Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study ...Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study evaluated the spoilage potential of P.fragi,P.lundensis and P.fragi+P.lundensis in vitro and in situ at 4℃.The results showed that P.fragi+P.lundensis performed the highest growth rate and displayed larger decomposition zone diameters on raw-pork juice agar(RJA)plates.P.fragi+P.lundensis inoculants exhibited the strongest proteolytic activity,which resulted in the highest values of trichloroacetic acid(TCA)-soluble peptides concentration,total volatile basic nitrogen(TVB-N)content and myofibril fragmentation index(MFI)in chilled pork.Moreover,the inoculated samples showed different pH and sensory changes.Notably,increased amounts of volatile organic compounds(VOCs),such as octanal,nonanal,2-nonanone,1-propanol,1-octanol,isopropyl acetate,and 2,6-dimethylpyazine,were observed in inoculated P.fragi+P.lundensis samples,hinting their potential use as spoilage markers for spoilage monitoring of co-cultures.This study would provide a deeper understanding of meat spoilage and serve as a reference for future studies to inhibit meat spoilage.展开更多
The objectives of this study were to analyze the number of microorganisms,fungal composition and the correlation between bacterial enrichment and air quality on three internal surfaces(the inner wall,shelf,and basket)...The objectives of this study were to analyze the number of microorganisms,fungal composition and the correlation between bacterial enrichment and air quality on three internal surfaces(the inner wall,shelf,and basket)of domestic refrigerators.The results showed that the inner wall had a significantly lower number of coliforms(P<0.05),and the range was 0.2−2.5 log MPN cm^(-2).The total bacterial counts and psychrophilic bacterial counts on three internal surfaces in the same refrigerator tended to be consistent.Moreover,the inner wall owned a simpler bacterial community structure.At the genus level of fungi,the dominant flora of both the inner wall and shelf were Saccharomyces spp.and Candida spp.,while Saccharomyces spp.,Candida spp.and Fistulina spp.took superiority in the basket.Specifically,Shannon index and Simpson index,which represent the bacterial community diversity,were the lowest on the wall,and six bacterial species on the inner wall had relative abundance higher than 0.5%of the total operational taxonomic units(OTUs),while for the shelf and basket,there were 12 and 11 bacterial species respectively.Also,there was a significant negative correlation in the basket between the chao1 index and PM2.5.This study could provide guidance for the sanitation and recommend adequate packaging of foods stored in refrigerators.展开更多
Cattle hooves have high levels of collagen,whereas the strong off-flavor reduces their consumption.This study compared the flavors and metabolite profiles of beef tendon(BT)/cattle hide(CH)collected from cattle hooves...Cattle hooves have high levels of collagen,whereas the strong off-flavor reduces their consumption.This study compared the flavors and metabolite profiles of beef tendon(BT)/cattle hide(CH)collected from cattle hooves with beef shank(BS)to reveal the origin of off-flavor of cattle hooves and approach to remove the off-flavor using proteolysis and glycation treatments was further explored.Time-dependent increases in off-flavor and alkanesrelated signals(W3S)were found in BT and CH during heating.Nonanal was the predominant aldehyde and higher levels of alkanes were detected in BT and CH during heating.Aroma recombination assay confirmed that nonanal and higher levels of alkanes were the major contributors to the formation of off-flavor,and hexanal,octanal,and 1-octen-3-ol in BS reduced the unpleasant odor caused by nonanal.Proteolysis-glycation combined treatments showed the best effect inhibiting the off-flavor of BT and CH(compared to heating)by reducing the formation of nonanal(by up to 88.82%)and alkanes(by up to 94.79%).展开更多
基金funded by the National Natural Science Foundation of China(32372404)the National Key Research and Development Program of China(2021YFD2100802-02)。
文摘Pseudomonas fragi and Pseudomonas lundensis have been reported as key spoilage bacteria in aerobicallystored chilled meat.However,the co-spoilage effect of these bacteria has not been effectively evaluated.This study evaluated the spoilage potential of P.fragi,P.lundensis and P.fragi+P.lundensis in vitro and in situ at 4℃.The results showed that P.fragi+P.lundensis performed the highest growth rate and displayed larger decomposition zone diameters on raw-pork juice agar(RJA)plates.P.fragi+P.lundensis inoculants exhibited the strongest proteolytic activity,which resulted in the highest values of trichloroacetic acid(TCA)-soluble peptides concentration,total volatile basic nitrogen(TVB-N)content and myofibril fragmentation index(MFI)in chilled pork.Moreover,the inoculated samples showed different pH and sensory changes.Notably,increased amounts of volatile organic compounds(VOCs),such as octanal,nonanal,2-nonanone,1-propanol,1-octanol,isopropyl acetate,and 2,6-dimethylpyazine,were observed in inoculated P.fragi+P.lundensis samples,hinting their potential use as spoilage markers for spoilage monitoring of co-cultures.This study would provide a deeper understanding of meat spoilage and serve as a reference for future studies to inhibit meat spoilage.
基金support received from the Fundamental Research Funds for the Central Universities (KYZZ2022001)the National Key Research and Development Program of China (2021YFD2100802-02).
文摘The objectives of this study were to analyze the number of microorganisms,fungal composition and the correlation between bacterial enrichment and air quality on three internal surfaces(the inner wall,shelf,and basket)of domestic refrigerators.The results showed that the inner wall had a significantly lower number of coliforms(P<0.05),and the range was 0.2−2.5 log MPN cm^(-2).The total bacterial counts and psychrophilic bacterial counts on three internal surfaces in the same refrigerator tended to be consistent.Moreover,the inner wall owned a simpler bacterial community structure.At the genus level of fungi,the dominant flora of both the inner wall and shelf were Saccharomyces spp.and Candida spp.,while Saccharomyces spp.,Candida spp.and Fistulina spp.took superiority in the basket.Specifically,Shannon index and Simpson index,which represent the bacterial community diversity,were the lowest on the wall,and six bacterial species on the inner wall had relative abundance higher than 0.5%of the total operational taxonomic units(OTUs),while for the shelf and basket,there were 12 and 11 bacterial species respectively.Also,there was a significant negative correlation in the basket between the chao1 index and PM2.5.This study could provide guidance for the sanitation and recommend adequate packaging of foods stored in refrigerators.
基金supported by the Science and Technology Program of Xinjiang Uygur Autonomous Region(2021A02003-4).
文摘Cattle hooves have high levels of collagen,whereas the strong off-flavor reduces their consumption.This study compared the flavors and metabolite profiles of beef tendon(BT)/cattle hide(CH)collected from cattle hooves with beef shank(BS)to reveal the origin of off-flavor of cattle hooves and approach to remove the off-flavor using proteolysis and glycation treatments was further explored.Time-dependent increases in off-flavor and alkanesrelated signals(W3S)were found in BT and CH during heating.Nonanal was the predominant aldehyde and higher levels of alkanes were detected in BT and CH during heating.Aroma recombination assay confirmed that nonanal and higher levels of alkanes were the major contributors to the formation of off-flavor,and hexanal,octanal,and 1-octen-3-ol in BS reduced the unpleasant odor caused by nonanal.Proteolysis-glycation combined treatments showed the best effect inhibiting the off-flavor of BT and CH(compared to heating)by reducing the formation of nonanal(by up to 88.82%)and alkanes(by up to 94.79%).
