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Basic Research
Effect of Resveratrol on Mitochondrial Biogenesis and Muscle Fiber Type Transformation in Bovine Myotubes via SIRT1/PGC-1α
ZHANG Jingyue, DONG Pengcheng, ZUO Huixin, LIANG Rongrong, MAO Yanwei, ZHANG Yimin, YANG Xiaoyin, LUO Xin, ZHU Lixian
2024, 45(4):  1-9.  doi:10.7506/spkx1002-6630-20230527-256
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This study investigated the effect of resveratrol on muscle fiber type transformation in bovine myotubes. Cell viability and related metabolic enzyme activities were measured by methyl thiazolyl tetrazolium (MTT) and colorimetric assays, and myogenic regulatory factors (MRFs), myosin heavy chains (MyHCs), and gene and protein expression related to mitochondrial biogenesis were determined. The results showed that resveratrol treatment significantly increased the gene expression of Myf5, Myf6, MyoG, and MyoD (P < 0.05) and promoted the differentiation of bovine myotubes. Resveratrol significantly increased slow MyHC expression and decreased fast MyHC expression, while upregulating the mRNA expression levels of MyHC I and MyHC IIa and downregulating the mRNA expression levels of MyHC IIx and MyHC IIb (P < 0.05). Resveratrol also significantly increased succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) activity and decreased lactic dehydrogenase (LDH) activity (P < 0.05). In addition, resveratrol increased the gene and protein expression levels of silent information regulator 1 (SIRT1), peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), nucleus respiratory factors-1 (NRF-1), mitochondrial transcription factor A (TFAM) (P < 0.05). Addition of the SIRT1 inhibitor 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide (EX527) significantly attenuated resveratrol-induced muscle fiber type transformation (P < 0.05), and the promoting effect of resveratrol on the gene and protein expression of SIRT1, PGC-1α, NRF-1, and TFAM (P < 0.05). Taken together, resveratrol can promote mitochondrial biogenesis and consequently muscle fiber type transformation by activating the SIRT1/PGC-1α signaling pathway.
Relationships of Polyphenol Content with Antioxidant Activity and Key Enzyme Activities Related to Polyphenol Metabolism in Peeled Kernels of Juglans sigillata Dode cv. ‘Qianhe 7’
JIANG Yi, PAN Xuejun, HONG Yanyang, SHI Binbin, LI Xue, ZHANG Wen’e
2024, 45(4):  10-17.  doi:10.7506/spkx1002-6630-20221212-122
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Peeled iron walnut kernels (Juglans sigillata Dode cv. ‘Qianhe 7’) were studied for the changes in the contents of total phenols, total flavonoids and monomeric phenols and the activities of key enzymes associated with phenolic metabolism during the development process and their relationship with antioxidant activity in vitro. The results showed that the contents of total phenols and total flavonoids and antioxidant activity in iron walnut kernels increased during the development process and reached the maximum level at maturation. The contents of total phenols and total flavonoids were 0.05 mg/g and 0.03 mg/g, respectively in the mature kernels, the ferric ion reducing antioxidant power (FRAP) was 0.019 mmol/g, and the free radical scavenging capacities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical were 43.57 and 16.86 mg/mL, respectively. Eight monomeric phenolics were identified in the kernels, and their contents varied greatly during the development process and decreased in general at the late stage of maturity; among these phenolics, the average content of syringic acid was the highest, followed by catechin, and the level of ferulic acid was the lowest. The contents of total phenols, gallic acid, caffeic acid, ferulic acid and quercetin were positively correlated with the FRAP value, while the contents of catechin, eugenic acid and rutin were positively correlated with the DPPH radical and ABTS cation radical scavenging capacities. The metabolic enzyme activities including chorismate mutase (CM), chorismate synthase (CS) and phenylalanine ammonia lyase (PAL) reached the highest levels at the kernel filling stage, while cinnamate 4-hydroxylase (C4H) activity showed an N-shaped trend and reached the maximum value at the late stage of maturity. The activities of 4-coumarate coenzyme A ligase (4CL), chalcone synthase (CHS) and chalcone isomerase (CHI) decreased rapidly and then increased slightly at the maturity stage. Total phenol, gallic acid, caffeic acid, ferulic acid and quercetin were positively correlated with CM, PAL and C4H, but negatively correlated with CS, 4CL, CHS and CHI. Syringic acid and rutin were positively correlated with CS. In conclusion, the polyphenols and antioxidant activity of peeled ‘Qianhe 7’ iron walnut kernels were higher during the ripening stage. This study provides a theoretical basis for the development of functional foods based on iron walnut kernels.
Multiscale Structural Characterization of the Assembly Mode of Amylose-Lycopene Complexes
ZHAO Wenhong, HE Ying, GONG Zhaohai, GUAN Erqi
2024, 45(4):  18-25.  doi:10.7506/spkx1002-6630-20230509-070
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The formation and supramolecular structures of inclusion complexes between amylose and lycopene (amylose-lycopene complexes, ALCs) were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and 13C CP/MAS nuclear magnetic resonance (NMR). The results showed that the complex index of amylose to lycopene in ALCs was (17.10 ± 0.01)%, indicating that lycopene could enter the spiral cavity of starch to form a complex. ALCs exhibited a type II composite structure consisting of spherical V-shaped sub-microcrystals with a crystallinity of (65.32 ± 0.22)% and a T0 of (106.72 ± 0.63) ℃. Moreover, no characteristic absorption of lycopene at 960 cm-1 was observed, indicating complexation between the host and guest molecules. Furthermore, the structural components of ALCs were ranked as follows: double helix > amorphous form > V-shaped single helix. Among them, the proportions of double and V-shaped single helix structures in ALCs were (55.95 ± 3.25)% and (17.84 ± 0.96)%, respectively. These results indicated that amylose can include and twine around lycopene to form a thermally stable composite structure. This study provides a theoretical basis for expanding the prospective pharmaceutical and nutraceutical applications of lycopene as a functional pigment.
Mechanism and Kinetic Analysis of Sterilization of Escherichia coli on Shell Eggs by Ultrasound-Assisted Steam Treatment
ZHANG Yaqi, CHI Yujie, CHI Yuan
2024, 45(4):  26-34.  doi:10.7506/spkx1002-6630-20230123-163
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In order to explore the predictive bactericidal effect of ultrasound-assisted steam treatment on Escherichia coli on the eggshell surface and the mechanism of bacterial damage and death, a kinetic model for the sterilization of E. coli on the eggshell surface by ultrasound-assisted steam treatment was constructed. By controlling the concentration of bacterial suspension used to artificially contaminate eggshells, the sterilization efficiencies of E. coli by ultrasound, steam and their combination were evaluated and compared with that using the sodium hypochlorite immersion method, commonly used in commercial sterilization. The Linear, Weibull, Log-Logistic and Modified Gompertz models were used to fit the inactivation curve of E. coli by ultrasound-assisted steam treatment, and the damage degree of cell morphology and the leakage of cell contents before and after sterilization were measured. The results showed that after 180 s of 150 W ultrasonic pretreatment and 3 s of steam treatment, the logarithm of the total number of E. coli decreased from 6.26 to 2.04 with a mortality rate of 67%. The sterilization process of ultrasound-assisted steam treatment was better fitted to the nonlinear dynamic model, while the Weibull model was more suitable to describe the dynamic process of sterilization with increasing ultrasonic intensity and steam treatment time. In addition, the combined treatment destroyed the ultrastructure of E. coli and the external structure of its cells, resulting in cytoplasm leakage and changes in the permeability of the membrane. Therefore, ultrasound-assisted steam treatment could aggravate the deformation and damage of bacteria, leading to bacterial death. The experimental results provide a theoretical basis for the inactivation of E. coli on the eggshell surface. According to the results of egg quality during storage, this method has broad application prospects in the production of clean eggs.
