Non-Conventional Yeasts from Mozzarella Cheese Whey and Artisanal Sourdoughs: Leavening Capacity and Impact on Bread Sensory Profile

Non-conventional yeasts (NCYs) (i.e., non-Saccharomyces) are used as alternative startersto promote aroma complexity of fermented foods (e.g., bakery products). A total of 66 yeastsisolated from artisanal food matrices (bread and pizza sourdoughs and milk whey) from differentgeographical areas of the Campania region (Italy) were screened for physiological and technologicalcharacteristics such as leavening ability, resistance to NaCl and pH, exopolysaccharide and phytaseactivity production, and carbohydrate assimilation. Selected and isolated microorganisms werealso used to study the leavening kinetics in experimental doughs as mixed inocula of two differentstrains. Volatile organic compounds (VOCs) of the inoculated doughs were analyzed with solidphase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). Most of the strainsbelonged to non-Saccharomyces species (Pichia kudriavzevii, Kluyveromyces marxianus) and Saccharomyces(S. cerevisiae). Several strains produced exopolysaccharides (EPSs), that are important for doughrheological properties. Moreover, yeasts isolated from whey showed extracellular phytase activity.The mixed starter culture of the S. cerevisiae and NCY strains showed a synergic effect that enhancedthe doughs' aroma complexity. The use of non-conventional yeasts mixed with S. cerevisiae strainscan be advantageous in the bakery industry because they improve the bread aroma profiles andnutritional properties by bioactive molecule production.