Avoiding non-enzymatic browning by high-intensity pulsed electric fields in strawberry, tomato and watermelon juices

Changes in color and 5-hydroxymethyl furfural (HMF) of strawberry, tomato and watermelon juices were evaluated after high-intensity pulsed electric field (HIPEF) processing using a response surface methodology and compared to the thermally-treated and unprocessed juices. HIPEF-processed juices retained the color better, and had lower HMF concentration than those treated by heat. The influence of pulse frequency, pulse width and polarity on color difference (ΔE) and HMF content of the juices were well fitted through second-order models. In the three products, monopolar mode and frequencies below 100 Hz promoted few changes on ΔE, keeping constant the initial amount of HMF. In addition, it was feasible to minimize non-enzymatic browning by the application of pulse widths beyond 4.5 μs for strawberry juice and up to 2.5 μs for tomato and watermelon juices.