Open Access

Alica Lammerskitten, Viacheslav Mykhailyk, Artur Wiktor, Stefan Töpfl, Malgorzata Nowacka, Michal Bialik, Jakub Czyżewski, Dorota Witrowa-Rajchert, Oleksii Parniakov

• The aim of this study was to analyze the impact of pulsed electric field (PEF) pre-treatment of apple tissue on kinetics of freeze-drying preceded by vacuum freezing and physical properties of such processed material. PEF intensified freeze-drying kinetics and thus reduced processing time by 57% in comparison to untreated apples slices. Furthermore, the effective water diffusion coefficient increased by 44% as a result of PEF application. Water activity changes during storage of freeze-dried apple tissue were more evident in the case of untreated material albeit initial water activity was higher in the case of electroporated samples. As proved by thermal properties measurements these differences were linked to higher crystallinity of the PEF treated samples (35.5%) in comparison to the untreated material (11.0%). The freeze-dried fruits subjected to PEF pretreatment absorbed more water than the untreated samples while no changes were observed for hygroscopicity and loss of the soluble solids during rehydration.