Nutritional Composition, Total Polyphenol Content, and Antioxidant Activity of Traditionally Processed Parole (Vigna unguiculata) Seed—A Wild Cowpea of Bangladesh

Abstract

This study evaluated the effects of boiling and pressure cooking on the nutritional composition, total polyphenol content (TPC), and antioxidant activity of unconventional cowpea ("parole") from the Chittagong region of Bangladesh. Parole seeds subjected to pressure cooking exhibited a higher proximate composition than those cooked by boiling. Raw seeds contained higher protein (25.47%), fat (3.87%), and ash (4.47%) than processed samples, with boiling causing the greatest reduction (17.46%, 2.84%, and 3.22%, respectively). Pressure cooking better retained nutrients (20.22% protein, 2.98% fat, 3.71% ash). Carbohydrate content increased in boiled samples (61.45%) compared to raw (51.38%) and pressure-cooked (58.58%) parole seeds. Thermal processing reduced calcium and magnesium levels but did not significantly affect moisture or energy content. TPC decreased most markedly in boiled samples (1.06 ± 0.02 µg/mg), followed by pressure-cooked (1.51 ± 0.10 µg/mg) and raw samples (2.76 ± 0.08 µg/mg), representing reductions of 61.59% and 45.28%, respectively. In contrast, antioxidant activity remained relatively constant across groups, with values of 71.03% for boiled samples, 72.76% for pressure-cooked samples, and 72.83% for raw seeds. The findings suggest that boiling and pressure cooking enhanced antioxidant activity despite reducing polyphenols and certain nutrients. Further research should optimize processing methods to improve nutrient retention and explore value-added product development.