Effect of pulsed electric field coupled with vacuum infusion on quality parameters of frozen/thawed strawberries

In this study, pulsed electric field (PEF) was coupled with vacuum infusion (VI) to impregnate strawberries with cryoprotectants. Electroporation of fruits was reached with 5 bi-polar, rectangular pulses of 100 μs width with a nominal electric field strength of 850 V/cm. After PEF treatment, the strawberries were vacuum infused with a cryoprotective solution (12 g/100 g trehalose and 0.2 g/100 g acclimated winter wheat extract containing antifreeze proteins) for 14 min. The strawberries were frozen in liquid nitrogen and thawed in air at 20 °C. Cell survival, texture and color were evaluated before and after freezing and thawing cycle. The fruit pre-treated with PEF prior to VI exhibited higher cell viability in epidermal layer and 30% more red color retention compared to just VI samples. However, no further improvement on strawberry quality in terms of drip loss and texture was observed upon the application of PEF.