodulatory activity, the effects of CSP-5 on the growth and proliferation, morphology, phagocytic activity, nitric oxide (NO) and cytokines secretion of RAW264.7 macrophages were detected by MTT assay, inverted microscope observation, neutral red phagocytosis assay, nitric acid reductase method and enzyme-linked immunosorbent assay (ELISA), respectively. The effects on the cell cycle distribution of macrophages were also observed. Our results showed that CSP-5, with molecular mass less than 3 kDa, could significantly promote the growth and proliferation of RAW264.7 macrophages, mainly at the G0/G1 phase. The cell phagocytosis, and NO and cytokine secretion capacity were also enhanced by CSP-5. Furthermore, morphological observation showed that macrophages became larger with more pseudopods after treatment with CSP-5. It is clear that the peptide obtained in this study has the potential to activate macrophages and enhance immune function.
Packaging & Storage
Effect of Osmotic Pretreatment on the Quality of Frozen Blueberry
CAO Xuehui, ZHAO Dongyu, ZHU Danshi, ZHANG Fangfang, LI Xinrui, LI Jianrong
2019, 40(7):  192-197.  doi:10.7506/spkx1002-6630-20180203-038
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In order to study the effect of osmotic pretreatment on freezing characteristics of blueberry, freezing curve, drip loss, color, soluble solids content, texture, anthocyanin content and water migration were used as indicators to evaluate the quality characteristics of frozen blueberry with different pretreatments using distilled water and trehalose alone and in combination with calcium chloride. The results showed that anthocyanin content, soluble solids content and hardness of trehalose-CaCl2 treated blueberry were significantly higher than those of the other two groups (P < 0.05). According to the freezing curve, the combined treatment group showed a markedly shorter time (886.67 s) to pass through the zone of maximum ice crystal formation than the other groups, thereby reducing cell damage caused by freezing. In addition, the trehalose treatment group exhibited a significantly lower T23 value (P < 0.05). The addition of trehalose could preserve the color and water retention of blueberry.
Effect of 24-Epibrassinolide on Cold Resistance and Soluble Sugar Content in Apricots during Postharvest Storage
ZHANG Zhurun, ZHANG Ruijie, ZHAO Jin, ZHU Xuan
2019, 40(7):  198-203.  doi:10.7506/spkx1002-6630-20180226-199
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In order to investigate the effect of 24-epibrassinolide (EBR) on cold resistance and soluble sugar content in apricots during postharvest storage, freshly harvested fruit of Xinjiang ‘Saimaiti’ apricot were decompress osmosis treated with 0.9 mg/L EBR and stored at 0 ℃ and relative humidity of 90%–95%. Chilling injury index, chilling injury rate, malondialdehyde content, cell membrane permeability and soluble sugar content were determined periodically during storage. The results showed that EBR effectively reduced the chilling injury index, chilling injury rate, malondialdehyde content, cell membrane permeability of apricots, and significantly increased the contents of fructose, sorbitol, glucose (P < 0.05), but reduced sucrose content (P < 0.05). Conclusively, this study indicated that EBR could enhance cold resistance in apricots, and the mechanism may be related to changes in fructose, sorbitol and glucose content.
