Profiling of functional properties of lactiplantibacillus plantarum isolate and its application in fermentation of finger millet-cassava complementary porridge

Abstract

In Kenya, children fed on high-energy foods, resulted in high levels of malnutrition, although they are rich in micronutrients. Controlled fermentation and malting are some of the processes that used to improve the nutritional and safety properties of food. This study aimed at developing a complementary food product with probiotic benefits and improved nutritional value. A Lactiplantibacillus plantarum strain that was previously isolated from spontaneously fermented milk analyzed for its probiotic properties, safety profile, and its application for product development. The strain was tested for temperature sensitivity pH tolerance and 0.4% phenol tolerance to observe its survival in the gastrointestinal tract of humans. For safety evaluation of the isolate, antagonistic activity against pathogenic strains, antibiotic susceptibility pattern examined using common antibiotics and hemolytic activity done using lamb blood agar. To test the isolate for product development, a blend of U15 variety of finger millet flour and a sweet variety of cassava (KME-2 variety) flour were used as ingredients. Finger millet was malted for 0 days, 1 day, and 2 days. The flours were mixed in three ratios, 50:50; 70:30, and 0:100, then made into porridge and cooled to 37°C, where the L. Plantarum isolate was inoculated and fermented for 0 h, 12 h, and 24 h. The porridge dried at 50°C to a moisture content of below 5%. The product analyzed for anti-nutritional content and descriptive sensory analysis. The results were recorded and analyzed using Excel and R studio software. The L. plantarum isolate had optimal growth at 37°C and demonstrated pH tolerance at pH 2.0 to 3.5 It was a le to maintain via ility after exposure to 0.4% phenol. The selected isolate showed inhibition against the pathogens, with S. typhi having the largest (ZDI = 31.0 ± 1.73 mm) zone of diameter inhibition (ZDI) and Candida albicans having the least (ZDI = 8 ± 76 mm) Moreover, the strain exhi ited γ -hemolytic activity hence safe for use as a starter culture and identified as a Lactobacillus plantarum strain Eger202111 based on 16S rRNA gene sequencing. Malting and fermentation had a significant (p=0.05) effect on phytates, tannins, and cyanide. There was a 14.6% and 49.5% decrease in phytates after 12hrs and 24hrs of fermentation respectively while after 24hrs of fermentation 88.2%, 60.3% and 27.3% decrease in tannins was observed. Cyanide decreased by 87.5%, 50% and 55% after 12hrs of fermentation. Loadings from principal component analysis (PCA) of 17 sensory attributes of porridge resulted in two principal components, which accounted for 97.3% of the total variability observed among the treatments. Malting and fermentation flavour and taste were evident in the samples. This study revealed L. plantarum isolate as an excellent probiotic starter culture for the fermented cassava-finger millet porridge, a nutritious complementary beverage for children.