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    Comparative analysis of sensory evaluation methods of Qingzhuan tea
    Lin Feng
    FOOD SCIENCE    0, (): 0-0.  
    Abstract108)      PDF(pc) (644KB)(58)       Save
    Taking the representative Hubei Qingzhuan tea as the research object, the influence of different brewing conditions on the sensory quality and the extraction rate of the main quality components of Qingzhuan tea was analyzed, and the sensory quality and chemical components of the tea soup obtained by the Chinese national standard brewing method were compared. The results showed that for the pressed Qingzhuan tea, the sensory quality of the brewing method was significantly better than that of the Chinese national standard, mainly due to the extraction rate of the main quality components such as water extract, tea polyphenols, amino acids, soluble sugar and tea pigments in the brewed tea soup was much higher. Judging from the sensory quality and the leaching rate of main quality components, the immersion tea brewing method was used to prepare Qingzhuan tea soup under the conditions of 1:80 tea-water ratio, 2 minutes of tea brewing, and 2-4 minutes of standing, with moderate concentration and relatively comprehensive endoplasmic quality. Further correlation study found that the correlation coefficient between soluble sugar, theabrownin, water extract and taste quality was higher. The results of this study provide a reference for the objective evaluation of sensory quality of Qingzhuan tea and other types of pressed tea.
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    Identification of key aroma compounds in fig extracts through sensomics approach
    王新惠
    FOOD SCIENCE    0, (): 0-0.  
    Abstract21)      PDF(pc) (487KB)(18)       Save
    Headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and gas chromatography-olfactory technique (GC-O) were applied to identify and analyze the volatile aroma compounds of fig extracts. The characteristic flavor compounds of fig extract were analyzed by aroma activity (OAV) and aroma recombination and omission tests. The results showed that a total of 40 volatile aroma components were detected in fig extracts by HS-SPME-GC-MS and GC-O, of which 18 compounds, such as isobutyrate, γ-butyl lactone, aromatic camphor, nonylaldehyde, vanillin and furfural, were important aroma components of fig extracts (OAV > 1). The recombination experiment showed that the sensory properties of recombination samples were similar to those of fig extracts. It is characterized by typical flavors such as fruity, sweet, baking and burnt sweet, with slight acidity, ointment and creaminess, and has a distinct fig extract flavor. Absence experiments further 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 flavors of fig extracts. The findings of this study would be helpful to the development and quality control of fig characteristic flavorings.
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    Dynamic change of flavor quality of Wuyi rock tea at different storage time
    Jun WU
    FOOD SCIENCE    0, (): 0-0.  
    Abstract58)      PDF(pc) (1279KB)(79)       Save
    Seven samples of Wuyi rock tea (Shui Xian) from different years were used for the study, and the effects of storage time on the flavor quality of Wuyi rock tea were investigated using multivariate analysis with a combination of sensory evaluation, detection of non-volatile and volatile substances. The results show that the flavour quality of Wuyi rock tea during storage can be divided into three transformation stages: 0~5 years, 10~15 years, and 20~30 years. As the storage time increases, the flavour gradually changes from mellow to stale, with the acidity appearing in the middle of storage and fading towards the end; The aroma gradually changes from flowery and fruity to aging, 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 was the main reasons for the taste conversion. 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 transformation. This study provides a comprehensive analysis of the flavour changes of Wuyi rock tea during storage and presents scientific insights with a view to providing reference for the storage of Wuyi rock tea and its scientific consumption by consumers.
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    Flavor and nutritional quality analysis of fresh sea buckthorn juice and sea buckthorn pulp
    Xiao JIA Gang Fan
    FOOD SCIENCE    0, (): 0-0.  