Preservation Effect of Gum Arabic Edible Coating Incorporated with White Roselle Extract (Hibiscus sabdariffa L.) on Cold-Stored Blueberries
ZOU Xiaobo, YANG Zhikun, SHI Jiyong, HUANG Xiaowei, ZHANG Wen, Haroon Elrasheid TAHIR
2019, 40(7):  204-211.  doi:10.7506/spkx1002-6630-20180305-032
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A new edible coating was developed to improve the quality of cold-stored blueberries since they are easy to deteriorate. Rabbiteye blueberries coated with three edible coating solutions, named M1, M2 and M3, were stored at (4.0 ± 0.5) ℃ with 75% relative humidity. M1 was composed of 100 mg/mL gum arabic (GA) and 1.5 % (V/V) glycerol; M2 was composed of 100 mg/mL GA, 1.5% (V/V) glycerol and 1.5% (V/V) white roselle extract (WRE); M3 was composed of 100 mg/mL GA, 1.5% (V/V) glycerol and 2.5% (V/V) WRE. The effect of edible coatings on the quality of blueberries was evaluated by detecting the physicochemical properties, the activity of antioxidant enzymes and the contents of antioxidants. The results showed that all GA edible coatings could significantly delay water loss, reduce decay incidence and slow down the decrease in hardness of blueberries. The treated samples maintained high total polyphenol content (TPC) and total anthocyanin content (TAC) and good sensory quality (P < 0.05) and showed significantly inhibited polyphenol oxidase (PPO) activity and reduced surface browning (P < 0.05). Edible coating M3 was the most effective in inhibiting PPO activity, matintaining TPC and TAC, improving the sensory quality of cold-stored blueberries. Based on all quality parameters, edible coating M3 was the most effective in preserving the quality of cold-stored blueberries.
Effect of Nanocomposite Antibacterial Packaging on Preserving Flavor Quality of White Lotus Roots
SUN Shixu, LI Li, HAN Xiangwen, ZHOU You, CAO Chongjiang
2019, 40(7):  212-218.  doi:10.7506/spkx1002-6630-20181130-352
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This study aimed to solve the problem of quality deterioration in white lotus roots during storage. A nanocomposite antibacterial packaging was prepared to delay the senescence of white lotus roots. Samples were subjected to normal packaging (NP) or nanocomposite antibacterial packaging (AP) and then storage at 25 ℃ and 35% relative humidity after vacuuming. Every 4 days, malondialdehyde (MDA) and total phenol (TP) contents were determined and the expression of genes related to volatile compound metabolism was evaluated on the 20th day of storage. The effect of the nanocomposite antibacterial packaging on the flavor quality was analyzed by electronic nose and gas chromatography-mass spectrometry (GC-MS). The results showed that MDA and TP levels in AP samples were 0.865 4 mmol/g and 5.873 mg/100 g at the end of the storage process, respectively. The activity of SOD and CAT in AP samples was higher than in control samples, indicating that AP inhibited the senescence of white lotus roots. In addition, the nanocomposite antibacterial packaging could regulate the expression of genes related to the metabolism of volatile components in white lotus roots. This study confirmed that the nanocomposite antibacterial packaging could preserve the quality of white lotus roots by regulating the expression of volatile metabolism-related genes.
Effects of Populations, Gender and Packaging Methods on the Oxidation of Sarcoplasmic Proteins in Chilled Yak Meat
LI Sining, TANG Shanhu
2019, 40(7):  219-227.  doi:10.7506/spkx1002-6630-20180226-213
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In an effort to explore the oxidation pattern of sarcoplasmic proteins in yak meat under chilled conditions, Longissimus dorsi muscles of male and female yaks from different populations were packaged in air or vacuum and stored under chilled conditions, and the oxidation of sarcoplasmic proteins in yak meat was evaluated by measurement of carbonyl content, sulfhydryl content and hydrophobicity, UV absorption spectroscopy and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the carbonyl content of sarcoplasmic proteins in both packaging treatments followed an increasing-decreasing-increasing trend (P < 0.05), whereas the total sulfhydryl content decreased with the prolongation of storage time. Surface hydrophobicity of air-packaged yak meat increased (P < 0.05), while that of vacuum-packaged meat revealed an initially increase and then decreased. Significant differences were observed for carbonyl content, total sulfhydryl content and surface hydrophobicity between different yak populations under the same packaging conditions (P < 0.05), but not between the genders (P > 0.05). For both packaging trearments, the most apparent change in the second-order derivative UV absorption spectra of sarcoplasmic proteins occurred on the 3rd day of the storage. As oxidation proceeded, the molecular masss of sarcoplasmic proteins decreased, and the intensity of all protein bands declined. During storage, the degradation degree of sarcoplasmic proteins under air packaging was larger than under vacuum packaging. UV absorption spectra and SDS-PAGE patterns of sarcoplasmic proteins in both packaging treatments did not vary between populations or genders after the same storage time. From this study we concluded that sarcoplasmic protein oxidation in yak meat during cold storage was closely related to packaging methods and populations but not genders.
