Aqueous extraction of bitter gourd (Momordica charantia L.) juice and optimization of operating conditions

Introduction. Bitter gourd (Momordica charantia), belonging to the Cucurbitaceae family, is a wellrecognized therapeutic herbal plant with numerous nutritious benefits, improving the overall health of consumers. It possesses many phytonutrients with medicinal activities. Aqueous extraction of phytonutrients is the safest procedure, which can circumvent the challenges associated with other extraction techniques. Materials and methods. To optimize the process parameters for aqueous extraction of bitter gourd juice, three independent variables, i.e. the fruit: water ratio, extraction time and temperature, were selected within the ranges of 0.3-1.0 g mL(-1), 20-160 min and 30-90 degrees C, respectively. A Box-Behnken design of a numerical optimization technique was used to optimize these variables. The corresponding responses were estimated in terms of concentrations of protein, polyphenols and total solids, and juice clarity. Results and discussion. The effects of linear, interaction and quadratic terms of independent variables on the responses were investigated. The present study generated a regression model that could explain 99% of the total variability, with a coefficient of determination (R-2) of 0.99. Conclusion. The optimum conditions for aqueous extraction of bitter gourd fruit are: a fruit: water ratio of 0.48 gmL(-1), an extraction time of 95 min and an extraction temperature of 68 degrees C. The corresponding responses at optimum points were estimated to be 131.7 mg L-1, 23.1 mg GAE 100 mL(-1), 0.89 g 100 mL(-1) and 60.6% for concentrations of protein, polyphenols, total solids and juice clarity, respectively.