Abstract: Through multidimensional evaluation (halotolerance/nitrite resistance, enzymatic activity, safety, and aroma-producing properties), three strains were selected as potential starter cultures from 33 yeast strains isolated from Xuanwei ham and identified as Rhodotorula mucilaginosa NYS12, Yamadazyma triangularis HI2, and Debaryomyces hansenii HI4. The results demonstrated that these three strains exhibited exceptional stress tolerance (growth index > 70 at 6% NaCl or 150 mg/kg NaNO2), no hemolytic activity or antibiotic susceptibility, and strong lipase and protease activities. Strain HI2 produced 2.14 g/L of esters. The total ester and ethyl acetate contents of the model ham system fermented with HI2 were significantly higher than those of the unfermented control, as determined by gas chromatography-mass spectrometry (GC-MS). Strain NYS12 efficiently synthesized nutty aldehydes, reshaping the flavor profile. Strain HI4 markedly enriched methyl ketones, imparting a distinctive cheesy aroma. Principal component analysis (PCA) confirmed that the three strains synergistically regulated the generation of volatile flavor compounds through divergent metabolic pathways.

Key words: Xuanwei ham; strain screening; yeast; gas chromatography-mass spectrometry; flavor