Pulsed electric field treatment of carrots before drying and rehydration

BACKGROUND: In this study the effects of pulsed electric field (PEF) pretreatment were evaluated during drying and rehydration of carrots. Carrots pretreated with an electric field intensity of 1 kV cm(-1) (capacitance 0.5 mu F, 20 pulses) or 1.5 kV cm(-1) (capacitance 1 mu F, 20 pulses) as well as blanched (100 degrees C, 3 min) carrots were used for the study. Following pretreatment, samples were oven dried at WC and then rehydrated in distilled water (1 :30w/v) at room temperature (24 +/- 1 degrees C). RESULTS: PEF pretreatment increased the drying rate of carrots. However, the rehydration rate of PEF-pretreated carrots was lower than that of blanched carrots. There were no colour differences between PEF-pretreated and blanched carrots before drying and after rehydration. In terms of texture, PEF-pretreated carrots were firmer than blanched carrots. PEF pretreatment reduced the activity of peroxidase by 30-50%, while blanching completely inactivated the enzyme (>95%). CONCLUSIONS: Overall, the results suggest that PEF could be an effective pretreatment during drying and rehydration of carrots. (C) 2009 Society of Chemical Industry