A continuous-flow, bench-scale system ELCRACK-HVP 5
(Quakenbr€uck, Germany), which delivers square-wave
pulses in bipolar mode, was used to treat the beverage
samples. The PEF system is composed of two cells that
have two stainless steel electrodes separated by a gap of
5 mm. Frequencies of 25 and 50 Hz and pulse widths of
11, 13 and 15 ls were fixed in the equipment which generated
a maximum electric field strength (E) of
36 kV cm
1. PEF treatments with pulse width of 11 ls at
frequencies of 25 and 50 Hz generated an E value of
27 kV cm
1, whereas treatments with pulse width of 13
and 15 ls at 25 and 50 Hz resulted in E values above
30 kV cm
1 (32–36 kV cm
1). The inoculated beverages
were placed in the hopper of the PEF equipment and
passed through the electrodes at a flow rate of 70 l h
1.
About 10 ml of sample was collected at the outlet of the
equipment, placed in capped sterile dilution glass bottles
(Pyrex, Mexico), and stored at 4°C during analysis. Using
a thermometer, beverage inlet and outlet temperatures
were measured showing a constant value of 25°C. Duplicate
runs were performed.