Staphylococcus simulans and Lactobacillus plantarum screened from Guizhou specialty food were used to prepare fermented pork loin ham. The sensory qualities and flavor profiles of fermented pork loin hams from 0 to 42 days were investigated in order to reveal the dynamics of fermented pork loin ham. The results show that total free amino acids (TFAA) content reached the highest value on the 35th day, and the umami amino acids, including aspartic acid (ASP), glutamic acid (GLU), glycine (GLY), and alanine (ALA), were the main amino acids in all periods. Notably, the RV coefficient (0.875) indicates that free amino acids (FAA) are highly correlated with the sensory score of the E-tongue. In terms of the volatile compounds identified, the esters content gradually increased between 7 and 42 days, and ethyl octanoate was the most abundant compound during all periods. These esters imparted a characteristic aroma component to the fermented pork loin ham. The most important finding was that the increase in the content of esters represented by octanoic acid-ethyl ester might be related to the increase in the content of FAA with the increase in fermentation time. Both the E-nose and E-tongue showed good discrimination ability for fermented tenderloin ham with different fermentation times, which was crucial in cases with large clusters. In addition, the multiple factor analysis (MFA) indicated that the E-nose aroma value might be the key factor in distinguishing fermented pork loin ham with different fermentation times.

Although coagulase-negative Staphylococcus (CNS) with technological activities plays a key role in fermented sausage flavour and nutrient production, the molecular mechanism of these activities remains elusive. In this study, 18 CNS strains with high proteolytic activity were isolated from Chinese Dong fermented pork (Nanx Wudl), and their technological and transcriptomic properties were investigated. After biochemical identification and genetic analysis, their technological properties, including nitrate reductase, catalase, antioxidant, and lipolytic activities, as well as their growth under varying temperatures, salt concentrations, and pH levels, were evaluated. Their aroma-producing potential was also determined in a model medium resembling fermented sausages. Transcriptomic analysis was performed using the most promising isolates. Biochemical identification and 16S rDNA sequencing revealed that the 18 Staphylococcus strains belonged to S. xylosus, S. saprophyticus, S. carnosus, S. sciuri, and S. equorum. In terms of technological properties, 16 strains showed a nitrate-reducing ability, while 11 strains had a lipolytic activity. All strains exhibited superoxide dismutase (SOD) and catalase activities; four strains displayed an SOD activity of > 50%. They also tolerated 10% NaCl and 150 mg/kg of nitrite. They showed significant differences in ketone and acid production. The transcriptomic analysis of S. xylosus strains Sx3 and Sx6, which were selected because of their excellent enzymatic activities and aroma-producing ability, revealed the remarkable effect of genes related to pyruvate catabolism and amino acid metabolism on aroma generation. Therefore, this study provided valuable insights into the metabolic mechanisms underlying the technological properties of CNS and identified promising candidates as starter cultures in fermented sausage manufacturing.

The increase in human population has led to imminent pressures to develop new edible proteins with decreased environmental footprints. The most promising approach involves the production of single cell protein (SCP) from yeasts, which have been utilized in a wide variety of foods for thousands of years. In this study, 102 yeast strains isolated from traditional fermented pork (Nanx wudl) were investigated for their potential as SCP producer for the first time. Based on preliminary screening, Saccharomyces cerevisiae Y70 and Candida parapsilosis H5Y13, both showing high protein content and excellent growth capability, were selected for further analysis via 4D-DIA Proteomics technology. Proteomic analysis indicated that the oxidative metabolism pathways, including TCA cycle, oxidative phosphorylation and pentose phosphate pathway, may have a significant impact on global protein synthesis and production. This study provides useful information for selecting SCP-producing yeast from Chinese fermented meat products and contribute to a deeper understanding of the underlying metabolic mechanisms behind global protein synthesis in yeast. Furthermore, these findings also provide potential molecular targets for genetic engineering modifications in yeast, aimed at constructing highly efficient cell factories for protein production.

The effects of direct inoculation of compound culture starter (Lactiplantibacillus plantarum and Saccharomyces cerevisiae) on the color, texture, and flavor qualities of fermented pork liver, sausage, and jerky were investigated. The results showed that inoculation with Lactiplantibacillus plantarum and Saccharomyces cerevisiae could significantly increase the lightness value (L*) and chroma value (C*) values of meat products and promote the color development of products. Meanwhile, it can also improve the tenderness of the products. The post-inoculation fermentation process enhanced the diversity and concentration of flavor compounds, improving the overall flavor of the product, and a total of 11 characteristic flavor compounds were identified. Inoculated fermentation reduced the levels of pentanal and methanethiol, which were unpleasant odor components in pork liver. In addition, inoculation fermentation could reduce the concentration of nonanal, which contributes to rancid fat odor in jerky. Inoculated fermentation enriched the flavor profile of meat products through the dual effects of “removing gamey flavor and enhancing aroma”. The results also showed that, after inoculation, the umami taste of meat products was enhanced, and bitter and sour tastes were inhibited. In conclusion, Lactiplantibacillus plantarum and Saccharomyces cerevisiae could serve as an excellent culture starter for industrial production, providing a feasible path for green and healthy meat processing.