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      • HARVEST
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      Drying characteristics of Saskatoon berries under microwave and combined microwave-convection heating

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      E_Thesis_L_Reddy_Mar_16_2006.pdf (2.514Mb)
      Date
      2006-03-02
      Author
      Reddy, Lakshminarayana
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      The study on dehydration of frozen saskatoon berries and the need for dried fruits has been strategically identified in the prairies. Our motivation was to find a suitable method for dehydration in order to extend saskatoon berry shelf life for preservation. Microwave, convection and microwave-convection combination drying processes were identified to finish-dry saskatoon berries after osmotic dehydration using sucrose and high fructose corn syrup (HFCS) sugar solutions. Osmotic dehydration removes moisture in small quantities and also introduces solutes into the fruit that acts as a preservative and also reduces the total drying time. Due to the very short harvesting season of saskatoon berries, an accelerated process like microwave combination drying can bring down the moisture to safe storage level, immediately after harvest. Untreated and osmotically dehydrated berries were subjected to convection (control), microwave and microwave-convection combination drying conditions at different product drying temperatures (60, 70 and 80C) until final moisture content was 25% dry basis. A laboratory-scale microwave combination dryer was developed, built with temperature and moisture loss data acquisition systems using LabView 6i software. Thin-layer cross flow dryer was used for convection-only drying and for comparison. Drying kinetics of the drying processes were studied and curve fitting with five empirical equations including Page equation, was carried to determine drying constant, R2 and standard error values. The microwave-combination drying method proved to be the best for drying saskatoon berries. Dehydrated product quality analysis by means of color changes, rehydration ratio measurements and observed structural changes with scanning electron microscope technique were the factors in drying method selection for saskatoon berries. This research was instrumental in the modification and development of a novel drying system for high-moisture agricultural materials. Microwave-convection combination drying at 70oC, yields good results with higher drying rates and better end-product quality.
      Degree
      Master of Science (M.Sc.)
      Department
      Agricultural and Bioresource Engineering
      Program
      Agricultural and Bioresource Engineering
      Supervisor
      Meda, Venkatesh
      Committee
      Nemati, Mehdi; Guo, Huiqing; Baik, Oon-Doo
      Copyright Date
      March 2006
      URI
      http://hdl.handle.net/10388/etd-03162006-160319
      Subject
      Dried Fruit
      Osmotic Dehydration
      Dielectric Property of berry
      Drying
      Post-harvest Processing
      Saskatoon Berry
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