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15 March 2024, Volume 45 Issue 5
Basic Research
The Study on the Mechanism of NO-Mediated Hypoxia-Inducible Factor-1α Activation on Glycolysis and Tenderness of Postmortem Yak Meat
SUN Nan, ZHU Xijin, XIN Keqi, HAN Ling, YU Qunli
2024, 45(5):  1-9.  doi:10.7506/spkx1002-6630-20230419-182
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This study aimed to investigate the effects of nitric oxide (NO)-mediated hypoxia-inducible factor-1α (HIF-1α) on the glycolysis and tenderness of postmortem yak muscle and its regulatory mechanism. In this study, Yak Longissimus dorsi was injected with 0.9% saline (control), 200 μmol/L S-nitrosoglutathione (GSNO), 200 μmol/L GSNO + 100 μmol/L YC-1 (HIF-1α inhibitor) or 200 μmol/L GSNO + 50 μmol/L PD98059 and aged, and NO level, HIF-1α, mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway activation, glycolysis-related enzyme activities, and shear force of muscle were analyzed at different aging time points (3, 6, 9, 12, 24 and 72 h). The results revealed that NO levels in the GSNO group were significantly higher than those in the control group during 3–72 h (P < 0.05), reaching a peak at 6 h. ERK1/2 and p-ERK1/2 expression levels were higher in the GSNO group than the control and GSNO + PD98059 groups during 3–72 h (P < 0.05), reaching a peak at 24 h. HIF-1α expression level in the GSNO group was significantly higher than that in the control and GSNO + YC-1 groups (P < 0.05), peaking at 12 h. Hexokinase (HK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) in the GSNO group reached their maximum values at 9, 12 and 12 h, respectively (P < 0.05) and were significantly higher than those in the control group; at 3, 12 and 72 h, the glycolytic potential in the GSNO group was significantly higher than that in the two other groups (P < 0.05); at 6, 9 and 72 h, the pH in the GSNO group was significantly lower than that in the other groups (P < 0.05). In addition, shear force and hematoxylin and eosin (HE) staining were used to assess the tenderness of yak meat. Shear force, myofiber cross-sectional area and diameter were lower and the space between myofibers was higher in the GSNO group than in the two other groups. In conclusion, during the early period of postmortem aging, NO mediates the MAPK/ERK signaling pathway, thereby activating HIF-1α expression and upregulating HK, PK and LDH activity, accelerating the rate of glycolysis of and reducing pH, and ultimately improving the tenderness of yak meat. The results of this study may serve as a potential regulatory mechanism for regulating the tenderness of yak meat and provide a theoretical basis for improving the theoretical system of glycolysis and tenderness during postmortem aging.
Use of the Fermi Function to Describe Wheat Four Water Sorption Hysteresis: Model Parameters χ and k Based on Vrentas-Vrentas Theoretical Simulation
YANG Yi, ZHAO Xuewei, WEI Xiaoxiao, WANG Hongwei, ZHANG Hua
2024, 45(5):  10-17.  doi:10.7506/spkx1002-6630-20230821-151
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Water sorption and its hysteresis are widespread phenomena that are important for food processing and food quality. In the present study, water sorption and desorption isotherms of wheat flour were measured at three temperatures using a dynamic vapor sorption (DVS) instrument, and modeled according to the Vrentas-Vrentas (VV) theory. Results showed that the degree of water sorption hysteresis decreased with an increase in temperature. In addition, overlapping between desorption and sorption isotherms was observed at high water activity. Based on this, an approach was proposed to determine the critical water content at which glass transition occurs. For both water sorption and desorption, the Flory-Huggins interaction parameter χ varied with the volume fraction of water, and a modified Fermi function was proposed using the Peleg model to describe this relationship. When desorption isotherms were modeled based on the sorption parameter χ, the VV model parameter k was expressed as a function of the volume fraction of water using a Fermi-type function.
Food Chemistry
Effect of Glutamine Transaminase on Physicochemical Properties of Chestnut Flour Dough
LI Tao, ZHOU Li, XU Yuanjie, YUAN Songkai, CAO Yanguang, HAO Jianxiong, LIU Junguo
2024, 45(5):  18-23.  doi:10.7506/spkx1002-6630-20230828-203
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The effect of glutamine transaminase (TG) addition at varying concentrations (0, 0.9, 1.8, 1.8, 2.7 and 3.6 U/g, based on the total mass of chestnut flour) on the texture, rheological, and gelatinization characteristics of chestnut flour dough was investigated and analyzed in terms of changes in the content of free sulfhydryl groups and the microstructure of chestnut dough was observed via a scanning electron microscope (SEM). The results showed that the incorporation of TG resulted in enhanced viscosity, hardness, elasticity, chewiness, and resilience of chestnut dough. Compared with the blank control group, the addition of TG at 2.7 U/g increased the final viscosity by 6.8 cP, hardness by 7.55 g, elasticity by 0.38, chewiness by 33.62 g, and resilience by 0.118, leading to a more stable internal structure. As TG addition increased, both the elastic modulus and viscosity modulus of chestnut dough showed an upward trend, contributing to an improvement in viscoelasticity. This enhancement strengthened the dough’s resistance to deformation and consequently improved its stability and processing performance. The content of free sulfhydryl groups in chestnut dough decreased with increasing TG addition, and decreased by 0.16 mmol/g at 2.7 U/g compared with the blank control group. However, it was observed that excessive TG addition led to excessive protein cross-linking, exposure of starch particles, and a subsequent reduction in the overall stability of the dough. This study suggests that the addition of 2.7 U/g of TG has the most pronounced effect on enhancing the physicochemical properties of chestnut dough.
Effect of Ferulic Acid on Thermo-Mechanical Properties of Whole Wheat Dough and Texture Quality of Whole Wheat Steamed Bread
SU Anxiang, YANG Qin, LI Wen, PEI Fei, MA Gaoxing, MA Ning, HU Qiuhui
2024, 45(5):  24-30.  doi:10.7506/spkx1002-6630-20231201-006
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This study investigated the effects of adding ferulic acid (FA) on the structural and thermo-mechanical properties of whole wheat dough as well as the texture quality and pore distribution of steamed whole wheat bread. The weakening degree of gluten proteins, starch gelatinization properties and whole wheat doughs incorporated with different proportions (0.5%, 1.0% and 1.5%) of FA were measured using a Mixolab apparatus. The microstructure was examined through scanning electron microscope (SEM). The quality changes of steamed whole wheat bread were evaluated by analyzing its textural properties and pore distribution. The results showed that compared with the control group, the addition of FA significantly shortened dough development time and stability time (P < 0.05), which were shortened by 21.02% and 42.41% upon the addition of 0.5% FA, respectively. The addition of 0.5% FA also promoted gluten proteins to form a continuous and uniform network structure, enhanced the water-holding capacity of whole wheat dough, effectively slowed down water loss from the core of steam whole wheat bread, and increased the specific volume of steamed whole wheat bread by 20.26%, thereby markedly improving the texture quality of steamed whole wheat bread in terms of microstructure, elasticity and cohesiveness. However, higher concentrations of FA (1.0%–1.5%) could lead to rupture of the gluten network structure, which negatively affected the rheological properties and texture quality of whole wheat dough. The results of this study will provide a new solution to the key problems of traditional steamed whole wheat bread such as rough taste and hard texture and provide the theoretical basis for improving the rheological properties of whole wheat dough and the texture quality of steamed whole wheat bread.