Pichia membranaefaciens Combined with Chitosan Treatment Induces Resistance to Anthracnose in Citrus Fruit
TIAN Ligang, PENG Ru, YAO Shixiang, DENG Lili, ZENG Kaifang
2019, 40(7):  228-237.  doi:10.7506/spkx1002-6630-20180913-120
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This study was undertaken in order to investigate the combined effect of Pichia membranaefaciens and chitosan on controlling anthracnose and inducing anthracnose resistance in citrus fruit (Citrus sinensis L. Osbeck. cv. Jincheng 447) inoculated with Colletotrichum gloeosporioides. The results showed that the application of P. membranaefaciens (1 × 108 cells/mL) or chitosan (0.1 g/L) were effective in inhibiting anthracnose but inferior to their combination. The combined treatment increased the contents of some signal substances including NO, salicylic acid and H2O2 as well as the contents of intermediate metabolites of phenylpropane (ferulic acid, p-coumaric acid and chlorogenic acid), and induced higher activities of defense-related enzymes including phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate:coenzyme A ligase, peroxidase and polyphenoloxidase and higher activities of pathogenesis-related proteins (PR-proteins) such as chintinase and β-1,3-glucanse. In conclusion, P. membranaefaciens combined with chitosan induces anthracnose resistance in citrus fruit.
Effect of Desulphurization on Postharvest Quality and Sulfite Metabolism in Sulfur-Fumigated ‘Heiye’ Litchi Fruit
LUO Tao, LI Shuangshuang, GUO Xiaomeng, HAN Dongmei, WU Zhenxian
2019, 40(7):  238-246.  doi:10.7506/spkx1002-6630-20180211-142
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The effect of desulfurization on the postharvest quality, sulfite residue and sulfite degradation of sulfurfumigated ‘Heiye’ litchi fruit was investigated. The color, browning index, decay incidence, sulfite residue of litchi fruit, and the activities and gene expression of sulfite oxidase (SO), adenosine 5’-phosphosulfatezoline reductase (APR), sulfite reductase (SiR), serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL) in pulp were measured in the control (treated with prochloraz), sulfur-fumigated and desulfurized fruits during storage at 4 ℃. Our results showed that the desulfurized fruit turned red earlier than the sulfur-fumigated fruit during storage. The browning index and decay incidence of the treated fruits were significantly lower than those of the control fruit. Desulfurized fruit showed a greater reduction in the moisture content and a greater increase in the relative conductivity of pericarp than did sulfur-fumigated fruit, whereas both treatments were similarly effective against respiration. After desulphurization, sulfite content in pericarp decreased significantly, and sulfite content in desulfurized litchi pulp decreased to a level comparable to that of the control on the 16th day of storage. During storage, the activities of all enzymes investigated except for APR increased in sulfur-fumigated and desulfurized fruits when compared with the control; the activities of SO and SAT in the treated fruits increased by 2.0 and 8.6–26.7 times, respectively. On day 0 of storage, SAT activity in desulfurized litchi increased by 11.1 times in comparison with the control, and then it decreased rapidly, reaching a level not significantly different from that of the control on Day 32. The gene expression of all five enzymes in sulfur-fumigated and desulfurized fruits was higher than that in the control at the middle and late stages of storage. This study indicated that desulfurization accelerated color recovery in the pericarp of sulfur-fumigated litchi fruit with achieving a preservation effect comparable to sulphur-fumigation, and dramatically reduced sulfite residue, thereby ensuring its safety for consumption. The increasing activity of SO and SAT in sulfur-fumigated and desulfurized fruit pulp indicated that oxidative degradation of sulfite catalyzed by SO was dominant and was the most stable way, which may be complemented by the reduction pathway controlled by SAT and SiR.
