Response Surface Optimization of Mechanized Drying of Wadi, a Legume-Fermented Food Condiment

Abstract

This work was aimed at optimizing the mechanized drying conditions for wadi using response surface methodology. Three separate variables, found to influence the quality of wadi, were selected. The effect of these independent variables, viz. relative humidity (RH) (20–65%), drying time (24–120 h) and sample diameter (15–35 mm), on the overall acceptability (OAA) based on its sensory attributes and the aw was studied using a central composite design. Twenty experimental runs in triplicate were conducted to obtain the optimal conditions as 42.5% RH, 72-h time and a sample diameter of 25 mm. Wadi prepared under these conditions was organoleptically acceptable. Although all the three factors had an influence on the OAA, the present study indicates that the drying time and size of wadi had a greater influence. The experimental value of both the responses OAA and aw obtained had no significant difference from the predicted values. Practical Applications Wadi is a legume-based condiment popularly consumed in the Indian subcontinent. In spite of its popularity, a large-scale production by mechanizing the manufacturing process is not carried out. The manufacturers rely on the solar energy for drying wadi, which restricts its production only to the winter season when the temperature and humidity are optimum for proper fermentation and drying. In order to remove this climate-dependent constraint, the present work was taken up with an aim to optimize the drying conditions of wadi inside a dehumidifier. The conditions, thus, optimized were found to produce wadi of satisfactory sensory qualities and aw values. The latter is an important factor determining the shelf stability of any food, and aw beyond the critical limit can lead to food spoilage. So, optimized manufacturing conditions will always ensure quality production.