Pulsed Electric Field Assisted Combined Freezing of Carrot Tissue: Preliminary Vacuum Freezing Followed by Supplementary Conventional Freezing

Abstract Pulsed electric field (PEF) assisted combined mode of freezing with the preliminary vacuum freezing (VF) down to − 6 °C followed by conventional freezing (CF) in the freezer at − 20 °C has been studied. The fresh carrot tissue was electroporated to different levels of cell disintegration index Z = 0–0.9 ( E = 0–400 V/cm, t PEF = 0–1 s). It was demonstrated that PEF significantly accelerated the kinetics of CF and impacted the texture, moisture losses, and microstructure of thawed carrots. For example, at a high disintegration index ( Z = 0.9), the total freezing time was shortened by ≈1.21 times for the CF procedure and by ≈1.57 times for the combined VF + CF procedure. The softening of textures of carrots was observed; however, for both CF and VF + CF procedures, they were comparable. Application of both CF and VF + CF procedures resulted in the increase of the size of pores inside the carrot tissues. However, the water losses for the combined VF + CF protocol were significantly smaller than those for the CF protocol.