Dehydrofreezing of apples
Freezing foodstuffs preserves the taste and nutrients with characteristics similar to those of fresh produce. However, it often results in a soft texture and lack of retention of finished products after baking - especially in the case of fruits and vegetables - due to cell walls rupture caused by ice crystals during freezing and thawing operations. This results in a poor sensory appreciation and a poor ability to use these products in many food preparations (pastries, cooked dishes, etc.).
L. Ben Haj Said et al. recently published a study* on a freezing process for partially dehydrated apples (dehydrofreezing). This preservation process comprises a drying process involving air convection followed by instantaneous controlled pressure drop, resulting in decontamination and texturization, and then freezing of the finished product. The results obtained demonstrate that following freezing/thawing, a significant preservation of firmness was obtained with samples with a low water content, while firmness decreased significantly with fresh apple samples and samples with a water content higher than 200% (dry basis). Thus, partial removal of water constitutes a promising solution to prevent the negative impacts of freezing on apple fruit firmness.
* Ben Haj Said et al. “La congélation de pommes partiellement séchées”. Revue Générale du Froid et du conditionnement d’air (November/December 2016).