Bioengineering
Screening and Fermentation Performance of Highly Efficient Starter Cultures for Semi-Dry Douchi
WANG Zeliang, DENG Weiqin, LIU Shuliang, LI Xiongbo, CHEN Xiangjie, FAN Zhiyi, LI Ting, LI Heng, ZHANG Qisheng, LI Long
2024, 45(5):  31-39.  doi:10.7506/spkx1002-6630-20230606-051
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To select high-efficiency strains suitable for semi-dry black douchi fermentation, this study compared and analyzed the koji-making effects of six Aspergillus oryzae strains and one Lichtheimia corymbifera strain with large differences in enzyme-producing capacity. The results showed that A. oryzae HN3.042, DM1 and DM2 had a strong ability to metabolize amylase, and the fermented douchi had a lower L* value. A. oryzae 24M-1, 30M-1, and PNM003 had a strong ability to produce protease, aminopeptidase, and carboxypeptidase, resulting in greater utilization of protein substrates and higher contents of total acid and amino nitrogen in the fermented douchi. In terms of volatile flavor substances, the douchi fermented with stains HN3.042, DM1, and DM2 had a relatively higher content of 1-octen-3-ol, isovaleric acid, and 4-methylpentanoic acid. The douchi fermented with strains 24M-1, 30M-1, and PNM003 had a relatively higher content of trans-2-nonenal, 3-octanone, and isophorone, resulting in richer and better flavor quality. L. corymbifera QM3 had lower enzymatic activity when compared with A. oryzae, resulting in poorer physicochemical indicators, lower contents of free amino acids and volatile flavor substances and poorer quality in douchi. The study suggests that the quality of douchi is related to the enzyme-producing capacity of the koji mold. The predominance of amylase in the koji enzyme system is conducive to the formation of color and acidic flavor substances in douchi, while with the predominance of proteolytic enzymes is conducive to the formation of amino nitrogen and good flavor quality in douchi.
Determination of Biological Activity of Monascus Cheese and Screening of ACE Inhibitory Peptides
JIA Xiangfei, ZHENG Yuanrong, LIU Zhenmin, WU Hanqing, ZHOU Yangyang
2024, 45(5):  40-48.  doi:10.7506/spkx1002-6630-20230830-228
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This study aimed to investigate the impact of Monascus on bioactive peptides, particularly angiotensin-converting enzyme (ACE) inhibitory peptides, during cheese maturation. The content of soluble nitrogen, α-glucosidase and ACE inhibitory activities during the ripening process were investigated. Cheese not inoculated with Monascus as a control group. The peptide profile of Monascus cheese was identified. The potential bioactive peptides were screened by bioinformatics and molecular docking, and the selected peptides were synthesized and evaluated. The results showed that compared with the control group, the pH 4.6 soluble nitrogen content (pH 4.6-SN) and trichloroacetic acid soluble nitrogen (TCA-SN) of Monascus cheese were increased by 57.98% and 38.34%, and the α-glucosidase and ACE inhibitory activities were increased by 32.21% and 73.98%, respectively. A total of 1 796 peptides were identified in the extract of Monascus cheese, including 51 ACE inhibitory peptides, 28 antioxidant peptides and 7 glucose-lowering peptides. Two ACE inhibitory peptides YPFPGPI and FPEVFGK were selected, whose half-maximal inhibitory concentration values were 207.31 and 410.61 μmol/L, respectively. The inhibition type was non-competitive. This study has provided a rapid screening method for ACE inhibitory peptides, and has proved that the addition of Monascus in cheese can effectively improve the ACE inhibitory activity, which provides a reference for exploring the potential functional properties of Monascus cheese.
Enzymatic Properties of Antifungal Endochitinase and Its Function in the Preparation of Chitosan Oligosaccharides
ZHAO Jiechang, WANG Qiyuan, SONG Kexin, CHEN Teng, WANG Feng, YANG Jie, GAO Zhaojian
2024, 45(5):  49-58.  doi:10.7506/spkx1002-6630-20230819-139
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In order to develop chitin and chitosan bioconversion of active oligosaccharides and achieve the application of chitinase in food preservation and biocontrol, chitinase (ChiA-Sa62) was isolated and purified from Streptomyces aureofaciens XZ-Sa62, and its bioconversion and antibacterial function were studied. ChiA-Sa62 was purified by Q-Sepharose Fast Flow, Sephadex G-100 chromatography, and reverse phase high performance liquid chromatography (RP-HPLC), with a purification factor of 41.3 and a specific activity of 1 119.8 U/mg. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) showed that ChiA-Sa62 was a single subunit protein with a molecular weight of 62.55 kDa. ChiA-Sa62 exhibited maximum activity at 50 ℃ and pH 5, and exhibited good stability below 60 ℃ and within pH range of 3.0-9.0. Ca2+, Mn2+, Mg2+, and Co2+ could activate enzyme activity. ChiA-Sa62 had a specific endonucleating hydrolysis activity on chitin and chitosan with a degree of deacetylation of 75%. Thin layer chromatography (TLC) showed that the hydrolysis products were 2-5 N-acetylglucosamine (GlcNAc) units of chitosan oligosaccharides and 2-4 D-glucosamine (GlcN) units of chitosan oligosaccharides, respectively. The colloidal chitin was used as the substrate, with ChiA-Sa62 Km and Vmax values of 2.75 mg/mL and 64.52 U/mg, respectively. ChiA-Sa62 strongly inhibited the tested pathogenic fungi, and propidium iodide (PI) staining showed that ChiA-Sa62 disrupted the integrity of the cell membrane of Botrytis cinerea. The hydrolyzed chitosan oligosaccharide had antibacterial activity against pathogenic G- bacteria (Escherichia coli and Pseudomonas aeruginosa) and G+ bacteria (Staphylococcus aureus and Bacillus cereus). LIVE/DEAD staining showed that chitosan oligosaccharide could cause the death of S. aureus. ChiA-Sa62 chitin and chitosan have great potentials for application in biotransformation, food preservation, and biological control.
Effect of Adding Green Tea on Physicochemical Characteristics and Bacterial Diversity of Daqu during Fermentation
ZHAO Liang, WANG Xinye, LUO Zhenbiao, JIANG Lu, WU Fuyong, ZHONG Yanxia, WANG Xiangyong
2024, 45(5):  59-68.  doi:10.7506/spkx1002-6630-20230821-152
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In this study, high-throughput sequencing technology and statistical analysis were employed to explore the effects of adding green tea at proportions of 10%, 20%, and 30% on physicochemical characteristics, bacterial community diversity and succession of Daqu during fermentation compared with pure wheat Daqu (control). The results showed that the addition of green tea significantly increased the bacterial community diversity of Daqu and improved its saccharification capacity, moisture content and acidity. However, the increase in tea addition did not exhibit a proportional relationship with the community diversity. The unique evolutionary structure of the bacterial communities in different types of Daqu was found to be the major factor affecting the physicochemical characteristics of Daqu. During the fermentation process, all four Daqu exhibited differentiation in bacterial community succession starting from the thermophilic stage, thereby leading to the formation of their unique community structure at the end of the fermentation process. The phyla Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria showed varying influences on the community succession of the four Daqu samples, thus making each of them have different physicochemical characteristics. Specifically, Pseudomonas was an important bacterial genus contributing to the physicochemical characteristics of the control and 10% tea Daqu, while Weissella and Pediococcus, were important contributors to the physicochemical characteristics of the 20% tea Daqu. Bacillus was found to be a significant bacterial genus contributing to the physicochemical characteristics of the 30% tea Daqu. This study provides a theoretical basis for process optimization in the production of tea-added Daqu and for the development of multi-raw material fermentation starters. It also has implications for improving the preparation process of Daqu and the application of tea in Daqu making.
Nutrition & Hygiene
Effect and Mechanism of Andrias davidianus Peptide Supplementation Combined with Treadmill Exercise on Body Mass Loss in Obese Rats
QIAN Jin, FANG Shuangxi, HU Yating, MA Kun, LIU Hui, JIA Shaohui
2024, 45(5):  69-77.  doi:10.7506/spkx1002-6630-20221124-288
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Objective: To evaluate the antiobesity effect and underlying mechanism of Andrias davidianus peptide (ADP) supplementation combined with treadmill exercise. Methods: A mouse model of obesity was established by feeding mice a high-fat diet (HFD), and the obese mice were randomly divided into four groups: model, treadmill exercise (Ex), ADP and ADP combined with treadmill exercise (ADP + Ex). The rats in the Ex group were subjected to a six-week treadmill exercise training. The rates in the ADP group were gavaged with ADP for six weeks. The rats in the ADP + Ex group were treated with ADP supplementation combined with treadmill exercise training. Normal Sprague Dawley (SD) rats were used as the control (CN) group. Body mass and food intake were recorded each week, and the serum levels of glucagon-like peptide-1 (GLP-1), neuropeptide Y (NPY), irisin, leptin, triglycerides (TG), total cholesterol (TC), low density lipoprotein (LDL) and high density lipoprotein (HDL) were investigated by enzyme-linked immunosorbent assay (ELISA). Western blot was used to detect the expression of appetite-regulated proteins (NPY and proopiomelanocortin (POMC)) and energy metabolism-related proteins. Results: Body mass, inguinal and epididymal fat accumulation, food intake, and serum TG, TC and LDL levels significantly decreased in the ADP + Ex group compared with the model group. In addition, ELISA results revealed that combination of ADP supplementation with treadmill exercise reduced the serum levels of NPY and leptin but increased the serum concentrations of GLP-1 and irisin in obese rats. Western blot analysis showed that ADP supplementation combined with treadmill exercise greatly up-regulated the expression of POMC and energy metabolism related proteins (irisin, phospho-adenosine monophosphate-activated protein kinase, peroxisome proliferator-activated receptor γ co-activated factor-1α, and fibronectin type III domain containing protein 5), but down-regulated the expression of NPY. Conclusion: The combination of ADP with aerobic exercise can effectively alleviate HFD-induced obesity, thereby providing a new promising strategy to alleviate HFD-induced obesity.
