Calcium alginate-whey protein isolate (CA-WPI) composite gel embedded with anthocyanins was prepared by in-situ release method using sodium alginate and whey protein isolate as raw materials. The raw materials were allocated to three treatments: CA-WPI both at room temperature, room temperature CA-heated WPI, and heated CA-heated WPI. The results showed that compared with the control CA gel, the addition of heated WPI reduced the dehydration shrinkage rate of the gel by 74.17% and increased the freeze-thaw stability by 36.37%. In addition, the linear viscoelastic region of the mixed gels was greatly extended, while the creep recovery rate was decreased. Compared with the control gel, the hardness of the composite gels decreased, the viscosity of the heated CA-heated WPI gel significantly increased to 0.68 mJ. The results of infrared spectroscopy and storage stability showed that the composite gels effectively encapsulated anthocyanins, and 85.01% of the anthocyanins embedded in the heated CA-heated WPI composite gel was retained after 15 days of storage at 25 ℃.

In this study, binary and ternary complexes were prepared by heat treatment or combined heat and ultrasonic treatment using casein micelles (MC) as matrix and proanthocyanidin (PC), catechin (Cat) and chlorophyllin sodium copper salt (Chl) or their binary combinations as ligands. The interactions between PC, Cat, Chl or their binary combinations and MC were analyzed, and the binding capacity of MC to the various active molecules was evaluated. In addition, the structure, microscopic morphology and thermal stability of the complexes were characterized, and the antioxidant properties and in vitro digestibility of the ternary complexes were investigated as well. The results showed that PC, Cat and Chl formed binary complexes with MC through hydrophobic interactions, among which MC showed the highest affinity for Chl. Under heat treatment conditions, MC bound one molecule through hydrophobic interaction and another one by van der Waals forces and hydrogen bonds. At 298 K, the binding of the first molecule improved the binding constant and the number of binding sites of the second one. The binding of PC, Cat, Chl or their binary complexes had no significant effect on the spatial structure or microscopic morphology of MC. The thermal stability of MC was enhanced after the binding of bioactive molecules under heat treatment conditions. In terms of antioxidant properties, heat treatment promoted the 2,2’-azino bis-(3-ethylbenzthiazoline-6-sulfonicacid) (ABTS) radical cation scavenging activity of the ternary complexes, while combined heat and ultrasonic treatment promoted their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. In addition, the loading of active molecules improved the digestibility of MC in simulated intestinal fluid. This study could provide a reference for the application of MC in the loading of bioactive molecules.

This study aimed to assess the effect of soy lecithin (Soy L, 0.2%–1.0%), glucose oxidase (GOX, 0.3–1.5 U/g), and transglutaminase (TG, 0.3–1.5 U/g) on dough elongation properties and texture qualities of steamed bread. The optimum formulation of steamed bread prepared from wheat flour (50%) and potato pulp (50%) was investigated. Results showed that Soy L and GOX significantly (P < 0.05) affected the specific volume and hardness of steamed bread, whereas TG significantly (P < 0.05) affected the resistance to extension and extensibility of dough, as well as the springiness and cohesiveness of steamed bread. The optimum formulation consisting of 0.65% Soy L, 0.92 U/g GOX, and 0.96 U/g TG increased the viscoelasticity and fermentation characteristics of dough and improved the specific volume, texture, and porosity of steamed bread enriched with potato pulp.

In the present study, pre-digested puffed rice flours with different dextrose equivalent (DE) values were prepared by using enzymatic pretreatment and extrusion, and their gelatinization characteristics, physicochemical and structural properties were analyzed. The results showed that compared with puffed rice flour, the water solubility index of pre-digested puffed rice flour increased by up to about 1.5 times with an increase in DE value, the water absorption index decreased by up to 76%, the slip angle decreased, the Carr index and Hausner ratio increased, and the reconstitutability and fluidity improved obviously. Moreover, the final viscosity and setback value of pre-digested puffed rice flour decreased with increasing DE value, decreasing by up to 37.79% and 94.87%, respectively. Moreover, after enzymatic pretreatment and extrusion, the soluble protein content of pre-digested puffed rice flour decreased, and the content of rapidly digestible starch increased significantly, while the secondary structure of protein and the crystalline structure of starch did not change significantly. The results provide a theoretical basis for the application of pre-digested puffed rice flour instead of maltodextrin in foods for special medical purpose.

In the present work, Pickering emulsions were fabricated using burdock RG-1-type pectic polysaccharides/zein composite particles as emulsifiers. The effects of polysaccharide concentration, pH, ionic strength, and oil phase volume fraction (φ) on the physicochemical properties of the Pickering emulsions were systematically analyzed. Besides, the efficacy of the emulsions for stabilizing and delivering curcumin were also elucidated. The results showed that the optimal conditions for the formation of Pickering emulsions were pectin concentration 10 mg/mL and pH 3–5. The emulsion was stable under NaCl concentration of 40–200 mmol/L and oil volume fraction of 0.17–0.75. Rheological results showed that low concentration of calcium ion effectively strengthened the interfacial structure of the emulsion containing curcumin, while when the concentration of calcium ion increased to 4 mmol/L, the emulsion gel shrank, reducing its viscoelasticity. The thermal stability and bioavailability of curcumin were significantly improved by high internal phase emulsion encapsulation. The bioavailability of curcumin encapsulated in the cross-linked emulsion with 1 or 2 mmol/L calcium ion was highest, more than 60%. This study is of positive significance to expand the application of RG-1-type pectic polysaccharides/zein composite nanoparticles in food delivery systems.

The occurrence of Maillard reaction in heated Torreya grandis cv. Merrilli seed oil was verified by detecting browning index and the contents of the Maillard reaction products (MRPs) 3-deoxyglucosone, methylglyoxal and 5-(hydroxymethyl)furfural, and the effects of the MRPs on the quantification of total phenolics using the Folin-Ciocalteu and Fast Blue BB assays were explored. The Folin-Ciocalteu assay showed that the content of total phenolics in the oil increased after treatment at 150 ℃ for 90 to 120 min, while the Fast Blue BB assay showed the opposite result. It was also observed that the absorbance of the oil at a wavelength of 294 nm increased after long-term low-temperature or high-temperature heat treatment. 3-Deoxyglucosone (0.21–0.47 μg/g) and 5-(hydroxymethyl)furfural (0.06–0.40 μg/g) were detected only in the 150 ℃ treated oil, while methylglyoxal (0.67–1.73 μg/g) existed in both oil samples. In the Folin-Ciocalteu assay, the absorbance at a wavelength of 765 nm of 3-deoxyglucosone and methylglyoxal linearly increased with an increase in their concentrations, and the decreasing order of the absorbance of the MRPs at the same concentration was 3-deoxyglucosone > methylglyoxal > 5-(hydroxymethyl)furfural. In the presence of 3-deoxyglucosone, the Folin-Ciocalteu result was greater than the actual value, and the degree of interference was not related to the content of total phenolics in samples, but instead was positively correlated with the concentration of 3-deoxyglucosone. In the Fast Blue BB assay, there was no significant difference in absorbance at 420 nm among the three MRPs. For food matrices prone to the formation of 3-deoxyglucosone and methylglyoxal during processing, the Fast Blue BB assay can be selected instead of the Folin-Ciocalteu assay to mitigate the interferences from the two substances in the quantification of total phenolics.

