Microwave and convective dehydration of ethanol treated and frozen apple - Physical properties and drying kinetics

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Tomas Funebo, Lília Ahrné, Frédéric Prothon, Siw Kidman, Maud Langton, Christina Skjöldebrand

The objective of this study was to examine how the drying kinetics and physical properties of apples are affected by pre-treatment with 95% ethanol or freezing at -18 °C before microwave-assisted air dehydration at 50, 60 and 70 °C. Microwave heating was used to obtain these temperatures in the centre of the apple cubes. After dehydration the shrinkage and rehydration capacity were measured. The texture of dehydrated and rehydrated samples was analysed with a puncture test in a texture analyser. Samples were also analysed with confocal laser scanning microscopy to determine the correlation between physical and microstructural properties. Diffusivity in the different dehydration processes was calculated. Ethanol-treated apples showed both high rehydration and high effective rehydration capacity compared with the other samples. Freezing before dehydration increased the diffusivity and reduced the firmness of rehydrated apples compared with no pre-treatment.

OriginalsprogEngelsk
TidsskriftInternational Journal of Food Science and Technology
Vol/bind37
Udgave nummer6
Sider (fra-til)603-614
Antal sider12
ISSN0950-5423
DOI
StatusUdgivet - 2002
Eksternt udgivetJa

ID: 202134928