Protective Effect and Mechanism of Rosa roxburghii Tratt Polysaccharides on Isoprenaline-Induced Myocardial Ischemia in Mice
WANG Qiwen, LUO Qing, XU Yangyang, WANG Ximin, ZENG Congyan, DAI Weibo, PENG Weiwen, DONG Gengting
2024, 45(5):  78-85.  doi:10.7506/spkx1002-6630-20230823-171
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Objective: To explore the protective effect and underlying mechanism of Rosa roxburghii Tratt polysaccharides on isoproterenol (ISO)-induced myocardial ischemia (MI) in mice. Methods: Forty male C57BL/6 mice were equally and randomly divided into five groups: control, model, propranolol (30 mg/kg), low- and high-dose R. roxburghii Tratt polysaccharides (50 and 100 mg/kg). Mice were pretreated with R. roxburghii Tratt polysaccharides for seven days followed by intraperitoneal injection of isoprenaline (ISO, 10 mL/kg) or physiological saline for seven days. Electrocardiograms were recorded 1 h after the last injection. The mice were anesthetized and hearts were excised to calculate cardiac index. Hematoxylin-eosin (HE) staining was used to evaluate myocardial pathological changes. The area of myocardial infarction was detected by 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining. Serum lactate dehydrogenase (LDH) activity, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were detected by biochemical kits. The protein expression of NADPH oxidase 2 (NOX2), B-cell lymphoma 2 (Bcl2), Bcl2-associated X (Bax), caspase 3, nuclear factor E2-related factor 2 (Nrf2), Kelch-like ECH-related protein 1 (Keap1) and heme oxygenase 1 (HO-1) in myocardial tissues were detected by Western blot. Results: Compared with the control group, heart coefficient was significantly increased in the model group and the ST segment of electrocardiogram was significantly elevated. Significantly pathological changes and increased myocardial infarction were found in the myocardial tissue of mice in the model group. Serum MDA and LDH levels were increased (P < 0.001) and SOD activity was inhibited in the model group (P < 0.05). The protein expressions of Nrf2, HO-1 and Bcl2 were significantly down-regulated (P < 0.05 or P < 0.01), while those of Keap1, NOX2, Bax and caspase 3 were significantly up-regulated in the model mice (P < 0.05 or P < 0.01). The ST segment of electrocardiogram was lowered, and myocardial pathological changes were restored in the polysaccharide treatment group compared with the model group. In addition, serum MDA and LDH levels were significantly decreased (P < 0.001) and SOD activity was significantly increased (P < 0.01 or P < 0.001). The protein expressions of Nrf2, HO-1 and Bcl2 were significantly up-regulated (P < 0.05 or P < 0.01), while those of Keap1, NOX2, Bax and caspase 3 were significantly down-regulated (P < 0.05, P < 0.01 or P < 0.001). Conclusion: R. roxburghii Tratt polysaccharides ameliorate ISO-induced myocardial ischemia though reducing oxidative stress, regulating caspase-3, Bax and Bcl2 protein expressions and suppressing myocardial cell apoptosis via the Keap1-Nrf2 signaling pathway.
Component Analysis
Proteomic Analysis of the Effect of Proteasome on Quality Changes in Qinchuan Beef during Postmortem Storage
HU Lijun, WANG Jinxia, LI Rong, ZHANG Qian, CHEN Xueyan, LI Yalei, LUO Ruiming
2024, 45(5):  86-93.  doi:10.7506/spkx1002-6630-20230412-118
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In this study, the Longissimus dorsi muscle of Qinchuan beef stored at 4 ℃ after slaughter was determined for its quality indicators, energy level and proteasome activity. Meanwhile, differentially expressed proteins (DEPs) associated with proteasomes were identified. Bioinformatics methods were used to analyze the response mechanism of proteasomes to the quality and energy metabolism of postmortem beef. The results showed that pH decreased and then increased with increasing storage time, b* and myofibrillar fragmentation index (MFI) increased, L*, a*, centrifugal loss, cooking loss and shear force increased first and then decreased, the contents of the basic energy substances ATP, ADP and AMP decreased, and the relative activity of the 20S proteasome decreased significantly (P < 0.05). The correlation analysis showed that the activity of the 20S proteasome was significantly negatively correlated with b* (P < 0.05), positively correlated with ADP content (P < 0.05), positively correlated with AMP content (P < 0.01), and negatively correlated with MFI (P < 0.01), indicating a close relationship between proteasome activity and energy metabolism as well as beef quality. Using 4D label-free quantitative (LFQ) proteomics, eight differentially expressed proteasome subunits and 27 DEPs were identified. Gene Ontology (GO) annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that these proteasome subunits and related DEPs had molecular functions such as endopeptidase activity, actin binding, microfilament motor activity, and were involved in biological processes such as ubiquitin-dependent proteolytic metabolism, skeletal muscle contraction, muscle contraction, and glycolysis, thus causing changes in the quality of Qinchuan beef. During the early postmortem period, the proteasomes regulated the biological pathways by consuming energy substances to catabolize proteins, and during the later period, when the energy substances were depleted, the proteasomes catabolized proteins in postmortem beef through the energy provided by glycolysis and non-ATP-dependent proteasome subunits, which eventually affected the quality of Qinchuan beef.
Application of Conductivity Combined with Various Other Instrumental Analyses in the Detection of the Freshness and Yolk-to-White Ratio of Liquid Egg
DOU Wenhao, WANG Hailing, HUANG Zilong, YANG Fuming, CHI Yuan, CHI Yujie
2024, 45(5):  94-101.  doi:10.7506/spkx1002-6630-20230831-238
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This study established a rapid and efficient technique to detect the freshness and yolk-to-white ratio of liquid egg based on conductivity combined with salinity, total dissolved solids (TDS), pH, and color parameters. The results showed that during the storage period of 0-45 days at 4 ℃, the conductivity, salinity, and TDS of egg yolk and egg white gradually increased. The color difference index and egg yolk pH of both decreased significantly, while the pH of egg white gradually increased. It was found that the accuracy of conductivity in detecting the freshness of egg yolk and egg white was 91% and 89%, respectively, while that of conductivity combined with other indices was 94%. Based on this, the criteria to classify liquid egg into four grades of AA, A, B and C were established for the first time. AA liquid eggs were selected to detect yolk-to-white ratio using conductivity as the major index combined with salinity, TDS and pH. The experimental results proved that the conductivity, salinity, TDS and pH were all highly significantly and linearly correlated with the proportion of egg yolk in liquid egg; therefore, the proportion of egg yolk in unknown liquid egg samples could be detected based on the regression equations. The ExpAssoc model showed an average relative error of 8.87%, indicating high reliability. The results of this study provide a theoretical basis for the detection of the freshness and yolk-to-white ratio of blended liquid egg, and provide a reference for industrial producers of liquid egg.