In this study, self-assembled quaternary complexes of lactoferrin (LF), epigallocatechin-3-gallate (EGCG), high methoxylated pectin (HMP) and β-cyclodextrin (β-CD) were constructed and characterized, and successfully utilized for stabilizing high internal phase Pickering emulsions (HIPPEs). In comparison with ternary complexes, the quaternary complexes had lower interfacial tension (reduced by about 3 mN/m) and more appropriate wettability (contact angle close to 90°), and were more effective in stabilizing HIPPEs (smaller droplet size and enhanced homogeneity). The dense cross-linking network of the quaternary complexes endowed HIPPEs with higher viscoelasticity (increasing elasticity and viscosity by up to 1.9 and 5.3 times, respectively), textural properties, 3D printing characteristics, and refrigeration stability. β-CD significantly improved the antioxidant activity of HIPPEs (up to 2.1 times) by interfering with the combination of EGCG with LF or HMP. In addition, the self-assembly sequence could flexibly regulate the structures and emulsifying properties of the quaternary complexes, with the LF-β-CD-EGCG-HMP complex having the most pronounced effect. In conclusion, this study provides a theoretical basis for the construction of protein-polyphenol-polysaccharide-polysaccharide complexes and their applications in HIPPEs.

The effect of Spirulina powder on the rheological properties, microstructure and gluten properties of wheat flour dough was investigated. The results showed that in terms of mixograph characteristics, the addition of Spirulina powder generally increased the water absorption rate, development time and peak curve area of dough, and increased the energy required to form dough. Adding a small amount of Spirulina powder enhanced the strength and reduced the viscosity of dough, but the kneading resistance became weaker at higher concentrations of added Spirulina powder. After adding Spirulina powder, the breaking force of dough gradually increased and the breaking distance decreased. Meanwhile, the free sulfhydryl content increased and the disulfide bond content decreased. When the amount of added Spirulina powder was more than 6%, the wet gluten content decreased significantly, and the micrograph showed that the gluten network was seriously damaged. Polyacrylamide gel electrophoresis (PAGE) showed that the proportion of high-molecular-mass glutenin decreased and the proportion of low-molecular-weight glutenin increased after adding Spirulina powder. The results of Fourier transform infrared (FT-IR) spectroscopy showed that the addition of Spirulina powder reduced the content of ordered structure and increased the content of disordered structure in gluten proteins. Therefore, it is speculated that when a small amount of Spirulina powder is added to dough, dietary fiber in Spirulina fills the gluten network in dough after absorbing water, strengthening the adhesive state of the gluten protein network and improving dough strength. However, when the amount of added Spirulina powder is higher than 6%, the cross-linking of gluten proteins is hindered, thereby weakening gluten, reducing the ordered structure content of gluten proteins, and ultimately deteriorating the rheological properties of dough.

The study was carried out to evaluate the contents of common biogenic amines, microbial community diversity and physicochemical indicators of seven samples of fermented liquid soybean products and seven samples of fermented solid soybean products. The results showed that the total amount of biogenic amines in defatted soy sauce, steamed fish soy sauce and oyster reduced salt soy sauce were all higher than 8 000 mg/L and significantly higher than those in the other samples (P < 0.05). The pH and Kjeldahl nitrogen contents of the samples were negatively correlated with the total content of biogenic amines, while water activity (factor loading 0.413), total acid content (factor loading 0.399) and salinity (factor loading 0.330) had a greater positive effect on the production of biogenic amines. Pseudomonas spp. and Bacillus spp. were positively and negatively correlated with the content of biogenic amines, respectively. The results of the study provide a theoretical basis for the development of relevant standards.

A fungal strain capable of degrading fumonisin B1 (FB1) from ground maize samples heavily contaminated with fumonisin was obtained by enrichment culture method. The strain was named as FDS-2, and was characterized for its growth and degradation characteristics, and the initial degradation pathway of FB1 by FDS-2 was investigated. The strain was identified as Exophiala spinifera according to its culture characteristics, microscopic characteristics and phylogenetic tree based on RNA-internal transcribed spacer (ITS) sequence characteristics. The optimum growth and degradation conditions were 30 ℃ and pH 5.0. Under these conditions, the strain could completely degrade 250 μg of FB1 within 48 h. Intracellular FB1-degrading enzymes were discovered in this strain. Using liquid chromatography-mass spectrometry (LC-MS) to analyze the degradation products, it was determined that the primary degradation pathway began with the degradation of FB1 into hydrolyzed FB1. This study provides a strain resource and a theoretical basis for the biodegradation of fumonisin in grain and feed.

In this study, the functional genomic characteristics of Lactiplantibilus plantarum ST were analyzed. Comparative genomic analysis was performed on the whole genome sequences of L. plantarum ST and the type strain L. plantarum ATCC 14197T as well as those of 152 L. plantarum strains published in the NCBI GenBank. A phylogenetic tree was constructed based on 1 262 core genes of these 154 L. plantarum strains, and the genetic distance between ST and the intestinal isolate BCC9546 was found to be the closest. The isolates originated from milk and meat products were concentrated in the upper part and the lower part of the second branch, respectively, and they were different due to different sources and could be aggregated. Meanwhile, Drosophila isolates showed a significant aggregation trend. Functional annotation analysis suggested that the ST genome contained genes related to the phosphotransferase system (PTS) as a major carbohydrate transport system. Genes related to the immune regulatory pathway were also annotated. There were many genes related to the hydrolysis or rearrangement of glycosidic bonds, but no virulence factors or antibiotics resistance genes found in ST. Compared with the other L. plantarum isolates, ST carried the unique functional gene ecfT related to energy transport function. In addition, ST had functional genes involved in the synthesis of the quorum-sensing signaling molecule AI-2, glutathione, and adhesion molecules. The results of API 50 CHL carbohydrate metabolism showed that L. plantarum ST could utilize a wide range of carbon sources and metabolize 29 carbon sources including monosaccharides, glycosides, disaccharides and polysaccharides. This study provides a genetic basis for the development and utilization of L. plantarum ST as a safe probiotic strain.

Objective: To investigate the toxin-encoding genes and antibiotic susceptibility of Staphylococcus aureus isolates from retail vegetables consumed raw. Methods: The 27 S. aureus isolates from tomato, lettuce, spinach and cabbage collected from supermarkets, farmers’ markets and vendors in Xi’an, Baoji, Hanzhong and Yan’an of Shaanxi province were identified by PCR amplification of the nuc gene, the prevalence of 19 toxin-encoding genes and 12 antibiotic resistance encoding genes in these isolates was evaluated, and the antibiotic susceptibility to 14 antibiotics was determined by the agar dilution method. Results: Seventeen of these isolates were identified as methicillin-susceptible S. aureus (MSSA) and the remaining 10 isolates were identified as oxacillin-susceptible methicillin-resistant S. aureus (OS-MRSA). A total of eight toxin-encoding genes were detected in the 27 isolates, and the detection rate (29.6%, 8/27) of sec was highest. In addition, 51.9% (14/27) of these isolates carried at least one toxin-encoding gene, and nine toxin-encoding gene profiles were totally identified. Seven antibiotic resistance genes including blaZ, mecA, ermC, tetK, dfrG, dfrK, and aac(6’)/aph(2”) were detected. The isolates were all susceptible to oxacillin, rifampicin and vancomycin. Resistance to amoxicillin/clavulanate was most commonly detected, followed by trimethoprim/sulfamethoxazole, ampicillin, erythromycin, cefoxitin, ciprofloxacin, ceftriaxone, gentamicin, amikacin, tetracycline and chloramphenicol. Twenty-four (88.9%) isolates were resistant to three or more antibiotics. Conclusion: OS-MRSA is prevalent in vegetables consumed raw in Shaanxi province, and it has multiple antibiotic resistances and carries multiple toxin-encoding gens, posing a potential food safety hazard.

