Exposure of Proso millet starch to superheated steam: Effect on physicochemical, techno-functional, rheological behavior, digestibility, and related mechanism

Abstract

In the present study, proso millet starch (PMS) was treated with SHS (120–160 °C for 1–5 min) to investigate the molecular interactions and techno-functional, rheological, and digestible properties. Exposure to SHS induced the degradation of helical structure, and longer chains, reducing amylose, blue value, optical density, and relative crystallinity. Meanwhile, SHS treatment might have introduced hydro‑carbonyl groups, eventually increasing water absorption capacity, swelling power, and transparency. As per SEM images, SHS-treated PMS had rough and irregular polygon surfaces with small pinholes. Compared to control, SHS treatment slightly improved the elastic nature of PMS samples. Furthermore, SHS treatment at 140 and 160 °C for 3 and 5 min increased the slowly digestible and resistant starch content. Multivariate analysis suggests that SHS treatment could be performed at 140 °C for 3 min to modify the PMS.