Influence of spirulina and whey protein hydrolysate on growth rate and activity of some probiotic bacteria in ayran

The aim of the study was to investigate enhancing the growth and activity of probiotic bacteria (Streptococcus thermophilus, Lactobacillus delbrueckii spp. bulgaricus, Lactobacillus acidophilus, and Bifidobacterium lactis) as function of adding Spirulina platensis and whey protein hydrolysate (WPH) into ayran. Effects of adding S. platensis, WPH, and probiotics at 0%, 0.25%, 0.5% and 1% concentrations on the growth of probiotic bacteria were studied before and after the fermentation, 7th, 14th, and 21st of the storage time. Spirulina platensis, WPH and probiotics had significant effects (P<0.05) on the growth of S. thermophilus, L. delbrueckii spp. bulgaricus, L. acidophilus and B. lactis, and the biochemical variables. The addition of S. platensis, WPH, and their mixtures significantly (P<0.05) increased the growth of probiotics compared to the control after the fermentation up to the 21st day of storage. The samples containing 0.25, 0.5, and 1 % of S. platensis, WPH, and probiotics had significantly (P<0.05) higher titratable acidity level compared to the control during the study time. The mixing of S. platensis, WPH and probiotics at 1% had the highest total solid and protein content compared to the control samples. The samples consisted of S. platensis, WPH and probiotics at 0.25, 0.5 and 1% concentrations decreased (P<0.05) viscosity during the storage time. The mixing of three biomaterials at 0.25, 0.5 and 1% values significantly (P<0.05) decreased L* and b* values compared to the control during the storage time. The mixtures of three biomaterials had a great potential for enhancing the growth of probiotic bacteria in ayran.