17A-4 |
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A. M. O. AL-ABDULKARIM1, S. A. Ibrahim1, J. P. Carr1, M. M. Salameh1, E. D. Wilson1, C. W. Seo1, and A. Shahbazi2. (1) Food Science & Nutrition Program, North Carolina A&T State Univ., Dept. of Human Environment & Family Sciences, 171-B Carver Hall, Greensboro, NC 27411-1064, (2) Bioenivromental Engineering Program, North Carolina A&T State Univ., Dept. of Natural Resources & Environmental Design, Carver Hall, Greensboro, NC 27411-1064 The potential health benefits of probiotics such as bifidobacteria has resulted in a strong interest in its inclusion in fermented dairy products. Unfortunately, during normal processing, these bacterial cells tend to be injured and fail to thrive and survive. The purpose of this work was to determine the effect of reducing agents on the recovery of these injured bifidobacteria cells in dairy products. Fifteen commercial yogurt products (which claimed to include bifidobacteria) were evaluated for viable bifidobacteria using modified Colombia agar and BIM 25 agar. A paired comparison was conducted to determine if reducing agents would have an effect on the recovery of any injured bifidobacteria cells. A recovery agent was made by mixing the following ingredients per liter: Peptone (2.00g), cysteine (0.25g), lithium chloride (3.00g), beef extract (2.00g), sodium thioglycolate (0.05g), Tween 20 (5 ml) and sodium pyruvate (0.01g). Yogurt samples (10.00g) were then mixed with the recovery agent solution (90.00 ml) and incubated at 37 °C for 4 hrs. Samples were then diluted, and plated onto modified Colombia agar and BIM 25 plates, plates were incubated at 37 °C for 72 hrs. Results show that the counts for bifidobacteria varied among the tested samples ranging from 1.50 to 5.0 log cfu/ml. The recovery step increased the bifidobacteria count. Significant differences were observed in thirteen yogurt samples. The increase in the bacterial populations ranged between 0.5-1.75 log cfu/ml in all tested samples. The findings suggest that the recovery step used in this study could be used by the dairy food industry to increase the count of active bifidobacteria in dairy products.
Session 17A, Dairy Foods: Cheese and microbiology
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