14A-4 |
Viability of bifidobacteria in commercial yogurt products during refrigerated storage |
J. P. CARR1, S. A. Ibrahim2, C. W. Seo2, A. Shahbazi3, and M. Worku4. (1) Food Science and Nutrition, North Carolina A&T State University, Greensboro, NC 27411-1064, (2) Dept. of Human Environment & Family Sciences, North Carolina A&T State Univ., Food Microbiology & Safety Lab., 171-B Carver Hall, Greensboro, NC 27411-1064, (3) Dept. of Agricultural & Biosystems Engineering, North Carolina A&T State Univ., Greensboro, NC 27411-1064, (4) Dept. of Animal Sciences, North Carolina A&T State Univ., Webb Hall, Greensboro, NC 27411-1064 Today, approximately 30-50% of refrigerated yogurt products in the US contain viable bifidobacteria. However, during processing and storage, the number of viable cells tends to decline due to exposure to oxygen and acid. The purpose of this work was to determine the viability of bifidobacteria in commercial yogurt products during refrigerated storage at 4o C. Fifty-eight commercial yogurt products (which claimed to include bifidobacteria) were obtained from local stores in Greensboro and examined for the presence of bifidobacteria. Samples were withdrawn at 0, 1, 2, 3 and 4 weeks and evaluated for viable bifidobacteria during refrigerated storage at 4o C using modified BIM-25 agar as selective medium. Our results showed that Bifidobacteria counts were variable, ranging from 0 to 5.5 log CFU/ml. Of the 58 products tested, only 44 (76 %) contained viable cultures. The results also showed that products made by only two manufacturers contained sufficiently high enough levels of bifidobacteria to promote health benefits. Viability of bifidobacteria in yogurt samples remained within the same levels during 3 weeks of storage at 4o C, however the bacterial count started to decline during the fourth week. Results obtained from this research can be used by the industry to develop new technologies to ensure consumers receive high quality products. Findings of this study can be used to help consumers become more aware of manufacturer’s claims and demand that products live up to any beneficial health claims.
Session 14A, Dairy Foods: General developments in dairy technology I
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