Food Chemistry
Effects of Different Additives Combined with Vacuum Permeation Treatment on the Stability of Myofibrillar Proteins from Peeled Shrimps during Frozen Storage
LUO Yiyuan, CHEN Liang, QI He, ZHANG Bin, FANG Chuandong
2024, 45(4):  35-41.  doi:10.7506/spkx1002-6630-20230517-162
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Shelled shrimps (Penaeus vannamei) vacuum-treated with sodium pyrophosphate, sodium tripolyphosphate, trehalose, alginate oligosaccharide or carrageenan oligosaccharide solutions were stored at −18 ℃ and evaluated for thawing loss, thermodynamic properties, myofibril protein content, Ca2+-ATPase activity, and surface hydrophobicity of myofibril proteins after 0, 30, 60 and 90 days and molecular mass distribution of proteins after 90 days. Our aim was to investigate the effect of different additives combined with vacuum permeation treatment on the stability of myofibrillar proteins from peeled shrimps. The results showed that compared with distilled water, vacuum treatment with each of the five additives effectively reduced the thawing loss of frozen shrimp muscle, improved the low-temperature stability of myofibrillar proteins, and inhibited their freeze denaturation. Among these additive, trehalose, alginate oligosaccharide and carrageenan oligosaccharide had more significant cryoprotective effects. This study can provide a basis for the research and utilization of natural antifreeze agents, and also provide a scientific basis for the processing of new shrimp products.
Identification and Separation of Transformed Products of tert-Butylhydroquinone Added in Different Oils and Fats during Storage
XU Mengqi, ZHU Zhenjie, CHEN Xiaojun, LI Jun, BI Yanlan
2024, 45(4):  42-49.  doi:10.7506/spkx1002-6630-20230608-067
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The transformation of tert-butylhydroquinone (TBHQ) added in lard, soybean and palm oil was investigated during storage. The results showed that when the storage time was extended, the sum of the remaining amount of TBHQ and the production of 2-tert-butyl-1,4-benzoquinone (TBBQ) in oil samples was less than the initial amount of TBHQ added. The same chromatographic peaks except for TBHQ and TBBQ were found in the gas chromatograms of the methanol extracts from different oil samples. The unknown chromatographic peaks were isolated and purified by preparative liquid chromatography (Prep-LC), and their structures were identified and characterized by ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS), nuclear magnetic resonance (NMR), ultraviolet (UV) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. These results showed that the conversion products of added TBHQ were the same in different oils and fats, including TBBQ and 2-methylallyl-hydroquinone (MAHQ).
Effects of Fat Composition and Crystallization Characteristics on the Quality and Whipping Performance of Cream
SU Yi, CHAI Xiuhang, HAN Wanjun, LIU Yuanfa
2024, 45(4):  50-59.  doi:10.7506/spkx1002-6630-20230506-050
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In order to establish the internal relationship between the composition and crystallization characteristics of fat and the product quality and whipping properties, the fat composition and crystallization characteristics, emulsion quality, whipped product quality and whipping properties of dairy, non-dairy and mixed creams were analyzed in this study. The results showed that the crystal network formed by mixed animal and vegetable fats had a dense structure and high susceptibility to shear-induced partial aggregation, the resulting emulsion had high viscosity and low overrun, while the whipped product had high hardness and moderate conformal capacity. However, the crystallization properties of vegetable fat were opposite to those of mixed animal and vegetable fats, and the susceptibility to shear-induced partial aggregation was low. The vegetable cream emulsion had low viscosity and high overrun, whereas the whipped product has low hardness and the best conformal capacity. Animal fat had the lowest solid fat content, resulting in the weakest crystal network structure; the rate of partial aggregation, viscosity and overrun of the resulting emulsion were the lowest, and the whipped product had the lowest hardness and conformal capacity. Therefore, the product quality and whipping performance can be controlled by regulating the fat composition and crystallization characteristics. This study can provide theoretical guidance for the development of high-quality whipped cream.
Properties of Composite Oleogels Based on Soybean Isolate Protein Reinforced with Sodium Carboxymethylcellulose
CUI Mengqi, SHAN Guancheng, SUN Ruohan, TIAN Bo, SUI Xiaonan
2024, 45(4):  60-67.  doi:10.7506/spkx1002-6630-20230521-199
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The indirect preparation of oleogels by the aerogel template method has received widespread attention due to its advantages such as simple operation and excellent performance. In this study, composite aerogels of carboxy methyl cellulose-Na (CMC-Na) and soybean protein isolate (SPI) were prepared by the electrostatic interaction between them. The effects of different protein contents on the average particle size, microstructure, Fourier transform infrared (FTIR) spectrum, oil absorption kinetics, oil absorption capacity and oil holding capacity of aerogels were investigated. The oleogels prepared based on aerogel templates were characterized for their textural properties, antibacterial properties, and storage stability. The results showed that SPI and CMC-Na formed stable complexes through electrostatic interactions, and the average particle size of the complexes increased with protein content. The composite aerogel displayed a denser porous network structure along with improved oil-holding capacity, but had unfavorable effects on oil absorption performance. Moreover, the addition of protein improved the strength and Young’s modulus, and enhanced the antibacterial effect and storage stability of the oleogel. Therefore, the aerogel template method is good for preparing oleogels and a stable oleogel system can be prepared by electrostatic adsorption between polysaccharides and proteins.
Physicochemical Properties and Potential Biological Activity of Conjugated Linoleic Acid Microcapsules from Tan Sheep Tail Fat
PEI Huimin, LI Yalei, CAO Songmin, LUO Ruiming, BI Yongzhao, FU Qihua
2024, 45(4):  68-76.  doi:10.7506/spkx1002-6630-20230417-168
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In this study, microcapsules were prepared using conjugated linoleic acid (CLA) from Tan sheep tail fat as the core material and whey protein isolate (WPI) and maltodextrin (MD) as the wall material, and their physicochemical properties were characterized using scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) analysis. Besides, the oxidative stability and release behavior of the microcapsules were analyzed through accelerated storage experiments and in vitro simulated digestion experiments, and their antioxidant and cholesterol lowering activities were evaluated as well. The results showed that the particles of the CLA microcapsules were intact, with a relatively smooth surface, and had good thermal stability, oxidative stability, and sustained-release performance. After gastrointestinal digestion, the antioxidant stability and cholesterol lowering activity of the microcapsules were significantly higher than those of free CLA. At the end of in vitro simulated digestion, the scavenging rates of the microcapsules against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical, and superoxide anion radical were (70.84 ± 3.97)%, (78.53 ± 4.28)%, and (59.88 ± 2.58)%, respectively. The inhibition rate against cholesterol micelles was (73.48 ± 2.53)%, and the binding rates to sodium taurocholate, sodium glycine cholate, and sodium cholate were (40.62 ± 3.14)%, (66.79 ± 3.01)%, and (55.43 ± 2.39)%, respectively. This study indicates that microencapsulation not only significantly enhances the oxidative stability of Tan sheep tail fat CLA, but also improves its antioxidant and cholesterol lowering activity. This study provides a theoretical basis for the deep processing and comprehensive utilization of Tan sheep tail fat CLA.
Composition of Turmeric Oil and Preparation, Characterization, Bioactivity and in Vitro Digestion of Its Microemulsion
ZHANG Jianuo, YANG Bing, GAO Wei, FAN Lipeng, SANG Yaxin
2024, 45(4):  77-87.  doi:10.7506/spkx1002-6630-20230516-154
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The active components of turmeric oil (TO) were analyzed using gas chromatography-mass spectrometry (GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS), and electronic nose. The major components of TO were found to be ar-curcumone (23.09%), curcumone (21.36%), and β-curcumone (14.93%). In order to maximize the stability of TO and to mask its irritating substances, a microemulsion encapsulating it (TO-ME) was constructed by the water titration method. Based on the pseudo ternary phase diagram constructed, the optimal process parameters were determined as follows: TO as the oil phase, Tween-80 as the surfactant, propylene glycol as the co-surfactant, deionized water as the aqueous phase, a mass ratio of surfactant to co-surfactant of 4:1, a mass ratio of mixed surfactant to oil phase of 8:2, and a water content of 70% in the microemulsion. The largest area of the microemulsion region was formed under these conditions. The resultant microemulsion had a pH of 6.81 ± 0.02, a density of (1.053 ± 0.001) g/mL, a polydispersity index (PDI) of 0.27 ± 0.11, and an average particle size of (32.81 ± 14.54) nm. The microemulsion was characterized as an oil-in-water (O/W) type microemulsion, with spherical or ellipsoidal droplets. The prepared TO-ME exhibited good centrifugal stability, storage stability, and resistance to oral and gastric digestion, and could be released and utilized in the intestine. The microemulsion system significantly improved the scavenging capacity of TO against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation radical. In conclusion, microemulsion encapsulation significantly improved the stability and antioxidant activity of TO while effectively facilitating its release and digestion in the intestine. Our research results provide a theoretical basis for the high-value development and utilization of TO.
