Sucrose ester microemulsions as microreactors for model Maillard reaction

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 (C2OH to C6OH). 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 degreesC. The kinetic constants (k) and energy of activation (Ea) were calculated. Microemulsions of W/O are excellent reaction media for the Maillard reaction providing a high selectivity, high conversion rates and specificity. (C) 2001 Elsevier Science B.V. All rights reserved.