Optimising the Processing Conditions of Plant-Based Cheese Produced From Cucumeropsis mannii Seed Kernel and Vigna subterranea Seed Milks

In recent times, animal-derived products have been related to many health issues and the animal system to environmental problems. Therefore, there is a growing interest in plant-based products as alternatives to animal products. This study was aimed at optimising the production conditions of cheese from Cucumeropsis mannii seed kernel milk (CMSKM) and Vigna subterranea seed milk (VSSM). Bambara groundnut seeds were sorted, dehulled, cleaned with water, soaked in distilled water, drained, blanched in water, cooled, milled with distilled water, filtered, and the milk collected. Egusi seeds were sorted, washed, soaked in distilled water, blanched, cooled, blended using distilled water, filtered, and the milk collected. The influence of six factors—time, temperature, pH, milk ratio (CMSKM/VSSM), enzyme concentration, and enzyme type—was evaluated using a 2^6–2 fractional design, with production yield and protein content as a response. The factors that significantly influenced the responses were used to optimise the processing conditions, and three factors (time, enzyme concentration, and milk ratio) were evaluated using a centred face central composite design to maximise yield, protein content, hardness, and general acceptability as responses. The samples from the different optimum conditions were produced to validate the predicted value and characterized for proximate composition, phytochemicals, and antinutrient contents. In general, the protein, fat, tannins, phytate, and oxalate contents of the samples increased with the proportion of CMSKM, while increasing the VSSM proportion increased the carbohydrate, ash, total phenols, flavonoid contents, DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric-reducing antioxidant power) activities of the samples, and the general acceptability score increased with an increase in enzyme concentration. The overall optimum condition for the production of cheese was at a coagulation time of 40.01 min, an enzyme concentration of 0.4 g/L, and a milk ratio of 4/1.91 (v/v, CMSKM/VSSM), which gave a sample with 33.37 g/100 g DM of protein, 17.95% of yield, a hardness of 49.97 N, and a score of 5.77 for general acceptability. All the samples have antioxidant activity; thus, VSSM and CMSKM can be used as raw materials to produce vegetal cheese as functional food using papain as the coagulant.