A Comparison of the Effects of Pulsed Electric Field and Thermal Treatments on Grape Juice

The work was aimed at comparing the effect of pulsed electric field (PEF) and thermal technologies on physical, chemical, microbiological, and nutritional properties of freshly squeezed grape juice of different varieties when they are applied using continuous flow systems. It has been evidenced that grape variety is a factor to be taken into account when comparing the processing effects of PEF and heat treatments. Nevertheless, results of general and specific microbial populations were not affected by it and followed a very similar trend with each processing treatment. Soluble solids, pH, acidity, and the electrical conductivity of grape juice were not affected by PEF processing. On average, PEF treatment reduced the radical scavenging activity a 9% in front of the 13% of the heat treatment whereas both treatments halved the protein content. Data of vitamin C, total polyphenol, cinnamic acid, free catechin and non-flavonoid content were not enough to show differences between both treatments. However, all these nutritionally related properties share the same behaviour, PEF processing yielded milder values than heat processed samples. Information comparing PEF and thermal processes on food products help to clarify the advantages and disadvantages of each technology even though the disparity in development and use of each one.