EFFECT OF OSMOTIC DEHYDRATION ON VISCOELASTIC PROPERTIES OF APPLE AND BANANA
作者:
M. K. Krokida,
V. T. Karathanos,
Z. B. Maioulis,
期刊:
Drying Technology
(Taylor Available online 2000)
卷期:
Volume 18,
issue 4-5
页码: 951-966
ISSN:0737-3937
年代: 2000
DOI:10.1080/07373930008917746
出版商: Taylor & Francis Group
关键词: Compression;Stress Relaxation;Apple;Banana
数据来源: Taylor
摘要:
The rheological behavior of osmotically dehydrated apple and banana was examined under uniaxial compression and relaxation tests of cylindrical specimens. Compression and relaxation tests were performed, following air drying of osmotically pre-treated samples, at various moisture contents ranging from 0.1 to 1.5 kg/kg dry basis. The maximum stress and the corresponding strain were correlated to the moisture content using simple mathematical equations. It was shown that both parameters increase as water was removed and their values are significantly higher than the corresponding values for untreated air dried samples. The effect of moisture content on compressive behavior of osmotically dried materials was introduced through its effect on the four model parameters: the maximum stress (σmax) the maximum strain (ϵmax), the elastic parameter (E) and the viscoelastic exponent (p). The stress relaxation data of osmotically treated samples were modeled using a two-term Maxwell model. It was shown that osmotic pre-treatment increased the remaining force and it decreased the relaxation time of dehydrated samples. The osmotic dehydration and therefore the sugar gain tend to increase the viscous nature of fruits and decrease their elasticity for both materials, causing plasticity of the structure.
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