Modeling of Peroxidase Inactivation and Temperature Profile During Infrared Blanching of Red Bell Pepper

Abstract

Infrared (IR) blanching resulted in moisture loss (∼1.6%), whereas fat, crude fiber, protein and carbohydrate contents were not affected. Retention of ascorbic acid (94.3%) and β-carotene (108.4%) was found to be high after IR blanching. Inactivation of peroxidase (POD) and temperature profile in red bell pepper was predicted by employing different models. Fractional conversion model and multiple regression analysis were used to predict the POD inactivation at different temperatures (130, 150 and 170C). The time–temperature–distance relationship and multiple regression analysis were used to predict the temperature at different points (0.5, 2.5 and 4.5 mm from top) of red bell pepper subjected to IR blanching at 150C. The multiple regression analysis was found to fit well (R2 = 0.996–0.997) with the experimental values for predicting POD inactivation than fractional conversion model (R2 = 0.868–0.943). The temperature profile during blanching of red bell pepper was predicted well by using time–temperature–distance relationship (R2 = 0.996–0.999) and multiple regression analysis (R2 = 0.979–0.989). Practical Applications Infrared (IR)-based dry blanching offers advantages such as higher retention of water-soluble nutrients, complete elimination of effluent generation, higher energy efficiency, and both blanching and drying operations in the same processing unit, which minimizes labor requirement and improves productivity. The present study showed that IR can be effectively used for peroxidase inactivation in red bell pepper at different processing temperatures. The quality of IR-blanched red bell pepper in terms of ascorbic acid, β-carotene, carbohydrates, protein, ash, fiber and moisture content was not affected significantly. Peroxidase inactivation during IR blanching is temperature dependent and it is essential to know the distribution of temperature in the material being processed to standardize the operating conditions. The inactivation rate constant and decimal reduction time of enzyme provide information to design a blanching process efficiently. This research area has been a scope for further studies and this technique can replace conventional water blanching.