This study aims to investigate the formation of alpha-dicarbonyl compounds in fruit juices and nectars during storage using multi-response kinetic modeling approach. Changes in the concentrations of sugars, amino acids, alpha-dicarbonyl compounds (glucosone, 3-deoxyglucosone, threosone, methylglyoxal, glyoxal) and 5-hydroxymethylfurfural in apple juice, orange juice and peach nectar were monitored during storage. The concentrations of free amino acids showed no statistically significant change during storage. This suggested that sugar degradation reactions were found responsible for a-dicarbonyl compound formation. In apple and orange juices, the reaction rate constant of glucosone formation was found higher than that of 3-deoxyglucosone formation. Contrary, in peach nectar, 3-deoxyglucosone formation was the dominant. The contribution of fructose dehydration through fructofuranosyl cation on the formation of 5-hydroxymethylfurfural was significantly higher (p < 0.05) than 3-deoxyglucosone dehydration. The use of multi-response kinetic modeling provided better understanding the most possible pathway of sugar degradation reactions in fruit juices.