Bioengineering
Fermented Grains from Different Layers of Cellar in the First and Second Rounds of Fermentation of Maotai-Flavor Baijiu: Analysis of microbial community structure and Acid Composition as Well as Correlation between Them
WAN Qiyu, CHENG Yuxin, HUANG Yongguang, SHE Rongshu, DENG Changwei, ZUO Qiancheng
2024, 45(4):  88-95.  doi:10.7506/spkx1002-6630-20230613-099
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In this study, the microbial community structure in fermented grains from the upper middle and lower layers of the cellar in the first and second rounds of fermentation of Maotai-flavor was analyzed by high-throughput sequencing, and the acid composition by ultra-high performance liquid chromatography (UPLC). Moreover, the correlation between them was investigated. The results showed that the total acid content of fermented grains was greater in the second round than the first round of fermentation. The radial distribution patterns of seven acidic compounds in different times and spaces of the cellar were different. The contents of lactic acid and acetic acid accounted for a large proportion in the two rounds of fermentation. For both rounds, the absolutely dominant bacterial genus was Limosilactobacillus, and the dominant fungal genera were Saccharomyces and Candida. As the fermentation time extended, there was a significant difference in the microbial community structure. The contents of total and individual acids were positively correlated with the relative abundance of Limosilactactacillacus, Schizosaccharomyces, Zygosaccharomyces, Candida and Kazachstania, and negatively correlated with the relative abundance of Lactobacillus, Saccharomyces, Paecilomyces and Torulaspora. This study provides a theoretical basis for further elucidating the fermentation mechanism of Maotai-flavor Baijiu cellar.
Effect of Glucose on Vanillin Tolerance of Starmerella bacillaris
ZHANG Qingyan, ZHAO Jun, ZHANG Zhe, CHEN Xiong, YAO Lan
2024, 45(4):  96-107.  doi:10.7506/spkx1002-6630-20230531-283
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This study focused on the effect of a typical phenolic inhibitor, vanillin, on the growth and ethanol production of Starmerella bacillaris R5, as well as the effect of varying levels of glucose on its growth and fermentation performance. The results indicated that when the vanillin concentration was fixed at 3 g/L, increasing glucose concentration in the medium from 2% to 6% shorten the lag phage by 25.92%, increased the specific growth rate by 82.1%, and the ethanol conversion rate by 17.88%. Further analysis showed that increased glucose concentration resulted in an increase in the proportion of cells containing reactive oxygen species (ROS), a decrease in membrane permeability, and a reduction in intracellular H2O2 content. In addition, the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) increased by 58%, 35.5%, and 2.3 times, respectively. Intracellular glycerol content increased by 1.82 times. The activity of pyruvate kinase (PK), related to glucose metabolism, decreased by 54.5%, and the activity of hexokinase (HK) and 6-phosphate glucose dehydrogenase (6-PGDH) increased by 4.16 and 11.8 times, respectively. The content of reduced nicotinamide adenine dinucleotide phosphate (NADPH) increased by 19.4%. The gene expression levels of hexokinase (HK), 6-phosphate fructose kinase (PFK), isocitrate dehydrogenase (IDH3), 6-phosphate glucose dehydrogenase (PGD), ethanol dehydrogenase (ADH5), pyruvate decarboxylase (PDC) and glycerol dehydrogenase 1 (GCY1) were up-regulated by 4.6, 2.5, 13.9, 12.2, 17.5, 34.8, and 34.9 times, respectively. In summary, increasing glucose concentration increased the activity of intracellular antioxidant enzymes, attenuated oxidative damage, and provided more adenosine triphosphate (ATP) and reducing powder to cope with environmental stress, thereby increasing the conversion rate of ethanol. The results of this study could provide new ideas for utilizing S. bacillaris for bioethanol production.
Pure Culture and Ultra-high Deep Metagenomic Sequencing for Analysis of the Differences in Microbial Diversity of High Temperature Daqu from Two Distilleries in Maotai Town
WANG Yurong, HOU Qiangchuan, TIAN Longxin, LIU Juzhen, ZHOU Jiaping, GUO Zhuang
2024, 45(4):  108-115.  doi:10.7506/spkx1002-6630-20230602-008
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In this study, the microbial diversity of high temperature Daqu from different distilleries in Maotai town was analyzed by the pure culture technique and macrogenomic sequencing. The results showed that a total of 212 Bacillus strains were isolated and identified including B. sonorensis (77 strains), B. licheniformis (39 strains) and B. amyloliquefaciens (19 strains). A total of 55 high-quality genomes were obtained by metagenomic binning, including 18 new strains suspected of being Bacillus sp., Lactobacillus sp. and Weissella sp.. The analysis of the microflora structure showed that the dominant bacteria in Daqu were Desmospora sp. 8437, B. sonorensis and B. amyloliquefaciens, and the relative abundance of B. sonorensis and B. amyloliquefaciens in Daqu from distillery A were significantly lower than that from distillery B (P < 0.05). The diversity and abundance of microorganisms in high temperature Daqu from distillery A were significantly lower than those in Daqu from distillery B (P < 0.05), and there was a significant difference in microflora structure between them. In terms of functions, the differential metabolic pathways with higher abundance in high temperature Daqu from distillery A were mainly related to the biosynthesis of amino acids, while those from distillery B was mainly related to the degradation of L-rhamnose. This study is of positive significance for improving the fermentation process and screening excellent strains in the future.
Effect of Inoculated Fermentation with Different Aspergillus Strains on the Formation of the Umami Taste of Liuyang Douchi
ZHOU Xiao, LI Pao, WU Ziqian, TANG Hui, XU Jucai, JIANG Liwen, QIN Yeyou, LIU Yang
2024, 45(4):  116-124.  doi:10.7506/spkx1002-6630-20230605-038
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In order to investigate the effect of inoculated fermentation with different Aspergillus strains on the umami taste of Liuyang Douchi, the differences in the umami taste and protein degradation of Liuyang Douchi fermented naturally (NF) or by four dominant Aspergillus flavus strains isolated from Douchi (A. flavus 7214, A. flavus 7622, A. flavus 6112, and A. flavus 5322) alone and their mixture in an equal proportion (M4) were compared. The results showed that the major protease produced by each of the four strains was serine proteases, and A. flavus 5322 had the strongest protease activity, with significantly higher activity of acidic protease than the other three strains. The contents of amino acid nitrogen and water-soluble protein in Aspergillus fermented Douchi were higher than those in NF Douchi after the end of pile-fermentation stage. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that the degradation trends of six proteins in Douchi were consistent, all of which exhibited rapid degradation during the pile-fermentation process. Additionally, the results of sensory evaluation and electronic tongue analysis showed that Douchi fermented by A. flavus 5322 showed the strongest umami taste, which significantly increased when compared with NF. Using ultra-high performance liquid chromatography-electrospray/quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) combined with correlation and peptidomics analysis, a total of 43 potential umami peptides were identified. The total peak area of potential umami peptides in Douchi fermented by A. flavus 6112 was the highest, followed by A. flavus 5322 with little difference, significantly greater than that in NF Douchi. In summary, inoculated fermentation, especially with A. flavus 5322, could promote protein degradation and the release of potential umami peptides, thereby enhancing the umami taste of Liuyang Douchi. This study will provide theoretical guidance for improving the umami taste of Liuyang Douchi and development of industrial production strains.