Effect of Rosemary Extract and ε-Polylysine Blend on the Quality and Moisture Migration of Large Yellow Croaker during Ice Storage
ZHANG Nannan, LAN Weiqing, HUANG Xia, WENG Zhongming, XIE Jing
2019, 40(7):  247-253.  doi:10.7506/spkx1002-6630-20180125-340
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Objective: To examine the effect of a blend of rosemary extract (RE) and ε-polylysine (PL) on the quality and water migration of large yellow croaker (Pseudosciaena crocea) during ice storage. Methods: The fish were immersed in the blended solution (RP) containing 2 g of RE and 1 g of PL per 1 L for 20 min, and then each sample was taken out of the solution, packaged in a polyethylene bag and kept on ice at 4 ℃. Control samples were treated with sterile water. Sensory evaluation, physicochemical properties (pH, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value, and electrical conductivity) and total viable count (TVC) were measured during storage. Water mobility was investigated by measurement of water-holding capacity (WHC) and low-field nuclear magnetic resonance (LF-NMR). Results: The control samples showed unacceptable sensory quality, with a dull color, loose texture and strong rancid smell on Day 9 of storage, whereas the RP treated samples maintained good sensory quality except for a slightly dull color on Day 13. pH and electrical conductivity descended firstly and then ascended during storage, and the values of the two parameters as well as TVB-N content, TBARS value and TVC in the RP group were lower than in the control group, suggesting that RP has great antioxidant and antibacterial activities. From the results of WHC and LF-NMR, it was apparent that RP could improve the WHC of large yellow croaker greatly, inhibit the increase in free water content and delay the deterioration process. The storage life of the control group was 6–9 days, and it was extended to 13–15 d by RP treatment. Conclusion: The composite preservative of RP can improve the storability and extend the shelf life of large yellow croaker without affecting its sensory quality.
Comparative Study of the Artificial Ripening of ‘Baxijiao’ and ‘Nantianhuang’ Bananas
XIAO Weiqiang, HUANG Bingzhi, DAI Hongfen, YANG Xingyu, XU Linbing
2019, 40(7):  254-260.  doi:10.7506/spkx1002-6630-20171227-339
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‘Nantianhuang’ is a new banana cultivar with good traits and resistance to Fusarium wilt. Artificial ripening conditions for this cultivar are different from those for the traditional cultivar ‘Baxijiao’. In practice, postharvest ‘Nantianhuang’ are always ripened in the same way as ‘Baxijiao’, which is misleading. In this study, in order to improve the quality and extend the shelf life of bananas, ‘Nantianhuang’ and ‘Baxijiao’ bananas were sprayed with 500 mg/L ethephon and then assigned to 4 treatments: storage at (22 ± 2) ℃ (T2), packaging in biaxially oriented polypropylene (BOPP) film + storage at (22 ± 2) ℃ (T-2), storage at 17 ℃ (T1), and packaging in BOPP film + storage at 17 ℃ (T-1). Peel color, pulp firmness, fruit mass loss, total soluble solids content and shelf life were determined during storage, and fruit appearance characteristics during shelf life were recorded to establish an appropriate ripening protocol for ‘Nantianhuang’. Results showed that ‘Nantianhuang’ turned yellow one day earlier than ‘Baxijiao’ at 17 ℃, but one day later for T2 treatment group. The shelf life of ‘Nantianhuang’ was two days longer than ‘Baxijiao’ for T1 and T2 treatment groups. For both cultivars, the firmness, L*, C* and a* values of yellowed fruits for T1 treatment group were higher than T2 treatment group, and shelf life at 17 ℃ was prolonged two days. However, the T2 treatment group bananas had a brighter yellow color than T1 treatment group. BOPP film packaging effectively delayed bananas from turning yellow, prolonged the maturation period by four days, and shortened the shelf life. Therefore, it was concluded that artificial ripening at 21 ℃ first and then at 17 ℃ is the best condition to improve the maturity quality and prolong the shelf life of ‘Nantianhuang’.
