The quality of Sichuan paocai in natural fermentation is often inconsistent due to the complexity of its microbial community and environmental influences. To address this, dominant microbial strains were selectively inoculated to improve the product's quality and safety. However, vacuum freeze-drying, commonly used to prepare direct vat set (DVS) starters, can significantly damage strains due to freezing stress. This study aimed to optimize a freeze-drying protection system for and to enhance their survival. Using response surface methodology, combinations of cryoprotectants were evaluated. A formulation comprising skim milk powder, glycerol, sucrose, and L-proline significantly improved strain viability after lyophilization, outperforming single cryoprotectants. Further investigation into storage conditions revealed that low temperatures (-20 °C) provided the best preservation for DVS starters. Furthermore, the optimized DVS starters demonstrated excellent fermentation performance in Sichuan paocai, enhancing its color, flavor, and sensory quality compared to natural fermentation. These findings offer a reliable freeze-drying protection strategy for survival and viability of and .
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http://dx.doi.org/10.3390/foods14020157 | DOI Listing |
Foods
January 2025
College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China.
The quality of Sichuan paocai in natural fermentation is often inconsistent due to the complexity of its microbial community and environmental influences. To address this, dominant microbial strains were selectively inoculated to improve the product's quality and safety. However, vacuum freeze-drying, commonly used to prepare direct vat set (DVS) starters, can significantly damage strains due to freezing stress.
View Article and Find Full Text PDFJ Biotechnol
January 2025
Shanghai Engineering Research Center of Food Microbiology, School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address:
Promoters are crucial elements for controlling gene expression in cells, yet lactic acid bacteria (LAB) often lack a diverse set of available constitutive promoters with quantitative characterization. To enrich the LAB promoter library, this study focused on the known strong constitutive promoter P in LAB. Through error-prone PCR and dNTP analog-induced random mutagenesis, a library of 247 mutants of P was generated by using the red fluorescent protein (RFP) fluorescence intensity as a high-throughput screening indicator in Streptococcus thermophilus.
View Article and Find Full Text PDFFoods
September 2024
College of Food Science, Sichuan Agricultural University, Ya'an 625014, China.
The paocai industry faces challenges related to the production of large volumes of high-salinity and acidic brine by-products. Maintaining paocai quality while reducing brine production is crucial. This study utilized high-throughput sequencing technology to analyze microbial changes throughout the fermentation process, along with the non-volatile flavor compounds and physicochemical properties, to assess the impact of hot-air and salt-pressing pre-dehydration treatments on paocai quality.
View Article and Find Full Text PDFInt J Food Microbiol
December 2024
College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China; Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China. Electronic address:
Foods
June 2024
Key Laboratory of Oceanic and Polar Fisheries, Ministry of Agriculture and Rural Affairs, East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 300 Jungong Road, Shanghai 200093, China.
Fermented vegetable products play a significant role in various cuisines, and understanding the fermentation dynamics of lactic acid bacteria (LAB) strains is essential for optimizing their production and quality. Here, we sought to investigate the fermentation performance of five LAB strains isolated from Sichuan paocai as starters for paocai. Sensory evaluation revealed that the inoculation of radish paocai samples with LAB strains effectively improved the overall liking and sensory satisfaction of participants, increasing the scores to varying degrees in terms of taste, flavor, texture, and coloration.
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