Shelf life of fresh-cut fruits and salad leaves treated with Pulsed Electric Field (PEF)

Sammanfattning: Application of Pulsed Electric Field (PEF) treatment on five fresh commodities was analysed for the changes in the metabolic and physiological effects on their shelf life. Treatment parameters were optimised in order to achieve uniform electroporation on the samples, which was analysed by Propidium Iodide staining for the leaf samples. The viability of electroporation of greenhouse (GH) rocket, commercial rocket and spinach leaves was evaluated by FDA vital staining. Bulk evaluation of electroporation of mango and kiwi fruits along with the leaf samples was done by impedance measurement, monitoring tissue leakage caused by permeabilization. The evaluation of metabolic responses of the samples was carried out by isothermal calorimeter where increase in metabolic heat production (thermal power) of all the treated samples was recorded. The increase in thermal power is the result of an increase in the internal metabolic activity of tissues, provoked by PEF induced stress. A decrease in metabolic heat rate was observed with increasing intensity of PEF parameters, due to the possible consequences of loss in cell viability. After the optimisation of PEF parameters, the samples were treated, packed and stored at 4 °C. Measurements for the colour change was recorded using spectrophotometer and composition of O2 and CO2 was monitored using a gas analyser. PEF treatment showed effective results in preserving the colour of greenhouse rocket leaves. No effects of treatment were observed in commercial rocket and spinach leaves and the treatment resulted in deterioration of mango and kiwi fruits. Composition of oxygen and carbon dioxide did not show differences among samples.