Effect of Lacticaseibacillus rhamnosus Yoba Fermentation on Physicochemical Properties, Amino Acids, and Antioxidant Activity of Cowpea-Peanut Milk

Abstract

The global renewed interest in plant-based milk and products is increasing amongst health-conscious consumers. There is increased utilisation of generic probiotics in the processing of legume milk as alternatives to dairy milk are scarce in Africa. This study evaluated the probiotic potential, physicochemical, and sensory properties of novel fermented cowpea-peanut milk with Lacticaseibacillus rhamnosus Yoba. A 3 × 1 factorial design as ratio of cowpea-peanut milk (1 : 1, 2 : 1, 3 : 1v/v) and the application of 2% w/v L. rhamnosus Yoba obtained from Yoba for Life Foundation, Netherlands, was used. The chemical and mineral contents of the fermented cowpea-peanut milk was analysed using Association of Official Analytical Chemists (AOAC) methods. Quality parameters such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging rate, total antioxidant activity, antinutrient, and amino acids content were determined. The fermented cowpea-peanut milk samples had 7.7–8.1 log CFU/mL viable L. rhamnosus Yoba cells after fermentation. Nutrient content range was given in g/100 g: carbohydrate 5.18–6.05, crude fat 3.3–3.5, crude protein 5.6–7.1, ash 1.04–1.26, crude fibre 0.72–1.18, and total reducing sugars 1.80–2.20. Lysine, leucine, and methionine content was 6.30–7.31, 6.60–8.75, and 1.7–1.86 g/100 g, respectively. Phytic acid and trypsin inhibitor content range was 0.3–0.34 mg/100 g and 0.86–1.12 TIU/mg, respectively. Iron and potassium content (mg/100 g) was 0.48–0.58 and 202–243 with pH 4.1–4.2. DPPH free radical scavenging, and total antioxidant rate was 56–59% and 49–54%, respectively. Physicochemical parameters were significantly different ( $p$  < 0.05). The fermented cowpea-peanut milk had an acceptance rating of 78%. The successful application and consumer acceptability of the fermented cowpea-peanut milk has the potential to increase the utilisation of these legumes and enhance their market value.