Optimization of oven drying conditions of banana (Musa spp., AAA Group, cv ‘Luvhele’ and ‘Mabonde’) using response surface methodology

Abstract

Luvhele and Mabonde banana varieties are bananas grown in Limpopo province of South Africa and they are rich in nutriments and antioxidants. Optimization of oven drying conditions of Luvhele and Mabonde banana varieties were studied using response surface methodology. The drying was performed according to a central composite rotatable design to explore two sets of variables: oven temperatures (40, 50 and, 60 °C) and drying time (1260, 1080, and 900 min) for Luvhele; (40, 50 and, 60 °C) and (1260, 900, and 600 min) for Mabonde. The color and texture (hardness) data were analyzed using ANOVA and regression analysis. Results indicated that L*, a*, b*, hue angle and hardness varied with drying conditions for the two banana varieties. The hue angle ranged between 63.38-74.70 and 60.14-72.80 in dried slices of the banana varieties, Luvhele and Mabonde. The hardness ranged between 1.15-14.62 N and 1.28-14.29 N. Oven temperature and drying time had significant (p0.05) effects on the overall color (hue) and hardness of both varieties. Models obtained for the prediction of overall color (hue) and hardness of dried slices of both banana varieties as a function of the process variables drying temperature and time had no significant (p0.05) lack of fit test, adequate and acceptable regression values: adjusted R2 between 0.78 and 0.80, coefficient of variance 10 %. The drying temperature of 47.56 °C for 944.87 min were optimum to obtain a quality product desirability of 0.97 to the Luvhele variety. Drying temperature of 40 °C and 646.17 min, with a desirability of 0.83, were predicted as optimum drying conditions to the Mabonde. The result of this study could be used as a standard for oven drying of Luvhele and Mabonde banana varieties.