EXAMINATION OF THE USEFULNESS OF EMPIRICAL KINETIC-EQUATIONS FOR DESCRIBING THE FORMATION OF 5-HMF IN GRAPEFRUIT JUICE

Formation of 5-hydroxy-methyl-furfural in grapefruit juice was investi gated at four temperatures and five heat-treatment time periods. Measu red data were evaluated by relatively new methods: search for an adequ ate transformation by minimizing the ratio of variances around regress ion lines and within groups; applying the method of mean square of suc cessive differences, Bartlett's test for homogeneity, un weighted and weighted regression analysis. Reaction order, according to the empiric al kinetics of formation was n = 0.31. Rate constants at four temperat ures and one common initial transformed concentration were also determ ined. Special analysis based on the least squares method provided acti vation energy and reference rate constant. Original concentrations var ied according to power functions of slightly autocatalytic nature.