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BIFIDUS MILK-A NEW CONCEPT IN HEALTH THERAPY
Dr. M.I. Baig and Dr. R.D. Kokane
Department of Dairy Science Bombay Veterinary College, Parel- Mumbai 400 012 |
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Fermentation is the process of physical and chemical change I organic substrate brought about by the enzymes synthesized by desirable microorganism. Milk, which is very rich in lactose and protein, is universally accepted as best organic medium for the growth and multiplication of wide array of Lactic Acid Bacteria (LAB). The normal fresh milk obtained from healthy cow and buffaloes has the pH of 6.6 to 6.8 with titrable acidity of 0.14 to 0.16%.
The desirable LAB (also called Starter Culture) when inoculated in fresh pasterurised milk at suitable temperature, bring about series of physico-chemical changes and thereafter the coagulation. The resultant product is often referred to as “fermented milk” or ‘Cultured Milk’. The important chemical changes are reduction of pH to 4.6 (isoelectric point of milk), production of Lactic acid, Diacetyl, Acetaldehyde and Acetic acid. The product assumes semi solid consistency, sour sweet taste and characteristic desirable flavour. Daho, Lassi, yoghurt, Bulgarian butter milk, kumiss, kefir, Bifido milk, Bifido yoghurt and cheese are some of the well known fermented milk products. Starter culture bacteria used for these products include Streptococcus lactic, Lactobacillus acidophilus. L. rhamnosus, S. thermophillus, S. diacetrylactics, S. cremoris, Lactobacillus bulgaricus and species of Bifidobacteria; besides this some species of Yeastae also used in Kumiss and Kefir. Each one of these organisms can be inoculated separately or in combination, at their specific inoculation rate and definite incubation temperature.
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Lactose Intolerance
Lactose intolerance is a worldwide problem in middle aged and elderly persons. This condition is developed due to lack of the enzyme -D- galactosidase (also known as lactase), which is a mian catalyst for the break down of lactose into glucose and galactose. The persons suffering from this condition (lactose intolerance) develop cramps, gassiness, flatulence, abdominal pain and diarrhoea after consumption of milk and heat coagulated milk products. The highest activity of -D galactosidase is observed in infants and growing children. With the advancement of age the concentration of this digestive enzyme gradually decreases and results into mal-absorption of lactose. Thestarter bacteria also synthesize the enzyme -D- galactosidase during the process of milk fermentation and hydrolyse lactose to lactic acid.
Thus lactose intolerance persons can better utilized the fermented milks without any deleterious effect because of the partial reduction in concentration of lactose (Pochart et al., 1989).
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Enhance assimilation
of Proteins
The starter bacteria produce protein-splitting enzymes such as proteinase and peptidase during milk fermentation and break down the casein and whey proteins into simpler assemble form such as peptides and amino acids. During this process certain vitamins are also produced. The cell biomass of starter bacteria also a protein source in cultured product. Thus the biological value of fermented milk product is always higher in comparison with unfermented product.
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Increase in immune
response system
Certain specific strains of LAB are known to increase immune response system, inhuman-being; Kakado-oka et al (1991) studied the five strains of bifidobacteria on mitogenic response of splenocytes and on on function of phagocytes. They concluded that B. longum SBT2928 had the very high levelof motogenic activity and immuno potentiating effect.
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Antagonistic action
against Pathogens
Several in-vivo and in-vitro studies suggested that starter bacteria normally used for fermented milks are having potent antagonistic effect against pathogens such as Enterococci, Coliforms, Clostridium, e. faecalis, Streptococcus aureus, Klebsiella ozacnac and Pseudomonas aeruginosa. In Japan and Scandinavian countries the fermented milk are routinely administered as the first choice for control of infectious diarrhoea (Renner, 1983). Pikinaet al (1999) reported the most potent antagonistic activity of Bifidobacterium longum from the vagina of clinically healthy women or reproductive age. All these species were active acid producers. Their in-vitro study uggestes that all these strains were capable of inhibiting the growth of Staphylococcus aureus, Enterococcus faecalis, Klebsiella ozacnac, Pseudomonas aeurginosa and E. coli. Thus the fermented milk products could be the natural remedy of different infection especially after resistance is developed due to constant antibiotics therapy.
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Reduction in Serum
Cholesterol level and control of Coronary Heart Disease
Richardson (1978) reported that regular consumption of fermented milk reduced the Serum Cholesterol levels and thereby reduce the risk of Coronary Heart Disease and related aliments. Hepner et al. (1979) also reported similar findings with the consumption of yoghurt and acidophilusmilk. Beenaand Prasad (1997) found the reduction in the total and LDL Cholesterol levels in laboratory animals fed with yoghurt and bifidoyoghurt. In-Vitro studies suggested that the LAB utilize cholesterol as the nutrient for their growth and thus reduce the uptake of cholesterol, thereby chances of Coronary Heart Disease can be minimized.
