Optimization of process parameters for bitter gourd candy production using response surface methodology

In this optimization study, response surface methodology was used for optimization of process parameters for osmotic drying of bitter gourd slices. The Box-Behnken design of three variables such as syrup concentration (40, 50 and 60 ⁰Brix), syrup temperature (40, 50 and 60 ℃) and duration of osmosis (60, 180 and 300 min) which includes 17 experiments formed by using 5 central points was used to optimize input parameters. The linear, quadratic and interaction effects of three variables were analysed for the responses. For each response, i.e. water loss and sugar gain, the second-order polynomial models were developed and the fitted model's analysis of variance (ANOVA) was performed to check the adequacy and accuracy of the fitted models. The response surfaces and contour maps showing the interaction of process variables were constructed. The analysis of variance (ANOVA) indicated that the linear terms of syrup concentration, syrup temperature and duration of osmosis were significant at the 1% level for both the responses, viz. water loss and sugar gain. The F-value indicated that the duration of osmosis was the most influential factor, followed by syrup concentration and syrup temperature for water loss and sugar gain. The optimized conditions for making bitter gourd candy was 48 ⁰Brix syrup concentration, 47 ℃ process temperature and 190 min duration of osmosis for osmotic drying, followed by convective drying at 40 ℃ drying air temperature and air velocity of 2 m/s.