effect of milk supplementation on growth and viability of starter and probiotic bacteria in yogurt during refrigerated storage

in the present study, the effects of milk supplementation on growth and viability of yogurt (streptococcus thermophilus and lactobacillus delbrueckii subsp. bulgaricus) and probiotic bacteria (lactobacillus acidophilus and bifidobacteria) were studied during yogurt production and 33 days of refrigerated storage. the incubation time to reach ph = 4.5 was greatly affected by the addition of milk powder (mp), tryptone (try) and sucrose (suc). also, the increase in titrable acidity depended on added supplement. viable counts of l. delbrueckii subsp. bulgaricus were significantly (p