FERMENTED DAIRY PRODUCTS OBTAINED BY USING BIFIDOBACTERIA
It is agreed by every one that human milk or breast milk is not available commercially to propagate the bifidobacteria, which requires bifidus factor for its growth and that is present only in human milk. Hence it may appear difficult to produce the bifidus milk containing the bifidobacteria from cow or buffalo milk.
The cow and buffalo milk, which are devoid of bifidus factor, naturally will form a poor substrate for the growth of bifidobacteria. Now the piquant situation arises. How to propagate the bifidobacteria in the absence of human milk and how to cajole them to acclimatize with the available cow or buffalo milk?
Certain strains of bifidobacteria grow very slowly in milk but require preformed simple protein and free amino acids for the initiation of the growth. Another alternative is to use fortified ultrafiltered cheese whey with threonine and adjusting the total solids to 15% for propagating bifidobacteria. The incubation should be done at 37°C for 24 h, which is generally considered very long in the dairy industry.
Bifidobacterium fermented products (milk with bifidus factor) do not possess the typical desirable flavour associated with curd, yoghurt or other fermented products. This is attributed to the acetic acid production at the expense of lactic acid and inability to produce flavour components like diacetyl, acetoin, acetaldehyde and 2,3 butylene glycol by the bifidobacteria.
Most of the bifidobacteria break down lactose in to lactic acid and acetic acid in the proportion of 2:3. This high concentration of acetic acid gives the product flat vinegar like taste and flavour, which will not go very well with the consumer. In order to obtain desired growth rate and flavour production in the bifidus milk, it is better to culture them along with other lactic acid bacteria. When cultured along with Lactobacillus acidophilus, the growth characteristics of bifidobacteria are not adversely affected.
Fortification of condensed whey solid and whey protein concentrate further boosted the growth of bifidobacteria. Symbiotic relationship exists between bifidobacteria and Streptococcus thermophilus when they are co-cultured. S.thermophilus releases carbon dioxide during fermentation of lactose, which provides the required anaerobic condition for the bifidobacteria, boosting its growth. A similar relationship also exists between the Lactobacillus bulgaricus and bifidobacteria; the former is highly proteolytic and breaks down casein in to peptides and amino acids, which favours the growth of the latter. In this way, the milk containing bifidobacterium or bifidus milk can indeed be manufactured with the available resources sans breast or human milk.
Bifidobacterium fermented dairy products (bifidus milk products) are very popular in developed countries such as Japan, EU and US. The available products include bifido-yoghurt, CULTRA AB, frozen bifido-yoghurt, and fruit bifido-yoghurt.
Thus, it can be safely concluded that the bifidobacteria can be cultured in the available cow or buffalo milk with certain modifications and culturing them along with other lactic cultures improves its growth rather than when cultured alone. The bifidus milk will provide incredibly excellent nutritional health benefits, especially for infants and growing child.