Analysis of microstructure, starch properties, and volatilomicse reveals the effect of nitrogen fertilizer on cooking quality of proso millet

The microstructure, starch and protein structures, cooking properties, and flavor substances of proso millet (PM) grains under high nitrogen fertilizer were analyzed, and their relationships were investigated. In terms of morphology, high nitrogen application caused shrinkage of the honeycomb pores of chyme flour and reduced the water absorption capacity, leading to increased difficulty in grain pasting. High nitrogen level results in a lumpy material and high crystallinity, which improves the stability of starch and affects the water absorption and swelling ratio of the PM during cooking. Normally, the aroma of PM porridge is mainly fruity and floral burnt, slightly woody, and earthy. The addition of nitrogen fertilizer has effect on the three main substances esters, terpenes, and aldehydes that determine the aroma of the cooked PM. Therefore, nitrogen fertilizer affects the cooking quality of PM by altering the structure of starch and protein as well as flavor substances.