Effect of Microbial Community in Artificial Pit Mud on the Formation of Flavor Metabolites during the Fermentation of Nongxiangxing Baijiu
MAO Fengjiao, HUANG Jun, ZHOU Rongqing, ZHANG Suyi, QIN Hui
2024, 45(4):  125-134.  doi:10.7506/spkx1002-6630-20230517-164
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In this study, a small-scale simulated fermentation system of fermented grains (Jiupei in Chinese) without pit mud (PM) was used as a control, and the differences in the microbial community and metabolite components between the PM and control groups were compared. The results indicated that PM significantly enhanced the contents of major flavor compounds in Jiupei including butyric acid, caproic acid, ethyl acetate, ethyl butyrate, and ethyl caproate, and reduced the contents of lactic acid and ethyl lactate. For both groups, the relative abundance of Lactobacillus, one of the dominant bacteria in the upper and bottom layers of Jiupei, significantly increased at the initial stage, and showed a slight difference between them at the end of fermentation. The decay period of Lactobacillus in the PM group was about 15 days earlier than that in the control group. At the same time, the relative abundance of Rhodococcus in the control group, and the relative abundance of Kroppenstedtia, Clostridium_sensu_stricto_12, and Acetobacter in the PM group increased. The abundance of most of the enzymes in the Embden-Meyerhof-Parnas (EMP) pathway, as well as that of caproic acid synthase (EC 1.3.1.38, EC 2.3.1.16, EC 6.2.1.1) and butyric acid synthase (EC 2.3.1.9, EC 2.8.3.8) increased during fermentation, and the abundance of these enzymes was significantly higher in the bottom layer of Jiupei than in the upper layer. The abundance of lactate dehydrogenase (EC 1.1.1.27), which uses lactic acid as a substrate, increased in the PM group. These findings reveal the contribution of PM to the microbial communities and metabolite components of Jiupei.
Nutrition & Hygiene
Preventive Effect of Volvariella volvacea Fruit Body Polypeptides on Acute Alcoholic Liver Injury in Mice and Its Influence on Intestinal Microflora
ZHANG Fangyi, LIN Hailu, CHEN Lili, LUO Xiaofang, CHU Lulu, JIANG Yuji, CHEN Bingzhi
2024, 45(4):  135-143.  doi:10.7506/spkx1002-6630-20221213-135
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To investigate the preventive effect of Volvariella volvacea fruit body polypeptides (VVFP) on acute alcoholic liver injury in mice and its influence on the intestinal microbiota, VVFP (1–3 kDa molecular mass) which had been previously obtained by our laboratory was given by gavage to mice. The mice were randomly divided into six groups: blank control, model, positive control, low-dose VVFP, moderate-dose VVFP and high-dose VVFP. Serum indexes, liver indexes and histopathological sections were compared among these groups, and 16S rDNA gene high-throughput sequencing was used to analyze the diversity of the intestinal microflora and the relative abundance at the phyla and genus levels in each sample. Results showed that VVFP significantly reduced the levels of triglycerides (TG), total cholesterol (TC), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in the serum and malondialdehyde (MDA) in the liver, and decreased the levels of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and significantly increased the activities of alcohol dehydrogenase (ADH), total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) in the liver. The 16S rRNA sequencing showed that VVFP significantly reduced the α-diversity indices Chao1 and observed species, increased the Shannon index, and regulated the abundance of Bacteroides, Firmicutes, Streptomyces, Lactobacillus and Vibrio, thereby reducing liver damage. In conclusion, VVFP can reduce alcoholic liver injury, which will provide a theoretical basis for the application of VVFP in the field of functional foods.
Component Analysis
Comparative Analysis of Sensory Evaluation Methods for Qingzhuan Tea
LIU Panpan, FENG Lin, ZHENG Lin, XUE Jinjin, WANG Shengpeng, WANG Xueping, YE Fei, TENG Jing, GUI Anhui, HAN Yanna, CHEN Junhai, ZHU Peng, GAO Shiwei, ZHENG Pengcheng
2024, 45(4):  144-153.  doi:10.7506/spkx1002-6630-20221121-237
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To propose a sensory evaluation method suitable for Qingzhuan tea, a representative Qingzhuan tea produced in Hubei was soak or spray boiled in order to analyze the effects of different boiling conditions on the sensory quality and the leaching rate of major chemical components of Qingzhuan tea. The sensory quality and chemical components of the tea infusions were compared with those of tea infusion obtained by the brewing method specified in the Chinese national standard. The results showed that the sensory quality of the boiled tea infusion was significantly better than that of the brewed tea infusion; the leaching rates of major quality components such as water extract, tea polyphenols, amino acids, soluble sugars and tea pigments were much higher in the former than in the latter. From the perspectives of sensory quality and the leaching rate of major quality components, tea infusion prepared by boiling for 2 min with a tea/water ratio of 1:80 and then standing for 2–4 min tasted moderate and had good internal quality. Further correlation analysis showed high correlation coefficients between the leaching rates of soluble sugars, theabrownine and water extract and taste quality. The results of this study provide a reference for the objective evaluation of the sensory quality of Qingzhuan tea and other types of compressed tea.
Analysis of Differential Muscle Metabolites in Bactrian Camels Slaughtered at Different Ages by Non-Targeted Metabolomics Based on Ultra-high Performance Liquid Chromatography-Mass Spectrometry
SI Rendalai, TUYATSETSEG Jambal, BANZRAGCH Maizul, MING Liang, HE Jing, JI Rimutu
2024, 45(4):  154-163.  doi:10.7506/spkx1002-6630-20230507-054
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In this study, non-targeted metabolomics based on ultra-high performance liquid chromatography Q-Exactive-mass spectrometry (UPLC-Q-Exactive-MS) was used to explore the differences in the metabolite profiles of muscles from Bactrian camels slaughtered at different ages. The results showed that a total of 710 differentially expressed metabolites (DEMs) were identified in the longissimus dorsi muscle of camels from three age groups: I (3–4 years old), II (6–7 years old), and III (9–10 years old). In total, 78 DEMs were found in groups I vs II, of which 47 were upregulated in group I and 31 were upregulated in group II. Totally, 49 DEMs were identified in groups II vs III, of which 18 were upregulated in group II and 31 were upregulated in group III. In addition, 65 DEMs were identified in groups I vs III, of which 29 were upregulated in group I and 36 were upregulated in group III. The results of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the DEMs were mainly enriched in pathways such as protein and amino acid metabolism, fatty acid metabolism, and vitamin and mineral metabolism, indicating that the digestion and metabolism of various nutrients in camels were different at different growth stages. The contents of polyunsaturated fatty acids (PUFA) (especially n-6 PUFA and n-3 PUFA) and the PUFA/unsaturated fatty acid (UFA) ratio were significantly higher in group I than III, which was mainly related to the significant upregulation of arachidonic acid, linoleic acid and 13-L-hydroperooleic acid concentrations in relevant metabolic pathways. Meanwhile, DEMs such as L-leucine, L-valine, and L-glutamine could serve as potential markers for evaluating the quality change of camel meat at different slaughter ages.
Analysis of Flavor and Nutritional Quality of Fresh Sea Buckthorn Juice and Pulp
REN Jingnan, JIA Xiao, ZHANG Zhifeng, WU Kangning, FAN Gang, LI Mingzhe, MA Youli, MA Xueli, SHAO Yalong, LIU Chunhai, WAN Xu, CHEN Yang, ZHAO Shiliang
2024, 45(4):  164-170.  doi:10.7506/spkx1002-6630-20230426-256
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Identification of odor compounds in fresh sea buckthorn juice (FSBJ) and pulp (SBP) was performed by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). A total of 39 and 36 odor compounds were identified in FSBJ and SBP, respectively. Further findings revealed that ethyl hexanoate, ethyl 2-methylbutyrate, ethyl 3-methylbutyrate, and 3-methylbutyl 3-methylbutanoate had high flavor dilution (FD) factors and were identified as the key odor compounds in FSBJ. In addition, the contents of ester compounds contributing to the fruity odor were significantly reduced in SBP after pasteurization. Sensory evaluation and electronic tongue analysis revealed that the sweetness and overall taste of SBP were superior to those of FSBJ. The contents of vitamin C and total flavonoids were significantly lower in SBP than in FSBJ, indicating that pasteurization reduces the nutritional quality of FSBJ. The results of the study can provide theoretical references for the flavor and nutritional quality optimization of sea buckthorn products.
