Effect of pasteurization processing and storage conditions on softening of acidified chili pepper: Pectin and it related enzymes

Temperature-driven divergence in molecular distribution and microbial invasion and the associated texture softening during dual-phase fermentation of Paocai

Temperature is an important driving force that shapes the texture of fermented vegetables through driving the molecular distribution and microbial invasion between the liquid phase (brine) and the solid phase (vegetables) during fermentation. The objective of this study was to investigate the texture softening by investigating firmness, microstructure, physicochemical properties, molecular distribution and microbial community between brine and vegetables of Paocai as affected by fermentation temperatures of 10 °C, 20 °C and 30 °C. Results demonstrated that, compared with 10 °C and 30 °C, 20 °C attenuated softening of Paocai by restraining microbial invasion and suppressing pectinolysis. Moreover, at 20 °C, a balanced molecular distribution and microbial community were achieved between vegetables and brine, thus accomplishing acid-production fermentation. By contrast, 10 °C and 30 °C promoted nonfermentative microbial genera, retarding fermentation. This study provided an understanding of the divergent influence of temperature on quality formation of fermented vegetables during fermentation.

Characterisation of flavour profiles and microbial communities of fermented peppers with different fermentation years by combining flavouromics and metagenomics

The changes in flavours, volatile aromas and microbial communities of fermented peppers with different fermentation years and their relationships were investigated in this study. Results indicated a gradual increase in organic acids during fermentation, whereas free amino acids and capsaicinoids reached stability after 1 year of fermentation. Overall, the analysis detected 340 volatile compounds in fermented peppers and regarded 69 of them as differential compounds. Peppers fermented for 2 (FY2) and 4 years (FY4) possessed a greater number of differential volatiles with large odour activity values, thus endowing them with more favourable flavours. Hence, metagenomic analysis compared their microbial communities and functional annotations. Results revealed that Lactiplantibacillus plantarum and Zygosaccharomyces rouxii were the dominant bacterium and fungus, and metabolism was the main Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway in FY2. Correlation analysis demonstrated that Hyphopichia, Kazachstania and Clavispora were highly positively correlated with 12 key aroma flavours.