Technological potential of a kefir-derived whey fraction as a sourdough starter material for breadmaking

Bread shelf life remains a major challenge for the bakery industry, particularly in clean-label products produced without chemical preservatives. In this context, sourdough fermentation has emerged as a promising strategy to improve bread quality and stability. This study evaluated the technological potential of kefir whey as a sourdough starter material for breadmaking, comparing its performance with those of traditional sourdough (TS) and baker's yeast-based sponge (BY). The resulting breads were characterized regarding fermentation performance, physicochemical properties, sensory acceptance, and shelf life. Kefir sourdough (KS) exhibited a slower dough expansion rate than TS and BY, requiring a longer fermentation period. Nevertheless, sourdough breads (KS and TS) showed higher acidity, a firmer texture, and lighter crust coloration than BY breads, while crumb coloration was darker in KS and TS than in BY. The higher acidity was associated with delayed visible mold growth under the tested storage conditions, with KS and TS breads showing approximately 40% and 70% longer shelf life, respectively, compared with BY bread. Despite the firmer texture, KS and TS breads showed only slight reductions in specific volume (5%-9%) and no significant differences in crumb porosity compared with BY breads. Sensory analysis revealed lower preference scores for TS bread, whereas KS bread showed acceptance and preference comparable to BY bread. These findings suggest that kefir whey has promising potential as a sourdough starter material for breadmaking, allowing the production of breads with extended shelf life and good consumer acceptance, and pointing towards possible applications for the valorization of this kefir-derived fraction.