Metabolic Profiling of Non-volatile Compounds during Xinyang Maojian Tea Processing Using Untargeted Metabolomics
KONG Yashuai, CHEN Lingzhi, CHENG En, ZHU Yao, WANG Jingjing, WANG Xiao, WANG Zihao, CHEN Yi, YIN Peng, GUO Guiyi
2024, 45(5):  102-110.  doi:10.7506/spkx1002-6630-20230824-188
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In order to understand the dynamic changes of non-volatile metabolites in Xinyang Maojian tea during processing, Xinyang Maojian tea samples from Xinyang tea population (Camellia sinensis cv. Quntizhong) taken during processing were systematically analyzed by non-targeted metabolomics. A total of 1 000 non-volatile metabolites were identified, and multivariate statistical analysis showed that non-volatile metabolites changed significantly during the processing stages after fixation. Meanwhile, a total of 53 differential compounds were screened out, including amino acids, catechins, flavonoid glycosides, lipids, purine nucleosides and organic acids that were identified as the key components contributing to the flavor and quality of Xinyang Maojian tea. In particular, the relative contents of some acylated flavonoid glycosides, lysophosphatidyls and purine nucleosides were significantly elevated during the processing stages after fixation. Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway enrichment analysis showed that the differential compounds were significantly enriched in the pathways of purine metabolism, glycerophospholipid metabolism, phenylalanine metabolism, aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine, and tryptophan biosynthesis, and glycine, serine and threonine metabolism (P < 0.05). This study provides a basis for understanding the formation mechanism of the flavor and quality of Xinyang Maojian tea.
Analysis of Key Aroma Components of Four Kinds of Single Malt Whisky
ZHANG Yi, LI Xiaoyan, NIU Limin, LI Hui, SHEN Bo, CHEN Wenbo, SHANGGUAN Jingyu
2024, 45(5):  111-117.  doi:10.7506/spkx1002-6630-20230829-220
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Aroma compounds in Scottish Macallan single malt and Japanese Yamazaki single malt whisky of two ages each were analyzed by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS). The results showed that esters, acids, and alcohols were the most abundant volatile compounds in all whisky samples, accounting for over 90% of the total. Odor activity value (OAV) was calculated for 58 of the 243 volatile compounds identified. Phenylethyl acetate, acacia alcohol, and trans-nerolid alcohol in Scotch Macallan whisky had higher OAVs, contributing to obvious floral aroma, while Japanese Yamazaki whisky had an obvious fruity aroma, due to higher OAVs of ethyl isovalerate, ethyl 2-methylbutyrate, and 1-decanol. Two-dimensional hierarchical clustering analysis suggested that the typical aroma compounds in Yamazaki whisky were 2-methylbutyrate ethyl ester, butyrate ethyl ester, and isovalerate ethyl ester, while those in Macallan whisky were acacia alcohol, trans-nerolid alcohol, and damastone. Additionally, principal component analysis (PCA) confirmed that each whisky had unique aroma characteristics. This study suggests that flavor characteristics are an important index for the evaluation of different whisky samples.
Quality Analysis of ‘Akizuki’ Pear Fruit (Pyrus pyrifolia) from Different Geographical Origins by Gas Chromatography-Ion Mobility Spectrometry
HE Wanlin, SHI Lu, LIN Menghua, LI Yahui, LIANG Ying, ZHANG Zhiyong
2024, 45(5):  118-125.  doi:10.7506/spkx1002-6630-20230828-196
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In order to explore the quality characteristics of ‘Akizuki’ pear fruit (Pyrus pyrifolia) from different regions, the quality indexes of pear fruit from six geographical origins were determined, and gas chromatography-ion mobility spectrometry (GC-IMS) was used to determine their volatile aromatic compounds. The results showed that the titratable acid content of pear fruit from Ningling, Henan province was significantly higher than that of pear fruit from the other regions. There were significant differences in the contents of soluble solids, total flavonoids, and total phenols among some regions (P < 0.05). Totally 76 volatile aroma components were identified in the pericarp and pulp of pear fruit from the six different regions, including 23 esters, 20 aldehydes, 11 alcohols, 4 ketones, 1 olefin, 3 acids, and 14 other compounds. There were 24 more volatile aroma components in the pericarp than in the pulp. The unique volatile aroma components including isobutyl acetate, methyl butyrate, and isovaleraldehyde were detected in pear fruit from Weixian, Hebei province when compared with the other regions. Similarity analysis from fingerprints showed clear distinction among pear fruit from different regions. This study has provided information about the quality and aroma characteristics of ‘Akizuki’ pear fruit from different regions, and demonstrated that GC-IMS has potential application prospects for geographical origin differentiation and traceability of ‘Akizuki’ pear fruit.
Analysis of Key Aroma Compounds in Fermented Goji Berry Wine
LIU Yaran, LI Junlong, GU Peishan, LI Ruotong, ZHU Baoqing, ZHANG Bolin
2024, 45(5):  126-136.  doi:10.7506/spkx1002-6630-20230602-016
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The volatile aroma compounds of wine fermented from goji berries were evaluated by liquid-liquid extraction-solvent-assisted evaporation-gas chromatography-mass spectrometry-olfactometry (LLE-SAFE-GC-MS-O) combined with GC-quadrupole-MS (GC-qMS) and GC-Orbitrap-MS. The key aroma compounds were identified by aroma reconstitution and quantitative descriptive sensory analysis. The results showed that ethyl esters (ethyl cinnamate, ethyl acetate, ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, ethyl lactate, ethyl octanoate, and ethyl decanoate), other esters (isoamyl acetate and isoamyl lactate), C13-norisoprenoids (β-damascenone and β-ionone), volatile phenols (4-ethylguaiacol, eugenol, 2,4-di-t-butylphenol), alcohols (1-octen-3-ol, benzyl alcohol, phenylethyl alcohol and isopentyl alcohol) and other compounds (naphthalene, methionol, octanoic acid and 2-acetylpyrrole) contributed the major aroma attributes of goji berry wine. This finding will help to enrich and improve the theoretical basis of the aroma of goji berry wine and lay the foundation for aroma enhancement and quality improvement of goji berry wine.
Dynamic Headspace Combined with Gas Chromatography-Olfactometry-Mass Spectrometry for Analysis of Volatile Components in Baked Green Tea from Different Cultivars
LI Weixuan, XIE Dongchao, SHAO Chenyang, ZHANG Yue, LÜ Haipeng, LIN Zhi, DU Qizhen, ZHU Yin
2024, 45(5):  137-148.  doi:10.7506/spkx1002-6630-20230624-177
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In this study, a dynamic headspace (DHS) combined with thermal desorption/gas chromatography-mass spectrometry (TD/GC-MS) method was established to analyze the volatile composition of baked green tea. Extraction parameters including tea amount, trapping temperature, incubation temperature, total purge volume, purge rate, and drying rate were optimized. Furthermore, the key odorants of baked green tea made from different tea cultivars were identified by gas chromatography-olfactometry-mass spectrometry (GC-O-MS). The results indicated that the optimal extraction conditions were as follows: tea amount of 200 mg, trapping temperature of 70 ℃, incubation temperature of 70 ℃, total purge volume of 350 mL, purge rate of 10 mL/min, and drying rate of 10 mL/min. A total of 74 volatile components were identified in green tea made from three representative varieties. Multivariate statistical analysis showed that the aroma compounds of the three green teas varied greatly, and 18 key differential volatile aroma components were identified. The contents of isopropylidesneacetone and linalool in LongJing 43 (LJ 43) baked green tea were the highest among these three teas. Fuding Dabaicha (FDDB) baked green tea contained the highest levels of 6-methyl-5-heptene-2-one, octanal, cyclohexanone, acetophenone, copaene and epicubenol. A total of 28 odorants were identified by GC-O-MS analysis. The odorants were mainly responsible for odor attributes such as green, refreshing, floral, fruity, herbal, woody and sweet aromas. The total aroma intensity of floral and fruity attributes was the highest, followed by the green and refreshing attributes. Taken collectively, linalool, calamenene, δ-cadinene, 6-methyl-5-heptene-2-one and octanal were the key differential odorants among the three green teas. Linalool contributed significantly to LJ 43 baked green tea, and the other four odorants contributed significantly to the formation of the aroma quality of FDDB baked green tea.