    Abstract130)      PDF(pc) (2295KB)(65)       Save
    Identification of odor compounds in fresh sea buckthorn juice (FSBJ) and sea buckthorn pulp (SBP) was performed by gas chromatography-mass spectrometry-olfactometer (GC-MS-O). A total of 39 and 36 odor compounds were identified in FSBJ and SBP, respectively. Further found 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 content of fruity esters odor compounds was significantly reduced in SBP after pasteurization. Taste sensory evaluation and electronic tongue analysis revealed that the sweetness and overall taste of SBP was superior to that of FSBJ. The content of vitamin C and total flavonoids in sea buckthorn pulp was significantly lower compared to FSBJ, indicating that pasteurization reduces the nutritional quality of FSBJ. The results of the study can provide theoretical references for flavor and nutritional quality optimization of sea buckthorn products.
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    Study on the profile of Chinese human milk oligosaccharides
    Li-juan MI
    FOOD SCIENCE    0, (): 0-0.  
    Abstract72)      PDF(pc) (1292KB)(29)       Save
    Aim: To analyze the impact of different regions, lactation time, and blood type genotypes on HMOs content in healthy lactating mothers’ breast milk in representative regions of China, and to explore the composition characteristics of milk oligosaccharides in China. Methods: Using the method of longitudinal cohort study, this research collected breast milk samples from 109 healthy mothers at three lactation stages in 6 cities in east, west, north and south of China. The contents of 23 kinds of HMOs were analyzed by ultra-high performance liquid chromatography tandem triple quadrupole mass spectrometry. Results: The contents of total HMOs and total Fucosyl neutral oligosaccharides in Kunming, Jinan and Shenzhen were significantly higher than those in Beijing, Baotou and Xining, and the contents of 3-FL, LDFT and LNnDFH-II in Baotou were significantly lower than those in Shenzhen and Jinan, Beijing, respectively; Eight neutral oligosaccharides (LNT, LNnT, LNFP-I,LNDFH-II, LNDFH-I&LNnDFH-I, MFLNH-I, DFpLNnH and DFLNHa) and four acidic oligosaccharides (6’-SL, DSLNT, 3’-SLNFP-II and 6’-SLNFP-VI) showed a significant decreasing trend with lactation time; 3-FL increased significantly with lactation time, LDFT and LNnDFH-II also increased with lactation time, but the difference was not significant; The contents of two kinds of mon-ofucosylhexasaccharides (MFLNnH and MFLNH-III) reached the highest in 1-month-old mature milk, and then remained unchanged or decreased slightly; According to the genotyping of blood groups inferred from oligosaccharide types, it was found that the lactating mothers in all cities were mainly Se+Le+, but the contents of other 18 oligosaccharides in this type of breast milk were lower than those of other blood groups except that the contents of LNDFH-II, LNDFH-I & LNnDFH-I, 6’-SL and LSTc were higher than those of other blood groups. Conclusion: This study revealed that region, lactation stage and maternal blood genotype lead to differences in the profile of human milk oligosaccharides, which provides scientific theoretical guidance for the accuracy of breast milk oligosaccharides in the nutritional intake of infants and young children in the early life stage.
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    The effects of different oil production processes on the quality and flavor of soybean oil were evaluated based on Electronic nose, HS-SPME-GC-MS and HS-GC-IMS.
    Si-Yu WU Xuan XIE Yao Guan
    FOOD SCIENCE    0, (): 0-0.  
    Abstract33)      PDF(pc) (2054KB)(20)       Save
    In order to explore the effects of different oil production processes (cold pressed, leached, cold pressed-leached) on the quality and flavor of tertiary soybean oil. The physicochemical properties and fatty acid composition of soybean oil were determined, and the volatile compounds in three soybean oils 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), and the volatile compounds’ data of the three soybean oils were analyzed by clustering heat map, principal component analysis (PCA) and partial orthogonal least squares discrimination analysis (OPLS-DA). The results showed that cold-pressed soybean oil had the lowest moisture content, and the peroxide value of leached soybean oil was significantly higher and the oil color was the darkest. Fragrant soybean oil has the most linoleic acid content and higher nutritional value; Among the volatile components detected, 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 large contributions were screened by OPLS-DA, and constructed a reliable model to identify fragrant soybean oil.In addition, a correlation was found between the quality and flavor of soybean oil.
