Radiation temperature of tomatoes and mechanical properties of their skin
 
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1
Department of Physics, University of Life Sciences, Akademicka 13, 20-950 Lublin, Poland
2
Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
 
Int. Agrophys. 2011, 25(2): 131–139
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ABSTRACT
This paper compares radiation temperature distributions on the skin surface and in the pedicle part of tomato fruit during storage at two ambient temperatures with the results of mechanical tests. Variations in Young’s modulus, Poisson’s ratio and critical surface tension were studied. An increase in Young’s modulus and critical surface tension was reported, while Poisson’s ratio stabilized at the level of 0.45-0.46. Thermographic studies were performed using passive and active methods, and fruit skin was subjected to mechanical tests where the prepared samples were uniaxially stretched to determine Young’s modulus and Poisson’s ratio of the skin. The results of passive thermography tests reveal that the differences between skin temperature and pedicel temperature decreased over time (fruit ripening), but a higher drop was noted in respect of the fruit stored at the temperature of 21 than 13°C. Regardless of ambient temperature, the highest water loss rate was observed in the first period of fruit storage. The heat response of tomato skin and pedicels showed significant differences in the thermal properties of the studied plant parts. The respective characteristics of the skin thermal response changed significantly over time, in particular at higher storage temperature (21°C). A corresponding, statistically significant decrease in Young’s modulus noted under the above storage conditions suggests a possible correlation between the thermal and mechanical characteristics of tomato skin.
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