Experimental and simulation studies on blanching and its impact on drying rate of carrot
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Date
2022-10
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G. B. Pant University of Agriculture and Technology, Pantnagar
Abstract
Fruits and vegetables are high in minerals, vitamins, antioxidants and fibers but low in fat and calories, which is beneficial to human health. Because fruits and vegetables are seasonal and do not hold for long, techniques such as drying, freezing and canning are used to extend their shelf life. Blanching is a heat treatment process performed before these processes to improve safety and quality. Carrots are one of the healthiest vegetables because they are high in carbohydrates, minerals like calcium, phosphorus, iron, sodium, zinc, magnesium and vitamin C. Blanching of carrot and its effect on drying rate of carrot has been investigated in this study by experimental and numerical methods. Besides this various thermo-physical properties required in simulation have been determined through experiments and using correlations. The simulation of the blanching process has been carried out using ANSYS Fluent software to determine the temperature distribution in carrot during blanching at optimum combination of temperature and time (95°C for 5 minutes). Carrots have been actually blanched at 4 different temperatures-time combinations; 80°C for 7 minutes, 85°C for 7 minutes, 90°C for 7 minutes and 95°C for 5 minutes. Under these blanching conditions, the effect of separating carrot cortex and core from the slice on their drying rate has also been studied. For various configurations, the Page model has been used to perform regression analysis and estimate the value of the drying constant (k). The hot air has been used for drying carrot samples, where a constant temperature of 70°C±0.1°C and a constant velocity of 0.5 m/s have been maintained. According to the present study, the drying rate of core has been found to be the highest for each blanching combinations followed by cortex and slice. Blanching also improves the drying constant and it can be seen that at optimum blanching conditions, the drying constant for slice, cortex and core is 22.84%, 24.90%, and 36.94%, respectively higher than for similar parts of the unblanched sample.