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    Chemical Composition Analysis of ‘Tieguanyin’ and ‘Shuixian’ Teas using Metabolomics Method
    Yan-Ni ZHAO Jia-Kun PENG Zhe WANG
    FOOD SCIENCE    0, (): 0-0.  
    Abstract38)      PDF(pc) (1367KB)(15)       Save
    Tea cultivar and processing technique are crucial to the formation of tea flavor quality. In order to investigate the changes in the chemical compositions caused by tea varieties and processing techniques, we analyzed the green tea, fresh-scent oolong tea, strong-scent oolong tea and black tea made from the fresh leaves of ‘Tieguanyin’ and ‘Shuixian’ cultivars from the same origin using metabolomics method based on ultra-performance liquid chromatography-time-of-flight mass spectrometry. The results showed that the chemical compositions of tea samples made from different tea cultivars had great differences. The contents of most lipids, alkaloids and methylated catechins in ‘Tieguanyin’ tea were higher than those in ‘Shuixian’ tea. ‘Shuixian’ tea contained higher contents of theanine, most catechins, flavone (flavonol) glycosides, phenolic acids and N-ethyl-2-pyrrolidinone-substituted flavan-3-ols than ‘Tieguanyin’ tea. The processing technique also had significant impacts on the chemical compositions of tea, and a total of 127 differential compounds were screened, among which most catechins, dimeric catechins, alkaloids and some amino acid compounds were significantly higher in green tea than those in other kinds of teas. Most amino acids and flavone (flavonol) glycosides (quercetin-3-galactoside, kaempferol-3-glucosylrutanoside, etc.) were higher in fresh-scent oolong tea. The contents of EPSF, some flavone (flavonol) glycosides [quercetin-3-glucoside, kaempferol-3-(6''-acetylgalactoside), etc]. and lipid compounds in strong-scent oolong tea were higher. On the other hand, black tea was richer in the contents of theaflavins. This study systematacially elucidated the differences in chemical composition in teas made from ‘Tieguanyin’ and ‘Shuixian’ varieties and the effects of different processing techniques on the chemical composition of tea.
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    Analysis of Differential Muscle Metabolites of Bactrian Camel Meat from Different Ages Using Non-Targeted Metabolomics Based on Ultra-high Performance Liquid Chromatography-Mass Spectrometry
    SI RENDALAI Ming-Liang jing HE
    FOOD SCIENCE    0, (): 0-0.  
    Abstract1)            Save
    In this study, non-targeted metabolomics method based on ultra-high performance liquid chromatography q exactive mass spectrometry (UHPLC-QE-MS) was used to explore the change in metabolite profile in Bactrian camel meat from different age groups. The results showed that a total of 710 differentially expressed metabolites (DEMs) were identified in the longissimus dorsi muscle of camel meat from three age groups (3~4 years, 6~7 years, and 9~10 years; represented by I, II, and III, respectively); The number of DEMs was 78 in the I vs II comparison group, of which 47 were upregulated in group I and 31 were upregulated in group II; there were 49 DEMs in the II vs. III comparison group, of which 18 were upregulated in the II group and 31 were upregulated in the III group; in the same way, there were 65 DEMs in the I vs III comparison group, with 29 upregulated in group I and 36 upregulated in group III. The KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis results showed that DEMs were mainly enriched in related pathways such as protein and amino acid metabolism, fatty acid metabolism, vitamin and mineral metabolism, indicating that the digestion and metabolism of various nutrients in camels at different growth stages were different. The content of polyunsaturated fatty acids (especially n-6 PUFA, n-3 PUFA) and the ratio of PUFA/UFA (Polyunsaturated fatty acid,PUFA;Unsaturated fatty acid, UFA) in group I were significantly higher than those in group III, which was mainly related to the significant increase of arachidonic acid, linoleic acid and 13-L-hydroperooleic acid concentrations in the related metabolic pathways; meanwhile, DEMs such as L-leucine, L-valine, and L-glutamine could be used as potential markers for evaluating the quality change of camel meat from different ages. The results of this study provide a theoretical basis for understanding postmortem metabolism in camel muscle and for quality control of camel meat from different ages.
