Kinetic Analysis of the Acid-catalyzed 5-Hydroxymenthylfurfual Formation from Sugar
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Abstract:
Acids such as phosphoric acid and citric acid in food can catalyze the transformation of sweet substances including glucose and fructose, into 5-hydroxymenthylfurfual (5-HMF). In this study, different sugar-acid solutions, namely, glucose-phosphate acid (GP), glucose-citric acid (GL), fructose-phosphate acid (FP), and fructose-citric acid (FL) systems were placed in ampoules and heated using an oil bath at three reaction temperatures: 373 K, 393 K and 413 K. 5-HMF concentration in the sugar-acid systems over time were monitored using high-pressure liquid chromatography (HPLC) during the eight-hour heating period. The formation kinetics model was estabishedby Origin 8.0 software. The catalytic efficiency of inorganic ternary phosphate acid was found to be higher than that of organic ternary citric acid. The conversion rate of fructose was higher than that of glucose. The concentrations of 5-HMF increased linearly with reaction time for all four sugar-acid systems tested, in accordance with the zero-order kinetics model, the reaction activation energy values were 109.16, 121.09, 102.89, and 112.36 kJ/mol, respectively, with highest values in GP and lowest values in FL system. Thus, phosphoric acid and fructose content had a major impact on 5-HMF concentration of sugar-acid food during thermal processing.
