KINETICS OF ANTIOXIDANTS DEGRADATION AND QUALITY CHANGES OF CITRON (Citrus medica) FRUIT JUICE CONCENTRATE DURING STORAGE

Abstract

The aim of the study was to develop fruit juice concentrate from Citron and its kinetic evaluation during storage at 10 ºC, 25 ºC and 40 ºC respectively, for 12^th week. The effect of different temperatures on the quality of the juice concentrate was also investigated. The concentration of ascorbic acid in the juice concentrate was monitored after every week of storage. The results showed that degradation kinetics of ascorbic acid during storage was followed by the first-order kinetics. The degradation rates of ascorbic acid during storage at 10 ° C, 25 °C and 40 °C  were obtained as 2.27 ± 0.24, 2.46 ± 0.31 and 2.56 ± 0.34 1/week  respectively. The higher degradation rate was observed at 40 °C storage temperature. Temperature-dependent rate constants of ascorbic acid of citron juice concentrate was obeyed the Arrhenius relationship with higher R² values as 0.96.  Total antioxidant degradation was also high at higher storage temperatures. The amount of total phenolic content was decreasing at the first few weeks of storage, but later period of storage it was in gradually increasing trend. The storage study demonsrated that ascorbic acid, total polyphenol and antioxidant activity were not degraded at lower temperature after 12^th week.