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    Rapid determination of active ingredient content in Gastrodia based on near-infrared spectroscopy combined with ARO-LSSVR
    null
    FOOD SCIENCE    0, (): 0-0.  
    Abstract0)            Save
    Gastrodia elata is one of the important medicinal herbs in Yunnan Province, and gastrodin and 4-Hydroxybenzyl Alcohol are the important active ingredients in Gastrodia elata, which are important indexes for evaluating the quality of Gastrodia elata. The detection methods of gastrodin and 4-Hydroxybenzyl Alcohol in Gastrodia elata are high performance liquid chromatography, gas chromatography, etc., which are time-consuming and complicated to operate. Near-infrared spectroscopy has the advantages of fast detection, convenience and non-pollution, and has a ?wide range of applications in quality control, quantitative as well as qualitative analysis in the field of Chinese herbal medicines. In order to realize the rapid and non-destructive detection of gastrodin and 4-Hydroxybenzyl Alcohol in Gastrodia elata, this study took Gastrodia elata from Zhaotong, Yunnan province as the experimental object, and collected spectral data in the range of 900-1700nm. Firstly, convolutional smoothing (SG) and standard normal variable transformation (SNV) are used for spectral data preprocessing, and secondly, feature wavelength extraction is carried out by CARS and IRIV, and according to the results of establishing LSSVR model based on feature wavelength, the best feature wavelength extraction method is selected. In order to improve the accuracy of the model, this study introduces an artificial rabbit intelligence algorithm to optimise the regularisation parameter γ and the kernel function density σ2 in LSSVR. And in order to evaluate the superiority of ARO, it was compared with PSO and GWO. The overall results show that ARO algorithm is superior to PSO and GWO in search speed and search ability. The best prediction models for both gastrodin and 4-Hydroxybenzyl Alcohol were CARS-ARO-LSSVR, with R2p of 0.9804 and 0.9797, and RMSEP of 0.0110 and 0.0140, respectively. Therefore, this study shows that near-infrared spectroscopy can be used for quantitative detection of active components in Gastrodia elata, which provides part of the theoretical basis for the development of rapid detection devices for Gastrodia elata.
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    Effect of kombucha consortium fermentation with Gastrodia elata on active ingredients and sensory quality
    Ying WANG Guo-qiang ZHANG Yue-feng HAN
    FOOD SCIENCE    0, (): 0-0.  
    Abstract1)            Save
    The changes of the main active ingredients and the sensory quality in liquid fermentation of Gastrodia elata with traditional kombucha consortium were further analyzed in the study. The results showed that after 5 days of kombucha fermentation, the pH of fermentation liquid decreased and the total acid content increased significantly, among which acetic acid, succinic acid and other organic acids increased most obviously. The fermentation with kombucha consortium significantly increased the contents of total polyphenols, total flavonoids and p-hydroxybenzyl alcohol.The volatile components of the fermentation broth of Gastrodia elata were analyzed by electronic nose combined with SPME-GC/MS (Solid Phase Microextraction-gas chromatography-mass spectrometry). The results showed that various flavor substances were produced by kombucha fermentation. Further sensory evaluation showed that kombucha fermentation could significantly reduce the unpleasant odor of Gastrodia elata and give it a fruity flavor.These studies provided theoretical basis and technical support for the in-depth development and utilization of Gastrodia elata.
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    Flavor characteristics of white tea made from oolong tea varieties based on HS-SPME-GC-MS and flavor-presenting substances analysis
    FOOD SCIENCE    0, (): 0-0.  
