Effects of Pulsed Electric Fields on the Physicochemical and Sensory Properties of Thompson Seedless Grapes

Abstract

While the treatment of red grapes with pulsed electric fields (PEFs) has been widely investigated, white grapes have been little studied to date. This work, therefore, investigates the PEF treatment of white grapes (Thompson Seedless) by applying different field strengths (2 to 6 kV/cm), resulting in different specific energy inputs (2.5 to 22.5 kJ/kg). Numerous parameters of the whole grapes and the extracted juice were analyzed, including the total phenolic index (TPI), reducing sugars, juice yields, and changes in color and texture. Changes in the aroma profile were investigated using instrument-based and sensory analysis. The most striking effect seen in the PEF-treated samples was the visual change in the grape skin, specifically browning. Depending on the field strength, the treated grapes showed a 26% to 50% reduction in crunchiness. No significant changes were measured in the juice yields compared with the control, although at E = 4.5 kV/cm there was an increase in reducing sugars of up to 11% (220.97 g/L) and a 30% higher TPI (398.90 mg/L). Aroma differences were not detected between the control and the treated grapes, meaning that consumers should not expect negative sensory effects in the juice of treated white grapes.