Real-time PTR–ToF–MS tracking of volatile sulfur compound release in food matrices: the role of whole saliva and the oral bacterial enzyme FnaPatB1

This study investigates the generation of volatile sulfur compounds from food matrices and cysteine S-conjugates in two complementary experimental systems: microbial C–S lyase activity associated with human whole saliva and the purified enzyme FnaPatB1. Using SPME–GC–MS alongside static and real-time PTR–ToF–MS, baseline profiles and subsequent volatile formation were investigated across four food matrices: aged garlic, shiitake mushroom, enoki mushroom and dried blackcurrant. Static screening revealed significant saliva-associated increases in sulfur-related signals for aged garlic and shiitake, while enoki and blackcurrant showed no comparable changes. Furthermore, real-time PTR–ToF–MS captured the dynamic formation of sulfur-related mass peaks following the addition of purified FnaPatB1 to aged-garlic and shiitake matrices, including signals tentatively assigned to methanethiol and allyl mercaptan in aged garlic. This work provides a framework for real-time tracking of enzyme- and saliva-associated sulfur volatile formation and supports further investigation of how oral microbial enzyme activity may influence sulfur-aroma formation.