Sucrose ester microemulsions as microreactors for model Maillard reaction

Abstract

Thermal reactions of cysteine/furfural mixture were studied as a model system to gain more insight into the influence of structured fluids such as water-in-oil nonionic microemulsions on the generation of aroma compounds. The microemulsion systems were composed of: sucrose ester/water/dodecane+alcohol(1/1), where the sucrose esters are sucrose stearate (S1570) and sucrose laurate (L1695), and the alcohols are medium-chain alcohols (C 2OH to C 6OH). Formation of predominately 2-furfurylthiol (FFT) is obtained in the aqueous cysteine/furfural system. The formation of FFT was enhanced under similar reaction conditions in water-in-oil microemulsions and led to the formation of two new sulfur compounds that were identified as 2-(2-furyl)-thiazolidine and tentatively N-(2-mercaptovinyl)-2-(2-furanyl)-thiazolidine. The reaction rates (furfural conversion or consumption) decrease with the decrease in the water content and the increase in alcohol chain length (C 2 to C 6 were used as cosurfactant) and with the increase of pH from 4 to 8 in the system containing butanol as the alcohol. The rates of reaction increase also with the increase of temperature in the range of temperatures studied from 30 to 60 °C. The kinetic constants ( k) and energy of activation ( E a) were calculated. Microemulsions of W/O are excellent reaction media for the Maillard reaction providing a high selectivity, high conversion rates and specificity.