Insights into yeast on amino acid metabolism, volatile compound evolutions, and sensory development during the processing of dry-cured ham

• The mechanism of yeast inoculation on volatile evolutions was firstly investigated. • The inoculation of RM showed highest scores in meaty aroma and overall acceptance. • Keto acid decarboxylase and aminotransferase contributed to amino acid metabolism. • The accumulation of aldehydes and pyrazines were responsible for aroma development. To investigate the mechanism of yeast inoculation on aroma improvement of Jinhua ham, microbial succession, myofibrillar protein hydrolysis, enzyme activities, amino acid metabolism, volatile compound evolutions, sensory attributes and the relationship between key volatiles and sensory attributes were investigated during the processing of Jinhua ham with the inoculation of R. mucilaginosa AUMC 9298 (RM), C. parapsilosis d70a (CP) or Pichia kudriavzevii XS-5 (PK), respectively. The inoculation of RM, CP and PK significantly increased the counts of fungal communities, and the fungal counts of the final products reached 6.33, 6.65, 7.35 and 7.55 log CFU*g −1 in CK, PK, RM and CP groups, respectively; the treatment of RM showed the highest sensory scores in meaty aroma, nutty aroma and overall acceptance among these groups. The treatment of RM showed highest capability to degrade myosin and actin. The total contents (P<0.01) of free amino acids increased from 2565.89 mg/100g of PK to 3141.46 mg/100g of RM and 2714.76 mg/100g of CP at the final products, and the most release of free amino acids was observed in RM among these groups. The activities of keto acid decarboxylase, aromatic and branched chain aminotransferase, and branched chain amino acid dehydrogenase in RM were significantly higher than that of CP and PK, which contributed to the metabolism of aromatic and branched chain amino acids. GC-MS and multivariate statistics demonstrated that benzaldehyde, 3-methyl butanal, 2,5-dimethyl pyrazine and 2,6-dimethyl pyrazine were responsible for the improvement of overall acceptance of Jinhua ham with RM inoculation.