KINETICS OF THE THERMAL DEGRADATION OF METHYLMETHIONINE SULFONIUM IONS IN CITRATE BUFFERS AND IN SWEET CORN AND TOMATO SERUM

Abstract
Thermal degradation of methylmethionine sulfonium ions was determined in sodium citrate buffers ranging in pH from 4.0–8.0. Reaction temperatures of 82 °, 88 °, 93 ° and 99 °C were studied at reaction times of 20, 40, 60 and 80 min. The same conditions were used to study the degradation of naturally occurring methylmethionine sulfonium ions in sweet corn and tomato serums. In each solvent system, the thermal degradation of these salts occurred according to first order kinetics; the reaction rates doubled for a 5–6 °C increase in temperature and activation energies of the reaction in the various media were comparable. The characteristic degradation kinetics provides a means of identifying methylmethionine sulfonium salts in fresh foods without having to resort to involved isolation procedures.