Yadong Wang,Qian Zhang,Junaid Yousaf,Fanyu Meng,Yanbo Wang,Bei Wang
Monascus-fermented cheese (MC) is a new cheese product that undergoes a multistrain fermentation process, which results in unique flavor qualities. Lipid metabolism plays an important role in the flavor formation of MC. To clarify the lipid composition of MC and the changes in lipid composition at four ripening periods, this study resolved the lipid profiles of MC by using UHPLC-QTRAP MS. The results identified 21 lipid classes and 748 lipid species, 72 of which were significantly different (VIP > 1, p < 0.01, |log 2FC| > 1). Additionally, 83 relevant metabolic pathways were enriched. Based on the enriched metabolic pathways and lipid changes, the pathways of differential lipid formation in MC were mapped. The results of this study comprehensively characterize the changes in lipids during the ripening process of MC, which can be used in the future to deeply analyze the mechanism of flavor formation in MC.
Summary During vacuum cooling, polypropylene turnover boxes are repeatedly used for containing vegetables for cooling, while Pectobacterium carotovorum subsp. carotovora ( Pcc ) can form a biofilm on polypropylene adhesion surface. This study evaluated the effects of multiple cycles of vacuum cooling on the morphology and composition of Pcc biofilm formed on polypropylene turnover boxes. Results showed that Pcc biofilm in different growth stages including adhesion, development and mature phases displayed different responses to vacuum cooling. Pcc biofilm in adhesion stage decreased from 10 6 to 10 5 CFU cm −2 , indicating the positive interference of vacuum cooling on biofilm formation in the initial developmental stage. However, with the increasing of the number of vacuum cooling cycles from 0 to 3, the biomass of Pcc biofilm in the development stage increased from 10 7 to 10 8 CFU cm −2 and the polysaccharide secretion increased from 7.96 to 16.7 mg cm −2 , showing the promotion of biofilm formation and the secretion of extracellular polymeric substances. Therefore, regular cleansing and sterilisation of turnover boxes are necessary to prevent cross-contamination during vacuum cooling.
危险品化学品经营许可证（带存储）