Effect of Fermentation on the Microbial and Nutrient Composition of Digue: A Fermented Food Obtained with Pumpkin (Cucurbita maxima) and Peanut (Arachis hypogaea)

Abstract

The aim of this work was to study the evolution of microbiological and selected physicochemical parameters during the production of Digue, food obtained from the addition of the paste of roasted Arachis hypogaea (peanuts) in Yam Digue, fermented juice of Cucurbita maxima (pumpkin). The evolution of the microbial flora, the content of reducing sugars, total polyphenols, phosphorus, potassium and titratable acidity were measured during 30 days. Microbiological analysis at the start of fermentation revealed the presence of 03 groups of pathogenic germs such as staphylococci, enterobacteria and moulds with concentrations of 3.2, 3.8 and 3.24 Log₁₀CFU/ml respectively. We also observed the presence of lactic acid bacteria (LAB) which were are the most represented bacterial flora in the medium with a microbial load of 5.2Log₁₀CFU/ml. During fermentation, enterobacteria, staphylococci and moulds respectively reached maximum values ​​of 3.2, 3.8 and 3.2log₁₀CFU/ml on the 7^th day. However, after the 21^st day, enterobacteria and mould were eliminated, unlike staphylococci which were completely inhibited only on the 28^th day. The highest phosphorus and potassium contents were recorded on the 21^st day with values ​​of 0.29% and 2.5% respectively. On the 14^th day, the LAB yielded much higher microbial concentration of 8.9Log₁₀CFU/ml which also led to the optimum production of titratable acidity (1.2%) in the medium. During the same period, the sugar content increased by 2.3% and the polyphenols were eliminated at 100%. The data obtained in this work reveal the elimination of microbial growth and increasing the physicochemical qualities at the 21^th day with fermentation. Thus, it would be recommended for producers to ferment it for over 21 days as result of appreciable yield in terms of microbial, organoleptic and chemical qualities.

Keywords: Cucurbita maxima, Digue, fermentation, nutritional, pathogenic germs

DOI: 10.7176/FSQM/103-05

Publication date: December 31^st 2020