Semester of Graduation

Fall 2021

Document Type

Thesis

Abstract

Oshikundu is a Namibian traditional low to non alcoholic cereal beverage fermented from malted sorghum (Sorghum bicolor L. Moench), pearl millet (Pennisetum glaucum), pearl millet bran, and water. Traditional Oshikundu fermentation has been passed from generation to generation. As a result, there is a high demand for Oshikundu; however, the beverage is highly perishable, approximately 6 hours shelf life at ambient, due the presence of coliforms and spoilage psychrophilic bacteria. Developing Oshikundu under laboratory conditions with viable probiotics may potentially lead to its commercialization. The study objective is to develop prototype methods using controlled mashing temperatures, Lactobacillus plantarum and Saccharomyces cerevisiae as starter cultures, and compare them with the traditional method. In the traditional method, mashing temperatures are not controlled, and natural florae are used to initiate fermentation at 30°C. Prototype methods employed 3 different mashing temperatures of 37°C (M37-LP), 65°C (M65-LP), and 75°C (M75-LP) and were fermented anaerobically at 30°C with L. plantarum and SafeAle S-33 yeast as starter cultures. The Oshikundu beverages were stored at 5°C and at 23°C for 48 h. Physiochemical properties, coliform, total psychrophilic bacteria, proximate analysis, and survival of lactic acid bacteria in simulated gastrointestinal conditions were evaluated for the Oshikundu beverages. Results from triplicate trials were statistically analyzed (p≤0.05). Coliform counts in Oshikundu produced with a traditional method and with M37-LP were 7.25 ±0.00 and 6.92 ±0.01 log respectively and non-detectable in M65-LP and M75-LP before fermentation. No coliforms were detected in an any beverage after fermentation or during storage. A reduction in total psychrophilic bacteria before fermentation and a significant increase (P≤0.05) during storage was observed in the all samples but M65-LP and M75-LP beverages had lower counts than the traditional and M37-LP beverages. The traditional method maintained an 8-log count of Lactic acid bacteria during 48 h storage. M37-LP, M65-LP, and M75-LP counts increased by 0.64 log, 0.96 log, and 0.80 log at 5°C, and 0.55, 0.81, and 0.48 log at 23°C during 48 h storage. Lactic acid bacteria in all of the beverages survived in the simulated gastrointestinal conditions. All beverages showed a reduction of soluble solids, an increase in lactic acid, and a reduction of pH after fermentation and 48 h storage. This study demonstrates that the prototype M65-LP and M75-LP beverages had non-detectable levels of coliform bacteria after fermentation and they had lower count of Psychrophilic bacteria. Further identification analysis of psychrophilic bacteria in the beverages might be recommended for further research. L. plantarum with brewer ale yeast could be used as starter cultures to produce Oshikundu beverage instead of using natural florae.

Committee Chair

Sathivel, Subramaniam

Available for download on Wednesday, August 30, 2028

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