Nutritional and functional characterization of a maize–soybean–orange-fleshed sweet potato complementary food blend via lactic acid fermentation

This study evaluated the effects of lactic acid fermentation on the functional, nutritional, and microbial characteristics of a complementary food blend formulated from maize, soybean, and orange-fleshed sweet potato (OFSP). The blend was fermented for 24 hours using Lactobacillus plantarum , Lactobacillus fermentum , and Lactococcus lactis , alongside a spontaneously fermented control. Samples were analysed for pH, viscosity, microbial load, proximate composition, and selected fermentation metabolites (organic acids, sugars, and ethanol) using validated chromatographic techniques. Fermentation significantly reduced pH (from 6.2 to < 4.0) and viscosity (from 2700 cPs to <1500 cPs), creating conditions unfavorable for spoilage organisms and improving product consistency for infant feeding. Although nutritional composition showed no major differences among fermentation treatments, the accumulation of lactic, acetic, and propionic acids and the concurrent reduction of fermentable sugars confirmed active microbial metabolism. Both starter culture and spontaneous fermentation produced microbiologically safe products, with comparable improvements in functional and safety attributes. These findings demonstrate that lactic acid fermentation can enhance the safety and suitability of maize–soybean–OFSP complementary foods. The comparable performance of spontaneous fermentation highlights its potential as a low-cost, culturally adaptable approach for improving infant nutrition in resource-limited settings. • Lactic acid fermentation improved protein content and energy value of the blend. • Viscosity decreased to levels suitable for infant feeding • Fermentation significantly reduced the pH of the blend, inhibiting spoilage organisms. • Organic acid levels increased, especially in L. plantarum -fermented samples • Spontaneous fermentation showed promising results for low-resource settings.