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ABSTRACT: Milk coagulation is an important step in the production of fermented dairy products such as yogurt and cheese. Jujube is gaining popularity and acceptance as a food ingredient. In China, jujube yogurt is popular among consumers. However, there is limited information on the effect of jujube on acid- and rennet-induced coagulation properties of milk. The objective of this study was to evaluate the effects of jujube pulp at different concentrations on acid- and rennet-induced coagulation kinetics of milk and the microstructure of acid- and rennet-induced gels. During acid-induced coagulation, with increasing jujube pulp concentration, the initial pH value decreased; however, the final pH value increased. The initial elasticity index (EI) value increased, and the time point at which the mean square displacement curves lost the linear trend advanced. The sample with 10% jujube pulp had the densest structure and highest EI value. During rennet-induced coagulation, with increasing jujube pulp concentration, the production rate and amount of caseinomacropeptide decreased, and the final EI value increased. Protein aggregates in rennet-induced gels became rough, and the sample with 20% jujube pulp had the highest EI value. This study provides a new perspective and understanding of the application of jujube in fermented dairy products.

The deliberately origin mislabeling of sweet cherry causes significantly disruptions to market integrity and consumers' trust. In this study, 153 cherry samples from five provinces in China and the corresponding irrigation water and soil samples were collected. 5 stable isotope ratios (δ13C, δ15N, δ2H, δ18O, 87Sr/86Sr) and 8 multi-element contents (Na, Mg, P, K, Ca, Fe, Zn, Se) of cherry were determined by EA-IRMS and ICP-MS to study isotopic fractionation and elemental enrichment mechanisms for origin traceability. The results show the δ2H and δ18O of cherry exhibit a strong correlated with its irrigation water (r2 > 0.85), while δ15N, 87Sr/86Sr, Fe, Zn and Se contents are related to its cultivated soil (r2 > 0.75), and the δ13C is related to the local microclimate. ANOVA reveals that the regional differences of δ13C, δ2H, δ18O, 87Sr/86Sr as well as Na, Mg, Ca contents of cherry are significant (P

Little information is known about the increased aroma compounds and possible mechanism in Tamarix ramosissima Ledeb roasted mutton (TRM). A comprehensive analysis of aroma compounds and lipids were firstly performed by lipidomics and sensomics approach. The results indicated that 9 out of 53 aroma compounds were considered as key odorants, including 5-methyl-2,3-diethylpyrazine. The roasted mutton contained highest levels of phosphatidylcholine (PC, 13.95%), triglyceride (TG, 13.50%), and phosphatidylethanolamine (PE, 12.25%). TG 18:0_18:0_18:1 and nine odorants were the potential biomarkers for discriminating differential samples due to variable importance in projection (VIP) > 1 and p

Smoked duck is a popular meat product in China. The aroma profile and key aroma compounds in smoked ducks were elucidated using solvent-assisted flavor evaporation-gas chromatography–olfactometry-mass spectrometry (SAFE-GC-O-MS), odor activity values (OAVs), aroma recombination and omission experiments, and sensory evaluation. The results indicated that the predominant aroma profiles of rice-, tea oil- and sugarcane-smoked ducks all contained strong smoky, roasty, fatty, meaty, and grassy aromas. A total of 31 aroma compounds were identified as important odorants by OAVs, including 8 aldehydes, 6 pyrazines, 5 phenols, and 2 sulfur compounds. The aroma recombination and omission experiments confirmed that 13 odorants were key aroma compounds in smoked ducks. Of these odorants, 2-methoxyphenol, 4-methylphenol, 5-ethyl-2,3-dimethylpyrazine, methional, 2-methyl-3-furanthiol, (E, E)-2,4-decadienal, 1-octen-3-ol, and anethole significantly contributed to the aroma profile of smoked duck flavor (p