Lipase activity was detected based on the fluorescence properties of gold nanoclusters (AuNCs) and the inner filter effect (IFE) of p-nitrophenol. Glutathione-modified AuNCs was used as fluorophore, and p-nitrophenol produced from the lipase-catalyzed hydrolysis of p-nitrophenol palmitate as fluorescence absorbent. The results showed that under the optimal conditions (p-nitrophenyl palmitate concentration 1.6 mg/mL, pH 7.5, temperature 50 ℃, and reaction time 20 min), the relative fluorescence intensity (F0–F, y) was positively correlated with lipase activity (x) in the range of 5.6–196 U/L, which was described by the equation y = 2.003 5 + 0.936 8x, with a correlation coefficient (r2) of 0.997 8, and the detection limit was 1.3 U/L (at a signal-to-noise ratio of 3). The developed method is simple and sensitive, and can be applied to the detection of lipase activity.

The current study was performed in order to explore the effect of Eurotium cristatum LJSC.2001 on the fermentation quality of raw dark tea. Golden flower loose tea was produced by using E. cristatum LJSC.2001 to ferment raw dark tea from the cultivars Zhuyeqi, Yuntaidaye and Taoyuandaye provided by representative manufacturers (Yuntaishan, Yunshang, Baishaxi and Junhe) in Anhua, Hunan province, and comparative analysis of their taste and aroma quality was carried out by sensory evaluation, basic physicochemical analysis, analysis of catechin components by high performance liquid chromatography (HPLC), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Results showed that after fermentation by E. cristatum LJSC.2001, the dry tea samples were darker in color and fully covered with golden flower; their infusions were darker in color, and had a strong fungal aroma and a mellow and full taste, and the brewed tea was soft. Raw dark tea from Baishaxi had a stronger fungal aroma after fermentation, while retaining a distinct pine smoke-like aroma. The contents of taste compounds including tea polyphenols, free amino acids, soluble carbohydrates, flavonoids, total catechins, myricetin, quercetin, and kaempferol showed an overall decreasing trend. The content of catechins in Yuntaidaye raw dark tea from Yuntaishan and Yunshang declined most. The relative contents of esters and aldehydes increased after fermentation. There were differences in the content of volatile components among the different fermented tea samples, methyl salicylate and (E,E)-2,4-heptadienal being the major ones. Multivariate statistical analysis showed significant differences in volatile composition between golden flower loose tea and raw black tea. There were 19 characteristic volatile components identified including methyl salicylate, (E,E)-2,4-heptadienal, (E)-linalool 3,7-oxide, (E)-furan oxidized linaloa, acetophenone, (E)-2-,(Z)-6-nonadienal, (E)-2-hexenal, (E,E)-3,5-octadien-2-one and n-tridecane. The contents of the nine volatile components increased significantly after fermentation, and they all contributed to the fungal aroma of golden flower loose tea. It can be seen that fermentation by E. cristatum LJSC.2001 can impart a more mellow and fuller taste and a more prominent fungal aroma to raw black tea.

After comparing the bacterial load of black-yolked salted duck eggs (BSE) and that of duck eggs with different cleanliness degrees, it was found that the total bacterial count on the shell of severely stained eggs (DE) was distinctly higher than that on the shell of non-visually stained eggs (CE), and the total bacterial count in the shell membrane and contents of BSE increased greatly. Furthermore, 16S rDNA gene sequencing was used to analyze the differences in the composition and abundance of bacterial communities in CE, DE and BSE. It turned out that Proteobacteria, Firmicutes and Actinobacteria were the dominant phyla, accounting for 34.35%, 27.25% and 17.28% of the total abundance, respectively, while Bacteroidetes accounted for 8.29% of the total abundance. Proteobacteria was the dominant bacteria in DE and accounted for 89.01% of the total abundance, while the relative abundance of Firmicutes and Actinobacteria were 6.16% and 3.98%. The dominant phyla in BSE were Proteobacteria (76.50%), Bacteroidetes (8.00%), Actinobacteria (6.76%) and Firmicutes (5.43%). The abundance of Proteobacteria in DE and BSE was significantly increased. The dominant bacterial genera in CE were Nesterdella (9.08%), Campylobacter (7.91%), Streptococcus (3.41%) and Oligomonas (2.92%). In DE, Psychrobacter was the dominant genus, accounting for 86.01% of the total abundance, and the relative abundance of Acinetobacter was 2.20%. The dominant bacteria in BSE were Rolstonia (22.91%), Serratia (5.05%) and Actinomycetes (3.32%). The cluster analysis of bacterial diversity showed that the dominant microorganisms of BSE were close to those of DE. The microbial phenotype analysis showed that the dominant microorganisms of BSE were Gram-negative bacteria, had high oxidative stress tolerance and pathogenicity, and could tolerate oxidizing detergents. The results of microbial gene function prediction and species composition of metabolic pathways demonstrated that bacterial carbohydrate decomposition, lipid transport and metabolic oxidation in DE were stronger than those in CE. More coenzyme transport and metabolic pathways could make the biochemical reactions of bacteria from DE faster to produce more secondary metabolites, thus resulting in changes in the quality of duck eggs. This is consistent with the highest bacterial abundance in the secondary metabolite biosynthesis, transport and catabolism pathways in BSE. The results of this study provide theoretical support for the cleaner production of duck eggs.

The composition of antifungal volatile compounds (VC) produced by Bacillus subtilis PW2 was identified by solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Then, the identified single components were selected to determine their inhibitory effect against Aspergillus ochraceus by plate buckling method, and the effect and mechanism of the most active VC on the growth and toxicity of A. ochraceu. The results showed that 41 components including esters, aldehydes, alkanes, alcohols, ketones, acids and olefins were identified in the VC produced by PW2. Among these compounds, 2-ethyl hexanol (2-EH) had the strongest inhibitory activity against A. ochraceus. Direct contact with 2-EH at a dose of 1 562.5 μL/L completely inhibited the growth of A. ochraceus and reduced the content of ochratoxin A (OTA) by 23.67%. 2-EH vapor at doses of 112 and 281 μL/L completely inhibited and killed A. ochraceus, respectively. The spores of A. ochraceus treated with 2-EH appeared wrinkled, sunken and shriveled, and the integrity of the cell membrane was destroyed. Furthermore, the mycelial ergosterol content decreased by 42.68%–65.40%, and nucleic acid and protein leaked out of the cells after this treatment. This study shows that 2-EH can inhibit and kill A. ochraceus by destroying its cell membrane, which provides a theoretical basis for the application of 2-EH in the prevention of food mildew.