Effect of Composting Treatment of Grape Branches on Wine Quality
TU Qian, DING Weikang, HUANG Yanping, LI Yuanyuan, LIU Shiqiu, MIN Xuwu, ZHENG Changhua, YUAN Chunlong
2024, 45(5):  149-157.  doi:10.7506/spkx1002-6630-20230829-216
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In order to study the effect of applying different proportions of compost made from grape branches in the vineyard on the quality of wine, 8-year-old ‘Pinot Noir’ grapevine was selected for this study, and compost made from 100% crushed grape branches (GB), compost made from 70% crushed grape branches + 30% sheep manure (GM1), compost made from 50% crushed grape branches + 50% sheep manure (GM2), compost made from 30% crushed grape branches + 70% sheep manure (GM3), and 100% sheep manure (SM) were applied to the vineyard , and the no compost addition treatment (CK) was used as a control. One year after fertilization, grape berries were taken to brew wine, and the basic physicochemical indexes of grapes and wine, the phenolic substances, color, and aroma substances and sensory evaluation of wine were determined. The results showed that the composting treatment significantly increased the contents of alcohol, total phenols, total anthocyanins, total flavan-3-ols, and total flavonoids in Pinot Noir wine, with the GM3 treatment showing the greatest increase in the levels of alcohol and titratable acids, by 16.5% and 24.03%, respectively. In terms of color, the composting treatments increased the color saturation of ‘Pinot Noir’ wine. Orthogonal partial least squares-discriminant analysis (OPLS-DA) of aroma substances showed that the major differential aroma substances in ‘Pinot Noir’ wine among different composting treatments were isoamyl alcohol, followed by ethyl acetate, 1-propanol, and phenylethanol, and that composting treatments with the addition of grape branches increased the levels of ethyl acetate, isoamyl acetate, ethyl caproate, and ethyl caproate in ‘Pinot Noir’ wine. In terms of sensory quality, the intensity of astringency, bitterness, and sweetness of ‘Pinot Noir’ wine was enhanced by the composting treatments, and the wine was improved in terms of taste and balance. This study provides a theoretical basis for the comprehensive utilization of grape branch waste and the improvement of wine quality.
Effect of Osmotic Concentration through Polydimethylsiloxane Membrane on Aroma of Freeze-Dried Rose Hydrolat
LIU Xiaoyu, LI Xuesong, SHAN Yanqin, ZHANG Boya, LI Jingming
2024, 45(5):  158-165.  doi:10.7506/spkx1002-6630-20230512-114
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In order to explore the effect of polydimethylsiloxane (PDMS) membrane pervaporation technology on the concentration of freeze-dried rose hydrolat (Rosa damascene), headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the volatile aroma components of freeze-dried rose hydrolat, and its sensory properties and applicability were evaluated by sensory analysis. The results showed that 54 aroma components were detected in rose hydrolat, and its characteristic aroma components including phenylethyl alcohol, citronellol and geraniol accounted for more than 90% of the total, indicating great utilization value. After two osmotic concentration cycles, the rose aroma became more intense and typical, and the content of benzene ring compounds significantly increased, characterized by total odor activity value (OAV) of rose aroma substances increased by 20.47%. The sensory flavor profile analysis also showed similar results: the proportion of floral aroma intensity (M value) increased from 37% to 51%, which was consistent with the result of partial least squares regression (PLSR) validation analysis. Additionally, it was found that the aroma intensity of freeze-dried rose hydrolat obtained after secondary osmosis was similar to that of rose essence sold in the market, and still higher than that of rose soda water sold in the market after 100-fold dilution, demonstrating its potential as a flavor enhancer in daily chemicals and beverages.
Food Engineering
Degradation effect and mechanism of Ochratoxin A in Raisins by Low-Temperature Discharge Plasma
ZHANG Shaojun, ZHANG Wenle, SUN Shoufeng, DUAN Yumeng, WANG Ying
2024, 45(5):  166-173.  doi:10.7506/spkx1002-6630-20230822-165
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In this study, the effect of ochratoxin A (OTA) concentration and discharge voltage on the degradation of OTA in artificially contaminated raisins by low-temperature discharge plasma was explore. The results indicated that OTA in raisins contaminated with 50 μg/mL OTA was completely degraded by plasma treatment for 10 minutes at a discharge voltage of 75 kV. The degraded products of OTA were detected by high performance liquid chromatography-quadruple-electrostatic field orbitrap high resolution mass spectrometry. Based on the primary and secondary mass spectra, two major degraded products with m/z 426.071 5 (B) and m/z 158.154 0 (C) and the possible degradation pathway of OTA were speculated. There was no significant change in the physicochemical quality of raisins before and after plasma treatment, and the relative contents of most acids, aldehydes, alcohols and ketones did not significantly change, except for a significant decrease in the contents of 3-methylbutyric acid, acetic acid and caprylic acid among acids, and a significant increase in the contents of formic acid, valeric acid, and 2-ethylhexanoic acid. The research results suggest that low temperature discharge plasma can effectively degrade OTA while having no significant effect on raisin quality, which can provide a reference for OTA degradation in contaminated foods.
Effect of Ultrasonic Treatment Combined with Enzymatic Hydrolysis on the Multilevel Structure and Adsorption Properties of Maize Starch
YU Yingtao, XIAO Liuyang, YANG Xiaofan, HAN Fujuan, HAN Lihong
2024, 45(5):  174-183.  doi:10.7506/spkx1002-6630-20230323-233
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In order to explore an effective method to improve the adsorption property of maize starch granules, ultrasonic pretreatment at different temperatures (0, 25, 45, and 65 ℃) below the gelatinization temperature combined with α-amylase was used to modify maize starch. The results showed that after ultrasonic pretreatment, the surface of starch granules became rough with grooves on it. The molecular mass, relative crystallinity and short-range molecular order of the starch samples were significantly decreased (P < 0.05). Compared with single enzymatic hydrolysis, the combinatorial treatment increased the specific surface area and pore capacity of starch consequently improving its adsorption performance. With an increase in the pretreatment temperature from 0 to 65 ℃, the water- and oil-adsorbing capacities of starch granules subjected to the combinatorial treatment increased from 114.71% and 142.16% to 144.77% and 189.70%, respectively. Therefore, ultrasonic treatment at high temperature below the gelatinization temperature combined with α-amylase could be an effective method to prepare a green and high efficiency starch-based adsorbent. This study will be helpful for better understanding of the mechanism by which ultrasonic treatment promotes the enzymatic hydrolysis of starch and will provide a theoretical basis for the development of high-efficiency starch-based adsorbents.
Effect of Static Magnetic Field on the Structure and Physicochemical Properties of Fermentation Products of Armillaria mellea
GAO Fei, ZHAO Yunan, ZHANG Xin, ZHANG Silin, CAI Dan, LIU Jingsheng
2024, 45(5):  184-192.  doi:10.7506/spkx1002-6630-20230824-185
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The effect of Armillaria mellea fermentation alone and combined with static magnetic field on the structure and physicochemical properties of zein was explored. Fourier transform infrared (FTIR) spectral analysis showed that static magnetic field treatment changed the secondary structure of the protein during the fermentation process. The analysis of ultraviolet (UV) absorption spectra and intrinsic fluorescence spectra showed that static magnetic field treatment resulted in protein unfolding and group exposure. The results of scanning electron microscopy (SEM) showed that after static magnetic field treatment, the surface of the protein became rougher with obvious pores and increased specific surface area. The results of thermodynamic analysis showed that static magnetic field treatment obviously increased the denaturation temperature of the protein, decreased the particle size, increased the absolute value of the zeta potential, and resulted in increased content of free sulfhydryl groups and decreased content of disulfide bonds. In addition, the physical and chemical properties of the protein were significantly changed by static magnetic field-assisted fermentation. The water and oil retention capacities, emulsification properties, foaming capacity and foam stability were increased significantly, reaching maximum values of 3.86 g/g, 4.22 g/g, 26.83 m2/g, 37.67% and 58.12%, respectively on the 7th day of fermentation. The emulsion stability was decreased significantly, reaching a minimum level of 34.10% on the 7th day. In summary, static magnetic field-assisted fermentation of zein by A. mellea can change its structure of and effectively improve its physical and chemical properties, thereby improving the added value and utilization rate of zein.
Preparation and Quality Characteristics of Ready-to-Eat Shrimp Using Ultra-high Pressure Combined with Sous-Vide Technology
ZENG Xinyao, SUN Ying, JIAO Dexin, ZHU Chen, LIU Huimin
2024, 45(5):  193-200.  doi:10.7506/spkx1002-6630-20230327-244
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In this study, Penaeus vannamei was used to analyze the quality of sous-vide combined with high pressure cooked and freeze-dried shrimp (SPF) and boiled and hot air dried shrimp (BH) prepared by traditional thermal processing. The results showed that compared with BH, SPF had lower hardness, fuller color and higher sensory score, which was more popular with consumers. The content of benzaldehyde was significantly higher in SPF than in BH, and SPF had a more prominent seafood-like flavor. The content of polyunsaturated fatty acids was also higher in SPF than in BH. Meanwhile, a dynamic model was established for shelf life prediction. According to the model, SPF had high oxidative stability. Therefore, sous-vide combined with high pressure can improve the quality and flavor of ready-to-eat shrimp. The results from this study provide a theoretical basis for the large-scale production of high-quality, convenience and ready-to-eat shrimp with unique flavor.
