Response surface methodology for optimizing the pre-processing conditions during canning of a newly developed and promising cowpea (Vigna unguiculata) variety Original Research Article

Cowpea (IT87D195Y) seeds were canned with the objective of investigating the optimal pre-processing conditions that would yield the best quality canned product from the newly developed cowpea variety. Pre-canning procedures such as blanching time, soaking time and sodium hexametaphosphate [(NaPO3)6] salt concentration were used as the independent variables for a Central Composite Rotatable Design (CCRD). The pre-processing parameters obtained from the CCRD were used for the canning of the cowpeas and the quality characteristics (moisture content, pH of the drained liquid, drained weight, splitting of the seeds, leached solids and seed hardness) of the canned products were studied using response surface methodology. Regression models were generated using regression analysis and used for the plotting of response surface curves. Adequacy of the model equation for predicting optimum response values was tested in the experiment using the blanching time of 2–12 min, soaking time of 0–24 h and salt concentration [(NaPO3)6] of 0–1%. Three optimal processing conditions of the canning procedures of the cowpeas were determined from the mathematical models. The results revealed that the soaking time, blanching time and salt concentration all significantly (p < 0.05) influenced most of the quality indices of the canned cowpeas. The optimal conditions required to achieve the optimum moisture content, pH level and other quality indices studied on the canned cowpeas were blanching time of 5 min, soaking time of 12 h and [(NaPO3)6] salt concentration of 0.5%.