Development of probiotic yogurt: effect of strain combination on nutritional, rheological, organoleptic and probiotic properties

Seven combinations of yogurt; C1 [yogurt starter culture (YSC)], T1, [YSC + Lactobacillus acidophilus (LA)], T2 [YSC + Bifidobacterium bifidum (BB)], T3 [YSC + Lactobacillus plantarum (LP)], T4 [YSC + Lactobacillus casei (LC)], T5 [YSC + LA + BB] and T6 [YSC + LP + LC] were developed. Nutritional [proximate and minerals], rheological [total soluble solids (TSS), pH, titratable acidity (TA), water holding capacity, synersis, viscosity] organoleptic and probiotic properties [viability, acid tolerance, bile salt tolerance] were assessed with standard methods. Nutritional composition differed significantly among samples except for the iron and zinc (P < 0.05). Yogurt containing LP as single or in combination with LC resulted in significantly higher ash, protein, calcium and phosphorous level. Probiotic combination also significantly affected the rheological properties of yogurts (P < 0.05). Yogurt with LP and LC as single or in combination lead to significantly higher TSS and viscosity while significantly low syneresis, whereas yogurt with LA as single or in combination resulted in low pH and high TA (P < 0.05). Interestingly, combination of LA and BB increased TSS, reduced pH and syneresis as compare to these bacteria as single probiotic source. Panel experts found yogurt with LP more flavourful. Combination of multi-strain and multi-species probiotic resulted in improved texture but we found no significant difference in overall acceptability. Combination of probiotic strains also resulted in better probiotic potential with multi-species combination found to be even more effective. BB seemed more stable than three other probiotic strains. The present study can be helpful to dairy industry in developing new probiotic products and may provide a rational for selecting a combination of probiotic strains.