Metabolomic Analysis of the Chemical Composition of ‘Tieguanyin’ and ‘Shuixian’ Tea
ZHOU Chuang, ZHAO Yanni, ZHOU Mengxue, PENG Jiakun, CHEN Dan, WANG Zhe, LIN Zhi, CHEN Xuefeng, DAI Weidong
2024, 45(4):  171-182.  doi:10.7506/spkx1002-6630-20230511-099
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In order to investigate the effect of cultivar and processing technique on the chemical composition of tea, this study analyzed green tea, fresh-scent oolong tea, strong-scent oolong tea and black tea made from the fresh leaves of the ‘Tieguanyin’ and ‘Shuixian’ cultivars from the same graphical origin using metabolomics based on ultra-high performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOF-MS). The results showed that the chemical compositions of tea samples made from different tea cultivars differed considerably. The contents of most lipids, alkaloids and methylated catechins were higher and the contents of theanine, most catechins, flavone (flavonol) glycosides, phenolic acids and N-ethyl-2-pyrrolidinone-substituted flavan-3-ols were lower in ‘Tieguanyin’ tea than in ‘Shuixian’ tea. Processing techniques also significantly impacted the chemical composition of tea. A total of 127 differential compounds were selected, among which the contents of most catechins, dimeric catechins, alkaloids and some amino acid compounds were significantly higher in green tea than in other kinds of tea. The contents of some amino acids and flavone (flavonol) glycosides (quercetin-3-galactoside, and kaempferol-3-glucosylrutanoside) were higher in fresh-scent oolong tea. The contents of N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSF), some flavone (flavonol) glycosides (quercetin-3-glucoside, and kaempferol-3-6”-acetylgalactoside), and lipid compounds in strong-scent oolong tea were higher, while black tea was richer in theaflavins and several flavone (flavonol) glycosides.
Effects of Different Production Processes on the Quality and Flavor of Soybean Oil as Evaluated by Electronic Nose, HS-SPME-GC-MS and HS-GC-IMS
WU Siyu, XIE Xuan, LIU Yuwen, SUN Shukun, CHEN Hao
2024, 45(4):  183-196.  doi:10.7506/spkx1002-6630-20230510-090
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In order to explore the effects of different production processes (cold pressing, leaching, and their combination) on the quality and flavor of soybean oil of third grade, the physicochemical properties and fatty acid composition of the three soybean oils were determined, and their volatile compounds were identified and analyzed by electronic nose, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and headspace-gas chromatography-ion mobility spectroscopy (HS-GC-IMS). Differential analysis of the volatile compound data among the soybean oils was performed by clustering heatmap analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). The results showed that cold-pressed soybean oil had the lowest moisture content; the peroxide value of leached soybean oil was significantly higher and its color was the darkest. Fragrant soybean oil had the highest linoleic acid content and a higher nutritional value; and among the detected volatile components, alcohols, aldehydes and pyrazine compounds mainly contributed to the formation of soybean oil flavor, and the reasons for the formation of some flavor compounds were clarified. Finally, 45 volatile compounds with high contributions were selected by OPLS-DA, and a reliable model was constructed for identifying fragrant soybean oil. In addition, a correlation was found between the quality and flavor of soybean oil.
Characteristics of Oligosaccharide Composition in Chinese Human Milk
MI Lijuan, YAN Jingyu, GUO Shanshan, JIA Ni, PANG Jinzhu
2024, 45(4):  197-206.  doi:10.7506/spkx1002-6630-20230428-279
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To analyze the impact of different regions, lactation times, and blood group genotypes on the oligosaccharide composition of healthy lactating mothers’ breast milk from representative regions of China, and to explore the compositional characteristics of oligosaccharides in Chinese human milk, in this longitudinal cohort study, the concentrations of 23 oligosaccharides in breast milk samples from 109 healthy mothers at three lactation stages in six cities in east, west, north and south China were analyzed by ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UPLC-MS-MS). Besides, the attribution of breast milk to blood group genotypes was investigated. The results showed that concentrations of total oligosaccharides and total fucosylated neutral oligosaccharides were significantly higher in samples from Kunming, Jinan and Shenzhen than those from Beijing, Baotou and Xining, and the concentrations of 3-fucosyllactose (3-FL), lactodifucotetraose (LDFT) and lacto-N-neodifucohexaose II (LNnDFH-II) were significantly lower in samples from Baotou than those from Shenzhen, Jinan and Beijing, respectively. The concentrations of eight neutral oligosaccharides and four acidic oligosaccharides showed a significant decreasing trend with lactation time, whereas 3-FL concentration increased significantly, and the concentrations of LDFT and LNnDFH-II also increased but not significantly. The concentrations of two monofucosylhexasaccharides were the highest in 1-month-old mature milk, and then remained unchanged or decreased slightly as lactation progressed. Based on oligosaccharide types, it was inferred that the major blood group genotype of lactating mothers was Se+Le+ for all the six cities. In this genotype, the concentrations of lacto-N-difucohexaose-II (LNDFH-II), LNDFH-I & LNnDFH-I, 6’-sialyllactose (6’-SL) and sialyllacto-tetrasaccharide c (LSTc) were higher and the concentrations of 18 other oligosaccharides were lower than in other genotypes. This study provides scientific theoretical guidance for precise estimation of the intake of breast milk oligosaccharides by infants and young children at the early life stage.
Rapid Determination of Active Ingredient Contents in Rhizoma Gastrodiae Using Near-Infrared Spectroscopy Combined with Artificial Rabbits Optimization-Least Square Support Vector Regression
LI Shanshan, ZHANG Fujie, LI Lixia, ZHANG Hao, DUAN Xingwei, SHI Lei, CUI Xiuming, LI Xiaoqing
2024, 45(4):  207-213.  doi:10.7506/spkx1002-6630-20230831-244
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In order to rapidly and non-destructively detect gastrodin and 4-hydroxybenzyl alcohol in Rhizoma Gastrodiae, near infrared spectral data of the dried tuber of Gastrodia elata Bl. f. glauca S. Chow were collected in the wavelength range of 900–1 700 nm. First, convolutional smoothing (SG) and standard normal variable transformation (SNV) were used for spectral data preprocessing. Second, feature wavelength extraction was carried out by competitive adaptive reweighted sampling (CARS) and iteratively retains informative variables (IRIV). According to the results of establishing least squares support vector machine (LSSVR) model based on feature wavelength, the best method of feature wavelength extraction was selected. In order to improve the accuracy of the model, this study introduced the artificial rabbits optimization (ARO) algorithm to optimize the regularization parameter γ and the kernel function density σ2 in LSSVR and the superiority of ARO to particle swarm optimization (PSO) and grey wolf optimizer (GWO) was evaluated. The results showed that the ARO algorithm was superior to PSO and GWO in in terms of optimization speed and ability. The best prediction models for gastrodin and 4-hydroxybenzyl alcohol were CARS-ARO-LSSVR, with prediction correlation coefficient (R2p) of 0.969 6 and 0.957 7, and root mean square error of prediction (RMSEP) of 0.014 and 0.020, respectively. Therefore, this study shows that near-infrared spectroscopy can be used for quantitative detection of active components in Rhizoma Gastrodiae, which provides a theoretical basis for the development of rapid detection devices for Rhizoma Gastrodiae.
Dynamic Changes in Flavor Quality of Wuyi Rock Tea at Different Storage Times
WU Jun, WANG Zhihui, LI Jing, DAI Haomin, SONG Bo, ZHANG Lingzhi, XU Jie, YUE Bin, SUN Weijiang
2024, 45(4):  214-224.  doi:10.7506/spkx1002-6630-20230505-037
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Seven samples of Wuyi rock tea (cv. Shuixian) stored for different times (0, 5, 10, 15, 20, 25, and 30 years) were collected to investigate the effect of storage time on the flavor quality of Wuyi rock tea by the combined use of sensory evaluation, non-volatile and volatile composition analysis and chemometrics methods. The results showed that the transformation of the flavor quality of Wuyi rock tea during storage was divided into three stages: 0–5, 10–15, and 20–30 years. As the storage time increased, the taste gradually transformed from mellow to stale, and a sour taste appeared at the middle stage of storage and then faded away at the late stage. The aroma gradually changed from flowery and fruity to aged, woody and herbal. A significant decrease in the content of tea polyphenols, catechins-like and theaflavins and an increase in the content of soluble sugars were the major reasons for the taste changes. Changes in the contents of 15 characteristic volatiles, including indole, trans-nerolidol, dihydroactinidiolide, hotrienol, α-terpineol, methyl salicylate, β-ionone, and (Z)-hexanoic acid-3-hexenyl ester, were the key factors affecting the aroma changes. This study provides a scientific reference for the storage and consumption of Wuyi rock tea.