Effects of High Hydrostatic Pressure versus Thermal Pretreatment on the Quality of Vacuum Freeze-Dried Reconstituted Fruit and Vegetable Cubes
YUAN Lin, LIANG Xujuan, CHENG Ruihua, CHEN Guogang, SHI Xun, LAO Fei, LI Xuefeng, WU Jihong
2024, 45(5):  201-209.  doi:10.7506/spkx1002-6630-20230508-055
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Mango, melon, pineapple, and carrot were processed into reconstituted fruits and vegetable cubes by conventional thermal pretreatment (TP) or high hydrostatic pressure (HHP) pretreatment at different pressures followed by freeze drying (FD). The effects of different HHP pressures on the physicochemical quality, bioactive substances, antioxidant activity, and sensory quality of FD fruits and vegetable cubes were investigated. The results showed that compared with TP, HHP significantly increased the a* and b* values, titratable acid content and antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, hydroxyl radical scavenging capacity, and ferric reducing powder), increased the contents of total phenols, flavonoids, and ascorbic acid by 21.11%–30.27%, 59.96%–68.58%, and 13.35%–15.34%, respectively, and increased the contents of volatile alcohols and ketones to 189.65–207.82 and 59.60–81.16 μg/kg, respectively. In addition, the sensory intensities of five aroma attributes and the preferences for color, aroma and taste of HHP-pretreated FD cubes were significantly higher than those of TP-pretreated FD cubes. The sensory quality of FD fruits and vegetable cubes pre-treated at 300 and 500 MPa were closest to that of the non-treatment group. HHP pretreatment improved the antioxidant activity by increasing cell membrane permeability, thereby promoting the release of bioactive and flavor substances. Compared with conventional TP, HHP can effectively improve the quality characteristics of FD fruits and vegetable cubes.
Effect of Mixed Culture Fermentation on the Quality of Non-fried Instant Noodles
ZHANG Weifeng, HUANG Zehua, WANG Yukun, ZHANG Jian, ZHAO Mengmeng, CUI Wanwan, AN Yanxia, YIN Guihong, ZHOU Penghui, ZHAO Yang
2024, 45(5):  210-216.  doi:10.7506/spkx1002-6630-20230724-269
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The effects of mixed culture fermentation with yeast, Lactobacillus bulgaricus and Streptococcus thermophilus on the quality of non-fried instant noodles were studied by rehydration test, texture analysis, electronic nose analysis and scanning electron microscopic (SEM) observation. The results showed that yeast largely affected the rehydration property and texture, while L. bulgaricus and S. thermophilus were mainly responsible for improving the flavor of non-fried instant noodles. The primary fermentation process was conducive to maintaining the cooking tolerance of non-fried instant noodles, while the secondary fermentation process was beneficial to improve the rehydration property and flavor, reducing the rehydration time to 4.0 min; the R(2) and R(7) responses of the rehydrated sample were 2.8 and 2.9, respectively. The SEM results showed that the samples had a uniform pore distribution after the secondary fermentation. Taken collectively, the optimal starter culture for the primary and secondary fermentation was 1.5% yeast + 0.075% L. bulgaricus + 0.075% S. thermophilus.
Effect of Microwave Combined with Metal Ions on the Properties and Structure of Wheat Germ Protein
GUO Yu, JIANG Chenghong, YANG Yuchan, ZHANG Yao, WANG Dongxu, GUO Yuanxin
2024, 45(5):  217-224.  doi:10.7506/spkx1002-6630-20230710-106
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Wheat germ protein (WGP) was extracted from wheat germ powder by alkali dissolution and acid precipitation, and WGP was modified by microwave and metal ion treatment. The functional properties, structure, and molecular mass of WGP before and after modification were determined. The results showed that compared with the control group, the solubility of WGP was increased by 86.61% after the combined treatment, the water-holding capacity (WHC) and oil-holding capacity (OHC) were increased by 22.86% and 82.16%, the emulsifying capacity, emulsion stability and foaming capacity were increased by 120.90%, 15.64% and 116.91%, respectively, and the foaming stability was reduced. The results of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that there was no significant change in the molecular mass of WGP after the combined treatment, while the structure became looser, and the secondary structure exhibited a trend toward a disordered state, mainly manifested as an increase of β-turn and random coil. The combined treatment was superior to either microwave or metal ion treatment alone in improving the functional characteristics of WGP. The combined treatment with microwave and metal ions offers WGP with good functional characteristics, thereby providing WGP the potential to be developed into a new functional food.
Packaging & Storage
Characterization and Analysis of Differentially Expressed Proteins in Raw Milk during Cold Storage
ZHUANG Jiao, JU Ning, ZHU Xiaoxue, LI Yafeng, DING Yuhong, GAO Yan, CHEN Yanhui, QI Jin, YANG Bingkun
2024, 45(5):  225-232.  doi:10.7506/spkx1002-6630-20230608-068
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Using data independent acquisition (DIA) proteomics, the composition and biological functions of differentially expressed proteins in raw milk during cold storage at 4 ℃ for up to 6 days were investigated. A total of 902 proteins were detected. Among them, 70 and 71 differentially expressed proteins were selected during the early (day 0 vs day 3) and late (day 3 vs day 6) stages of refrigeration, respectively. The differentially expressed proteins played an important role in the response to nerve growth factors and the regulation of cells and tissues at the early stage of refrigeration, and were mainly involved in the biological processes of cells. At the late stage of refrigeration, the differentially expressed proteins could regulate the metabolic processes of carbohydrate and RNA, and mainly participated in the sugar metabolic pathways. Protein-protein interaction (PPI) network analysis indicated that cell division control protein 42 homolog (CDC42) was the hub node protein for both refrigeration periods, which was closely related to phagocytosis. These findings revealed the compositional changes and functional diversity of functions in raw milk proteins during refrigeration, which will provide a theoretical basis for the cold storage of raw milk and be of great significance for the quality control of raw milk.
Preparation and Characterization of Modified Guar Gum/Whey Protein/Rutin Composite Membrane and Its Effect on Storage Quality of Agaricus bisporus
LIU Haipeng, LI Ling, HAN Jiali, JIANG Xin, FENG Lei, WANG Jia
2024, 45(5):  233-242.  doi:10.7506/spkx1002-6630-20230425-239
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Modified guar gum and whey protein were used as raw materials for the preparation of a composite film. It was found that when the mass ratio of modified guar gum and whey protein was 1:0.6, the best mechanical properties, barrier properties, and thermal stability of the composite film were obtained; the tensile strength (TS) of the film was 39.92 MPa, the elongation at break was 31.13%, and the thermal decomposition temperature was 147.85 ℃. The composite film could effectively remedy the defects of the single-component films. In addition, the results of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) indicated that the film was smooth and transparent, and the compatibility between modified guar gum and whey protein was good. A modified guar gum/whey protein/rutin composite film (G’/W-R) was prepared by adding rutin to the film. Addition of rutin was found to impart good antioxidant activity to the film. Meanwhile, when applying the composite film to Agaricus bisporus preservation, it was found that G’/W-R could effectively delay the browning of mushroom, maintain high hardness, and inhibit the respiratory rate; the peak respiratory rate was only 2.8 × 103 mL/(kg·h), and the overall mass loss rate was only 25% of the control group. Moreover, this treatment effectively suppressed the levels of hydrogen peroxide (H2O2), superoxide anion radical and malondialdehyde (MDA), which was conducive to maintaining the integrity and stability of the cell membrane. Also, it terminated the free radical chain reaction, maintained the activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), removed the excess reactive oxygen species (ROS) in mushroom tissues, and consequently the shelf life of mushroom.
