Physicochemical characterization of dried pumpkin using osmosis – microwave method

Pumpkin is important cucurbit with very high nutritional value. In this study, the effect of osmosis - microwave combination drying of pumpkin slices with a thickness of 5 and 7 mm, sucrose osmotic solution concentrations of 45, 55 and 65% and at times of 15, 30, 45, 60, 90, 120, 150 and 180 min and power of 100, 300 and 500 watts were used as complementary drying. Physical parameters such as texture, shrinkage, color and chemical parameters such as protein, ash, moisture, β-carotene, fat, iron, calcium, sodium, potassium, phosphorus, fiber and vitamin A were studied. Osmotic treatments have reduced the resistance and firmness. The lowest amount of shrinkage was related to dried pumpkin at 100 watt power (71.09%) and significantly difference was observed between samples. The amount of β-carotene for pumpkin with thickness of 0.5 and 0.7 cm dried at a concentration of 55% was between 2.6-3.5%. According to the statistical results there was no significant difference of fiber in the dried samples at power of 100 and 300 watts, but dried samples with the power of 500 watts were significantly different. Amount of pumpkin sodium with thickness of 0.5 and 0.7 cm dried at the 100 watt in microwave oven was between 0.01-0.02%. Calcium content of pumpkin with 0.5 cm thick dried under the powers of 100, 300 and 500 watts were between 1.05-1.08%. The dried pumpkin slices with microwave with 100 watt power had lower darkness related to 300 and 500 watt. A total time of 150 minutes for the osmosis process and power of 500 w was selected for the microwave dryer.