Ultraviolet and Pulsed Electric Field Treatments Have Additive Effect on Inactivation of E. coli in Apple Juice

Abstract

Apple juice inoculated with Escherichia coli ATCC 23472 was processed continuously using either ultraviolet (UV), high-voltage pulsed electric field (PEF), or a combination of the PEF and UV treatment systems. Apple juice was pumped through either of the systems at 3 flow rates (8, 14, and 20 mL/min). E. coli was reduced by 3.46 log CFU/mL when exposed in a 50 cm length of UV treatment chamber at 8 mL/min (2.94 s treatment time with a product temperature increase of 13 degrees C). E. coli inactivation of 4.87 log CFU/mL was achieved with a peak electric field strength of 60 kV/cm and 11.3 pulses (average pulse width of 3.5 mus, product temperature increased to 52 degrees C). E. coli reductions resulting from a combination treatment of UV and PEF applied sequentially were evaluated. A maximum E. coli reduction of 5.35 log CFU/mL was achieved using PEF (electrical field strength of 60 kV/cm, specific energy of 162 J/mL, and 11.3 pulses) and UV treatments (length of 50 cm, treatment time of 2.94 s, and flow rate of 8 mL/min). An additive effect was observed for the combination treatments (PEF and UV), regardless of the order of treatment (P > 0.05). E. coli reductions of 5.35 and 5.30 log CFU/mL with PEF treatment (electrical field strength of 60 kV/cm, specific energy of 162 J/mL, and 11.3 pulses) followed by UV (length of 30 cm, treatment time of 1.8 s, and flow rate of 8 mL/min) and UV treatment followed by PEF (same treatment conditions), respectively. No synergistic effect was observed.

Effectiveness of combined Pulsed Electric Field (PEF) and Manothermosonication (MTS) for the control of Listeria innocua in a smoothie type beverage

“…However, few studies have compared the efficacy of hurdle combinations of novel preservation technologies against traditional methods (Caminiti et al, 2010;Gachovska, Kumar, Thippareddi, Subbiah, & Williams, 2008;Noci, Walkling-Ribeiro, Cronin, Morgan, & Lyng, 2009). The present study compared the effects of two technologies, PEF and MTS, when applied under selected conditions, either individually or in combination (PEF þ MTS and its reverse) on microbial inactivation.…”

“…However, the sequence order had no significant effect on microbial inactivation (log reductions of 2.3 and 2.25 for PEF þ TS and TS þ PEF, respectively). Gachovska et al (2008) observed an additive effect on E. coli in apple juice when treated by a combination of PEF (60 kV/cm, 11.3 pulses) and UV processing (exposure for 1.8 s in a 30 cm length chamber). Also, Noci et al (2008) reported an additive effect on the inactivation of native microbiota in freshly squeezed apple juice when a batch UV pretreatment was followed by PEF at 40 kV/cm.…”

The Effect of Ultraviolet Light on Microbial Inactivation and Quality Attributes of Apple Juice

“…Geveke (2005b) found that L. innocua exhibited a higher degree of resistance to UV light than E. coli. Different flow rates (8, 14 and 20 ml/min) and lengths of UV treatment chamber (30, 40 and 50 cm) were tested by Gachovska et al (2008), who achieved a reduction of 3.46 log cfu/ml for E. coli in apple juice when exposed in a 50-cm length of UV treatment chamber at 8 ml/min. Ngadi et al (2003) Results are expressed as log cfu/ ml TSA tryptone soya agar medium, LSA listeria selective agar medium, EMB eosin-methylene blue medium, ND counts were below limit of detection investigated the effect of pH (3.5 and 9.1), depth of food medium (1, 3.5, 5 and 10 mm) and UV light dosage (0 to 0.39 J/cm 2 ) on E. coli inactivation in apple juice and liquid egg white.…”

The Ultraviolet radiation (UV-C) for the microbiological stabilization of red wine

“…The application of ultraviolet C light (UV-C, 200-280 nm) was successfully used to inactivate microorganisms in water and various types of liquid foods and beverages, such as fruit juices, soft drinks, beer and wine [4,12,16,17,[24][25][26][27][28][29][30][31].…”