71A-27 |
|
M. M. SALAMEH, S. A. Ibrahim, and C. W. Seo. Food Science and Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment and Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064 Fermented milk products containing probiotic cultures are generally considered as functional foods. These fermented products have the potential to improve lactose digestion and immune function. However, in order to provide health benefits, fermented milk products should contain a minimum level of living probiotic bacteria. Probiotic bacteria grow poorly in milk and often lose viability during refrigerated storage. The addition of peptide and nonprotein nitrogen has been shown to improve the viability of probiotic culture in fermented milk. The objective of this study was to evaluate the effect of milk protein hydrolysates on the survival and growth of probiotic culture, bifidobacteria, and Lactobacillus reuteri in laboratory media. Four different milk protein hydrolysates were used in this study. Each ingredient (5.00g) was mixed in 100ml modified M17 broth and was then inoculated with one of the following strains of bifidobacteria: two commercial isolates (CH-93 and BF-13), three B. longum (ATCC 15707, ATCC 15708, 79), two B. breve (ATCC 15700, ATCC 15698), three B. infantis (ATCC 15702, ATCC 25962, ATCC 15697) and three strains of Lactobacillus reuteri (MM 2 3, MM 7, and DSM 20016) to obtain a final inoculum level of 5 log cfu/ml. Control samples consisting of M17 broth without any supplements also were prepared. Samples were then incubated at 37 °C for 48 hr. During the incubation period, samples were withdrawn every 12 hr and analyzed for growth rate (optical density at 610nm) and acid production (titratable acidity (T.A.) and pH value). The experiment was repeated in a randomized complete block design to determine whether significant differences existed (P < 0.05). Our results showed that the addition of milk hydrolysates enhanced the growth and acid production of the tested strains. Samples supplemented with milk protein hydrolysates showed high bacterial cell density as observed by higher O.D. (O.D. > 1.20) when compared to control samples (O. D. < 0.90). Higher cell density was observed with bifidobacteria strains. Addition of milk protein hydrolysates supplements could have a positive effect on the survival and growth of probiotic bacteria.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |