Novel insights into different kefir grains usefulness as valuable multiple starter cultures to achieve bioactive gluten-free sourdoughs

Abstract

The milk and water kefir grains are often used for fermented beverages' production with technological and functional effects. These complex natural consortia of microorganisms can have promising applications in other fields of food industry. This work aimed to select the most performant artisanal starter culture, between different water (WKG1, WKG2) or milk (MKG) kefir grains, for gluten-free sourdoughs production. The impact of ingredients' combination, sterilization, gelatinization, and type of fermentation (liquid- and solid-state fermentation) on the microbial consortium's biochemical behavior, antifungal, antioxidant, and acidification potential was evaluated. The proposed flow chart involving the individual sterilization of the composite flour from the fermentation medium, respectively the distilled water, and the freeze-dried WKG2 as starter culture revealed that two up to four backsloppings stabilized the microbiome without alterations of the antioxidant and antifungal properties (p > 0.05). Furthermore, the addition of okara in the fermentation substrate had a positive effect on the organic acids' (lactic, acetic, citric, propionic, and butyric) and bioactive compounds' concentration from the sourdough. Using the kefir grains cultures for the diversification of gluten-free functional sourdough breads can be an approachable way to obtain healthy bioingredients for safe bakery products' manufacture, through the natural microbiomes.