Modifications in peroxidase activity, nutritional quality, techno-functional properties and microstructure of popcorn flours obtained from pretreated kernels.

Popcorn flours (PCF) were obtained from whole kernels that were dry heat treated at different time-temperature conditions or steamed in order to inactivate lipase and increase stability during storage. Lipase inactivation was assessed through peroxidase enzyme activity and two treatments were selected: dry heating at 130 °C for 1 h (PCF-D) and steaming during 4 min (PCF-S). Control flour was obtained from non-treated kernels (PCF-C). Flours were characterized by their compositional, physicochemical microscopical and thermal properties. Oxidative stability indices (OSI) were obtained at different temperatures to estimate shelf life at 20 °C. The treatments did not substantially modify the nutritional profile. PCF-D exhibited higher oxidative stability than PCF-S across the 110-130 °C range. Furthermore, PCF-D presented an estimated shelf life of 11 months, compared to 5 months for PCF-S. Conversely, PCF-S underwent more pronounced color and microstructural alterations-including a lower yellow index and enlarged granules- alongside lower gelatinization enthalpy.