VAPOR-PRESSURE AND STABILITY OF ALLYL ISOTHIOCYANATE

Allyl isothiocyanate, a main flavoring constituent of wasabi and musta rd, is known to have strong antimicrobial activity. A study was made o f the vapor pressure changes and the stability under various condition s of this substance as part of a research program aimed at producing a preparation which would allow exploitation of its antibacterial effec t for industrial purposes. It was found that the vapor pressures of al lyl isothiocyanate at relative humidities of 0 and 80% were almost the same, and that vapor pressure could be controlled through dilution wi th non-volatile oils such as ODO (MCT: medium chain triglyceride). The investigation of stability revealed that, after one year's storage at room temperature, the residual level of allyl isothiocyanate was more than 90%. Further improvement of its stability was observed when the head space gas was replaced with nitrogen. In the presence of ethanol, allyl isothiocyanate produced an additional compound, and for this re ason it was considered that the development of a preparation based on a mixture of these two substances would be impractical. Heat treatment caused allyl isothiocyanate to decompose rapidly at temperatures betw een 170 and 180-degrees-C, indicating that processing at temperatures of this level and above might not be feasible.