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The therapeutic benefits of fermented milks are only possible if the starter bacteria remain viable at the time of consumption and should survive during the gastric transit. These bacteria should also be able to establish in the intestinal epithelium in sizable number byreplacing resident harmful pathogens (Gilliland, 1979; Hoover, 1993) Almost all the bacteria in starter culture except the species of bifidobacteria do not conform to above norms. Even though majority of fermented milk products are nutritionally superior (than plain milk) and have better palatability and digestibility but actual therapeutic benefit in-vivo are proved only in the product which contain viable biomass of starter bacteria of human origin i.e. Lactobacillus acidophilus and bifidobacteria. All reported to be acid and bile resistant, survive the environment of gastrointestinal tract and implant themselves in intestinal epithelium while others are not. The species of bifidobacteria that are being employed as the starter culture in preparation of bifidus milk are B. bifidium, B. infantis, B. longum, B. breve, B. adolenscentis, B. animalis.
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Bifido bacteria are gram positive, anaerobic, rod shaped organisms. The morphology is very variable depending on species and strains. They may be short, regular, thin cells with pointed ends or long cells with slight bend or protuberances. They might also be found as club shaped or with spatulated extremities, and also in star like arrangement or disposed in “v” or palisade arrangement (Scardovi, 1986). The bifidobacteria species are the natural inhabitant of breast fed infant intestine. Laroia and Martin (1990) reported that the human milk is the very good substrate for the growth of bifidobacteria because of the presence of bifidus factor. Bifidobacteria of infant origin such as are B. bifidium, B. infantis start growing and get implanted in the intestinal epithlium after birth if fed on human milk. As the age advances and the child is weaned from the mother, the bifidobacteria in the intestine is replaced by the other type of some pathogenic and non-pathogenic organisms. Thus it was found that those children getting mother’s milk up to 4-5 months of age remain healthier and grow faster than those that are bottle fed.
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Cow and buffalo milk which does not possed bifido factor are not good substrates for growth of bifido bacteria. Schuler-Malyoth et al (1968) reported that certain strain of bifido bacteria grow but very slowly in milk and also require preformed simple protein and free amino acid for initiation of their growth. Fortification of ultra filtrated cheese whey with threonine and adjusting total milk solids to 15% is suggested by Marshall et al (1982) for the preparation of bifidus fermented product of good quality. However, incubation period is 24 hours at 370 C, which in dairy industry is considered as very long. The fermented milk products produced from bifido bacteria alone lack the desirable flavour and aroma associated with dahi or yoghurt or similar product (Tamime and Robison 1988). This may be due to production of acetic acid at the expense of lactic acid and failure to produce flavouring compound like diacetyl and acetaldehyde by the bifidobacteria species. The majority of bifido bacteria species are known to break down lactose into acetic acid and lactic acid in 3:2 molar ratio (Scardovi, 1986). High concentration of acetic acid in the product gives flat vinegar like taste and flavour, which are generally not liked by the consumer. To overcome slow growth rate in milk and prepare a product with good flavour and aroma and of acceptable quality, it was suggested to co-culture the bifidobacteria along with other lactic acid bacterial culture. The growth of bifidobacteria was found to be optimum when cultured in association with Lactobacillus acidophilus, (Ishibashi and Shimamura 1993)
The B. bifidum count as reported by Baig and Prasad (1996) was 2.25 x 109 – 3.43 x 109 cfu/ml. If given along in milk with S. thermophilus and L. bulgaricus. The fortification of condensed whey solid and whey protein concentrate further boosted the growth. S. thermophilus are reported to release CO2 during fermentation in milk. The CO2 might have stimulated the growth of B. bifidum as they are an acrobic in nature. Similarly the L. bulgaricus has more proteolytic activity and breakdowns casein into simple forms. The peptide and amino acids thus formed might have been utilized by B. bifidum for their multiplication and growth. Thus, S thermophilus and L. bulgaricus was found to have stimulatory effect for getting the optimum population of B.bifidum in fermented milk. This yoghurt like product had an acceptable flavour and aroma. Some of the products with bifidobacteria popular in Western countries and Japan ae bifido-yoghurt, CULTRA AB, frozen Bifido yoghurt and fruit Bifido yoghurt. Thus it can be concluded that the fermented milk products prepared with the species of bifidobacteria as a mixed culture are having incredibly excellent nutritional and health benefits. These products if prepared commercially in our country, will help out to overcome many problems of health and nutritional status especially of infants and growing children.
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Baig M. I. And Prasad V. (1996). Effect of incorporation of coltage cheese whey solids and Bifidobacterium bifidum in freshly made yoghurt.J.Dairy Res. 63:467-473.
Beena and Prasad V. (1997). Effect of yoghurt and bifidus yoghurt fortified with skim milk powder, condensed whey on serum cholesterol and triglycerol level in rats. J. Dairy Res. 64:453.
Gilliland, S.E. (1979) Beneficial interrelationship between certain microorganisms and human; Candidate micro organisms for use as dietary adjuncts. J. FoodProd. 42: 164-167.
Hepner G; FriedR; St. Joer S; Fusetti L and Moriu R (1979). Hypocholesterolemic effect of yoghurt and milk. Am J. Clin. Nutr. 32:19.
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