Research on the fungi in dry-cured hams from different regions and exploration of new resources of flavor yeast.

Abstract

Traditional fermented meat products with diverse flavors from different regions of China serve as a natural reservoir of high-quality fermentative strains. This study collected traditional naturally fermented hams from different geographical and climatic regions and investigated the relationships among environmental factors, fungal communities, and flavor profiles. High-throughput sequencing and GC-IMS were used to explore the fungal diversity and volatile flavor compounds of 10 ham samples. The results demonstrated that Ascomycota was the dominant phylum (relative abundance >95 %) in Chinese dry-cured hams. The distribution of Candida, Meyerozyma, Debaryomyces, and Yamadazyma in hams was significantly influenced by environmental factors (latitude, altitude, and temperature) and positively associated with the concentrations of essential flavor compounds such as aldehydes, ketones, and esters. Three yeast strains with prominent flavor characteristics were isolated: Candida parapsilosis X2-3, Debaryomyces hansenii R0-8, and Yamadazyma tenuis X2-8. Whole-genome sequencing indicated that the genes of the aforementioned strains are enriched in lipid and amino acid metabolic pathways. No typical pathogenic genes were identified upon comparison with the Database of Fungal Virulence Factors (DFVF). As co-starter of fermented sausage, Y. tenuis X2-8 significantly enhanced flavor scores, promoting the hydrolysis of proteins and triglycerides and the formation of flavor compounds. This study constructed a coupling model of fungi, flavor, and geographical factors in traditional Chinese dry-cured ham, and provided research insights for the development of novel flavor-enhancing fungi.