Formulation of Fermented Peanuts Milk and Millet Milk Blend as a Carrier for Bifidobacterium longum BB536

Abstract

This study was carried out to develop probiotic fermented beverages. The commercial strain Bifidobacterium longum BB536 was used. The growth of the strain and its related physicochemical changes during fermentation was evaluated. The strain survival during refrigeration storage was also examined. In addition, the physicochemical composition of different fermented beverages at initial and maximum growth of the strain were also determined .Growth medium were formulated from fresh cow milk, pure peanut milk, pure millet milk. As will as, to three different blends based on peanut milk prepared by partial substitution of 15% (A), 30%(B) and 45%(C) with millet milk .Peanut contains high levels of fat and protein. Moreover, levels of carbohydrates, fiber and ash were high in millet. Roasting of peanut increased fat , proteins, fiber, ash and Carbohydrates in ratio of 0.23, 1.43, 0.32, 0.1 and 0.62% respectively, as compared to raw peanut. The results obtained on B. longum BB536 viable count revealed significant (P < 0.05) increases by extended fermentation period in all type of formulated beverages, as compared to strain level at beginning of fermentation. The rate of B. longum BB536 increases in different fermented beverages were 3.15, 2.9, 2.89, 2.76, 2.43, % and 2.1% in fermented peanut milk, millet milk, cow milk, blend ( B), blend (A) and blend ( C ) ,respectively. In spite of declining in viable count of B. longum BB536 in all types of fermented beverages at 24h fermentation , the count still above the number required to presence in probiotic food which is at least 6 log CFU/ml fermented products. Except fermented beverage C (5.77 CFU/ml) is not fulfill propiotic requirement in food. During fermentation process with strain BB536 there were significant (P<0.05) decrease in pH levels in all type of beverages by extended fermentation period to 24h .The decreases in pH are due to increased of acids production during fermentation process as a result of fermenting sugar by Bifidobacterium BB536 . TSS levels decrease in all types of fermented beverages. The rates of TSS decreases at maximum growth were 0.3, 0.4, 1.3, 0.1and 0.9 in fermented peanut milk, millet milk followed by the blend (a),blend (b) and blend (c) , respectively. Sugars also decrease in all fermented beverages by extended fermentation period to 24 h. The rates of sugar reduction at maximum growth of strain BB536 were 0.15, 0.04, 0.03,0.02 ,and 0.01 in fermented peanut milk, blend (C), blend ( B), millet milk and then blend (A) , respectively. During the fermentation of the fermented beverages there were no significant (p>0.05) changes in compound of beverages. There were increase in moisture, portion, ash and fiber, tend to decrease in fat, carbohydrate and total soluble solid of fermented of peanut milk .On the other hand, during refrigeration storage of different formulated beverages. There were significant (p<0.05) reduction in B. longum BB536 viable count in all fermented beverages .The rate of reduction in the first week of the refrigeration storage were 2.39, 2.08, 1.84, 1.7, 1.43and 0.77 CFU /ml in fermented millet milk, peanut milk, blend (C), blend (B), blend (A) and cow milk, respectively. Hopefully, the final viable count of B. longum BB536 in fermented, peanut milk, cow milk and blend (A) was above the minimum number required to presence in probiotic to exert health benefits upon consumption. During two weeks refrigeration there were significant reductions in B. longum BB536 in all types of fermented beverages, except fermented cow milk. Nevertheless, the number required to presence in probiotic foods, which is 6 log CFU/ml fulfilled in peanut and blend (A) during only one week storage, while achieved in fermented cow milk during two weeks storage. Therefore, they are suitable carrier to deliver B. longum BB536 to consumer at the same time the fermented beverages provide other essential nutrients such as protein, fat, minerals and fiber.