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Improving Grape Quality Using Microwave Vacuum Drying Associated with Temperature Control

Authors

  • C. D. Clary,

    1. Author Clary is with Horticulture and Landscape Architecture, Washington State Univ., Pullman, WA 99164–6414. Author Mejia-Meza is with Food Science and Human Nutrition, Washington State Univ., Pullman, WA 99164-6376. Author Wang is with Biological Systems Engineering, Washington State Univ., Pullman, WA 99164-6120. Author Petrucci is with Emeritus, Viticulture and Enology Research Center, California State Univ., Fresno, CA 93740-0089. Direct inquiries to author Clary (E-mail: cclary@wsu.edu).
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  • E. Mejia-Meza,

    1. Author Clary is with Horticulture and Landscape Architecture, Washington State Univ., Pullman, WA 99164–6414. Author Mejia-Meza is with Food Science and Human Nutrition, Washington State Univ., Pullman, WA 99164-6376. Author Wang is with Biological Systems Engineering, Washington State Univ., Pullman, WA 99164-6120. Author Petrucci is with Emeritus, Viticulture and Enology Research Center, California State Univ., Fresno, CA 93740-0089. Direct inquiries to author Clary (E-mail: cclary@wsu.edu).
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  • S. Wang,

    1. Author Clary is with Horticulture and Landscape Architecture, Washington State Univ., Pullman, WA 99164–6414. Author Mejia-Meza is with Food Science and Human Nutrition, Washington State Univ., Pullman, WA 99164-6376. Author Wang is with Biological Systems Engineering, Washington State Univ., Pullman, WA 99164-6120. Author Petrucci is with Emeritus, Viticulture and Enology Research Center, California State Univ., Fresno, CA 93740-0089. Direct inquiries to author Clary (E-mail: cclary@wsu.edu).
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  • V. E. Petrucci

    1. Author Clary is with Horticulture and Landscape Architecture, Washington State Univ., Pullman, WA 99164–6414. Author Mejia-Meza is with Food Science and Human Nutrition, Washington State Univ., Pullman, WA 99164-6376. Author Wang is with Biological Systems Engineering, Washington State Univ., Pullman, WA 99164-6120. Author Petrucci is with Emeritus, Viticulture and Enology Research Center, California State Univ., Fresno, CA 93740-0089. Direct inquiries to author Clary (E-mail: cclary@wsu.edu).
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Abstract

ABSTRACT:  Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r2= 0.942 for prediction of final moisture content and r2= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins.

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