Influence of osmotic dehydration process parameters on the quality of candied pumpkins |
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Authors: | Ana S Abraão André M Lemos Alice Vilela José M Sousa Fernando M Nunes |
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Affiliation: | 1. CQ-VR, Chemistry Research Centre, Chemistry Department, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5000-801 Vila Real, Portugal;2. Institute for Biotechnology and Bioengineering, Centre of Genomic and Biotechnology (IBB/CGB-UTAD), University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal;3. LEPAE-Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, 4200-465 Porto, Portugal |
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Abstract: | The influence of osmotic dehydration process parameters on the efficiency of water loss and sucrose gain of pumpkins and the influence on the quality of the final product are essential for production of superior quality candied pumpkins. Mass transfer kinetics during osmotic dehydration of pumpkins were modelled by assuming Fickian diffusion of sucrose and water in unsteady state conditions, which described very well the experimental results for water loss and sugar gain. Water and sucrose effective diffusion coefficients increase significantly with temperature. Temperature and sucrose concentration had a significant influence on both water and sugar diffusion, increasing as the solution temperature increased. Significant increase in the effective water diffusivity and decrease in the sucrose effective diffusivity was observed when the sucrose solution concentration increased from 40 °Brix to 50 and 60 °Brix. From 50 to 60 °Brix, no difference in the effective diffusivities was observed. Candied pumpkins with higher sucrose content have a higher breaking stress, less breaking strain and lower work to fracture. Moreover, the product becomes harder and less elastic with increasing sucrose content, resulting in more brittle products, which seems to be related with reinforcement of the pumpkin cell wall matrix. |
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Keywords: | Candying Osmotic dehydration Diffusion Fracture Viscoelastic Pumpkin Fick's law Numerical solution |
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