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|Type:||Artigo de periódico|
|Title:||Determination of particle density and porosity in foods and porous materials with high moisture content|
|Abstract:||A simple gas pycnometer was developed to obtain the volume of porous food materials. The volume is obtained by measuring the change in pressure experienced by an amount of compressed gas filling a constant volume reference chamber when it expands into a second chamber containing a sample of the material to be tested. From such pressure change and the knowledge of the volumes of the two chambers the volume of the sample solid matrix is determined. The main difference between the proposed pycnometer and the typical helium pycnometer is the sequence of chambers; in the latter gas compression is made in the sample chamber, producing evaporation of water and volatiles when the gas is expanded into the reference chamber. For these reasons the helium pycnometer is only recommended for volume measurements of bone dry solids. The performance of the gas pycnometer was assessed by measuring the volume of different solids (non-porous metallic cylinder, glass spheres, porous metallic cylinder, sintered sand cylinder and apples) and by comparing the results with values from other methods. The gas pycnometer reproducibility of 0.019%, obtained with dried porous materials, is excellent when compared with a commercial helium pycnometer. The gas pycnometer proposed in this work can be easily built and offers reliable results of particle volume for any type of solids, specifically foods and other materials with high moisture content.|
|Editor:||Taylor & Francis Inc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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