Heat Transfer Model: Preservation of Antioxidant via Progressive Freeze Concentration

Antioxidants have been a vital component of several pharmaceutical and food industries due to their numerous benefits such as reducing the risk of diseases. Cucumbers are known to contain considerable amounts of antioxidants and a significant amount of water, which increase the probability of microorganism growth. Therefore, it is essential to find out the best approach to reduce the water content and preserve the antioxidants in cucumbers. Progressive Freeze Concentration (PFC) is a concentration enhancement process, whereby impurities are removed in a single ice block. This research is intended to determine the effect of coolant temperatures (-2°C to -10°C) on the preservation of antioxidants in cucumbers using the PFC process. The antioxidant content in concentrated cucumber juice was assessed by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay. It was determined that the lower the coolant temperature used in the PFC process, the lower the amount of antioxidant content. The optimum coolant temperature was discovered at a temperature of -2°C, where the antioxidant activity percentage (AA%) was at 93.17 %. A heat transfer model to predict the mass of antioxidants procured was also constructed from the study. Data comparison between experimental values and the model resulted in the Average Absolute Relative Deviation (AARD) value of 0.74% which is considered highly consistent. Therefore, the model constructed to predict the AA% of the concentrated cucumber juice with different coolant temperatures was successful.