The role of long-term storage and temperature in modulating cooking qualities and physicochemical properties of foxtail millet

The purpose of this study was to provide a comprehensive account of the potential storage effects of high temperature (37 °C), ambient temperature (25 °C) and low temperature (4 °C) on cooking qualities and physicochemical properties of foxtail millet seeds. In addition, correlation analysis and principal component analysis was performed further to learn the correlation among the indicators and the representative indicators of stored millet seeds. Results showed that 37 °C significantly increased free fatty acids (FAA) contents after long-term storage, while 25 °C and 4 °C exhibited less FAA. Moreover, 37 °C caused the degradation and unfolding of peptide chains in millet protein, as well as lignification of cell wall, accompanied by the decrease of cooking loss, pasting viscosities and the increase of water absorption index and hardness. Although 4 °C maintained the pasting viscosities of millet flour, it was found to accelerate the color changes of millet. Comparatively, millet stored at 25 °C exhibited no visible changes of starch granules evidenced by SEM, and favorable sensorial properties after 3 months storage. FAA acted as critical quality index which showed distinct correlations with cooking qualities, textual properties and pasting behaviors. This study revealed that by adjusting storage temperature and durations, the quality of foxtail millet can be controlled.