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

Florence M Mashitoa; Vimbainashe Manhivi; Retha M Slabbert; Jerry L Shai; Dharini Sivakumar

doi:10.1007/s10068-021-00916-w

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

Food Sci Biotechnol. 2021 Jun 7;30(6):793-800. doi: 10.1007/s10068-021-00916-w. eCollection 2021 Jun.

Authors

Florence M Mashitoa¹, Vimbainashe Manhivi², Retha M Slabbert¹, Jerry L Shai³, Dharini Sivakumar²

Affiliations

¹ Department of Horticulture, Tshwane University of Technology, Pretoria West, 0001 Gauteng South Africa.
² Phytochemical Food Network Group, Department of Crop Sciences, Tshwane University of Technology, Pretoria West, 0001 Gauteng South Africa.
³ Department of Biomedical Sciences, Tshwane University of Technology, Arcadia, Pretoria, 0001 Gauteng South Africa.

Abstract

Pumpkin leaves (Cucurbita moschata) 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 p-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 p-coumaric (195.40 mg kg^-1) and ferulic acids (103.90 mg kg^-1) 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.

Keywords: Antioxidant capacity; Indigenous leafy vegetables; Oxalates; α-glucosidase activity.