Effects of Thermal Processing on the Contents and Bioaccessibility of Polyphenols and Carotenoids in Fresh Waxy Corn

As a typical whole-grain food, fresh waxy corn contains several health-promoting compounds including polyphenols and carotenoids. However, different processing methods can affect the content and health effects of these compounds. This study investigated the effects of atmospheric boiling (AB), high-pressure boiling (HB), high-pressure steaming (HS), and high-speed pulping (HP) on polyphenol and carotenoid content, antioxidant activity, and digestive properties in fresh waxy corn. The results showed that compared with the untreated group, HB could significantly increase the content of polyphenols and carotenoids (p < 0.05), with the contents of ferulic acid, quercetin, rutin and proanthocyanidins increasing by 29.06%, 23.71%, 38.15% and 20.82%, while lutein and zeaxanthin increased by 42.31% and 40.43%, respectively. The contents of ferulic acid and zeaxanthin in fresh waxy corn had the greatest correlation with the total antioxidant capacity. In vitro digestion experiments demonstrated that HB treatment improved the bioavailability of polyphenols and carotenoids; however, compared with young adults, polyphenols, including gallic acid, rutin, and quercetin, rather than carotenoids, acted as components with restricted absorption in the elderly gastrointestinal environment.