Physicochemical and Processing Properties of Different Types and Varieties of Proso Millet

In this study, 13 different varieties of non-waxy, intermediate-type and waxy proso millets were compared for differences in their basic components, structural, pasting, textural properties, cooking and aroma properties, and the relationship between structural and processing properties was investigated. The results showed that significant differences in basic components among the varieties, with the greatest variation observed in the amylose content. The relative crystallinity and short-range ordered degree of waxy proso millet flour were higher than those of intermediate-type and non-waxy proso millet flour, whereas the pasting properties of non-waxy proso millet flour were higher than those of intermediate-type and waxy proso millet flour. Non-waxy proso millet flour gels had higher hardness, gumminess and chewiness, waxy proso millet flour gels had higher springiness, cohesiveness and resilience, and intermediate-type proso millet flour was intermediate. During cooking, non-waxy proso millet showed higher water absorption and swelling capacity, while waxy proso millet displayed higher dissolution rate with its soup having higher pH. By solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS), 43, 44, and 51 volatile compounds were identified in non-waxy, intermediate-type and waxy proso millet, respectively. Correlation analysis indicated that the difference in amylose content among the different proso millet varieties was a key factor affecting their structural and processing properties, and there was a correlation between structural and processing properties. This study provides a theoretical basis and guidance for the processing and utilization of different types of proso millet as whole grain food ingredients.