In the context of POD inactivation, no significant difference between
vertical and parallel positions was observed (Fig. 2b). The application of
lowest specific energy input of 1 kJ/kg resulted in 8% to 10% reduction of
POD activity. Thus, no activation or release of POD was observed during
PEF treatment of carrot pieces. When the specific energy input was increased
up to 166 kJ/kg, the maximal inactivation of POD was approximately
30%. Whilst considering the significant batch-to-batch variation
of POD and AAO activity in carrots due to storage and growing conditions,
both vertical and parallel positioning of the carrot pieces gave
similar effects on POD inactivation. It is evident that treating carrot
pieces (solid matrix) rather than carrot mash (semi-solid matrix) with
PEF is able to decrease the residual activity of AAO and POD.