    Abstract1)            Save
    In order to investigate the flavor quality differences between white tea made by Oolong tea varieties and traditional white tea, eight white teas made by Oolong tea varieties, including Zimeigui, were studied, and traditional white tea made by Fuding Da Hao tea was used as a control, combined with sensory evaluation, biochemical testing and multivariate statistical analysis. The results showed that the appearance and soup color of white tea made by oolong tea varieties were darker than those of traditional white tea, and the sensory perception was poor; however, the taste and aroma were often better than those of traditional white tea. The analysis of biochemical components revealed that the differences in conductivity, pH, soluble sugars, free amino acids, GCG and EGCG were important factors that led to the great differences in taste between traditional white tea and white tea made by oolong tea varieties. Volatile substance detection showed that trans-2-nonenal, cis-3-nonen-1-ol, methyl palmitate, linalool, methyl linoleate, cypress brain, geranyl formate, phenethyl alcohol, nerolidol, methyl salicylate, dibutyl phthalate and phytone were the key differential aroma components affecting the aroma presentation of white tea made by traditional white tea and oolong tea varieties. This study reveals the flavor quality differences between white tea made by oolong tea varieties and traditional white tea, demonstrates the potential of oolong tea varieties to develop floral white tea, and provides a theoretical reference for further diversification of white tea flavor.
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    Aroma quality evaluation of high-quality black tea and defective black tea by fusion of electronic nose and GC-MS
    Yanqin Yang 缪 雯伊雯
    FOOD SCIENCE    0, (): 0-0.  
    Abstract2)            Save
    As one of the key indexes of black tea quality, aroma is often used to evaluate the quality of black tea. According to the results of sensory evaluation performed by experts, a total of 14 black tea samples were divided into two groups according to the aroma quality: high-quality black tea and defective black tea. Based on the fast gas chromatography electronic nose (GC-E-Nose) and gas chromatography-mass spectrometry (GC-MS) fusion technology combined with multivariate statistical analysis, the two groups of tea samples were subjected to discriminant analysis, and the key differential components were screened. The results showed that 117-dimensional data set can be obtained by the fusion of GC-E-Nose (44 dimensions) and GC-MS (73 dimensions). Accurate classification of two types of black tea could be achieved by the OPLS-DA model, and the model interpretation ability and prediction ability (R2Y = 0.976, Q2 = 0.959) were better than single GC-E-Nose or GC-MS data model. Based on double variable principle of variable important in projection (VIP) > 1.6 and p < 0.05, 8 key aroma components including dimethyl sulfide (B3, B25), β-ionone (A59), (3E)-4,8-dimethylnon-1,3,7-triene (A20), dihydroactinidiolide (A64), linalool (A17), phenylethyl alcohol (A19), δ-octyl lactone (A41) and γ-nonalatone (A45) were screened out, which played an important role in the classification. The results show that the fusion technology of GC-E-Nose and GC-MS can achieve the rapid and accurate classification of defective black tea and high-quality black tea, which can be used as a supplement to the traditional sensory evaluation method, and provide technical support for quality control and quality improvement of black tea.
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    Analysis of Characteristic Quality Indexes of Gaoyou Duck Egg
    null
    FOOD SCIENCE    0, (): 0-0.  
