Swell-drying Chapter in Scopus uri icon


  • © Springer Science+Business Media New York 2014.Shrinkage of biological materials is generally considered to be one of the key issues that results from drying. It is often highly prejudicial for both the quality of the material and the performance of the process. First, shrinkage results in a smaller exchange surface and hinders the diffusion of moisture through the porous structure, for both dehydration and rehydration processes. The dried products are not suitable for grinding and the resulting powders, which generally consist of compact granules and a low specific surface area, are characterized by a lack of uniformity in terms of particle diameter. Secondly, the compact structure of dried food material usually triggers poor organoleptic quality. Freeze-drying is the only way to preserve the initial product volume because most of the free water is frozen. However, it is a costly, time-consuming process which only provides a slight improvement in the quality of the structured products so it is of limited value to industry. Thus, it is becoming very important to couple conventional drying processes to appropriate texturing processes. Given this objective, instant controlled pressure drop (DIC) technology could be included in the drying process to provide an appropriate expansion of the structure. DIC generally intensifies the whole drying operation, markedly improving the product quality and the performance of the drying process. Finally, microbiological contamination and the presence of insects and larvae cause serious problems for a large category of dried, and even freeze-dried, fruits and vegetables. DIC technology can be used as a ultrahigh temperature (UHT) treatment to decontaminate these foodstuffs. Such dried, expanded, and completely decontaminated products can be used as highly nutritional ¿snacks.¿ They can also be ground easily to produce expanded granule powders with excellent sensory, nutritional, functional, and textural properties.

Publication date

  • January 1, 2014