A Review of Recent Literature on Effects of Bioactive Compounds in Foods on Trimethylamine-N-oxide-Mediated Atherosclerosis
GUO Jingting, JIAO Rui, JIANG Xinwei, LI Xia, LI Xusheng, RAN Guojing, BAI Weibin
2019, 40(7):  261-267.  doi:10.7506/spkx1002-6630-20180313-164
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Cardiovascular disease is one of the major causes of death worldwide, and atherosclerosis (AS) is the major pathological basis for its development. In recent years, studies have shown that trimethylamine-N-oxide (TMAO) as a metabolite of choline and L-carnitine produced by the gut microbiota through enzymatic hydrolysis can promote atherosclerosis, thereby leading to cardiovascular disease. However, choline intake should not be completely avoided because it is a human essential nutrient. Preventing the synthesis and metabolism of TMAO is necessary to reduce the risk of AS. Studies have demonstrated that bioactive compounds in foods could regulate the formation of TMAO. In this review, we summarize the mechanisms by which food bioactive compounds interfere with TMAO-induced atherosclerosis from the perspectives of remodeling the gut microbiota, inhibiting liver flavin-containing monooxygenase 3 activity, promoting bile acid synthesis and transport, and reducing foam cell formation. We hope that this review will provide a theoretical basis for further study and application of food bioactive compounds in regulating atherosclerosis.
Advances in Understanding Dietary Carbohydrates and Metabolic Syndrome
LI Lu, ZHANG Xianyi, TANG Xiaofang, WU Wenying, LI Wenjuan
2019, 40(7):  268-273.  doi:10.7506/spkx1002-6630-20171210-117
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Metabolic syndrome is a common pathological basis of critical diseases such as cardiovascular diseases and type 2 diabetes mellitus and is the leading cause of morbidity and mortality. Metabolic disorders of carbohydrates and fats in the diet play a crucial role in the occurrence and development of metabolic syndrome. Numerous studies have focused on the relationship between the adverse effects of high-fat diets and metabolic syndrome. However, little is known about how increased proportion and excessive consumption of refined carbohydrates in the diet promote metabolic syndrome. Currently, there is increasing evidence that dietary carbohydrate is closely related to the development and progression of metabolic syndrome. Therefore, this article aims to review the relationship between carbohydrate intake and metabolic syndrome in order to provide theoretical guidance for developing healthy diets.
Recent Progress in Synthesis of Oxidized Dimeric Catechin Catalyzed by Exogenous Polyphenol Oxidase
FU Jing, JIANG Heyuan, ZHANG Jianyong, SHI Liting, WANG Weiwei
2019, 40(7):  274-280.  doi:10.7506/spkx1002-6630-20180206-089
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During black tea processing, catechin is converted into a wide variety of oxidized polymers with complicated structures through many pathways, and the unique color and taste of black tea is due to these compounds. Currently, most studies on oxidized dimeric catechin have focused on theaflavins (TFs) and theasinensins (TSs). This review summarizes recent advances in understanding the reaction pathways for the formation of oxidized dimeric catechin, the exogenous polyphenol oxidases responsible for enzymatic oxidation of catechin and their substrate specificity, and the bioactivity of oxidized dimeric catechin and recent advances in applying oxidized dimeric catechin in tea processing. The aim of the present review is to provide a better understanding of the enzymatic oxidation mechanism of catechin and to provide a scientific basis for tea deep processing.
