Freeze-drying: Perceptions and challenges for drying foodstuffs and plant extracts

One of the most important features of foodstuffs and plant extract-based products is related to their fragile stability, especially when exposed to several ambient factors such as air, light radiation, heat and water vapour. The latter may contribute to the increase of free or bound water associated to the product. In this scenario, these variables may lead to different phenomena such as self-oxidation and hydrolysis of functional compounds and thus, a considerable inconsistency of products where these substances are part of occurs. On the other hand, these factors affect more drastically the product stability, especially when they possess a high intrinsic surface area and thus, are more likely to absorb a significant amount of water. Furthermore, in liquid products oxidation, hydrolysis and precipitation problems are more probable to happen