    Abstract16)      PDF(pc) (601KB)(8)       Save
    Abstract: Gaoyou duck eggs have big sizes and good quality. They were approved as national geographical indication agricultural products in 2020, but there are problems, such as unclear characteristic components and an incomplete quality evaluation index system. To explore the quality characteristics of Gaoyou duck egg, metabolomic, and other techniques were used to analyze the duck egg primarynutritional, indexes and small molecule metabolites. The results showed that the conventional indicators of Gaoyou duck egg, such as egg weight, egg shape index, egg yolk degree, huff unit, egg height, egg yolk index, and crude protein content, were higher than other breeds. The high content of total amino acids, umami amino acids, branched-chain amino acid, total fatty acids, unsaturated fatty acids, and low content of saturated fatty acids indicated that some sensory egg quality parameters, amino acids and fatty acids of Gaoyou duck egg could characterize the characteristic quality of Gaoyou duck eggs. Based on metabolomics technology, the metabolic fingerprint of Gaoyou duck egg was drawn, and the typical components of Gaoyou duck eggs were excavated by principal component analysis (PCA), partial least-squares discrimination analysis (PLS-DA) model, hierarchical cluster analysis (HCA) and other methods. 252 compounds and 22 differential compounds were identified in the yolk, 184 compounds and 40 differential compounds were identified in the egg white. Among them, uridine 5'-monophosphate, guanosine 5'-monophosphate, N-acetyl-D-glucosamine were the main differential nutrients, arachidonic acid was the unique nutrient of Gaoyou duck egg in egg yolk. indole was not detected in Gaoyou duck egg in egg white. This study used conventional egg quality indexes, basic nutritional indexes and small molecule metabolites to evaluate the characteristic quality indicators of Gaoyou duck egg.
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    Effect of Empoasca onukii Puncturing on Aroma and Taste Metabolites of Qingxindamao Beauty Tea
    Chun-Mei HE Shan Jin
    FOOD SCIENCE    0, (): 0-0.  
    Abstract8)      PDF(pc) (2394KB)(3)       Save
    To explore the effects of Empoasca onukii puncturing on metabolites of beauty tea produced by ‘Qingxindamao’ variety, sensory evaluation, ultrahigh performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and gas chromatography-mass spectrometry(GC-MS) were used to compare the sensory quality and metabolites of beauty tea processed from fresh tea leaves that were healthy and punctured by Empoasca onukii. The results showed that the quality of beauty tea with Empoasca onukii was better. Flavonoids, phenolic acids, theaflavins, glycoside derivatives and tannins in EG showed increased levels compare with CG, while amino acid, soluble sugar and lipids showed decreased levels. Based on odor activity value (OAV) and partial least squares discriminant analysis (PLS-DA), a total of 7 characteristic volatiles, including geraniol, linallinol, β-Myrcene, trans-β-ionone, methyl salicylate, dihydrolinalool and d-limonene, were identified. From the perspective of plant metabolomics, this study revealed the differences of metabolites of beauty tea made from fresh leaves of tea without Empoasca onukii and tea with Empoasca onukii.
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    Analysis of Flavor Components in Cold-Pressed Flaxseed Oils
    Yunping YAO Changmo LI
    FOOD SCIENCE    0, (): 0-0.  
    Abstract202)      PDF(pc) (385KB)(128)       Save
    In this study, the flavors and volatile compounds from cold-pressed flaxseed oils were identified and comparatively studied using quantitative descriptive analysis method, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) of headspace solid phase microextraction and simultaneous distillation extraction coupled with chemometrics. The results showed that cold-pressed flaxseed oils have a unique flavor, mainly presenting grassy and fishy flavors. Totally 34 characteristic components of cold-pressed flaxseed oils were detected, including 12 aldehydes, 7 alcohols, 5 acids, 3 terpenes, 3 alkanes, 2 ketones and 2 aromatic compounds. According to GC-O, detection frequency (DF≥6)and odor activity value(OAV≥1), indicating that 2-ethyl hexanol, hexanol, (E)-2-hexenal, hexanal, (E,E)-2,4-heptadienal with grassy flavor and (Z)-4-heptenal with fishy flavor from cold-pressed flaxseed oils. In the PCA model, characteristic flavor intensity was associated with sensory flavor of different areas cold-pressed flaxseed oils. The results of this study can provide a theoretical basis for improving the aroma, process and quality of cold-pressed flaxseed oils.
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    Profiling of Changes in the Flavor Quality of Flower and Fruit Scented Black Tea Stored at Room Temperature
    null
    FOOD SCIENCE    0, (): 0-0.  
