Effect of Calcium Ion and Microwave Power on Structural and Quality Changes in Drying of Apple Slices |
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Authors: | Gang-Cheng Wu Arun S. Mujumdar Rui Wang |
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Affiliation: | 1. State Key Laboratory of Food Science and Technology , Jiangnan University , Wuxi , Jiangsu , China;2. Department of Mechanical Engineering &3. Engineering Science Program , National University of Singapore , Singapore |
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Abstract: | Effects of impregnated calcium ion and microwave (MW) power on texture, rehydration, shrinkage, color, and other selected indexes of freeze-dried apple slices were investigated. Apple slices were dried by freeze drying and microwave freeze drying (MFD) separately. Vacuum impregnated (VI) and non-vacuum-impregnated apple slices were dried at various microwave power levels. Non-vacuum-impregnated apple slices were found to preserve their mechanical structure better than the VI-treated ones. Microwave application resulted in decreased protopectin fraction as well as total pectin content. As microwave power varied from 1.2 to 2.0 W/g, the total pectin content decreased from 0.810 to 0.521 (expressed as g galacturonic acid/100 g fresh sample). The effect of microwave power in decreasing the drying time was significant. The color of MFD apple slices varied to a minor extent with MW power level over the range of parameters studied. |
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Keywords: | Calcium ion Color Drying time Microwave freeze drying Pretreatment |
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