ABSTRACT: This study was performed to develop a predictive growth model of Pseudomonas spp. to ensure the safety of fresh duck breast. Sterile fresh duck breasts were inoculated with Pseudomonas spp. and stored at 4°C, 10°C, 15°C, 20°C, 25°C, and 30°C to measure the microbial change. The Baranyi primary model was used to simulate the growth changes of Pseudomonas spp. at different temperatures. The square root type model and hyperbolic function as secondary models were used to model the effect of temperature on the maximum specific growth rate and lag phase duration. The results showed that the primary models fitted the growth data well (all R2 > 0.900 and RMSE were close to 0). In validation study of secondary model, R2 were 0.987 and 0.925, RMSE were 0.017 and 1.825, respectively, indicating that the parameters of primary models were accurately predicted by secondary models. The validation experiments at tested temperatures proved that the changes of Pseudomonas spp. could be predicted accurately by the developed models combining primary and secondary models both at constant and variable temperatures. The model could be applied to predict the growth of Pseudomonas spp. in logistics for avoiding microbial spoilage on fresh duck breast.

Chinese spicy cabbage (CSC) is a common traditional fermented vegetable mainly made of Chinese cabbage. In addition to eating raw, boiling and stir-frying are the most common cooking methods for CSC. To identify the impacts of boiling or stir-frying on the quality of CSC, the physicochemical properties, flavor compounds, and sensory properties of CSC were analyzed. A total of 47 volatile flavor compounds (VFCs) were detected by gas chromatography–mass spectrometry. Sulfide was determined as the main flavor compound of CSC, mainly contributed by cabbage, garlic, and onion odors. The content of sulfide decreased significantly after cooking. Nonanal, geranyl acetate, and linalool were newly generated after boiling with odor activity value (OAV) > 1, and contributed fatty, sweet, fruity, and floral odors to BL-CSC. 1-Octen-3-one, 1-octen-3-ol, octanal, nonanal, and (E)-2-nonenal were newly generated after stir-frying with OAV > 1, and contributed mushroom, fatty, and green odors to SF-CSC. Diallyl trisulfide, nonanal, (E)-β-ionone, β-sesquiphellandrene, and (E)-2-decenal were considered as the potential key aroma compounds (KACs) to distinguish the CSCs after different heat treatment. After cooking, the total titratable acidity of CSC increased and the sensory properties changed significantly. This study provides valuable information and guidance on the sensory and flavor changes of thermal processing fermented vegetables.

Prunus tomentosa Thunb. has excellent nutritional, economic, and ornamental values with different fruit color. The red coloration of fruit is determined by anthocyanin pigmentation, which is an attractive trait for consumers. However, the mechanisms underlying fruit color formation in the P. tomentosa cherry are not well understood. In this research, the pigmentation patterns in red-color P. tomentosa (RP) fruit and white-color P. tomentosa (WP) were evaluated. Anthocyanin content in matured RP fruit was significantly abundant compared with WP fruit. Metabolomic profiling revealed that pelargonidin 3-O-glucoside, cyanidin 3-O-rutinoside, and pelargonidin 3-O-rutinoside were the predominant anthocyanin compounds in the RP fruit, while, WP fruit had less anthocyanin compositions and lower level. Then, integrative analyses of transcriptome and metabolome identified 285 significant differentially expressed genes (DEGs) closely related to anthocyanin differentially expressed metabolites (DEMs). Among them, nine genes were involved in anthocyanin biosynthesis, transport and degradation pathway, including four biosynthesis genes (PtPAL1, PtDFR, PtANS, and PtUFGT), two transport genes (PtGST11, PtABC10), and three degradation genes (PtPOD1, PtPOD16, PtPOD73). Transcriptome data and real-time PCR showed that the transcript levels of biosynthesis and transport genes were significantly higher in RP than in WP, especially PtANS, PtUFGT, and PtGST11, suggesting they may play key roles in red-colored fruit formation. Meanwhile, the degradation-related genes PtPOD1/16/73 took on exactly opposite trend, suggesting their potential effects on anthocyanin degradation. These results provide novel insights into color patterns formation mechanisms of cherries fruit, and the candidate key genes identified in anthocyanin biosynthesis, transport and degradation may provide a valuable resource for cherry breeding research in future.

