Abstract

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Lactic acid bacteria (LAB) are widely employed in food fermentation processes for the biosynthesis of certain important products or metabolites which helps in breaking down anti-nutritional factors in some food. This study investigated the role of LAB in extending the shelf life and reduction in anti- nutritional factors of ‘pupuru’ produced with selected LAB strain with the best technological properties. Fresh cassava tubers (Manihot esculenta Crantz) were purchased at Oja Tun-tun, Ile-Ife, Nigeria. The cassava tubers were washed with distilled water to remove adhered surface soil particles, peeled, chopped and thoroughly washed with sterile distilled water. Two LAB strains with desirable technological properties were selected as starter for this study. The cassava chips were divided into three portions for fermentation (one was fermented with L. plantarum only, the second was co-fermented with L. plantarum and L. fermentum and the third portion was fermented spontaneously that is without starter culture Changes in pH, titratable acidity, and hydrogen cyanide were monitored using standard procedures during fermentation. Reduction in anti nutrient and microbial load of the starter- produced and spontaneously- produced ‘Pupuru’ samples were determined. Lactic acid, hydrogen peroxide and diacetyl production by the isolates ranged from 0.2365-0.6418, 0.0008-0.0014, and 0.0962-0.2217 g/L respectively. There was a reduction in the hydrogen cyanide content of ‘Pupuru’ samples as fermentation progressed (0.13-0.00 mg/100g). Cyanogenic glycosides reduced from 0.87-0.02 mg/100g, phytate from 65.00-31.67 mg/100g and protease inhibitor from 0.47-0.00 mg/100g. The microbiological monitoring of the quality assessment showed that ‘Pupuru’ produced through combined starter had a consistent microbiological quality during storage and the microbial load was within acceptable levels when compared with spontaneously fermented ones. The study concluded that combination of Lactobacillus plantarum and L. fermentum could be used as starter to reduce the anti-nutritional factors and assess the microbiological quality of smoked fermented cassava (‘Pupuru’) during storage.

Keywords: Anti-nutritional factors, Enzyme, Storage, Cassava, Lactic acid bacteria