Date of Award

2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Ibrahim, Salam A.

Abstract

This study investigated the impact of ten selected gums (carrageenan, carrageenan-maltodextrin, guar, locust bean, pectin, pectin- dextrose, pectin-carrageenan, guar-locust bean-carrageenan, inulin, and xanthan) on the growth of eight Lactobacillus strains in laboratory media. The bacterial population for eight Lactobacillus strains was determined in modified basal media at different concentration (0%, 0.25% and 0.5% w/v) of gums stored up to 12 hours at 37 °C. Findings show significant differences (p < 0.05) between the treated and control sample. Guar was found to be the best gum to enhance growth of L. rhamnosus GG B101, L. rhamnosus GG B101, L. delbrueckii subsp. bulgaricus SD35, L. delbrueckii subsp. bulgaricus SD33, L. acidophilus SD 16, L. acidophilus EF7, L. reuteri DSM20016, L. reuteri CF2-2F during 12 hours of storage at 37 C in laboratory media. The population of L. rhamnosus GGB101 in the samples containing gums were significantly (p < 0.05) higher than the control without gums. Samples containing 0.5% gums showed slightly higher bacterial population than those with 0.25% of gum. A minimum of 12 hour of incubation period was shown to be adequate to reach a bacterial population of 6 log CFU/mL in the presence of gums. Addition of guar (0.5%) led to the highest (1.31 log CFU/mL) increase in population of the treated L. rhamnosus GGB101 over the control. There was no marked (p < 0.05) change in pH and titratable acidity.

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