The inhibitory and bactericidal activities of thyme oil against the foodborne multiple antibiotics-resistant Enterococcus faecalis biofilm were evaluated in this study. Gas chromatography-mass spectrometry revealed that more than 70% of the composition of thyme oil is thymol. Crystal violet staining assay showed that 128 and 256 μg/mL thyme oil significantly inhibited the biofilm formation of E. faecalis. The cell adherence of E. faecalis, as shown by its swimming and swarming motilities, was reduced by thyme oil. The exopolysaccharide (EPS) quantification assay showed that thyme oil inhibited the EPS synthesis in E. faecalis biofilms. The 3D-view observations through confocal laser scanning and scanning electron microscopy suggested that cell adherence and biofilm thickness were decreased in thyme oil–treated biofilms. Quantitative real-time analyses showed that the transcription of ebp and epa gene clusters, which were related to cell mobility and EPS production, was inhibited by thyme oil. Thus, thyme oil effectively inhibited the biofilm formation of E. faecalis by affecting cell adherence and EPS synthesis. Furthermore, 2,048 and 4,096 μg/mL thyme oil can effectively inactivate E. faecalis population in the mature E. faecalis biofilms by 5.75 and 7.20 log CFU/mL, respectively, after 30 min of treatment. Thus, thyme oil at different concentrations can be used as an effective antibiofilm or germicidal agent to control E. faecalis biofilms.

The effect of CO2 concentrations on the preservation of sweet cherries in modified atmosphere packaging was greatly different. In the present paper, an accurate gas-regulating storage device was used to set the concentrations of CO2 at 0%, 5%, 10%, 15%, 20% and 25%, respectively (O2 was set at 5% and the remaining parts were filled with N2) to store sweet cherries. Then the quality change of sweet cherries was determined aproximately from -1 to +1 °C and from 80 to 85% relative humidity. The results showed that all six air treatments had a certain inhibitory effect on deterioration of sweet cherries. In particular, the 10% CO2 group could reduce rotting rate, maintain firmness, delay the change of soluble solids and vitamin C, reduce the activity of polyphenol oxidase and peroxidase. This group always had good firmness, nutrition and taste after 120 days of storage. So the 10% CO2 concentration provides suitable gas storage conditions of sweet cherries in modified atmosphere packaging.

Abstract Background Aroma is an important organoleptic quality for fruit and has a large influence on consumer preference. Kiwifruit esters undergo rapid and substantial changes contributing to the flavor during fruit ripening. Part of enzymes and their coding genes have been indicated potential candidates for flavor-related esters synthesis. However, there still exist obvious gaps in the biosynthetic pathways of esters and the mechanisms regulating ester biosynthesis in kiwifruit remain unknown. Results Using gas chromatography-mass spectrometry (GC-MS), volatile compounds of kiwifruit were quantified in response to ethylene (ETH, 100 μl/l, 24 h, 20 °C) and 1-methylcyclopropene (1-MCP, 1 μl/l, 24 h, 20 °C). The results indicated that esters showed the most substantial changes enhanced by ethylene and were inhibited by 1-MCP. Correlations between RNA-seq results and concentrations of esters, constructed using Weighted Gene Co-Expression Network Analysis (WGCNA) indicated that three structural genes (fatty acid desaturase, AdFAD1; aldehyde dehydrogenase, AdALDH2; alcohol acyltransferase, AdAT17) had similar expression patterns that paralled the changes in total ester content, and AdFAD1 transcripts exhibited the highest correlation. In order to search for potential regulators for ester biosynthesis, 14 previously reported ethylene-responsive transcription factors (TFs) were included in the correlation analysis with esters and their biosynthetic genes. Using dual-luciferase assay, the in vivo regulatory activities of TFs on ester biosynthetic gene promoters were investigated and the results indicated that AdNAC5 and AdDof4 (DNA binding with one finger) trans-activated and trans-suppressed the AdFAD1 promoter. Conclusions The present study advanced the molecular basis of ripening-related ester biosynthesis in kiwifruit by identifying three biosynthetic related genes AdFAD1, AdALDH2 and AdAT17 by transcriptome analysis, and highlighted the function of two TFs by transactivation studies.

