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vol. 17, nr. 1 (2011)
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The influence of osmotic dehydration on colour and mechanical properties of freeze-dried strawberries
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Agnieszka Ciurzyńska, Andrzej Lenart, , Monika Siemiątkowska
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Department of Food Engineering and Process Management, Faculty of Food Sciences, Warsaw University of Life Sciences, SGGW, ul. Nowoursynowska159c, 02-787 Warszawa, Polan |
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vol. 17 (2011), nr. 1,
pp. 17-32
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abstract:
In this work the effect of osmotic dehydration and type of osmotic solution on the colour and mechanical properties of osmotically dehydrated freeze-dried strawberries was shown. Strawberries were osmotically dehydrated in glucose and sucrose solutions with water activity of 0.9. Fruit were freeze-dried at heating shelves temperature of 50°C. It was shown that osmotic pre-treatment in sucrose and glucose solution does not cause any significant changes of colour coefficients and index for a majority of surfaces and for fragmented freeze-dried strawberries. The use of osmotic dehydration caused changes in the shape of compression curves for strawberries freeze-dried at tem-perature of 50°C. Many deflections were observed in the compression curves. Osmotic dehydration caused a decrease in the compression force necessary for deformation of dried fruit and work done to obtain this deformation in comparison to strawberries dried without osmotic pre-treatment.
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keywords:
freeze-drying, osmotic dehydration, mechanical properties, colour, strawberries
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original in:
Polish
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