Formation of fluorescent substances and correlation with process flavor changes of dehydrated Maillard reaction intermediates of peanut protein hydrolysates

Maillard reaction intermediates (MRIs) derived from peanut protein hydrolysates (PPH) and xylose (Xyl) were prepared using the water bath combined with spray drying and vacuum drying. The monitoring of free amino content, browning precursors, and taste characteristics was carried out throughout the thermal treatment at low temperature, where the Maillard reaction process was slowed down, and the formation and degradation of MRIs were dynamically balanced at low conversion rates. The reaction between amino compounds and the reducing sugars contributed to the increased taste characteristics during the early phase of Maillard reaction. Fluorescence intensity was reduced after reaching its maximum value and browning intensity was significantly increased during vacuum drying, which confirmed that the Maillard reaction entered into an advanced stage. Vacuum drying also led to a significant increase in the total amount of volatile compounds in the subsequent thermal processing reaction (from 212.93 ng/g to 564.91 ng/g), which demonstrated that the higher fluorescence intensities resulted in the more accumulation of MRIs and better capabilities of flavor formation. • The degradation of intermediates led to an increase in free amino group content. • Saltiness enhancement of products increased during low temperature heat treatment. • Fluorescence intensity was a crucial indicator for Maillard reaction extent.