The microbial community structure and diversity of Jiang-flavor Daqu (TS, WS, WM, MH and DJ) from different areas of Maotai town were analyzed by using the third-generation nanopore sequencing platform, and its physicochemical indexes and characteristic flavor substances were measured. The results showed that there were some similarities and differences between Daqu in different areas of Maotai town. In terms of microbial community structure, Bacillus, Saccharopolyspora, Weissella, Staphylococcus and Streptomyces were the common dominant bacterial genera in the five Daqu samples. Among them, Bacillus was the absolute dominant bacteria in MH and DJ. Aspergillus and Penicillium were the common dominant fungal genera, and the proportions of Lichtheimia and Saccharomycopsis in TS, WM and MH were significantly higher than those in DJ and WS. Compared with TS and WM, network correlation analysis showed that MH, DJ and WS had stronger interactions among dominant bacteria. In addition, redundancy analysis (RDA) showed that Weissella was positively correlated with esterification power, liquefaction power, saccharification power, acetic acid, ethyl acetate, ethyl lactate and n-pentanol. Lichtheimia was positively correlated with liquefaction power, saccharification power, acetic acid, isovaleric acid, 2,3-butanediol, phenylacetaldehyde and dibutyl phthalate. Saccharomycopsis was positively correlated with esterification power and ethyl acetate. Bacillus was positively correlated with 2,3,5,6-tetramethylpyrazine, propionic acid, isovaleric acid, dibutyl phthalate, 2,3-butanediol and phenacetaldehyde.

The effect of electrical current stimulation on the fermentation characteristics of Corynebacterium crenatum under anaerobic conditions was investigated, and the impacting mechanism was discussed by calculating metabolic fluxes and measuring gene expression levels. It turned out that electrical current stimulation greatly contributed to glucose metabolism and succinic acid synthesis. Applying an electric current of −5 mA increased the glucose consumption rate, the concentration of succinic acid in the fermentation broth, the yield of succinic acid, the metabolic flux in the pentose phosphate pathway (HMP), and intracellular NADH/NAD+ ratio by 27.4%, 109.4%, 62.5%, 150.6% and 30.8% respectively, compared with the control group (0 mA). The results of metabolic flux and key enzyme gene expression levels indicated that glucose-6-phosphate was the key node that could influence the production of succinic acid. Electrical current stimulation up-regulated the expression levels of the glucose-6-phosphate dehydrogenase gene (zwf) and the phosphoenolpyruvate carboxylase gene (pepc), and increased the metabolic fluxes in the HMP and succinic acid biosynthesis pathway, thereby increasing the production of succinic acid. These results support the combined application of electrochemistry and fermentation.

High-throughput sequencing technology was used to analyze the microbial community of fermented grains for Fuhexiangxing baijiu during mechanized and traditional stack fermentation. The results showed that microbial exchange, succession and enrichment occurred during the fermentation process. In both fermented grains, the microbial communities were composed of four major bacterial genera including Bacillus, Weissella, Acetobacter and Ralstonia, and six major fungal genera including Aspergillus, Lichtheimia, Candida, Pichia, Wickerhamomyces and Saccharomyces. The diversity of bacteria was significantly higher in mechanized than traditional stack fermentation, while the diversity of fungi was significantly lower in traditional than mechanized stack fermentation. Moreover, bacterial diversity was lower on the surface than in the interior of fermented grains, whereas fungal diversity was higher on the surface than in the interior of fermented grains. These results provide a basis for continuous optimization of the mechanized brewing process of Fuhexiangxing baijiu and for improving the quality of base baijiu.

In this study, MiSeq high-throughput sequencing technology was used to analyze the bacterial and fungal diversity in Laozao produced in Liquan. The results showed that the dominant bacterial phyla in Liquan’s Laozao were Firmicutes (97.20%) and Proteobacteria (2.29%), accounting for 99.49% of the total abundance, and the dominant bacterial genera were Lactobacillus (85.25%), Pediococcus (5.50%), Leuconostoc (1.68%), Streptococcus (1.63%) and Lactococcus (1.12%). The dominant fungal phyla were Mucoromycota (56.90%) and Ascomycota (43.10%), and the dominant fungal genera were Rhizopus (56.66%), Saccharomyces (23.28%), Saccharomycopsis (12.24%) and Candida (5.35%). Diversity analysis found that the microbial community of Liquan’s Laozao could be divided into two groups, which showed significant differences in bacterial diversity and fungal richness (P < 0.05). Gene and phenotype prediction showed that the relative expression levels of amino acid transport and metabolism, potential pathogenicity and mobile elements were significantly different between the two groups (P < 0.05).

Objective: The aim was to investigate whether a bacterial flora exists in the eggs of healthy laying ducks (Ma breed), and if yes, whether the bacterial flora could be associated with those in the genital tract and cecum. Methods: Healthy laying ducks were dissected to collect genital tract and cecum tissues, as well as soft- and hard-shelled duck eggs, and cultivable bacteria were counted by plate count method, and the diversity and correlation of uncultured bacterial flora were analyzed by MiSeq high-throughput sequencing. Results: The decreasing order of the total bacterial counts in the samples was cecum > genital tract > hard-shelled egg > soft-shelled egg. The bacterial gene sequences belonged to 56 phyla and 1 319 genera. The abundance and species evenness of bacteria in the cecum and genital tract were higher. The dominant genera included Bacteroides, Megamonas and Campylobacter. Species abundance and dominant concentration were higher in soft- and hard-shell eggs. Pseudomonas and Acinetobacter accounted for 19.01% and 10.01% of the total abundance, respectively. Gene function prediction showed that all samples had high abundance of metabolic and glycolytic functions. The gram-positive and anaerobic phenotypes in the cecum and genital tract were abundant. The pathogenicity and oxidative stress of bacteria in soft and hard shell eggs were significant. The dominant bacterial genera in the four samples were overlapped, and the overlap rates of egg content with the cecum and genital tract were 13.96% and 24.35%, respectively. In addition, the phylogenetic tree analysis showed that the genera in all samples were closely related to each other and shared homology with the significantly contributing genus Bacteroides in the cecum. Conclusion: Duck eggs are not formed in a sterile environment, the bacteria residing in the cecum and reproductive tract of healthy laying ducks can infect different egg structures during its formation and become a part of the internal flora in duck eggs. These results can provide a reference for further research on the characteristics and control of non-pathogenic bacteria in egg contents.

In order to increase the added value of table grape products and consequently improve the income of fruit farmers, this experiment systematically studied the relationship between fungal diversity and “Hutai 8 ” wine quality during the winemaking process. Fungal diversity changes during natural and inoculated wine fermentation were studied by high-throughput sequencing, and changes in flavor characteristics were evaluated as well. The results showed that compared with inoculated fermentation, naturally fermented wine had lower alcohol content and higher acetic acid content. Moreover, the contents of volatile alcohols and esters were higher than those of the wine produced by inoculated fermentation, and the content of fatty acids was lower. At the early stage of natural fermentation, Hanseniaspora was dominant in the microbial community of naturally fermented wine, a large number of Saccharomyces appeared at the middle stage, and there were still a large number of Hanseniaspora at the late stage. S. cerevisiae remained dominant during inoculated fermentation. Ethyl acetate and some alcohols, such as benzyl alcohol, benzyl alcohol, hexanol, cis-3-nonene-1-ol, were correlated with the genera Alternaria, Acremonium and Cladosporium. In addition, there could be a risk of naturally fermented “Hutai 8” wine deteriorating and producing a large amount of ethyl acetate, which can adversely affect the aroma. Therefore, inoculated fermentation is recommended to produce “Hutai 8” wine.

