The Proliferation Fermentation Differences Of Bifidobacterium&L. Acidophilus Between Cow's&Goat's Milk And The Functional Features Evaluation Of Their Fermented Products

Bifidobacterium and L. acidophilus act as significant parts of the natural microflora ofhuman intestinal tract, the viable counts and metabolites of their fermented milk playbeneficial effects on human health. Recently, the bendfits of consumption of probioticproducts were proposed, such as alleviate lactose intolerance, antioxidative activity,cholesterol-degrading effect and anti-cancer et al. To get these benefits, ther are tworequirements must to be met, the viable counts and survival rate in probiotic products duringchill storage. Thus, the high activity of probiotic fermented dairy products become a hot spot,and the fermented goat's milk rich in probiotics and their related research was seldomlyreported. Therefore, in this paper, Lactobacillus acidophilus and bifidobacterium were used asculture, the proliferation growth, acid-producing properties, proteolytic activity in goat's andcow's milk were analyzed as well as the survival rate of the two kinds of probiotics in chillstorage, at the same time, the antioxidatiive activity of six different mix culture fermentedmilk were disucussed as well as the cholesterol-degrading effects. The main conclusions wereas follows:(1) During fermentation and chill storage period, compared with cow's milk, the acidproduction of L. acidophilus and bifidobacteria in goat's milk was faster and better than incow's milk (P<0.05), The highest viable counts of Bifidobacterium and L. acidophilus ingoat's milk were1.91×1010and3.10×1010mL^-1, greater than in cow's milk which were2.37×109and4.64×109mL^-1, two kinds of probiotics showed better fermentation performancein goat's milk. Both goat's&cow's fermented milk had consistent variation trend of viablecounts during chill storage (P>0.05). Between1-21d, the viable counts of Bifidobacteriumand L.acidophilus maintained at a higher level of activity with a non-significance. During21-26d chill storage, both surival rate of bifidobacterium and L. acidophilus reducedsignificantly, which in cow's milk dropped to77.34%and88.51%, and in goat's milk droppedto77.63%and85.61%, but there was no significant difference between cow's and goat's milk (P>0.05), and the cell viability of L. acidophilus in goat's and cow's milk were generallyhigher than Bifidobacteria with significance difference (P<0.05).(2) The proteolytic activity of goat's milk products was higher than cow's milk products.During after-ripening refrigerated stage, the proteolytic activity of Bifidobacterium and L.acidophilus in goat milk increased0.0874and0.4399, which were higher than in cow's milk0.0795and0.2187(P<0.05). During1-26d of refrigeration, the proteolytic activity ofBifidobacterium and L. acidophilus fermented milk increased continuously, and the fermentedgoat's milk always had higher proteolytic activity than fermented cow's milk (P<0.05),therefore, in the aspect of proteolytic activity, goat's milk was higher than cow's milk, L.acidophilus is stronger than Bifidobacterium.(3) The DPPH free radical-scavenging activity and Fe2+ion-chelation capacity of goat'smilk were57.40%and61.72%, higher than49.51%and56.15%in cow's milk. The reducingactivity of cow's milk was0.5622, stronger than goat's milk which was0.4133. In differentmilk substrate, the DPPH free radical-scavenging activity of L. acidophilus fermented milkwas always the highest, which were52.20%and70.38%in cow's&goat's milk. Thereducing ability of all fermented milk was higher than0.6, which had no significantdifferences between different strains. The Fe2+ion-chelation capacity of traditional yoghurtwas strongest in all fermented milk. Therefore, in the aspect of antioxidatiive activity, goat'smilk was higher than cow's milk, and there were no signifcant differences between the sixdifferent mix culture fermented milk.(4) The cholesterol in goat's milk was (60.73±7.53) μg/mL, which was higher than cow'smilk (40.81±4.04) μg/mL. In different milk substrate, comparing the cholesterol-loweringleffects of traditional yogurt, probiotic yogurt, L. acidophilus and Bifidobacterium fermentedmilk, yogurt starter culture had the best cholesterol-loweringl effects. The degradation rate ofcholesterol in cow's milk was11.96%, and in goat's milk was16.31%, and in goat's milk, L.acidophilus was stronger than Bifidobacterium in cholesterol-loweringl effects. The fermentedgoat's milk was generally better than fermented cow's milk. Therefore, goat's milk was moreconducive to the production of high quality yogurt products.