    Abstract27)      PDF(pc) (660KB)(12)       Save
    To explore the changes of sensory quality and biochemical composition of the flower and fruit scented black tea during storage at room temperature for 0, 1, 2 and 3 years, this experiment was conducted to investigate the changes of sensory quality of the flower and fruit scented black tea, and to detect volatile and non-volatile compounds in flower and fruit scented black tea by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-performance liquid chromatography coupled to orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS). The results showed that the sensory quality of flower and fruit scented black tea was significantly affected by storage at room temperature, and the floral and fruit aroma quality characteristics were no longer present after 3 years of storage at room temperature, and the quality characteristics of aged acidity were obvious. The tea samples were divided into four groups of different years by principal component analysis (PCA) and systematic cluster analysis (HCA), 15 volatile differential compounds such as linalool, cis-β-ocimene, and hexanoic acid (VIP > 1 and p < 0.05), and 154 non-volatile differential compounds such as and theanine, epicatechin, and gluconic acid (VIP > 2 and p < 0.05) were screened by partial least squares discriminant analysis (PLS-DA) and one-way analysis of variance (ANOVA). The content of volatile compounds such as linalool, hexanal, cis-β-ocimene, and 2-pentylfuran decreased with increasing storage age, while the content of hexanoic acid, dihydroactinidolide 1-ethyl-2-formyl-1H-pyrrole, and β-ionone increased during storage. The contents of non-volatile compounds such as most amino acids, nucleotides, sugars, tea polyphenols, tended to decrease with increasing storage time, while the contents of most organic acids and lipid compounds showed an increasing trend. This study can provide a biochemical basis for elucidating the quality changes in the storage process of flower and fruit scented black tea, and are also helpful for guiding the market to store tea rationally and consume it scientifically.
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    Proteome Differences of Camel Meat from Different Ages
    SI RENDALAI jing HE Ming-Liang
    FOOD SCIENCE    0, (): 0-0.  
    Abstract23)      PDF(pc) (1466KB)(5)       Save
    The proteome differences of camel meat from different age groups were analyzed by tandem mass tag (TMT)-based quantitative proteomics and liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify the key proteins related to quality characteristics of camel meat. The result showed that the differentially expressed proteins (DEPs) had an important effect on meat quality of camel meat from different ages (3~4 years, 6~7 years, and 9~10 years; represented by I, II, and III, respectively). A total of 311 DEPs were identified in the longissimus dorsi muscle of camels from three age groups. The number of DEPs was 245 in the I vs II comparison group, 16 in the II vs III comparison group, and 139 in the I vs III comparison group. 194, 1, and 110 DEPs were up-regulated, where as 51, 15, and 29 DEPs were down-regulated. Gene Ontology (GO) functional annotation analysis indicated that structural proteins, metabolic proteins, and heat stress proteins could be used as biomarkers for different ages of camel meat. KEGG pathway analysis showed that DEPs were mainly involved in fatty acid metabolism, glycolysis/glucose production, amino acid biosynthesis, and HIF-1 signaling pathway. PPI analysis shows that metabolic enzyme proteins were key network connecting proteins that affect camel meat of different ages. Correlation analysis between DEPs and quality traits of camel meat showed that there were 16 DEPs with significant correlation were correlated closely with tenderness quality. The tenderness of camel meat from three age groups was mainly influenced by actin, histone and protein kinases. The results of this study can provide scientific basis for the grading and evaluation of camel meat, the selection of optimal slaughter age, and the study of camel meat quality characteristics.
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    Analysis of Non-volatile Components and Silk's Structure in Fresh Leaves of Zigui Simian Tu Tea variety
    ZHI YU NI DE-JIANG CHEN Yuqiong
    FOOD SCIENCE    0, (): 0-0.  