The microbial community diversity in huangjiu (yellow rice wine) vinasse during spontaneous fermentation into Xiangzao was analyzed by high-throughput sequencing. It turned out that the bacterial and fungal diversity was abundant. During the whole fermentation process, Proteobacteria was the dominant bacterial phylum, whose relative abundance ranged from 71.26% to 75.27%. The relative abundance of Firmicutes was 16.09% in the initial stage of fermentation and showed a downward trend in the middle and late stages. The dominant bacterial genera were Aquabacterium and Brevundimonas. The relative abundance of Aquabacterium was 22.48% at the beginning of fermentation, increased to 24.94% at the middle, and decreased to 21.29% at the end. Bacillus and Lactobacillus were also found during fermentation. The dominant phylum of fungi was Ascomycota, and its relative abundance decreased from 63.46% at the beginning of fermentation to 51.68% at the end. The dominant genus of fungi was Pichia, and its relative abundance ranged from 6.58% to 13.79%. Additionally, the relative abundance of Tausonia and Mortierella was above 3%. To sum up, the microbial community diversity is abundant during the spontaneous fermentation of huangjiu vinasse, and the fermentation process has a significant impact on the relative abundance of microorganisms.

In this study, the nutritional components of Hongjundouzha inoculated with Neurospora crassa at different fermentation times were analyzed. RNA sequencing (RNA-seq), quantitative real-time polymerase chain reaction (real-time PCR) and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based non-target metabolomics were used to find out the main differentially expressed genes (DEGs), key metabolites and metabolic pathways affecting the fermentation of this strain, and the transcription and expression of cellulase, an important gene, was explored. The results showed that the second day of fermentation was the key period for the transformation of nutrients in Hongjundouzha and the most active period of gene expression, where cellulase expression was the highest. Carbohydrates in okara were metabolized through the starch and sucrose metabolism and carbon metabolism pathways to produce D-arabinose, sorbitol, D-xylose, L-fucose, linoleic acid, gamma-linolenic acid and arachidonic acid. On the third day, amino acid metabolism occurred. Proteins in okara were metabolized into glutamate, alanine, valine and other amino acids through the amino acid biosynthesis pathway. On the fourth day, secondary metabolites were produced. Daidzein, genistein and genistin in okara were transformed into neohesperidin, strychnine, squamolone and other substances with special physiological activities through the secondary metabolite biosynthesis pathway. The mycelia began to age, lysophosphatidyl choline (LPC) 18:4/18:1 and 18:1, lipids indicating food spoilage, appeared. In general, the second day of fermentation was the most active period of nutrient transformation in Hongjundouzha. The product matured on the third day of fermentation, and began to age and rot on the fourth day.

The effect of spatial heterogeneity on the microbial community and physicochemical properties during the primary fermentation of Daqu were investigated by high-throughput sequencing technology and conventional detection methods. Nongxiangxing baijiu Daqu inoculated with the unique ripe starter obtained by gradually culturing and expanding Daqu treated by cosmic rays was used. The results showed that although the intensity of change in driving factors varied among layer, their trends were the same. The liquefying, saccharifying and esterifying power of Daqu were higher in the bottom layer than in the upper and middle layers at the same fermentation time and the fluctuation was small. The microbial community of Daqu was composed of 12 dominant bacterial genera, including Lactobacillus, Weissella, Bacillus, Kosakonia, Staphylococcu and Thermoactinomyces, and seven dominant fungal genera, such as Pichia, Thermoascus, and Rhizomucor. Principal co-ordinates analysis and hierarchical clustering analysis showed significant differences in the bacterial and fungal community structure among fermentation stages and layers. Procrustes analysis and Mantel test showed that moisture had a significant effect on the bacterial community in Daqu, and acidity had a significant effect on the bacterial community in the middle and bottom layers of Daqu. Moreover, moisture had a significant effect on the fungal community in the upper and middle layers of Daqu. Redundancy analysis showed that moisture and acidity were positively correlated with Lactobacillus and Pichia, while driving factors had different influences on the microbial communities in different layers of Daqu. Therefore, the interaction and co-occurrence patterns of microbial genera in Daqu could change due to the differences in driving factors among different layers of Daqu. These results suggested that regulating driving factors during the Daqu making process is an effective way to improve the microbial community structure and quality of Daqu.

Using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), we separated and identified 148 non-volatile organic compounds including flavonoids, organic acids and amino acids in navel orange pulp in 37 min. The volatile organic compounds (VOCs) in the pulp of navel oranges from four major production regions in southern Jiangxi Province, Ruijin, Xinfeng, Anyuan and Nankang were detected by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). In total, 97 VOCs were identified including esters, alcohols, aldehydes and terpenes. The results of this study provide detailed data for further research on chemical substances in the pulp of Gannan navel oranges.

Taiping Houkui green tea is mainly made from the young shoots of the sextual tea line ‘Shidacha’. In the present study, the differences in the quality and genetic evolution of green tea made from the young shoots of five ‘Shidacha’ varieties (Gaojiazao, Huangzhong, Shidacha No.2, Shidacha No.6, and Guangyangzao) and two non-‘Shidacha’ tea varieties (Fuzao No.2 and Shuchazao) were explored. The volatile and non-volatile metabolites of the seven tea samples were analyzed, and the differences in genome-wide transcriptional levels and genetic background among the seven tea varieties were analyzed using RNA sequencing (RNA-seq). No significant differences in catechin content or the total content of free amino acids were found among all tea samples except Shuchazao, whereas caffeine content differed significantly among all samples. The contents of floral aroma compounds such as linalool, linalool oxide, geraniol and jasmone were relatively high in the infusion of ‘Shidacha’ green tea. RNA sequencing results showed that the genome-wide transcriptional level of Guangyangzao was close to that of the non-‘Shidacha’ tea varieties. In principal component analysis (PCA), Guangyangzao and the other ‘Shidacha’ varieties were distributed in different quadrants. Phylogenetic analysis showed that the non-‘Shidacha’ tea varieties had a close genetic relationship with each other as well as Gaojiazao and Huangzhong, but was far away from the other ‘Shidacha’ varieties. The transcriptional levels of most of the key enzyme genes involved in the biosynthesis of linalool, indole, nerolidol and jasmone lactone were higher in the ‘Shidacha’ tea varieties than in the non-‘Shidacha’ ones. This study provides important theoretical support for the breeding of excellent ‘Shidacha’ varieties and provides a theoretical basis for follow-up research on the formation mechanism of floral aroma compounds in tea leaves.

In order to explore the dynamic changes and stage specificity of metabolites in bamboo shoots during its growth, widely targeted metabolomics based on ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to analyze fresh bamboo shoots harvested at heights of 10 and 25 cm. The results showed that a total of 875 metabolites belonging to 13 categories were identified from bamboo shoots, including sugars, alcohols and flavonoids, whose relative contents significantly increased in 25 cm-high bamboo shoots. Moreover, the results of multivariate statistical analyses showed that the metabolites in bamboo shoots had an obvious stage specificity. Totally 283 significantly differential metabolites were identified between the two growth stages, of which 102 metabolites were annotated to 82 metabolic pathways. The contents of 20 major nutrients did not significantly differ between the two growth stages; however, the contents of metabolites related to taste, flavor and bioactive function were higher, while the content of bitter compounds was lower in the 25 cm-high bamboo shoots. Therefore, compared with the 10 cm-high bamboo shoots, the 25 cm-high bamboo shoots have a higher comprehensive economic value and are more suitable for harvesting. The results of this study can provide a theoretical reference for the comprehensive development and sustainable utilization of Chimonobambusa tumidissinoda.

