Assessment of different cereal brans (sorghum, barely and millet) as prebiotics in goat milk fermented with Bifidbacterium longum BB536

Abstract

This study was carried out to explore prebiotic effect of different cereal bran on Bifidobacterium longum BB536 growth stimulation for developing functional food. Fermentation medium was formulated from goat milk supplemented with 10% inulin (controlled) or each of the different cereal bran sorghum, barley, and millet. Probiotic strain B. longum BB 536 was used for fermentation. Prebiotic effects of different cereal bran were examined. Safety and beneficial effect of fermented goat milk supplemented with different bran on colon bacterial groups of fed rats were evaluated. Different analyses including proximate, mineral, strain BB536 viable count, physicochemical analysis were conducted. Thirty male Albino rats were acclimatized for two weeks to experimental conditions and randomly assigned into five groups. The control group received a normal rat diet. Other rats groups received fermented goat milk supplemented with each of inulin, sorghum bran, barley bran and millet bran. The experimental trials were extended for 6 weeks. Inulin was an excellent source of fiber, carbohydrate, and minerals (Ca, K, Mg and Na). Among cereal, bran barley contained the highest level of fiber, followed by sorghum and then millet barn. Moreover, cereal bran is a good source of protein, fat and ash. During fermentation, the maximum growths of the strain BB 536 (12 h incubation) were 7.53±0.16b -8.43±0.03cLog CFU/ml in fermented goat milk supplemented with inulin and different cereal bran. These counts exceed the minimum number (6 log CFU/ml products) required to the presence in probiotic food. Further, rates of strain BB 536 increases induced by different cereal bran (7.65 – 8.43CFU/ml) are comparable to that of the commercial prebiotic inulin (7.53 CFU/ml). Therefore, different types of cereal bran have a prebiotic effect on strain BB 536 growth when supplemented with goat milk for the development of functional food. Fermentation process was accompanied by significant (p<0.05) changes in physicochemical properties chemical composition. The maximum viable existence of strain BB 536 throughout refrigeration (two weeks) was in fermented goat milk supplemented with millet bran (lowest reduction of 1.48CFU /ml); whereas, the best existence in the first week was in fermented goat milk supplemented with barley bran (0.76 CFU /ml). Therefore, the strain BB 536 existence trend was dependent mainly on both types of fiber sources and the refrigeration period. Hopefully, the final viable count of strain BB536 in all formulated products was above the minimum number required to the presence in probiotic food to exert health benefits upon consumption. During fermentation, significant (p<0.05) increases in acidity and reductions in reducing sugar, TSS, and pH; were revealed due to the strain BB536 enzymatic activities. In experimental rats, the general health of rats indicated significant (p< 0.05) differences in feed intake, weight gain and water consumption between different five groups. However, there were no blood hematology abnormalities and no signs of any moderate and mild deficiencies of nutrients as revealed based on the results of blood biochemistry. Enzymes of the liver such as serum ALT, AST, and ALP of fed rats groups were within the standard normal range of rats. Feeding with fermented goat milk products promoted significant (p< 0.05) increases of bifidobacteria and lactobacillus viable count in colon of rats. Besides that, significant (P<0.05) decreases in pathogenic bacteria (Salmonella, Staphylococcus, Enterococcus and Enterobacteriaceae) in colon of rats groups were revealed. Therefore, different cereal bran (sorghum, barely and millet) were safe prebiotics. They exerted a prebiotic effect by stimulation growth of comairtial probiotic strain BB536 (IN VIVO) and enhanced of beneficial bacteria and suppression of pathogens in colon of rats (IN VITRO).Thus they are useful for synibiotic (probiotic and prebiotic in same product) application in dairy functional foods.