Effect of Carboxymethyl Chitosan on Cell Wall Metabolism of Grapefruits Induced by Cryptococcus laurentii
DU Rongyu, HUANG Erbin, WU Huayu, WANG Fang, DENG Jia
2024, 45(5):  243-249.  doi:10.7506/spkx1002-6630-20230220-185
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The hardness of ‘Rio Red’ grapefruits treated postharvest with carboxymethyl chitosan (CMCS), Cryptococcus laurentii or C. laurentii induced by CMCS was measured during storage. The results showed that compared with the control group (treatment with sterile water), CMCS-C. laurentii treatment significantly maintained the firmness of grapefruits during storage (P < 0.05). Moreover, fruit mass loss percentage and the polysaccharide content and polysaccharide hydrolase activity of the cell wall were measured and cell wall microstructure was observed during storage for 75 days. The results indicated that CMCS-C. laurentii treatment was effective in maintaining the contents of sodium carbonate soluble pectin (SCSP) and 24% KOH-soluble fraction (24KSF) and reducing the contents of water-soluble pectin (WSP), ionic-soluble pectin (ISP) and 4% KOH-soluble fraction (4KSF) in the fruit. Compared with the control group, the activities of the cell wall-degrading enzymes pectin methylesterase (PE), polygalacturonase (PG), cellulase (CX), α-L-arabinofuranosidase (α-L-Af) and β-galactosidase (β-Gal) were significantly inhibited by CMCS-C. laurentii treatment. In the middle and later stages of storage, the cell wall structure of the fruit treated with CMCS-C. laurentii was more stable and the intracellular structure was relatively intact. In conclusion, CMCS-C. laurentii treatment can slow down the degradation of organelles and cell walls in postharvest grapefruits, maintain cell integrity better and delay fruit softening.
Relationship between Superficial Scald Induced by 6-Methyl-5-hepten-2-one and Reactive Oxygen Species Metabolism in ‘Dangshansuli’ Pear Fruit
CUI Zixuan, GAO Xu, CHANG Shan, YANG Xiaolu, HUI Wei
2024, 45(5):  250-256.  doi:10.7506/spkx1002-6630-20230331-313
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In this study, the relationship between 6-methyl-5-hepten-2-one (MHO) treatment and superficial scald in ‘Dangshansuli’ pear fruit and its impact on reactive oxygen species (ROS) metabolism were explored. The levels of α-farnesene, conjugated trienes, MHO, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide anion radical and total phenols, and the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and polyphenol oxidase (PPO) in the pericarp of ‘Dangshansuli’ pear fruit treated by MHO during cold storage were measured. In addition, the development of superficial scald was observed and recorded. The results indicated that exogenous MHO could induce symptoms similar to superficial scald in ‘Dangshansuli’ pears, significantly increase the contents of MHO, H2O2 and superoxide anion radical, and decrease the activities of the antioxidant enzymes CAT, POD and SOD, and increase the contents of α-farnesene and conjugated trienes. The content of MHO in the pericarp was significantly related to the contents of H2O2 and superoxide anion radical, but was more closely correlated with the incidence rate of superficial scald than H2O2 levels. These results reveal that MHO can induce superficial scald by increasing the accumulation of ROS.
Effect of Superchilling Combined with Modified Atmosphere Packaging on Quality Indicators of Truffle and Correlation among Them as Analyzed by Principal Component Analysis
DAI Ya, TAN Xingyi, LI Xiang, WU Yiyou, HUANG Bo, WU Xinyuan, WANG Jianhui, LIU Dayu
2024, 45(5):  257-264.  doi:10.7506/spkx1002-6630-20230824-187
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Objective: To investigate the effect of superchilling combined with modified atmosphere packaging (MAP) on the quality indicators of truffle during storage. Methods: Truffle samples were stored at −(4.4 ± 0.2) ℃ under normal atmosphere (control) and 40% O2 + 60% CO2 atmosphere (group A), and quality changes during storage were determined. Discriminant models were established using principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). Results: Each quality index showed different trends under the two different storage atmospheres. Truffle was preserved significantly better in group A than the control group; the water loss and decay rate were effectively reduced in group A. On the 20th day of storage, the moisture content, decay rate and mass loss rate of group A were 63.62%, 6.94% and 1.02%, respectively; moisture content was significantly higher than control group (P < 0.05), and decay rate and mass loss rate were lower than control group, respectively (P < 0.05). Truffle quality was maintained better in group A than the control group, in terms of maintaining textural characteristics such as hardness and elasticity and delaying the decline in the contents of polysaccharides, total polyphenols, total flavonoids and crude protein and ferric ion reducing power. After 20 days of storage, the contents of polysaccharides, total polyphenols, total flavonoids and crude protein, and ferric ion reducing power were reduced by 27.94%, 32.51%, 16.18%, 68.58%, and 18.13%, respectively, which were lower than those in the control group. Correlation analysis and the developed discriminant models could effectively distinguish the quality differences of the samples under different treatments, indicating that physicochemical indexes influenced the quality of truffle during the storage period. OPLS-DA could also effectively differentiate the components of the truffle samples under different treatments. Conclusion: Superchilling combined with MAP can better preserve fresh truffle, and this study provides a theoretical basis for the development of new truffle preservation technologies.
Safety Detection
Determination of the Residues of Three Sulfonamides in Fish by Graphene Foam-Based Electro-Enhanced Solid-Phase Microextraction Coupled with High Performance Liquid Chromatography
SUN Ruixue, FANG Yuwen, CHEN Dongyan, CHEN Quansheng, CHEN Xiaomei
2024, 45(5):  265-274.  doi:10.7506/spkx1002-6630-20230822-160
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A rapid and sensitive method for the determination of sulfonamide (SA) residues in fish was developed using electro-enhanced solid-phase microextraction (EE-SPME) based on nitrogen-doped three-dimensional graphene foam (NGF) functionalized monolithic column (monolith@NGF, M@NGF) combined with high performance liquid chromatography (HPLC). To improve the enrichment efficiency of SA residues in fish, porous M@NGF was prepared on the surface of stainless-steel wires by in situ polymerization using ionic liquids as the functional monomer and NGF as the conductivity enhancer. The EE-SPME method was applied for the extraction of sulfathiazole (ST), sulfamethazine (SM2), and sulfadimethoxypyrimidine (SMM) from fish. Adsorption time, agitation speed, adsorption voltage, ionic strength, the pH of sample solution, desorption time, desorption voltage, and the composition of desorption solution were optimized. The results showed that the M@NGF-based EE-SPME method enriched ST, SM2 and SMM by 74, 58 and 64 folds, respectively, and shortened the adsorption equilibrium time to 35 min. In the linear range of 5–5 000 μg/kg, the limits of detection (LODs) of this method were 1.78, 3.16 and 1.84 μg/kg for ST, SM2 and SMM, respectively, and the limits of quantification (LOQs) were 5 μg/kg for all analytes. Coefficients of determination (R2) for linear regression analysis of this method were all greater than 0.999 0, and the recoveries from spiked samples ranged from 79.2% to 110.1%, with relative standard deviations (RSDs) ranging from 1.4% to 9.8% (n = 5). This method solved the problems of low extraction efficiency and serious matrix interference of SA residues in fish, and allowed the rapid, sensitive detection of SA residues in fish.
Contamination Status of Psychrotolerant Morganella psychrotolerans in Fish and Histamine-Producing Capacity of Its Isolates
LI Jin, WANG Di, CHEN Shengjun, WU Yanyan, LI Chunsheng, WANG Yueqi
2024, 45(5):  275-282.  doi:10.7506/spkx1002-6630-20230830-222
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The contamination status of cold resistant Morganella psychrotolerans in commercially available aquatic products was investigated, and the generation of histamine by its isolates was explored. A total of 100 samples of commercially available fish from Guangdong province were surveyed. The results revealed a widespread distribution of M. psychrotolerans with a contamination rate of 34%. The contamination rates for red-fleshed and white-fleshed fish were 35.9% and 27.3%, respectively. Specifically, the mackerel samples had a contamination rate of 38.24%, and the tuna samples had a contamination rate of 29.41% among all positive samples. Sixteen strains of M. psychrotolerans were isolated from the positive samples, and all isolates produced histamine levels exceeding 1 000 mg/L after 48 h incubation at 20 ℃. Notably, isolate 1 showed higher histamine-producing capacity than the type strain. Although the two strains exhibited no significant differences in growth curves at varying temperatures (4 and 20 ℃), their histamine-producing capacities were different. After 10 days of culture at 4 ℃, histamine production was higher by isolate 1 than the type strain, while the opposite result was observed after 60 h of culture at 20 ℃. These findings offer crucial theoretical support for addressing the problem of histamine accumulation in cold chain aquatic products.
