Influence of Agitation Speed and Water Temperature on Dried Squash (Cucurbita pepo) Properties during its Rehydration Process

Document Type : Research Paper


1 Scientific member, Department of Food Science and Technology, Shoushtar Branch, Islamic Azad University, Shoushtar, Iran

2 Assistant Professor, Department of Food Science and Technology,Faculty of Agriculture, Isfahan University of Technology, Isfahan, Iran


Throughout the present research, squash (Cucurbita pepo) slices (0.4 cm thickness and 4 cm diameter) were blanched in a steam chamber for 4 min. Following cooling to room temperature, the squash slices were dehydrated by use of a hotair dryer, under air temperature of 60°C up to moisture content of 0.1065 kg H2O per kg d.m. Squash slices of specified weights were rehydrated by immersion in distilled water at different temperatures (25, 50, and 75°C). They were agitated at different speeds (0,100, and 200 rpm). For any of the experiments, the dry matter to water ratio was kept at 1:25. The squash samples were removed from water at specified time intervals of up to 300 min. Then their weight, dry matter content and water absorption content (in percent) were determined. The squash slice color was examined over a 180 min period. The results showed thatrehydration time, water temperatureand agitation speed had significant effects (p˂0.01) on dry matter content, water absorption (percent) and color indices (L*, a*, b*, and ΔE) in the dried squash slices. Water absorption percent and total color difference (ΔE) of squash slices increased, whereas dry matter content and color indices (a*, b*, and L*) decreased with rehydration time. Maximum water absorption and ΔE, minimum dry matter content as well as color indices (a*, b*, and L*), were observed in squash slices rehydrated into 75°C water and agitated at 200 rpm.


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