Optimization of the Process of Reducing the Bitterness of Bitter Melon with Response Surface Methodology

Bitter melon fruit (Momordica charantia, Linn.) is rich in vitamins and minerals, antioxidants, and steroid saponins, which taste bitter and are not liked. Steroid saponin compounds have a good role in biological activities such as antidiabetic, anti-hypercholesterolemia, anti-obesity, anti-tumor, anti-inflammatory, analgesic, antiviral, and antidepressant. Currently, many efforts have been made to reduce the bitter taste, such as salting. To optimize the salting process, the response surface method with the developed model was employed. The design in this study was a 2k or partial factorial design with two levels for each variable coded -1 and +1 and expanded with a value of α, where α = 2k/4, and k = number of variables. To check the accuracy of the second-order polynomial model, the observations were repeated five times at the center point (X1 = 0 and X2 = 0). Bitter taste response parameters were measured using descriptive sensory tests and LC-MS chromatographic analysis of diosgenin compounds. The optimization results show that the quadratic polynomial regression equation is Y = 2.468 – 0.1053X1-0.0176X2 + 0.0153X12 + 0.0178X22 + 0.085X1X2 where X1 = salt concentration and X2 = salting time. A minimal bitter taste response was obtained at a salt concentration of 5 % and 15 min of salting time with a desirability value of 94.1%. In the condition of a minimum bitter taste response of 2.145,