In order to determine the characteristic flavor of Jingyang Fu brick tea, a national geographical indication product, the volatile compounds of Jingyang Fu brick tea, Anhua Fu brick tea and four other dark teas were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) in this study. The results showed that in total 154 compounds were identified by GC-IMS and HS-SPME-GC-MS, and the flavor composition of Jingyang Fu brick tea was clearly distinguished from that of Anhua Fu-brick tea and that of the other dark teas. Totally 12 characteristic substances of Jingyang Fu brick tea were obtained by comparative analysis with the other dark tea, seven of which were validated by GC-IMS, including 1-octen-3-one, n-hexanol, guaiacol, β-pinene, methyl butyrate, n-propanol and 2-heptanone, and the remaining five were characterized by HS-SPME-GC-MS based on aroma activity values, including hexanal, decanal, (E,E)-3,5-octadien-2-one, methyl salicylate and α-viologenone. The identification of characteristic flavor substances can provide a theoretical basis for the identification, origin tracing and processing optimization of Jingyang Fu brick tea.

Based on sensory descriptors developed by a sensory evaluation panel for 48 commercial Chinese brewed soy sauce samples, a flavor wheel of Chinese brewed soy sauce with 55 descriptors in the dimensions of aroma and flavor was developed for the first time. Meanwhile, a lexicon of sensory descriptors for brewed soy sauce containing reference samples with different intensities was established, and 20 brewed soy sauce samples of different grades and from different geographical origins were subjected to sensory evaluation by quantitative descriptive analysis (QDA) using this lexicon. The results showed that the characteristic flavor attributes of soy sauce were soy paste-like, salty, umami, Chinese herbal, and cooked soybean-like aromas. Through analysis of variance (ANOVA), principal component analysis (PCA) and discriminant analysis (DA), it was found that there were significant differences in sensory properties among soy sauce of different grades and from different regions. This study can provide a methodological reference for sensory quality analysis of Chinese brewed soy sauce.

The characteristic aroma compounds of qingxiangxing baijiu were analyzed and the differences in sensory characteristics and aroma compounds between young and aged baijiu were clarified by sensory evaluation and techniques for qualitative and quantitative analysis of aroma compounds. Totally 69 odor-active compounds with flavor dilution (FD) factor ≥ 2 were confirmed by comparative aroma extract dilution analysis (CAEDA). A total of 40 odor-active compounds in young qingxiangxing baijiu and 43 in aged qingxiangxing baijiu were identified based on odor activity value (OAV). The important aroma compounds of young and aged baijiu were verified by aroma recombination experiments. Finally, heatmap analysis showed that the differential important aroma compounds (P ≤ 0.05) between young and aged qingxiangxing baijiu mainly included γ-butyrolactone, ethyl isovalerate, γ-nonanolactone, ethyl isobutyrate, 3-methylbutanoic acid, 1,1-diethoxyethane, β-phenylethanol, 2-pentyl furan, acetaldehyde, butanoic acid, ethyl hexanoate, benzaldehyde, furfural, vanillin, hexanal, 3-hydroxy-2-butanone, and 2,3-butanedione. In summary, microconstituents were more abundant in aged than young baijiu, and so were most esters, organic acids, aldehydes, and ketones, while the opposite was found for propanol, isobutanol, and 3-methylbutanol. These could be the major reasons for the significant differences in the sensory characteristics of young and aged baijiu.

The effects of blanching followed by spray drying on volatile flavor compounds in sweet corn were investigated. The volatile flavor compounds in fresh, blanched and spray-dried sweet corn were analyzed by headspace solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). The qualitative analysis was carried out by comparison of the spectra for the chromatogram peaks with those in the NIST14 database library and comparison of retention index (RI), and the quantitative analysis by an internal standard method. Gas chromatography-olfactometry (GC-O) was used to analyze the composition of odor-active compounds and overall flavor profiles. The results showed that a total of 58 volatile flavor compounds were detected in fresh, blanched and spray-dried samples. Blanching and spray drying had significant effects on the types and contents of volatile flavor compounds in sweet corn. After blanching treatment, the contents of ketones, aromatic compounds, terpenes and aldehydes were decreased, and the total content of volatile flavor compounds decreased by 36.60%. After spray drying, the total content of volatile flavor compounds was increased by 19.21 and 30.30 times compared with those of fresh and blanched sweet corn, respectively. Among them, the contents of aldehydes, ketones, alcohols and heterocyclic compounds were increased, and new substances such as dimethyl thioether and 2-acetyl-1-pyrroline were detected. Principal component analysis (PCA) showed that the decreases in the contents of 2-nonenal (E), 3-ethyl-2-methyl-1, 3-hexadiene, octanal and D-limonene were closely related to blanching, while the increases in the contents of dimethyl thioether, 2-acetyl-1-pyrroline, 2-methylpropanal, 3-methylbutanal, 2-methylbutanal 2-methyl-(E)-2-butenal compounds were highly correlated with spray drying. Thirty-three odor-active compounds were detected by GC-O, 10 of which had odor intensity value (OIV) equal to or larger than 3. Flavor profile analysis showed that the intensity of fruity aroma was the highest in fresh sweet corn, followed by floral, nutty and green aroma. After blanching treatment, the overall aroma intensity was decreased and in particular, the grassy aroma intensity was decreased significantly. After spray drying, the overall aroma intensity was significantly increased, the intensity of nutty and green aroma was significantly enhanced, and a strong barbecue aroma appeared.

Sensory evaluation, gas chromatography-ion mobility spectrometry (GC-IMS) and chemometrics were applied to analyze the change of volatile flavor compounds in Pixian bean paste during cooking. The results indicated that Pixian bean paste showed the strongest fruity aroma after four minutes of stir frying, and strongest woody, nutty and burnt aromas after five minutes. As the stir-frying time increased, the spicy aroma of Pixian bean paste was weakened. The volatile components of Pixian bean paste with different stir-frying times were well separated by GC-IMS and a total of 97 volatile components were detected at five stir-frying times, aldehydes, ketones and esters being the major ones. The relative contents of aldehydes and esters increased as the stir-frying time prolonged, including butanal, isobutenal, 2-methylpropanal, valental, 3-methylbutanal, isobutyl butyrate, ethyl butyrate and methyl acetate. Totally 34 signature volatile components were identified by orthogonal partial least squares-discriminant analysis (OPLS-DA). Pearson correlation analysis showed that the woody, nutty and burnt aromas were strongly negatively correlated with the concentrations of most aroma compounds. The spicy aroma was strongly positively correlated with the concentrations of most aroma components.

