Improved nutritional composition and in vitro protein digestibility of fermented soy beverages produced with vaginal probiotics as adjunct cultures

Fermented soy beverages, made with yogurt starter cultures and formulated with functional vaginal bacteria, namely Lactobacillus crispatus BC4 and Lactobacillus gasseri BC9, were characterized in terms of centesimal, fatty acids, mineral, vitamins and amino acids composition. The products were subjected to simulated gastro-duodenal digestion to determine protein hydrolysis and protein bioaccessibility. Although a species-specific effect was osbserved, samples containing the vaginal strain mix presented lower carbohydrates but a higher protein, iron, magnesium, and essential amino acid content, compared to the product with only yogurt starters. Eventually, samples produced with the mix of vaginal strains showed lower lipid quality indices but higher protein hydrolysis and bioaccessibility (total protein content was 2-fold higher than the control at the end of duodenal phase). The use of vaginal probiotic strains as adjunct cultures represents a suitable vehicle to deliver probiotics and to improve the nutritional value of the final product.