Mechanisms underlying the formation of main volatile odor sulfur compounds in foods during thermal processing

Volatile sulfur compounds (VSCs) significantly influence food flavor and garner considerable attention in flavor research due to their low sensory thresholds, diverse odor attributes, and high reactivity. Extensive research studies have explored VSC formation through thermal processes such as the Maillard reaction, thermal pyrolysis, oxidation, and enzymatic reactions. However, understanding of the specific reaction mechanisms and processes remains limited. This is due to the dispersed nature of existing studies, the undefined intermediates involved, and the complexity of the matrices and processing conditions. Given these limitations, the authors have shifted their focus from foods to sulfides. The structure, source, and chemical characteristics of common precursors (sulfur-containing amino acids and derivatives, thiamine, thioglucoside, and lentinic acid) and their corresponding reactive intermediates (hydrogen sulfide, thiol, alkyl sulfide, alkyl sulfenic acid, and thial) are provided, and the degradation mechanisms, reaction rules, and matrix conditions are summarized based on their chemical characteristics. Additionally, the VSC formation processes in several typical foods during processing are elucidated, adhering to these identified rules. This article provides a comprehensive overview of VSCs, from precursors and intermediates to end products, and is crucial for understanding the mechanisms behind VSC formation and managing the flavor qualities of processed foods.