To evaluate the tea processing suitability of the leaves of ‘Guixing’ tea, a wild tea plant germplasm resource in Guangxi, the water extract content, polyphenolic composition, sensory properties and volatile aroma composition of the tea leaves as well as green, oolong, white and black tea processed from the tea leaves were measured and compared with each other. The results showed that ‘Guixing’ tea was a unique tea germplasm resource with low caffeine content and a ratio of phenol to ammonia of 11.8, which was more suitable for black tea production. After processing into white and black tea, the epigallocatechin content in the leaves decreased to 0, and the catechin content of green tea decreased significantly compared with that of the leaves. The results of sensory evaluation showed that white and black tea had a rich almond-like aroma, while the other kinds of tea did not. A total of 53 aroma components were detected, which could be divided into two types. Each type had same aroma components. The first type included tea leaves, green tea and oolong tea, without almond-like aroma, and had 40 aroma components, the major ones being β-linalool and limonene. The second type included white tea and black tea, with strong almond-like aroma, and contained 42 aroma components, the main one being benzaldehyde. A total of 28 aroma components were found to be common to these tea samples, all of which contained benzaldehyde. The decreasing order of the relative contents of benzaldehyde in them was black tea (61.97%) > white tea (31.73%) > oolong tea (14.65%) > leaves (4.24%) > green tea (2.88%). Benzaldehyde was mainly produced during withering, rolling and fermentation. With extended withering time, the content of benzaldehyde increased. The higher the content of benzaldehyde, the stronger the almond-like aroma of tea. Therefore, benzaldehyde is key for almond-like aroma formation.

Mopan persimmon brandy with an alcohol content of 42% (V/V), prepared by fermentation and distillation, was aged after being added with 5–20 g/L of Chinese-made moderately roasted oak chips. The volatile and non-volatile components of persimmon brandy were analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), the total phenol content and antioxidant activity were determined, and sensory evaluation was also performed. The results showed that a total of 33 volatile components were identified by GC-MS, among which the major components were ethyl acetate, ethyl decanoate, and ethyl laurate. The content of volatile components was the highest upon the addition of 10 g/L of oak chips. The results of LC-MS showed that the number of non-volatile substances increased by 183 after aging. The total phenol content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity increased with increasing addition of oak chips, but was basically stable after 90 days of aging. In the sensory evaluation, persimmon brandy with 15 g/L of oak chip scored the highest (72.5 points).

To explore the differences in aroma between compressed dark tea and raw dark tea, headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were used to analyze and compare the flavor quality and aroma composition of four kinds of Hunan compressed dark tea and raw dark tea stored under the same condition. The results showed that compared with the raw tea, the pine smoke-like aroma and the crude, green, sour and other miscellaneous off-odors of the compressed tea were weaker, the concentration of aroma was higher and more long-lasting, and the stable flavor was more prominent. Furthermore, the contents of 15 unpleasant aroma components such as (E,Z)-2,4-heptadienal, 2,3,5,6-tetramethylpyrazine, and acetic acid in the compressed tea decreased, while the contents of 11 pleasant aroma components such as (E,E)-2,4-heptadienal, saffron aldehyde and butylated hydroxytoluene increased. Through principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), 10 characteristic aroma components which could potentially be used to discriminate between compressed dark tea and raw dark tea were identified including acetic acid, 2-butyl-1-octanol, 1,2,3-trimethylbenzene, (Z)-2-decylenaldehyde, linalool, octanol, α-terpineol, 3-tridecanone, (E,Z)-2,6-nonadienol and phenylethanol. These results can provide a reference for further research on the quality formation mechanism of Hunan dark tea and the development of dark tea products.

To explore the effect of storage time on the flavor and quality of white peony tea, sensory evaluation and volatile and non-volatile composition analysis of 12 white peony tea samples made from three different varieties: Fudingdahao (FDDH), Zhenghedabai (ZHDB) and Fujiangshuixian (FJSX) were carried out, and the resulting data were analyzed by multivariate statistical analysis combined with multivariate statistical analysis. The results showed that during the storage process, the content of tea polyphenols and free amino acids decreased, and the ratio of polyphenols to amino and the contents of soluble sugar, flavonoids and thearubigin increased, so that the taste of white peony tea was sweet, mellow, sweet after taste and stale. The large decrease in the content of alcohol substances resulted in a reduction in the refreshing and floral aroma of white peony tea. Totally 12 differential volatiles were key to changing the aroma types of white peony tea. α-Farnesene, linalool oxide II, methyl salicylate, linalool, cis-2-pentene-1-alcohol and hexanal were the key components responsible for the floral, pekoe-like and refreshing aroma. cis-Linalool oxide and neryl oxide were also positively related to the formation of the floral aroma, and the latter was also key to the formation of the pekoe-like aroma. cis-3-Hexen-1-ol and phenethyl alcohol were also positively correlated with the formation of the refreshing aroma. In addition, 4-isopropyltoluene was the key component responsible for the honey-like and herbal aroma. Linalool oxide II and neryl oxide were the key components responsible for the jujube-like aroma. cis-Linalool oxide was the key component responsible for the plum-like aroma. The 4-isopropyltoluene and isobutyraldehyde were the key components contributing to the woody aroma. This study provides scientific insights into the formation of the differences in the flavor and quality of white peony tea of different ages, which could provide a reference for the improvement of tea flavor.

In this study, liquid-liquid extraction-solvent assisted flavor evaporation (LLE-SAFE), headspace solid phase microextraction extraction (HS-SPME), gas chromatography-quadrupole-mass spectrometry (GC-Quadrupole-MS), gas chromatography-orbitrap-mass spectrometry (GC-Orbitrap-MS) and gas chromatography-olfactometry (GC-O) were used in combination to identify the volatile components in a fermented hawthorn wine (SBL-J) and a prepared hawthorn wine (FS), and the results of sensory analysis, modified frequency (MF) and odor activity value (OAV) were used to determine the key aroma compounds. Totally 89 aroma compounds were identified by LLE-SAFE/GC-O-MS. In addition, 29 and 38 aroma compounds with MF values of more than 20% were found in SBL-J and FS, respectively. A total of 123 volatile components were detected by HS-SPME/GC-Quadrupole-MS and HS-SPME/GC-Orbitrap-MS and there were 29 and 33 aroma compounds with OAV of greater than 1 (0.1 for esters) identified in SBL-J and FS, respectively. 2-Methybutyl acetate, ethyl hexanoate, ethyl octanoate and phenylethyl alcohol were the key aroma compounds in the two samples. To our knowledge, 2-methybutyl acetate, ethyl isovalerate, (E,E)-2,4-hexadienoic acid ethyl ester and ethyl butyrate, were identified for the first time as the key aroma components of hawthorn wine.

This study aimed to analyze the difference in aroma components and aroma characteristics of different types (white, oolong, yellow and black) of fermented Lingyun Baihao tea. The aroma components were identified by solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS), and odor activity value (OAV) was used to determine the key flavor components. By combined use of principal component analysis (PCA), orthogonal partial least square-discriminant analysis (OPLS-DA), cluster analysis and sensory evaluation, the aroma of fermented Lingyun baihao tea was comprehensively evaluated. The results showed that a total of 48 aroma compounds were identified in the tea samples, including 15 key flavor components and flavor-modifying components (OAV > 0.1). The cumulative interpretation rate R2X (cum) and the cumulative prediction rate Q2 (cum) of the PCA model were 0.984 and 0.846, respectively, and those of the OPLS-DA model were greater than 0.7 and 0.9, respectively. Both models had good fitness. The major differential components were linalool, isoamyl alcohol, 2-methylbutyraldehyde, β-ionone, nonanal and jasmone. The 15 aroma components were classified into three categories by hierarchical cluster analysis (HCA). Class I contained indole and dehydroalinalool, Class II contained linalool, nonanal, phenylacetaldehyde, hexanal, 2-methylbutyraldehyde, isovaleraldehyde, phenylethanol and isobutyraldehyde, and Class III contained jasmone, β-ionone, methyl salicylate, 2-pentylfuran and dimethyl sulfide. Class I was prominent in oolong tea samples, Class II was prominent in black tea samples, Class III was prominent in white tea samples, and Class II and III were prominent in yellow tea samples. These aroma characteristics were consistent with the results of sensory aroma evaluation. GC-MS analysis and OAV calculation combined with PCA, OPLS-DA and HCA can enable the identification and evaluation of Lingyun Baihao fermented tea aroma. The results of this study can provide a reference for the further development of Lingyun Baihao tea.