Reviews
Research Progress on Functional Properties of Polysaccharide-Based Food Colloids and Their Application in Food Processing
YANG Rong, ZANG Yiyu, WU Peng, SUN Cuixia, FANG Yapeng
2024, 45(5):  283-292.  doi:10.7506/spkx1002-6630-20230410-083
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Food colloids refer to the common multicomponent heterogeneous dispersion systems found in foods, which can be divided into protein-based and polysaccharide-based colloids according to their components. Those colloids play an important role in food processing, such as thickening, emulsification, suspension, gelling, adhesion, water retention, stabilization and film formation, and are widely used in many fields such as the food processing industry. This article reviews the basic concept, composition, and classification of food colloids, with an emphasis on the functional properties of common polysaccharide-based colloids (carrageenan, agar, sodium alginate, Arabic gum, guar gum, konjac glucomannan, xanthan gum, gellan gum and curdlan) including rheological properties, gel properties, stability and combined use. Furthermore, this article also summarizes the current status and future perspectives of colloids based on polysaccharides from marine algae, plants and microbes in the food processing industry. We believe that this review will provide a theoretical basis for further development and utilization of polysaccharide-based food colloids.
Research Progress on Effect of Transglutaminase-Induced Cross-Linking on Gel Properties of Myofibrillar Protein
ZHANG Jingming, FENG Yangyang, SHI Pingru, KONG Baohua, CAO Chuan’ai, WANG Hui, LIU Qian
2024, 45(5):  293-302.  doi:10.7506/spkx1002-6630-20230410-080
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Transglutaminase (TGase), an efficient protein cross-linking agent, has been widely applied in the meat industry to enhance the quality of meat products by modifying the structure of myofibrillar protein (MP) and consequently improving the heat-induced gel properties of MP. Meanwhile, degree of cross-linking (DCL) is the most important indicator to evaluate the cross-linking effect catalyzed by TGase, which is of particular importance for analyzing the effect of covalent cross-linking catalyzed by TGase on the conformational characteristics, physicochemical properties, and gel properties of MP. Therefore, this article systematically reviews the influential factors of DCL in TGase-catalyzed covalent cross-linking of MP, and dissects the molecular mechanisms of the effect of exogenous additives and novel processing technologies on TGase-catalyzed cross-linking. The aim of this article is to establish the relationship among structural modification, molecular mechanism and quality improvement for TGase-modified MP, which will provide innovative theoretical and technical support for the development of new types of meat products.
Research Progress in In Vitro Intestinal Cell Models and Their Applications in Evaluating Anthocyanin Absorption and Transport
ZHONG Hao, XU Jie, CHEN Ling, LIU Xiaofeng, GUAN Rongfa
2024, 45(5):  303-313.  doi:10.7506/spkx1002-6630-20230823-176
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Anthocyanins are ubiquitous in plants, and many studies indicate that they possess diverse biological activities depending on their bioaccessibility and bioavailability. Numerous studies have revealed that absorption and transport by intestinal epithelial cells are crucial factors for determining the bioavailability of anthocyanins. Consequently, intestinal cell absorption models have been extensively employed to investigate the absorption and transport of anthocyanins and the underlying mechanisms. This article presents an outline of the intestinal cell models employed to investigate the absorption and transport of functionally active compounds, and highlights the underlying mechanisms of anthocyanin uptake and transport, especially based on the Caco-2 cell monolayer model. We hope that this review will provide a reference for future research to explore the absorption and utilization of functionally active constituents in intestinal cell models.
Recent Progress in Application of Metal-Organic Framework Materials in Aquatic Product Safety Detection
LI Yingrou, MI Chunxiao, CHEN Ju, JIAO Ruiwen, LI Xiang, REN Dandan, HE Yunhai, WANG Qiukuan, WU Long, ZHOU Hui
2024, 45(5):  314-323.  doi:10.7506/spkx1002-6630-20230328-279
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Aquatic product safety incidents have occurred frequently because of serious pollution in the farming environment, use of illicit veterinary drugs during the farming process, and the natural occurrence of pathogenic bacteria in aquatic products. However, due to the low content of target analytes, the complexity of aquatic product matrices, and the interaction between target analytes and food components, it is very difficult to separate and purify residual pollutants from aquatic products, so there is an urgent need for accurate and precise methods with a low limit of detection for the safety detection of aquatic products. Metal-organic frameworks (MOFs) are porous crystalline materials with large specific surface area, good thermal stability, and adjustable surface modification. MOFs have been successfully applied to the safety testing of aquatic products owing to the excellent adsorption properties. This article summarizes the major structure of MOFs, discusses the adsorption mechanisms of MOFs, and reviews the applications of MOFs in the safety detection of residual pollutants (fishery drugs, heavy metals, and organic pollutants) in aquatic products, in order to provide a reference for researchers engaged in the safety detection of aquatic products.
Formation, Development and Trend of Sensory Quality Description of Jiang-flavor Baijiu
NIU Junjie, SHI Bolin, WANG Houyin, ZHAO Lei, ZHONG Kui, ZHANG Yao, GAO Haiyan, YUN Zhenyu
2024, 45(5):  324-334.  doi:10.7506/spkx1002-6630-20230703-019
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Jiang-flavor Baijiu is popular among consumers because of its profound cultural deposits, traditional solid-state brewing process, unique flavor, and sensory experience. In this study, 537 sensory descriptors for Jiang-flavor Baijiu were obtained from 121 articles and 96 standards regarding ‘Jiang-flavor’ and ‘Jiang-flavor Baijiu’ retrieved from China National Knowledge Infrastructure (CNKI), the National Public Service Platform for Standards Information and the Foodmate Website. By sorting out and analyzing these literature data, this paper briefly describes the formation, development, trend and standardization of the sensory quality descriptions of Jiang-flavor Baijiu, summarizes the relationship between the flavor substances and the odor characteristics of Jiang-flavor Baijiu, analyzes the problems with the existing descriptors, and proposes ideas and suggestions for constructing a sensory quality description system for Jiang-flavor Baijiu and using modern sensory evaluation techniques to characterize the sensory quality of Jiang-flavor Baijiu.
Application of High and new Technology in Processing of Natural Products and Healthy Foods
ZHU Yinfei, KANG Songhao, LIU Xingyu, PENG Yu, LI Mo, NI Yuanying, WEN Xin
2024, 45(5):  335-344.  doi:10.7506/spkx1002-6630-20230821-155
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Healthy foods are foods that have additional health benefits when compared with ordinary foods. In recent years, with the vigorous development of the healthy food industry, healthy foods have gradually entered the public eye and become a hot spot. Natural products are a class of bioactive compounds that play an important role in healthy foods, and the processing is a vital part of the development of the healthy food industry. The development of healthy foods is inseparable from the ever-changing food processing technology. Based on this, this article summarizes the high-tech processing technologies for healthy foods, comprehensively compares and analyzes the high and new technologies applied in the processing steps such as natural product production, active ingredient protection, component modification, preservation, sterilization, and product design, and provides an outlook on the future development of healthy foods by using high and new technologies.
Research Progress on Dietary Risk Factors and Regulatory Mechanisms of Food Allergy
SUN Jiachen, ZHANG Qiaozhi, LI Huatao, ZHANG Yan, FU Linglin
2024, 45(5):  345-357.  doi:10.7506/spkx1002-6630-20230420-199
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At present, the incidence of food allergy is increasing worldwide. Food allergy has become a food safety and public health issue of growing concern. In addition to genetic factors, dietary factors are important factors causing increased risks of food allergy, and the intestinal microbiota plays an important mediating role between diet and the immune system. In view of this, this article systematically reviews recent studies on dietary risk factors for food allergy by summarizing the immunological mechanisms of action of different risk factors and the results of cohort studies and intervention experiments and by providing an in-depth discussion on the role of the intestinal flora in this regard. This review will provide references and new ideas for researchers to develop strategies for the prevention and control of food allergy, as well as understand the mechanism of food allergy using the intestinal microbiota as a target and develop regulatory strategies.