Process Technology for Raisins

The process of osmotic dehydration followed by tray drying was studied on grapes for raisin preparation. Grapes were dried out by osmosis using sugar syrup at grapes to sugar syrup ratio of 1:4, which were than dried in a commercial tray dryer maintained at 60°C temperature to obtained raisin. The grapes were dipped in sugar syrup of 40°Brix, 50°Brix, 60°Brix and 70°Brix concentration in beakers having fruit to syrup ratio 1:4 at 60°C temperature and time of immersion was 30 minutes and one hour for osmotic dehydration. From this it was concluded that, acidity and ascorbic acid decreases with increase in syrup concentration, temperature of solution and time of concentration and total, reducing and non-reducing sugar increases with increase in syrup concentration, temperature of solution and time of concentration.

• Highest moisture loss was occurred on 4^th day, after 180 min, 12.80% (60^°Bx) and minimum moisture loss was recorded on 1^st day after 30 min (1^st observation) i.e.; 0.61% (50^° Bri) of Osmotic dehydrated grapes

• The raisins are having nice texture, appearance as well as good flavor.