Enhancing anti-diabetic potential of bitter gourd juice using pectinase: A response surface methodology approach

- Extraction of bitter gourd juice was optimized using Response Surface Methodology.
- Phenolic content was 1.5 times higher in pectinase treated juice.
- 2.47 and 3.74 fold higher α-amylase and α-glucosidase inhibition was obtained.
- Nature of phenolic constituents was identified using HPLC.

Bitter gourd exhibits significant anti-diabetic activity. In the present study, pectinase concentration (4.04-15.92 ml kg−1), incubation time (48-191 min) and temperature (31-55 °C) were optimized using response surface methodology (RSM) for obtaining increased juice yield with higher anti-diabetic (α-amylase and α-glucosidase inhibition) activity, total phenolics and antioxidant activity. The optimum conditions i.e. pectinase concentration (10.2 ml kg−1), incubation time (140 min) and temperature (48.8 °C) resulted in juice yield of 82%, α-amylase and α-glucosidase inhibition activity of 23 and 59%, respectively, with total phenolic and antioxidant content of 710 and 198 μg GAE ml−1, respectively. In comparison, control (prepared without enzyme treatment) had significantly (p < 0.05) lower juice yield, α-amylase and α-glucosidase inhibition activity of 59, 8 and 17%, respectively. Control samples also demonstrated significantly (p < 0.05) lower total phenolic and antioxidant content of 464 and 162 μg GAE ml−1, respectively. RSM optimized juice also demonstrated significantly (p > 0.05) higher contents of phenolic acids as compared to control juice.