Mass exchange during osmotic drying of ginger treated banana slices

Abstract

The ripe banana slices of 20 mm thickness were osmo dried by immersing them in sugar syrup solutions of three different concentrations 40, 50 and 60 oBrix mixed with ginger juice (12:1) at three different osmotic temperatures 35, 45 and 55 oC having the solution to sample ratio 5:1 for five hours. The effect of process parameters during osmotic dehydration such as duration of osmosis, concentrations and temperatures of sugar solution on water loss, sugar gain and weight reduction were evaluated. It was found that the water loss, sugar gain and weight reduction increased with an increase of syrup concentration and temperature. The initial moisture content of banana samples was 75.5-78.5% (wb), which was reduced to 61.1-68.02% (wb). After 5 hours of osmotic dehydration, the minimum and maximum water loss, sugar gain and weight reduction were found in the range of 9.41 to 28.63, 3.86 to 6.79 and 5.55 to 24.34 per cent, corresponding to low levels (40 oBrix, 35 oC) and high levels (60 oBrix, 55 oC) of syrup concentration and temperature, respectively. The regression equations of second order polynomial were found to predict the kinetics of osmotic dehydration process of banana slices.