Identification of Key Aroma Compounds in Fig Extract through Sensomics Approach
WANG Xinhui, HE Feng, LI Ruili, WANG Hanshu, LIANG Miao, ZHANG Yihan, PAN Wenliang, ZHANG Junsong
2024, 45(4):  225-231.  doi:10.7506/spkx1002-6630-20230429-286
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In this study, headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and gas chromatography-olfactory (GC-O) were applied to identify and analyze the volatile aroma compounds of the ethanol extract of figs. Its key characteristic flavor compounds were analyzed by odor activity (OAV) and aroma recombination and omission tests. The results showed that a total of 40 volatile aroma components were identified, of which 18 compounds, such as isobutyrate, γ-butyl lactone, aromatic camphor, nonaldehyde, vanillin and furfural, were important aroma components in the fig extract (OAV > 1). The aroma recombination experiments showed that the sensory properties of the recombined samples, which had typical aroma characteristics such as fruity, sweet, baked and burnt sweet with slight sour, ointment-like and milky, were similar to those of the fig extract. Furthermore, the aroma omission experiments identified gamma-hexanoate, ethyl palmitate, phenmethanol, aromatic camphor, vanillin, benzaldehyde, 4-hydroxy-2,5-dimethyl-3 (2H)-furan, 5-hydroxymyfuran, and methyl cyclopentanolone as key characteristic flavor compounds of the fig extract. The findings of this study provide a theoretical basis for the development and quality control of fig characteristic flavorings.
Effect of Kombucha Consortium Fermentation on Active Ingredients and Sensory Quality of Gastrodia elata
WANG Ying, DONG Mingsheng, ZHANG Guoqiang, HAN Yuefeng
2024, 45(4):  232-238.  doi:10.7506/spkx1002-6630-20230901-001
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The changes in the main active ingredients and sensory quality of Gastrodia elata during liquid-state fermentation with the traditional Kombucha consortium were analyzed in the study. The results showed that the total acid concentration of the fermentation broth increased, and consequently the pH decreased after 5 days of fermentation, among which acetic acid and succinic acid increased most obviously. Fermentation with the Kombucha consortium significantly increased the contents of total polyphenols, total flavonoids and p-hydroxybenzyl alcohol. The volatile components of the fermentation broth were analyzed by electronic nose combined with solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). It was found that many flavor substances were produced through the fermentation process. Sensory evaluation indicated that Kombucha consortium fermentation significantly reduced the unpleasant odor of G. elata and imparted it a fruity flavor. This study provides a theoretical basis and technical support for the in-depth development and utilization of G. elata.
Food Engineering
Effect of Heat Treatment on the Structure and Physicochemical Properties of Buckwheat Bran Protein
CHEN Jing, WANG Libo, REN Yanjuan, YAN Minghuan, ZHANG Jie, ZHANG Bin, LIU Wenchao, WANG Haoran, WU Weijing, LUO Denglin
2024, 45(4):  239-246.  doi:10.7506/spkx1002-6630-20230904-021
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To analyze the effect of heat treatment on the structure and physicochemical properties of buckwheat bran protein (BBP), the molecular mass, secondary structure, intrinsic fluorescence spectrum, free sulfhydryl content, disulfide bond content, microstructure, thermal properties, and rheological properties of BBP were characterized before and after heat treatment. The results showed that part of the subunits of BBP were degraded into small polypeptides or oligopeptides. The α-helical structure was transformed into β-sheet, β-turn and random coil, and the contents of free sulfhydryl groups and disulfide bonds were significantly increased. Compared with soy protein isolate (SPI), the peak temperature, denaturation enthalpy, apparent viscosity, storage modulus (G’) and loss modulus (G”) of BBP were significantly lower. The surface of heat-induced gels of BBP was rougher, and there were obvious cracks on the gel wall, indicating that the thermal stability of BBP was lower than that of SPI. In summary, heat treatment could change the structure of BBP, and have different effects on its physicochemical properties.
Effect of Microwave Treatment on the Changes in Lipids of Rice during Storage
CAO Ruge, WU Xiaohui, HUANG Wenda
2024, 45(4):  247-256.  doi:10.7506/spkx1002-6630-20221215-163
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The aim of this study was to reveal the changes of lipids in rice with and without microwave pretreatment during storage. Different varieties of rice (Jindao 919, Chaobei 2, and Daohuaxiang 2) were microwaved at 850 W for 50 s and stored under different conditions for up to three months. The changes of lipase, lipoxygenase, peroxidase and catalase activity, fatty acid value (FAV), peroxide value (POV), and carbonyl value (CV), water distribution and volatile components were evaluated. The results showed that microwave treatment effectively reduced the water activity of rice, changed the microstructure of rice grains, and inactivated the activity of lipases. After microwave treatment, the activities of lipase, lipoxygenase, peroxidase and catalase decreased by an average of 54.03%, 71.11%, 95.94%, and 46.04% for Jindao 919, Chaobei 2, Daohuaxiang 2, respectively. After storage at 37 ℃ for 90 days, FAV, POV and CV were only increased by 0.716–1.436 mg/100 g, 2.859–6.734 mmol/kg and 3.697–5.308 mmol/kg, respectively. It was demonstrated that microwave treatment could effectively deactivate the activity of lipolytic enzymes, and reduce the production of free fatty acids and hydroperoxides from the hydrolysis and oxidation of rice lipids and the production of volatile aldehydes and ketones, thereby delaying quality deterioration in rice during the storage process.
Effect of Infrared Pretreatment on Quality and Storage Stability of Cold-Pressed Pecan Oil
JI Qin, PAN Lihua, LI Hexing, LUO Shuizhong, ZHENG Zhi
2024, 45(4):  257-263.  doi:10.7506/spkx1002-6630-20221209-097
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After infrared (IR) pretreatment for 22, 41, 68, 104 and 148 s, the internal temperature of pecan kernels reached 70, 90, 110, 130 and 150 ℃, respectively. To investigate the effect of IR pretreatment on the quality and storage stability of cold-pressed pecan oil, oil yield, fatty acid composition, lipid concomitants, physicochemical indicators, microstructure, and antioxidant capacity and storage stability were analyzed. The results showed that IR pretreatment increased the oil yield of pecan kernels by 11.10%–58.42% compared with the control group, but had no significant effect on the fatty acid composition of cold-pressed pecan oil. Moreover, IR pretreatment significantly the activities of lipase and polyphenol oxidase in pecan oil (P < 0.05). Non-enzymatic browning index, the release of carotenoids and the content of total phenolics were positively correlated with IR pretreatment time, and the color of cold-pressed pecan oil turned darker with increasing time of IR pretreatment. Compared with the control group, IR pretreatment for 148 s resulted in a slight but not significant reduction in γ-tocopherol content (P > 0.05), and a 23.52% and 13.16% increase in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and ferric reducing antioxidant power (FRAP), respectively, thereby significantly enhancing the storage stability. To summarize, IR pretreatment for 148 s is the best pretreatment method to obtain cold-pressed pecan oil. The results of this study provide a theoretical basis for the application of IR pretreatment in the preparation of cold-pressed pecan oil.