Prevalence and Detection of Arcobacter as an Emerging Foodborne Pathogen in Foods: A Review
WU Yufan, WANG Xiang, CUI Siyu, SHAO Jingdong
2019, 40(7):  281-288.  doi:10.7506/spkx1002-6630-20180314-181
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Arcobacter is an emerging foodborne zoonotic pathogen. It was first known as ‘aerotolerant campylobacters’ due to its morphological resemblance and close relatedness to the genus Campylobacter. In the Arcobacter genus, A. butzleri, A. cryaerophilus and A. skirrowii are predominantly associated with human diseases (gastroenteritis, severe diarrhea and bacteremia). Arcobacter has been reported to be widely distributed in livestock and poultry products, and the environment. Its high prevalence in livestock and poultry products may be ascribed to post-slaughter contamination due to either the contaminated production facilities or processed water. Arcobacter is difficult to differentiate from Campylobacter due to their high physiological similarity. Molecular biological methods have been popular for laboratorial diagnosis of Arcobacters at the genus and species level. As an emerging foodborne zoonotic pathogen, Arcobacter has been a major concern for researchers. However, unlike other common foodborne pathogens, the current knowledge about Arcobacter is still limited. This review summarizes the current knowledge concerning Arcobacter distribution and its epidemiological characteristics as well as recent advances in its laboratorial diagnosis. Our aim is to provide valuable information for researchers interested in this area.
Ethyl Carbamate in Wine: A Review
LIU Yang, LI Yunkui, HAN Fuliang, WANG Wanni, LIU Liang
2019, 40(7):  289-295.  doi:10.7506/spkx1002-6630-20180211-131
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Ethyl carbamate (EC), a carcinogen commonly found in wine and other fermented foods, has mutagenicity, multisite carcinogenicity, immunosuppressing and heart rate inhibitory activity. This article presents a systematic review of the health hazards and formation mechanism of EC in wine, worldwide maximum residue limits for it as well as changes in its concentration during wine storage, the factors affecting it and regulatory strategies to reduce and even eliminate it. With this review, we hope to provide a scientific basis for improving the safety of wines in China.
Recent Advances and Future Prospects in Analytical Techniques for Authentication of Edible Bird’s Nest
MA Xueting, ZHANG Jiukai, CHEN Ying, LIANG Jinzhong
2019, 40(7):  296-303.  doi:10.7506/spkx1002-6630-20180322-289
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Edible bird’s nest (EBN) is the nest of swiftlet and other closely related species of the Aerodramus genus, which mainly inhabit in Southeast Asian countries such as Malaysia and Indonesia. Since ancient times, EBN has been regarded as a precious and valuable traditional Chinese medicinal material and food material. In recent years, the consumption of EBN in China is growing annually. Driven by huge profits, economically motivated adulteration has been found in the whole supply chain of EBN. Authentication of EBN has been moving forward with innovations in order to realize the effective supervision of EBN quality. In this article, we illustrate the current status of EBN authentication with respect to adulteration identification, identification of species and geographical origin and traceability. Future research priorities and trends are also discussed. This review is expected to provide useful information for researchers interested in this field.
Advances in Identification of Sea Cucumber
HU Ranran, XING Ranran, ZHANG Jiukai, GE Yiqiang, CHEN Ying
2019, 40(7):  304-313.  doi:10.7506/spkx1002-6630-20171130-373
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Sea cucumber is broadly favored by consumers due to its high nutritional value and great taste. There are many kinds of sea cucumber products on the market, and the quality and price of various sea cucumber products are different. Nowadays, driven by economic benefits, a number of people mislabel and adulterate high valued sea cucumber products, which has greatly harmed the interests of consumers. Beginning with the current status of adulteration of sea cucumber, this review summarizes the recent progress in the identification of sea cucumber from morphological, physicochemical and molecular biological perspectives. Finally, we discuss future directions in this area of research.
