Keywords: locust beans, Box–Behnken design, dehulling, process optimisation, softening, re–cooking, fermentation, compressive stress, iru production, process design
Optimisation of process conditions for dehulling and softening of locust bean (Parkia biglobosa, Jacq. Benth) seeds prior to fermentation in iru production
The study optimised the fundamental processes (dehulling and softening) on iru production from locust bean using independent variables, steam pressure (40–60 kPa gauge), volume of water (2–6 L) and time (50–70 min) in the Box–Behnken design. The regression coefficients were used to generate surface and contour maps. Optimum dehulling conditions were ca pressure 50 kPa, volume of water 4 L, and time 54 min resulting in maximum percentage weight of dehulled seeds of 53.42 g/100g of raw locust bean seeds. The optimum condition for softening were 90 g of dehulled seeds, 3 L of water and 15 min with maximum compressive stress on cooked seeds being 0.36 MPa. The adequacy (R2) of the models was highly satisfactory for the two processes being 0.96 and 0.79, respectively. The optimal conditions enabled the attainment of process variables to minimise drudgery in locust bean processing into condiments.