Changes in antinutrients, phenolics, antioxidant activities and in vitro α-glucosidase inhibitory activity in pumpkin leaves () during different domestic cooking methods.

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Pumpkin leaves () were subjected to different household cooking methods (boiling, microwaving, steaming, and stir-frying) to evaluate their effect on antinutrients, phenolic compounds, antioxidant properties (ABTS, and DPPH) and in vitro α-glucosidase activity. All cooking methods studied significantly reduced the antinutrients and antioxidant activities, whilst phenolic compounds -coumaric and ferulic acids significantly increased. The cooking methods reduced the oxalates by more than 50%, tannins by 47% and phytates by 79.22%. Steaming and boiling resulted in highest concentrations of -coumaric (195.40 mg kg) and ferulic acids (103.90 mg kg) compared to other methods. Overall, boiled leaves retained the highest total phenolic compounds, whilst steamed leaves retained the highest antioxidant capacity. Raw pumpkin leaf extracts showed higher in vitro α-glucosidase inhibitory effects than the cooked leaves. Thus, cooking affected the inhibitory effect of in vitro α-glucosidase activity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10068-021-00916-w.