    Abstract22)      PDF(pc) (2272KB)(34)       Save
    Simian tea is produced in Zigui County, Hubei Province. Due to its rich silk in fresh leaves and excellent quality, it has become a famous green tea in Hubei Province. In order to study the quality formation of simian tea, six leaves from different positions of the local tea tree, simian tu tea variety, in Zigui were used as experimental samples. The non-volatile components, mineral elements, and silk structure were respectively analyzed using UHPLC-Q-TOF-MS (ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry), ICP-OES (inductively coupled plasma optical emission spectrometer), and SEM (scanning electron microscope). The results showed that the non-volatile components in the fresh leaves were more abundant in the leaves with higher tenderness, with most amino acids, alkaloids, catechins, and aroma glycosides mainly concentrated in the first (L1) and second leaves (L2), theanine, phenolic acids, and flavonoids mainly concentrated in the third leaves (L3), while the content of non-volatile components in the leaves with lower tenderness was relatively low. The elements content of different tenderness fresh leaf was quite different, with the contents of nitrogen, phosphorus, potassium, zinc, and copper being higher in tender leaves (L1 and f L2), while the content of magnesium, iron, manganese, and calcium being higher in mature leaves. Through scanning electron microscope observation, it was found that the silk structure in the fresh leaves was mostly in the form of three parallel or single strand curls, which existed in the inner thread or ring-shaped vessels of the xylem of the main and lateral veins; and the number of silk in 2-4 leaves is more than that in bud and the first leaf (L1).
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    Study on Change Rules of Characteristic Components in Black Garlic Processing Based on Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry
    Ping-Xiang LIU Rui Gao Zhengrong Wang
    FOOD SCIENCE    0, (): 0-0.  
    Abstract26)      PDF(pc) (950KB)(16)       Save
    An ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry method for simultaneous determination of 10 flavor precursors and 21 free amino acids in black garlic was established in the present study. The method has high sensitivity and accuracy, and can meet the detection requirements. The method was applied to the study on the change law of characteristic components in the processing of black garlic. The results showed that the characteristic components in black garlic changed significantly during the processing at 75 ℃ and 85% humidity. Among them, γ-aminobutyric acid, S-allyl-L-cysteine, isoalliin, glutamine, methiin, alliin, tryptophan, and γ-L-glutamyl-S-allyl-L-cysteine were the most obvious, and were the chemical markers screened in garlic during fermentation.
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    Study on the Chemical Constituents and Digestion-promoting Effect of Maojian Green Tea
    FOOD SCIENCE    0, (): 0-0.  
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    Maojian green tea, a substitute tea derived from the fresh leaves of a traditional herbal plant Dracocephalum rupestre Hance, has been used as digestive herb in Xinzhou, Shanxi. However, scientific evidence regarding its efficacy is still lacking. In this study, we assessed the digestion-promoting effect of Maojian green tea extract (MJ-GTE). The functional food evaluation methods including intestinal propulsion ratio in mice and the body weight, weight gain, food intake, food utilization, pepsin activity, and pepsin excretion in rats were used to evaluate the digestion-promoting effect, and the chemical compositions were then investigated using an ultrahigh performance liquid chromatography-quadrupole orbitrap mass spectrometer. Animal experiments results showed that the intestinal propulsion ratio in high-dose MJ-GTE group mice (0.83 g/kg/d) was significantly increased comparing with the model group (P < 0.05), and the pepsin excretion in medium-dose MJ-GTE group rats (0.21 g/kg/d) was significantly increased comparing with the negative control group (deionized water) (P < 0.05), which indicated MJ-GTE has a digestion-promoting effect. The metabolomics analysis resulted in the identification of 98 compounds, among which flavones (apigenin and luteolin, 0.14-0.77 mg/g), flavanones (naringenin and eriodictyol, 0.49-1.49 mg/g), flavone-7-O-glycosides (0.57-9.07 mg/g), and flavanone-7-O-glycosides (4.49-38.98 mg/g) were the main components in MJ-GTE. This study systematically evaluated the digestion-promoting effect of MT-GTE and then analyzed the main chemical composition, as well as provided a theoretical basis for the promotion and development of MJ-GT and its new products in future.
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