KINETICS OF DETERIORATION OF PINEAPPLE CONCENTRATE

Pineapple juice concentrate undergoes reactions leading to color formation and quality loss. Kinetics were studied calorimetrically, spectrally and by chemical analysis. Two exothermic processes occurred between 40-degrees and 80-degrees-C, one independent of, and one dependent on O2 concentration. The rate of the O2 independent reaction decreased exponentially with time, (sucrose hydrolysis). The rate of the O2 dependent process was constant with time, complex, and not defined. Heat producing reaction rates were not altered by concentrations of major sugars/organic acids. Development of color occurred later than heat production. Color development had a complex dependence on solids and O2 concentration, and correlated with initial rate of 5-hydroxymethylfurfural (HMF) formation. CO2, decrease in titratable amines and amino acids, and loss of reducing agents accompanied color development. Heat and color production and chemical changes correlated with sensory quality.