Sweet cherry (Prunus avium L.), one of the most appreciated and most important commercial temperate fruits, has high sensory quality and nutritional value. Investigating its metabolic variations provides valuable information on the formation of fruit quality. In this study, widely targeted LC-MS/MS based metabolomics was used to identify and quantify metabolic changes during ‘Black Pearl’ sweet cherry development and ripening. A total of 263 significant differentially expressed metabolites (DEMs) were detected during the four fruit-development stages. Significant differences were observed in the composition and content of compounds in the four stages of cherry development, especially sugars, organic acids, and flavonoids. Moreover, transcriptome analysis provided a molecular basis for metabolic variations during fruit development. A total of 6724 significant differentially expressed genes (DEGs) were identified. Further correlation analysis of major DEMs and DEGs showed that 19 key DEGs were involved in sugar metabolism, 23 key DEGs in organic acid metabolism, and 13 key DEGs in flavonoid metabolism. The upregulated genes involved in the flavonoid pathway probably play an important role in regulating the rapid increase of anthocyanin content during fruit development. These comprehensive analysis data provide a better understanding to improve fruit quality traits based on molecular and metabolic levels.

Anthocyanin is the key factor that results in the attractive color of sweet cherry fruits. However, information regarding sweet cherry coloration and the potential mechanisms underlying anthocyanin biosynthesis is limited. In this study, we found that the anthocyanin accumulation varied in sweet cherry flesh and peel, while the anthocyanin content increased sharply in the dark red (DR) stage. Correlations between anthocyanin concentrations and RNA sequencing (RNA-seq), constructed with Weighted Gene Co-Expression Network Analysis (WGCNA), indicated that two structural genes (Pac4CL2, PacANS) and 11 transcription factors (PacbHLH13/74, PacDIV, PacERF109/115, PacGATA8, PacGT2, PacGTE10, PacMYB308, PacPosF21, and PacWRKY7) had similar expression patterns with the changes in anthocyanin content. Additionally, real-time PCR verified all of these gene expression patterns and revealed that PacANS exhibited the highest transcription level. In order to search for potential regulators for anthocyanin biosynthesis, a dual-luciferase assay was performed to investigate the regulatory activities of 11 transcription factors on the PacANS promoter. The results revealed that two novelty bHLHs, PacbHLH13 and PacbHLH74, can trans-activate the PacANS promoter and they might be the candidate genes for regulating anthocyanin synthesis in sweet cherry fruits. The present findings provide a novel viewpoint with regard to anthocyanin biosynthesis mechanisms and the regulatory transcriptional network of fruit coloration in sweet cherries.

The effect of CO2 concentrations on the preservation of sweet cherries in modified atmosphere packaging was greatly different. In the present paper, an accurate gas-regulating storage device was used to set the concentrations of CO2 at 0%, 5%, 10%, 15%, 20% and 25%, respectively (O2 was set at 5% and the remaining parts were filled with N2) to store sweet cherries. Then the quality change of sweet cherries was determined aproximately from -1 to +1 °C and from 80 to 85% relative humidity. The results showed that all six air treatments had a certain inhibitory effect on deterioration of sweet cherries. In particular, the 10% CO2 group could reduce rotting rate, maintain firmness, delay the change of soluble solids and vitamin C, reduce the activity of polyphenol oxidase and peroxidase. This group always had good firmness, nutrition and taste after 120 days of storage. So the 10% CO2 concentration provides suitable gas storage conditions of sweet cherries in modified atmosphere packaging. [ABSTRACT FROM AUTHOR]