Use of an Electric Field to extend the Shelf Life of Apples

An effort was made to assess the effect of electric field treatment on the shelf life of Fuji, Rome Beauty, Golden Delicious and Starking Delicious apple varieties. The direct current electric field was generated by a 50 Hz alternating current supply. Ionisation by negative corona discharge was facilitated using needles as the cathode and an aluminium plate (of diameter 180 mm) as the grounded anode. The electrodes were 8 cm apart. Seven days continuous treatment with the electric field (generated by 10 kV) at 23°C air temperature and 75% relative humidity resulted in suppression of CO2 evolution in the treated apples compared to control samples. Short treatment periods (1 and 2 h) at 10 and 20 kV reduced respiration in the apples. The total colour difference and soluble sugar concentration changes were lower in treated samples compared to control samples. Mechanical properties evaluated from the stress–strain relationship showed that the treated apple tissues were stiffer than the untreated ones.