Associative growth behavior of dahi and yoghurt starter cultures with Bifidobacterium bifidum and Lactobacillus acidophilus in buffalo skim milk

We report here for the first time variations in the
viability and biochemical activity of dahi and yoghurt cultures,
when grown together with therapeutic cultures, such
as Lactobacillus acidophilus I and Bifidobacterium bifidum
R, in buffalo skim milk. Nearly one log reduction in mesophilic
lactic count was observed in dahi supplemented with
probiotic cultures after 18 h of incubation at 30 °C. Associative
growth increased the titratable acidity (TA) of dahi
marginally (from 0.93 to 1.18 % lactic acid) but reduced the
TA in yoghurt (from 1.68 to 1.44 % lactic acid). Probiotic
culture supplementation reduced volatile acidity (VA) (from
36.0 to 15.8 ml) and diacetyl (from 4.05 to 2.80 ppm) and
tyrosine (from 0.46 to 0.36 μg tyrosine/g curd ) content in
dahi, whereas it increased VA (from 8.2 to 8.6 ml of 0.01 %
NaoH/50 g) and acetaldehyde (from 28.4 to 34.6 ppm)
production in yoghurt. Based on these results, the associative
growth had no effect on proteolytic activity of probiotic
yoghurt.