Optimal Conditions for Production of Fermented Flour from Pumpkin (Cucurbita pepo L.) for Infant Foods

Abstract

The aim of this study was to determine the optimal conditions for production of a fermented pumpkin flour by lactic fermentation using Lactobacillus plantarum and the effect of the fermentation on nutritional potential and functional properties of pumpkin. To achieve this, pumpkin fruit was collected in the Ngaoundere main market, peeled, sliced, and the flesh obtained was grated, pasteurized at 90ºC for 5 minutes and placed under lactic fermentation using L. plantarum (108 cfu/mL). The sample obtained was dried at 45ºC ± 2ºC for 24 hours and crushed to obtain a flour with particle size ≤ 500 µm. According to the Doehlert's plan used, time and temperature of fermentation varied from 24 to 96 hours and 30 to 50°C respectively. Responses sought were the optimal levels of total carotenoids and reducing sugars in the flours. Chemical composition of flour was determined to evaluate the effect of fermentation on food matrix used. Results indicate that to produce a pumpkin flour with highest content in both carotenoids and reducing sugars, optimal conditions of lactic fermentation with L. plantarum are 70h at 45°C. Under these conditions, there is a decrease of 72.1% of proteins and 67% of fibers, against an increase of 106% of reducing sugars. Total carotenoids content decreased by 4.6%, but the level is still higher than the threshold recommended for infant food formulation, while mineral content increases with fermentation. A reduction of anti-nutrients (phytates, tannins, phenolic compounds and oxalates) of more than 50% is also observed when fermenting pumpkin. The functional properties of fermented pulp show a decrease of water absorption capacity of 24% and an increase of 134.4% in bulk density. Fermented pumpkin flour could be used in infant food formulation, but need to be associated with other sources of proteins and minerals.