Kinetics of the sulphite-inhibited browning of fructose.

Sulphite species, S(IV), inhibit the non-enzymic browning of fructose-amino acid mixtures. Inhibition of browning is accompanied by a loss of S(IV). The kinetics of the reaction of S(IV) in the system: fructose-glycine-S(IV) are described in detail; two distinct mechanisms have been identified. One involves only fructose in the rate determining step. The other requires fructose and both the glycine and S(IV). Some amines (e.g. taurine and ethanolamine) can markedly increase the rate of the S(IV)-independent step. Arginine and lysine are particularly effective for increasing the rate of reaction of S(IV) in the S(IV)-dependent reaction.