Process kinetics on physico-chemical and peroxidase activity for different blanching methods of sweet corn

Abstract

Blanching was performed to inactivate the enzyme using microwave, steam and hot water blanching methods and effect on the enzymatic activity, chemical properties and physical properties of the sweet corn were studied. The effectiveness of each blanching process was evaluated by measuring the loss of peroxidase activity, which was lost after 60, 90 and 120 s with k-values 0.016, 0.024 and 0.028 s^-1 following first order kinetics for microwave, steam and hot water blanching respectively. The total sugar, ascorbic acid, moisture content, kernel mass and geometric diameter changed from 8.40 to 6.30, 7.20 and 7.50 g/100 g; 7.15 to 5.70, 6.10 and 6.60 mg/100 g; 76 to 79.20, 78.20 and 75.30%; 0.47 to 0.53, 0.50 and 0.42 g; 8.00 to 8.50, 8.30 and 7.20 mm at optimum level of blanching during microwave, steam and hot water blanching respectively, indicating higher retention of total sugar and ascorbic acid in microwave blanching. The change in colour, especially increase in brownness was observed during blanching processes. The average R² for zero-order model was 0.945, suggesting use of model for prediction of physico-chemical parameters during blanching process of sweet corn.

Keywords: Blanching; Peroxidase activity; Physico-chemical properties; Sweet corn.

Fig. 1

Variation in peroxidase (POD) activity of sweet corn during blanching

Fig. 2

Variation in physico-chemical parameter of sweet corn during blanching

Fig. 3

Variation in colour of sweet corn during blanching