Effect of Multifrequency Ultrasonic-Assisted Vacuum Cooking on the Muscle Fiber Structure and Water-Holding Capacity of Stewed Marinated Beef
CAI Huazhen, DAI Hongyu, CHEN Jiangong, LU Kaiyi, FENG Tengxun, ZHOU Di, CHEN Yang
2024, 45(4):  264-270.  doi:10.7506/spkx1002-6630-20230503-006
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The effect of multifrequency ultrasonic-assisted vacuum cooking on the muscle fiber structure and water-holding capacity of stewed marinated beef was studied. Changes in the muscle fiber structure, texture properties and moisture content of stewed marinated beef prepared from beef shank under different ultrasonic frequencies (40/52/68, 40/52, 40/68, 52/68, 40, 52, 68 and 0 kHz) were measured. The results showed that with increasing the number of ultrasound frequencies, myofibrillar fragmentation index (MFI), the contents of β-turn and random coil increased, and the texture attribute of elasticity tended to increase, while the contents of α-helix and β-sheet decreased, and so did the hardness, chewiness, and cohesiveness of stewed marinated beef. Meanwhile, the solubility of connective tissue on the surface of muscle fibers increased, the separation and fracture of muscle fibers became more apparent. Low field-nuclear magnetic resonance (LF-NMR) results showed that ultrasound treatment caused a leftward shift of the transverse relaxation time (T2) and shortened it, thus changing the water distribution. As the number of ultrasonic frequencies increased, the shifting range of transverse relaxation time to the left increased, and the contents of bound water and free water also increased, while the content of quasi-bound water correspondingly decreased. Cooking loss was significantly lower in the triple-frequency group than in the dual-frequency and single-frequency groups, while the product yield showed an opposite trend, the highest value being found in the triple-frequency group. In summary, ultrasound treatment destroyed the muscle fiber structure and improved the water-holding capacity of stewed beef; the more the number of ultrasonic frequencies, the more pronounced the effect.
Packaging & Storage
Temporary Cultivation and Live Transport with Water Based on Gradient Cooling of Grass Carp (Ctenopharyngodon idellas)
HE Jingyi, WEI Ya, CEN Jianwei, HAO Shuxian, CHEN Shengjun, HUANG Hui,ZHAO Yongqiang, WANG Yueqi, YANG Shaoling, LIN Zhi
2024, 45(4):  271-278.  doi:10.7506/spkx1002-6630-20230411-098
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The study investigated the semi-hibernation and critical temperature of grass carp based on gradient cooling, and explore the effects of temperature (12–24 ℃) on the survival of grass carp and the concentration of ammonia nitrogen in the water. The temperature was reduced from room temperature (23–25 ℃) to the semi-dormant temperature (16 ℃) at cooling rate of 1, 3, or 5 ℃/h. The control group was reared at room temperature, and sampling was conducted after 0, 12, 24, 36, and 48 h. Serum biochemical and antioxidant parameters were measured to obtain the maximum cooling rate for grass crap. The results showed that the semi-dormant temperature of grass carp was 16 ℃, the critical temperature was 6–8 ℃, and the optimal cooling rate was 3 ℃/h. At 16 ℃, grass carp exhibited delayed stress response and decreased metabolism, and lower concentrations of ammonia nitrogen in the water. Except for aspartate aminotransferase level, the maximum values of other serum biochemical indexes at the cooling rate of 3 ℃/h, were significantly lower than those at 1 and 5 ℃/h (P < 0.05). The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) exhibited a trend of initially increasing and then decreasing with survival time, whereas the content of malondialdehyde (MDA) showed an opposite trend, reaching a minimum value of 5.27 mmol/mg after 36 h. Compared to the control group, the contents of all biochemical and antioxidant indexes in the three cooling groups showed significant changes with survival time. Therefore, cooling grass carp at a rate of 3 ℃/h could reduce the stress response and allowed it to enter a semi-hibernation state at a more suitable time. The results from this study provide key parameters for the temporary cultivation and transport of grass carp, as well as useful guidelines for reducing the transport mortality.
Transcriptomic Analysis of the Effect of Combined Treatment with 1-Methylcyclopropene and 2,4-Epibrassionolide on the Postharvest Senescence of Fresh Daylily (Hemerocallis citrina)
LI Kexin, HAN Chenrui, SUN Minmin, CAO Jiankang
2024, 45(4):  279-288.  doi:10.7506/spkx1002-6630-20230419-185
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In this experiment, we used different doses of 1-methylcyclopropene (1-MCP), 2,4-epibrassionolide (EBR), and their combination to treat fresh daylily and conducted a 15-day storage experiment at ‒1 to 1 ℃. By measuring physicochemical indicators and conducting transcriptomic analysis, the effects of 1-MCP and/or EBR on the postharvest senescence of fresh daylily were studied. The results indicated that combined treatment with 1 μL/L 1-MCP and 1 mg/L EBR after harvest was more effective in delaying adverse changes, such as yellowing, elongation, softening, dispersal, mass loss, and chlorophyll degradation, thereby greatly maintaining the storage quality of fresh daylily. Transcriptomic analysis revealed that the combined treatment regulated the transcription levels of senescence-related genes in daylily; significantly inhibiting the transcription of genes related to the ethylene biosynthesis and signal transduction pathways while activating the transcription of genes related to the brassinolide biosynthesis signal transduction pathway, therefore altering the metabolic balance of growth and senescence hormone levels in daylily. The combined treatment inhibited the transcription of genes related to the chlorophyll degradation pathway, which was beneficial for maintaining the quality of fresh daylily. Additionally, the combined treatment inhibited the transcription of E3 ubiquitin ligase genes closely related to senescence, thereby delaying protein degradation and postponing the physiological process of postharvest senescence in fresh daylily. This study provides a theoretical basis and practical reference for delaying the postharvest senescence and maintaining the storage quality of fresh daylily flower buds.
Safety Detection
Simultaneous Determination of 30 Foodborne Stimulant Drug Residues in Animal-Derived Foods by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry with Pass-Through Solid Phase Extraction
LIU Chuan, LI Jiajia, WU Xueying, CHEN Yanqiu, SHI Peiyu, SONG Juan, DAI Qin
2024, 45(4):  289-299.  doi:10.7506/spkx1002-6630-20230427-268
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In order to solve the problems of the detection of various foodborne stimulants in different animal-derived foods such as significant differences in matrix effects and many types of interference, a method was established for the determination of 10 protein anabolic agents, 8 glucocorticoids, and 12 diuretics in animal-derived foods by pass-through solid phase extraction (SPE) and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted with 5% formic acid in acetonitrile, and the extract was purified by pass-through solid phase extraction before being analyzed by UPLC-MS/MS. The internal standard method was used for quantification. The results showed that good linearity was observed for all analytes within their respective concentration ranges. The average recoveries ranged from 67.5% to 114.3% with relative standard deviations (RSDs) between 0.7% and 16.1% (n = 6). This method is characterized by high sensitivity, simple operation, high throughput and high detection efficiency, which improves the measurement accuracy of different complex matrices and can meet the need for the detection of the 30 foodborne stimulants in animal-derived foods used in sports events.
Authentication of Xinjiang Pishan Hong Sheep Meat Based on Multi-element Fingerprinting
ZHAO Laiyu, ZHANG Hongru, WANG Jing, ZHANG Chunhui
2024, 45(4):  300-306.  doi:10.7506/spkx1002-6630-20230509-077
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The study explored a method based on multi-elements combined with multivariate analysis to authenticate Xinjiang Pishan Hong sheep meat. A total of 36 Pishan Hong sheep and 36 Hu sheep were collected and slaughtered. Semitendinosus and longissimus dorsi muscles were excised from each carcass for analysis of 51 mineral elements by inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that the mineral elements, especially rare elements, in Xinjiang Pishan Hong sheep meat had distinctive fingerprint characteristics. The linear discriminant analysis (LDA) model built based on the mineral element data showed good discriminant performance for Xinjiang Pishan Hong sheep meat, especially longissimus dorsi with an accuracy of 100% and 99.29% for breed and muscle, respectively. Besides, La, Zn, Cs, Sn, Ho, Fe, Rh, Co, Se, Te, Mo, Al and Sb could be used as the major mineral elements to identify Pishan Hong sheep meat. Among them, Rh, Te and Ho had the highest variable importance in the projection (VIP) scores, and were found only in Pishan Hong sheep meat, thus being the key mineral markers for identifying Pishan Hong sheep meat. The accumulation of characteristic elements was related to regional characteristics.
