Impact of Gums on the Growth of Probiotic Microorganisms

Abstract

Probiotics are increasingly being used as dietary supplements in functional food products. The ingredients in food contribute to maintaining the growth of probiotics in food products. Gums are polysaccharides used as stabilizers and emulsifiers in foods and could also be used to enhance the growth of probiotics. Thus, the objective of this study was to determine the impact of different gums on the growth of Lactobacillus reuteri in laboratory media. Modified M17 media was prepared with 0.5 % (w/v) of one of the following gums: locust bean, carrageenan-locust bean-guar, guar, guar-pectin, carrageenan-maltodextrin, pectin, pectin-carrageenan, and inulin pectin-dextrose. Two liters of modified M17 medium was prepared and divided into ten portions. Batches of 200 ml samples with 1 g of each gum were sterilized at 110 °C for 10 min. Sterilized samples were allowed to cool to 42 °C and then inoculated with L. reuteri strains at a final inoculum level of 3 log CFU/mL. The inoculated samples were incubated at 37 °C for 16 h, serially diluted, and plated on lactobacilli MRS agar to obtain final bacterial counts. The results showed higher bacterial counts in samples with gums compared to the control. The bacterial population in the control sample increased from initial counts of 2.78 to 7.16 log CFU/mL whereas samples with pectin increased from 3.3 to 9.0 log CFU/mL. The bacterial population in samples with carrageenan also increased from 3.1 to 8.9 log CFU/mL. The average pH samples at the end of incubation ranged from 5.62 (for sample with pectin) to 6.47 (for control without gum). These findings could lead to the use of pectin and carrageenan-maltodextrin as microbial growth enhancers that could subsequently improve the therapeutic quality of functional food.