z. shahabbaspour

Nowadays, production of vegetable probiotic products, such as probiotic fermented soymilk has considered as a functional food. The aim of this study was to investigate the effect of type of probiotic culture and cow’s milk to soymilk proportion on biochemical and microbiological aspects of soy based probiotic fermented drink.

In this study, the different proportions of cow's milk to soymilk (complete amount of cow's milk, 3:1, 1:1, 1:3, complete amount of soymilk) were prepared using reconstituted skim milk powder and soymilk, and two type of probiotic culture (Lactobacillus acidophilus La-5 and Lactobacillus casei L-01) were inoculated. The biochemical (pH, titratable acidity, redox potential, amounts of lactic acid and acetic acid) and microbiological (viability of probiotics) and sensory characteristics of produced samples were investigated.

The amounts of lactic and acetic acids decreased by increase of proportion of soymilk. The treatment of T8 (equal proportion of cow's milk: soymilk, L. casei co-cultured with yogurt starter cultures) showed the highest viability)8.69 log cfu/ml.(The highest sensory characteristics were related to the treatments which had the highest proportion of cow's milk and then the treatment of T8 was set in fourth grade in total acceptability.

Probiotic cultures had good growth in equal proportion of cow's milk to soymilk, therefore, soy-based probiotic drink was introduced as a functional product containing probiotics and bioactive compounds.

Worldwide, the demand for consumption of functional foods is growing rapidly due to the increased awareness of the consumers from the impact of food on healthProduction of soy based probiotic yoghurt will improve the functional potential. The aim of this study was to assess the effect of cow’s milk to soymilk proportion and type of probiotic starins on qualitative aspects of soy based probiotic yoghurt.

proportions of cow's milk to soymilk (100:0, 75:25, 50:50, 75:25, 0:100) were prepared using reconstituted skim milk powder, and two type of mix starter culture (ABY-1 and ABY-2 that contains Lactobacillus acidophilus LA-5 and bifidobacterium Lactis Bb-12 and traditional yoghurt starter culture) were inoculated. pH, titratable acidity and redox potential parameters, amounts of lactic acid and acetic acid and viability of probiotics and sensory attributes of samples were analysed.

probiotic bacteria in starter culture ABY-1 in proportion of (50:50) had the highest viability (p<0.05). The greatest sensory properties were related to the treatments which had the highest proportion of cow's milk and then it was treatment of cultured with starter culture ABY-1 and proportion of 50% of cow's milk to 50% of soymilk (50:50-ABY-1) which was set in third grade in total acceptance manner (p<0.05).

The equal proportion of cow's milk to soymilk represented the highest biochemical changes, and with adding amount of soymilk, viability of probiotics increased probably due to the presence of prebiotics ingredients of soy and proteolitic activity decline of yoghurt starter cultures.