Determination of the Concentrations of 176 Pharmaceutical and Personal Care Products in Drinking Water Samples by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry
WU Shaoming, LIU Wenjing, DAI Ming, HE Menghang, CHEN Yankai, WANG Zheng, ZHAN Chongqing, OUYANG Liqun
2024, 45(4):  307-314.  doi:10.7506/spkx1002-6630-20230530-282
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A method for simultaneous determination of 176 pharmaceuticals and personal care products (PPCPs) in drinking water samples was established by combining solid-phase extraction (SPE) with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The water samples were adjusted to pH 7, and then subjected to enrichment and purification using a Cleanert PEP SPE column. After concentration of the eluate with dimethyl sulfoxide (DMSO), the chromatographic separation was carried out on an HSS T3 column (2.1 mm × 150 mm, 1.8 μm) using methanol-0.1% formic acid water (containing 0.2 mmol ammonium acetate) as the mobile phase. The detection was performed in positive and negative ionization switching modes with multiple reaction monitoring (MRM). Methodological validation results showed that good linearity for the 176 PPCPs was achieved in the concentration range of 5–200 ng/mL, with a correlation coefficient higher than 0.99. The limit of quantitation (LOQ) of the method for all the PPCPs was 0.1 ng/mL. The average recoveries of spiked blank samples at three levels (0.1, 0.4 and 1.0 ng/mL) were between 68.0% and 126.7%, with relative standard deviation (RSD) between 1.1% and 10.3% (n = 6). In conclusion, the method established in this study is simple, rapid, reproducible, and highly sensitive, and can meet the requirements of the high-throughput detection of the 176 PPCPs in drinking water sources.
Detection and Changes in Contents of Flavor Nucleotide-Related Compounds in Low-Salt Pickled Potherb Mustard during Storage
XU Xiang, GU Guizhang, SHANG Jiayu, ZHANG Jinjie, LIN Bangchu, XIE Hongfeng, XU Dalun
2024, 45(4):  315-322.  doi:10.7506/spkx1002-6630-20230425-252
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In order to explore the changes in flavor nucleotide-related compounds in low-salt pickled potherb mustard during storage and transportation, a high-performance liquid chromatography (HPLC) method was established to analyze the changes in the contents of flavor nucleotide-associated substances in low-salt pickled potherb mustard during storage at (25 ± 5) ℃ (J-25), (4 ± 1) ℃ (J-4), and (25 ± 5) ℃ after sterilization (M-25) or (4 ± 1) ℃ after sterilization (M-4) were analyzed. Moreover, the changes in sensory quality were monitored. The results showed that 12 compounds related to flavor nucleotides were effectively separated within 33 min. Both sterilization and cold storage inhibited the deterioration of sensory quality and flavor nucleotide-associated substances, and their combination was more effective than either alone. The contents of adenosine triphosphate (ATP) and inosine monophosphate (IMP) in group M-4 were 29.7% and 66.4% of the initial values after 60 days, respectively, and the sensory quality was still acceptable. The total amount of ATP-related compounds in pickled potherb mustard stored at (25 ± 5) ℃ increased first and then decreased rapidly, and the sensory acceptance period of group J-25 was only 9 days. Both sterilization and cold storage effectively inhibited the changes of flavor nucleotides including adenosine monophosphate (AMP), guanosine monophosphate (GMP), cytidine monophosphate (CMP), uridine monophosphate (UMP) in pickled potherb mustard, and the total amount of these four flavor nucleotides in group M-4 was as high as 4.30 mg/100 g at the end of storage. Microbial metabolism in pickled potherb mustard and high temperatures accelerated the deterioration of flavor nucleotide-related compounds during storage, while sterilization and cold storage were beneficial to the maintenance of flavor nucleotide-associated compounds. The results of this study provide theoretical support for the processing and storage of low-salt pickled potherb mustard.
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Research Progress on the Effect of the Interaction Between Calcium and Iron on Their Absorption in the Intestine
LI Yi, CHENG Yongqiang, TANG Ning
2024, 45(4):  323-335.  doi:10.7506/spkx1002-6630-20230313-132
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Calcium and iron are essential metal elements for human health, as they play important roles in various metabolic processes such as bone formation and oxygen transport. Their interactions may interfere with each other’s absorption and bioavailability; however, deficiencies of calcium and iron are common nutritional problems that may cause osteoporosis and anemia, respectively. Therefore, understanding the mechanism of the intestinal absorption of calcium and iron and their interactions is crucial for developing effective strategies to prevent or treat these nutritional diseases. Many studies have demonstrated that calcium could inhibit iron absorption on a short-term basis, while long-term calcium supplementation has no effect the overall iron homeostasis, perhaps because the effect of calcium intake on iron absorption is a transient and adaptive response. The molecular mechanisms involved may include modulation of iron transporters by calcium, but more research is needed to elucidate this process. Furthermore, there are few studies on how iron affects calcium absorption. High doses of iron may have a negative effect on calcium absorption and retention; however, the specific effect of iron on calcium absorption is not clear. In this article, the current understanding of the intestinal absorption mechanism of calcium and iron, their interactions during the absorption process, and the underlying molecular mechanisms governing their reciprocal effects on each other’s absorption are summarized, which is of guiding significance for formulating efficient strategies for improving calcium and iron intake and absorption as well as for preventing public health problems caused by nutritional deficiencies.
Research Progress on Starch-Polyphenol Composite Film: from Functional Properties to Food Packaging Application
WANG Zhijing, CHEN Qianqian, CAI Jie
2024, 45(4):  336-343.  doi:10.7506/spkx1002-6630-20230903-016
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Plastic packaging pollution is a global environmental problem. Hence, the development of biodegradable materials has gained extensive attention in the field of food packaging. Starch, a common polysaccharide in nature, has the advantages of low price, safety, non-toxicity, and easy processing, and has shown great potential in the development of environmentally friendly food packaging materials. However, pure starch films have poor barrier performance and monotonous functional characteristics, which cannot satisfy people’s increasing requirements for food storage period and freshness. Polyphenols are natural antioxidants with a variety of beneficial health effects, so different types of polyphenols can be introduced into starch-based films to fabricate starch-polyphenol composite films with various functional properties. In this article, three preparation methods for starch-polyphenol composite films, extrusion, electrospinning and solvent casting are reviewed in terms of the preparation process, influential factors, advantages and disadvantages, and the interaction between starch and polyphenols is elucidated. The effects of adding polyphenols on physicochemical properties of starch-based composite films and their applications in the field of food packaging are analyzed, and future developments and challenges for starch-polyphenol composite films are discussed.
Research Progress on the Application and Mechanism of Medium-Chain Fatty Acids in Adjuvant Therapy of Diseases
JIA Xiwen, XU Jiajie, LIANG Xueyan, ZHANG Hui, LIN Hao, DING Kaili, HE Yinghui, LIU Luoyang, HAN Lujia, XIAO Weihua
2024, 45(4):  344-351.  doi:10.7506/spkx1002-6630-20230303-034
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As people’s consumption levels and health awareness have risen, the consumer demand for functional foods is steadily increasing. Medium-chain fatty acids (MCFAs), an important class of dietary fatty acids, have been regarded as high-value functional foods due to their unique transportation system and the fact that they can be metabolized rapidly in the body while producing high energy. Beginning with an overview of the types and structures of MCFAs, this paper goes on to elaborate the metabolic pathway of MCFAs in the human body and then summarize recent research on MCFAs in the adjuvant treatment of different diseases. This article focuses on the positive role of MCFAs in the adjuvant treatment of Alzheimer’s disease, epilepsy, cancer, diabetes, obesity, and other diseases, and expounds their action mechanism. Finally, an outlook on the future development of MCFAs is given. Overall, this review provides a theoretical basis for promoting the application of MCFAs in the fields of food and medicine.
Progress in the application of extracellular polysaccharides of Weissiella in fermented foods
HUANG Qian, LIANG Anjian, ZHU Pengcheng, LI Dongliang, TANG Junni
2024, 45(4):  352-359.  doi:10.7506/spkx1002-6630-20230312-111
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Exopolysaccharides (EPS) are natural high polymers metabolized into the extracellular space by lactic acid bacteria during their growth. EPS have a broad spectrum of biological activities including antitumor, antioxidant, cholesterol-lowering, and intestinal microflora balance promoting functions. They can also be used as a food thickening agent, emulsifier, and stabilizer. Weissella, which was discovered recently, has a strong ability to produce EPS. This article mainly reviews the sources of Weissella and the synthesis pathway, classification, functions and application in fermented foods of EPS produced by Weissella. Hopefully, this review will provide a scientific basis for the processing and application of EPS from Weissella.