Application of Response Surface Methodology for Optimizing the Pre-processing Conditions of Bambara Groundnut (Voandzei Subterranea) during Canning

Abstract

Bambara groundnut (Voandzei subterranea) seeds were canned with the objective of investigating the optimal pre-processing conditions that would yield the best quality canned product from it. 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 for k = 3 were used for the canning of the bambara groundnuts 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 the optimum responses were tested in the experiment using the blanching time of 2-12 minutes, soaking time of 0-24 hours and salt concentration [(NaPO3)6] of 0-1%. Three optimal processing conditions of the canning procedures of the bambara groundnuts 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 bambara groundnuts. The optimal conditions required to achieve the optimum moisture content, pH level and other quality indices studied on the canned bambara groundnuts were blanching time of 5 min, soaking time of 12 h and [(NaPO3)6] salt concentration of 0.5 %. These conditions would give the best quality canned product from bambara groundnut with acceptable quality characteristics.