Selection of Debaryomyces hansenii isolates as starters in meat products based on phenotypic virulence factors, tolerance to abiotic stress conditions and aroma generation.

ABSTRACT

INTRODUCTION: Debaryomyces hansenii is a yeast widely used in meat fermentations as starter for the purpose of improving the aromatic quality of the final product. However, it has not been the subject of an extensive study regarding phenotypic characteristics important for starter selection, such as the capacity to grow at abiotic stress conditions occurring during fermentation, the ability to generate desirable aromas and the absence of virulence traits in yeasts. AIMS: The aim of this study was to screen 60 strains of D. hansenii isolated from assorted foods for their potential application as starters in dry-cured fermented sausages manufacture. METHODS: The abiotic stress factors tested were low aw and pH and high concentration of salt, acetic acid and lactic acid. The phenotypic virulence traits explored were growth at 37°C, pseudohyphal and biofilm generation, invasiveness and enzymatic activities present in virulent yeasts. The generation of desirable meat aromas was tested in models containing aroma precursors applying an olfactory analysis. A quantitative profiling of stress tolerance was used to test the potential performance of selected strains in meat fermentations. RESULTS: The results demonstrated that most strains displayed no virulence trait or were only positive for biofilm production. Moreover, the strains showed large heterogeneity regarding their tolerance to abiotic stress factors, although most of them could grow at intermediate to high levels of the traits. The sensory analysis was the criteria determining the selection of starter strains. CONCLUSIONS: The evaluation of the phenotypic traits demonstrates that D. hansenii is a safe yeast, it is able to tolerate the stress in meat fermentation and it is able to generate desirable aromas. SIGNIFICANCE AND IMPACT OF THE STUDY The results of this study confirm the adequacy of selected D. hansenii strains to be applied as starters in meat products.