Thermal processing of pigmented popcorn snacks: Effects on in vitro starch digestibility, nutraceutical compounds preservation and quality features

Abstract

This study investigated the effects of hot air, microwave, and wet cooking methods on six pigmented popcorn varieties, focusing on nutritional composition, starch digestibility, nutraceutical properties, and popping quality. Hot air popping generally yielded optimal results, producing the highest total starch content, increased resistant starch, and enhanced retention of anthocyanins and phenolic compounds. Black and blue popcorn varieties demonstrated enhanced nutraceutical potential, with black popcorn showing the highest anthocyanin content (150.25 ± 0.57 mg C3G kg⁻¹ for hot air). Hot air popping also exhibited better expansion times and yields than microwave and wet cooking. Starch digestibility varied across methods and pigmentation, with black and yellow popcorn consistently showing higher slow-digestible (∼27 g/100 g) and total-digestible starch values (∼61 g/100 g). Scanning electron microscopy revealed different cell sizes in popped kernels. Microwave cooking resulted in longer expansion times and lower yields but preserved certain bioactive compounds. PCA analysis revealed that the thermal method strongly influences resistant starch formation, and that phenolic content varies and is affected by quality features. This study provides insights for optimizing popcorn processing to enhance digestibility and nutraceutical features, highlighting pigmented popcorn's potential in functional food applications.