Optimization of Blanching Process for Carrots

Investigations were carried out to study the effects of selected blanching treatments on the quality of carrots over a temperature range of 80–100C. The blanching treatments selected were steam, water, 0.05 N acetic acid solution and 0.2% calcium chloride solution. These blanching treatments were evaluated with respect to the inactivation time of peroxidase (POD) and catalase, and the process was optimized on the basis of the maximum yield of carrot juice and minimum loss of vitamin C and b-carotene. The most effective blanching treatment was 5 min in hot water at 95C. At this time–temperature combination, POD and catalase were completely inactivated and the yield of carrot juice and vitamin C and b-carotene contents were found to be 55%, 8.192 mg/100 g and 3.18 mg/100 g, respectively. The kinetics of thermal inactivation of POD in carrot juice using various enzyme inactivation models available in the literature was critically evaluated. The Weibull distribution model provided a good description of the kinetics of the inactivation of POD in carrot juice over the temperature range of 80–100C. PRACTICAL APPLICATIONS Blanching is an important unit operation before processing fruits and vegetables for freezing, pureeing or dehydration. The findings of this study 4 Corresponding author. TEL: 91-172-2548315; FAX: 91-172-2779173; EMAIL: [email protected] Journal of Food Process Engineering 32 (2009) 587–605. All Rights Reserved. © Copyright the Authors Journal Compilation © 2008 Wiley Periodicals, Inc. DOI: 10.1111/j.1745-4530.2007.00234.x 587 would be useful in determining the process parameters for blanching carrots with maximal retention of nutrients. The enzyme residual activity curve indicates the destructive effect of heat on the affected enzymes. A successful modeling will enable the processors to modulate their process according to different time–temperature combinations.