A Review of the Application of Superchilling on Beef and Mutton
CHEN Xue, LUO Xin, ZHU Lixian, DONG Pengcheng, HANG Mingshan, HAO Jiangang, ZHANG Yimin
2019, 40(7):  314-319.  doi:10.7506/spkx1002-6630-20180123-313
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Superchilling (–0.5 to –2.8 ℃) can inhibit the activity of endogenous proteolytic enzymes in meat and slow down the growth of most bacteria, consequently maintaining good quality of meat products. However, the current literature lacks a systematic review of the effect and underlying mechanism of superchilling on the quality of beef and mutton; notably, it is uncertain yet whether superchilling causes a positive or negative effect on meat tenderness. In this review, we present recent progress in understanding the effect of superchilling on the tenderness of beef and mutton as well as its effect on meat color, flavor (lipid oxidation), purge loss, and bacterial growth. Additionally, the existing problems and future trends are also discussed. With this review, we hope to provide theoretical guidance for industrial application of superchilling on fresh meat in China.
A Comparison of China’s Previous and Current National Standards for Raw Milk with Respect to Major Quality Indexes
GU Mei, ZHENG Nan, LIU Huimin, MENG Lu, ZHAO Shancang, DONG Yanjie, SU Chuanyou, ZHAO Huifen, LI Songli, WANG Jiaqi
2019, 40(7):  320-327.  doi:10.7506/spkx1002-6630-20171203-022
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This article provides an overview of the historical evolution of China’s national standard for raw milk. A comparison of the national standards issued from 1977 to 2010 is made with respect to scope of application, definition, technical requirements and other aspects. Furthermore, this article summarizes the national standards for raw milk of several other countries. It is expected that this review can provide valuable information for future revision of China’s national standard for raw milk.
Monoterpene Compounds in Hops and Beer: A Review
HONG Kai, MA Changwei
2019, 40(7):  328-334.  doi:10.7506/spkx1002-6630-20180306-074
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Monoterpene compounds are important components in hops and beer, responsible for the typical hop aroma attributes in beer. In nature, these compounds exist in both free and glycosidically bound forms. This review focuses on recent progress in understanding the monoterpene biosynthesis pathways, the key enzymes and genes involved in monoterpene synthesis in hops and the important enzymes responsible for the conversion of monoterpene alcohols during beer fermentation. Meanwhile, the change of monoterpenoids in hops and beer and the factors affecting it, as well as the structures and contents of glycoside-bound monoterpenoids and analytical methods for the analysis of these compounds are also reviewed in this paper. Finally, future research directions are discussed.
Advances in Our Understanding of the Transgalactosylation Activity of β-Galactosidase from Bifidobacteria and Lactic Acid Bacteria
JIANG Chenbo, HANG Feng
2019, 40(7):  335-341.  doi:10.7506/spkx1002-6630-20180302-024
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Bifidobacteria and lactic acid bacteria are generally recognized as safe (GRAS) microorganisms and are good sources of β-galactosidase (β-gal). β-gal with transgalactosylation activity from some strains of bifidobacteria and lactic acid bacteria can be used to produce prebiotic galactooligosaccharides (GOS) with lactose as the substrate. However, the β-gal producer and reaction conditions have an impact on the yield and composition of GOS products. Therefore, this review summarizes bifidobacteria and lactic acid bacteria strains that can produce β-gal with transgalactosylation activity and compares the enzymatic properties of β-gal from both microbial sources. This review also sheds light on the application of β-gal in GOS synthesis.
Recent Progress in Molecular Characterization and Detection of Sesame Allergens
MA Xiuli, HUANG Wensheng, ZHANG Jiukai, HAN Jianxun, GE Yiqiang, CHEN Ying
2019, 40(7):  342-351.  doi:10.7506/spkx1002-6630-20171220-247
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Food allergy has become a worldwide public health concern. As one of the most common food allergens, sesame has been intensively researched recently. Seven allergens in sesame have been recognized (Ses i 1–7). This article summarizes recent worldwide regulations on the management of sesame allergy, the structural characteristics of sesame allergens and the effects of processing on their structure and allergenic activity, as well as the detection methods for sesame allergens. This review is expected to provide a theoretical basis for eliminating or reducing the allergenicity of sesame allergens and for the implementation of allergen labeling. Finally, we present the current status of knowledge of sesame allergens and discuss future research trends.