41-2 |
Immobilization of Lactobacillus reuteri in sodium alginate for lactic acid production |
S. PHETSOMPHOU1, H. Yang1, A. Shahbazi2, C. W. Seo3, and S. A. Ibrahim1. (1) Dept. of Human Environment & Family Sciences, North Carolina A&T State Univ., Food Microbiology & Safety Lab., 171-B Carver Hall, Greensboro, NC 27411-1064, (2) Dept. of Agricultural & Biosystems Engineering, North Carolina A&T State Univ., Greensboro, NC 27411-1064, (3) Food Science and Nutrition, North Carolina A&T State University, Greensboro, NC 27411-1064 Immobilization of viable lactic acid bacteria has attracted considerable interest in the past 20 years. Immobilization of cells offers a number of advantages over free-cell fermentations, including greater productivity and long-term operating stability. To date, few data are available regarding continuous production of lactic acid using immobilized cells of Lactobacillus reuteri (L. reuteri). The objective of this research was to determine the ability of immobilized cells of L. reuteri in sodium alginate to produce lactic acid. Five strains of L. reuteri, CF 2-F, DSM 20016, SD2112, MM 7, and MM 2-3 were used. These strains were grown in lactobacillus MRS at 37° C for 16 hrs. The cells were then washed and suspended in 10-ml peptone water. Sodium alginate beads were prepared by resuspending the 10-ml culture in 100-ml 7% sodium alginate solution. Beads were manufactured by dropping sodium alginate culture into ice-cold (2° C) 0.4M calcium chloride using a separatory funnel. Under comparable conditions the sodium alginate immobilized cells were allowed to ferment in 500-ml lactobacillus MRS and whey based medium at 37° C for 24 hrs. Samples were withdrawn at two hour intervals during storage period and analyzed for pH value, lactose, glucose, and lactic acid. Results showed that the pH reached 4.00 within 15 hrs with beads fermentation and reached 5.40 using conventional batch fermentation. Strain MM 2-3 produced the highest lactic acid yield as measured by pH value (pH 3.70), lactic acid (8.0%) and lactose conversion rate (80%) while strain SD2112 produced the lowest acid yield as measured by pH value (pH 4.18), lactic acid (2.0%) and lactose conversion rate (50%). Immobilization of L. reuteri could have potential use in the production of lactic acid for commercial applications in food and pharmaceutical industries.
Session 41, Dairy Foods: Dairy microbiology
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