The major characteristic aroma components of Japanese apricot fruit grown in Dayi county, Sichuan Province were determined by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) based on odor activity values (OAVs). The pattern of accumulation of the major aroma components was investigated by analysis of aroma precursors and their correlation with climate factors was analyzed. The results showed that ethyl butyrate, β-myrcene, ethyl 3-methyl-butyrate, benzaldehyde and nonanal were the major characteristic aroma substances of Japanese apricot fruit, and C6 and C9 compounds were the major aroma components. C6 aroma substances had a high correlation with unsaturated fatty acid precursors. There was a positive correlation between the synthesis of C6 and C9 aroma substances. Climate significantly affected aroma accumulation during fruit ripening. Precipitation was the key factor affecting the content of C6 substances in the early ripening stage, mainly affecting the accumulation of bound hexenol. At the late stage of maturity, air temperature had a great influence on the content of free substances such as hexanol and hexanoic acid. These results provide a basis for follow-up research to analyze the flavor and quality of processed Japanese apricot fruit, explore the effects of climate factors on Japanese apricot fruit and its products, and identify the production region of raw materials and processed products for flavor evaluation.

To establish a method to identify the authenticity of manuka honey, this study compared different methods of DNA extraction from mānuka honey pollen, and it developed a DNA extraction method for mānuka honey supernatant and a real-time polymerase chain reaction (real-time PCR) method for the detection of plant-derived ingredients in mānuka honey, including plant internal control, mānuka and kānuka. By analyzing the specificity, sensitivity, detection limit and comparing with the method of the New Zealand Ministry for Primary Industries (MPI), the feasibility, accuracy and equivalence of this method were confirmed. The proposed DNA detection method could replace the MPI method, not only shaking off the dependence on kits, but also making up for the deficiency of identifying mānuka honey pollen only. It has an important application value and scientific significance for the identification of mānuka honey.

A novel efficient and accurate ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the detection of 13 diuretics in animal-derived foods was developed. The samples were extracted with acetonitrile or 90% acetonitrile solution and cleaned up on a PRiME HLB pass-through solid phase extraction (SPE) column. Then, an ACQUITY HSS T3 column (100 mm × 2.1 mm, 1.8 μm) was used for chromatographic separation by gradient elution using a mobile phase consisting of 5 mmol/L aqueous ammonium acetate and acetonitrile, and an electrospray ionization source (ESI) operated in both positive and negative ion scanning modes with multiple reaction monitoring (MRM) was used to detect the diuretics qualitatively and quantitatively. The results showed that the calibration curves for all the analytes exhibited good linearity with correlation coefficients above 0.997 0. The limits of quantification ranged from 2.0 to 5.0 μg/kg. The recoveries of the proposed method ranged between 68.3% and 118.0%, with relative standard deviations (RSDs) between 0.47% and 9.5% (n = 6). This method is a fast, simple, accurate, and practical one for the detection of diuretics.

A fluorescent aptasensor was constructed for the high-sensitivity and high-selectivity detection of 17β-estradiol (E2) based on the fluorescence quenching effect of gold nanoparticles (AuNPs) on carbon quantum dots (CQDs) and the specific affinity of aptamers to targets. Under the optimal conditions (particle size of AuNPs = 39 nm, AuNPs amount = 200 μL, quenching time = 20 min, and fluorescence recovery time = 60 min), a good linear relationship was observed between the fluorescence recovery degree (y) of the sensor and the logarithmic value (x) of E2 concentration (2 × 10-5–2 × 10-9 mol/L), which was fitted with the following equation: y = 58.50x + 558.95 with a determination coefficient (R2) of 0.992. The detection of limit (LOD) of E2 was 3.4 × 10-10 mol/L. Finally, the aptasensor was successfully applied to the detection of E2 spiked in milk and environmental water samples with good recoveries of 89.67%‒113.36%, suggesting the potential for practical application.

The purpose of this study was to identify whether liquid fruit waxes could be added with bleached shellac. The compounds of bleached shellac from different sources were analyzed by targeted metabolomics based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) combined with liquid chromatography with evaporative light scattering detection. Twelve target compounds were selected by multivariate statistical analysis including unsupervised principal component analysis (PCA) and supervised partial least squares discriminant analysis (PLS-DA). According to variable importance in the projection (VIP) value, five differential compounds and seven shared compounds were identified. Finally, the viability of this method in the detection of commercial liquid fruit wax products was verified using the shared compounds as biomarkers. These results showed that chromatography combined with mass spectrometry can identify whether bleached shellac could be added in liquid fruit wax.

Objective: Field trials were conducted in 13 citrus production regions including Hunan and Hubei provinces to evaluate the safety of the application of acetamiprid and pyriproxyfen on citrus. The residue, dissipation dynamics and dietary risk assessment of acetamiprid and pyriproxyfen in citrus fruit were investigated. Methods: The samples were extracted with 1% acetic acid in acetonitrile, purified using a mixture of primary secondary amine and graphitized carbon black, and detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Results: Excellent linearity (R2 > 0.99) was observed between the response peak area and the concentration of acetamiprid and pyriproxyfen in the range of 0.001–0.5 mg/L. In whole citrus fruit and flesh spiked at 0.01, 0.5 and 2.5 mg/kg, the recoveries of acetamiprid and pyriproxyfen ranged from 83.0% to 104.3% and from 74.8% to 98.7% with relative standard deviation (RSDs) of 3.8% to 10.0% and 2.0 to 6.0%, respectively. The limits of quantification (LOQs) for the analytes were both 0.01 mg/kg. The dissipation dynamics of acetamiprid and pyriproxyfen in whole citrus fruit was fitted to a first-order kinetics model. The degradation half-lives of acetamiprid and pyriproxyfen in whole citrus fruit were 5.1–15.8 days and 4.5–21.2 days, respectively. Twenty-seven percent acetamiprid-pyriproxyfen dispersible concentrate was sprayed twice on citrus at the recommended dosage of 500 g/hm2 (2 000 × dilution). At a 7-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.45 mg/kg and to 0.68 mg/kg, respectively. At a 10-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.40 mg/kg and to 0.56 mg/kg, respectively and were both lower than the maximum residue limits (MRLs) for acetamiprid (0.5 mg/kg) and pyriproxyfen (2.0 mg/kg) according to the Chinese national standard. The risk assessment results showed that the acute and chronic dietary exposure risk of acetamiprid and pyriproxyfen ranged from 0.0% to 53.0% (much lower than 100%) for people in different age groups, which was at an acceptable level. Conclusion: This study can provide guidance for the safety evaluation and rational application of acetamiprid and pyriproxyfen in citrus.