Effect of infrared heating on degradation kinetics of key lime juice physicochemical properties

Abstract

The effect of IR heating on retention and kinetics of some physicochemical properties of key lime juice were investigated. The juice was thermally treated at 60, 70, 80 and 90 °C in 15, 10, 5, 2.5 min using IR and conventional thermal treatment in water bath. The effect of heating on ascorbic acid (AA), pectin methylesterase (PME), cloud stability and color of the juice were studied. The higher Z-value of AA during IR heating (25.12 °C) indicated the higher thermal resistance of this vitamin compared to conventional method (24.15 °C)). Higher PME inactivation and cloud stability were observed during conventional treatment. IR heating was effective in color preservation of the juice because of lower changes in browning index and L* × a* × b* combination. All these obtained results were related to shorter come up time during IR heating. Finally, correlation matrix was used to evaluate the linear relation between the juice properties. In this study, infrared (IR) heating was used as an alternative method for key lime juice thermal processing. Come up time decreased due to quick rising in initial temperature of the juice to the target temperature during IR heating. Hence, the juice was heated less during this method compared to the conventional thermal treatment in water bath. Totally, IR heating could be introduced as a new and effective method for the preservation of nutritional values and color of juice such as key lime juice.