Skinless chicken breasts were inoculated with Listeria monocytogenes before being vacuum shrink wrapped and treated with various doses of UV-C iradiation to determine the microbial reduction.
Main conclusions
- The inoculaion method impacts the microbial reduction on the meat.
- With dip inoculation, no greater than 0.75 average log reduction was achieved up to 200 mJ/cm2, with increasing dose having no effect on reduction achieved.
- With spray inoculation, higher average reductions achieved, with 80 mJ/cm2 optimal dosage with 1.31average log reduction. No increase in microbial reduction observed with increasing UV-C dose up to 610 mJ/cm2.
Purpose
UV-C treatment of meat in pack can potentially increase the safety of food with minimal risk of post process contamination. The trial assessed the feasability of UV-C for in-pack decontamination. The lowest dose for maximum microbial reductions was assessed.
Methods
Skinless chicken breasts were purchased from a local UK wholesaler. The breasts were inoculated either by dip or spray method (seperate trials), with an initial load of around 3 log CFU/100 ml of L. monocytogenes. The breasts were vacuum shrink wrapped by exposing the packaging to 85°C for 2sin UV-C transmisable packaging (around 65% transmission).
The packaged breasts were then passed through a UV-C tunnel delivering a UV-C doses of 80, 120, 160 and 200 mJ/cm2 for dip inoculation and 80, 160, 320 and 640 mJ/cm2 for spray inoculation within the packs, with 5 relicates per dose.
The level of microorganims on the treated breasts were compared to the control samples to determine the log reduction achieved.
What was investigated/ examined/ measured
The average microbial reduction achieved for each UV-C dose.
Parameter 1 Population of L.monocytogeneson treated breasts (dip inoculation)
- 80 mJ/cm2–0.55±0.27 CFU/100 ml reduction
- 120 mJ/cm2–0.48 ±0.31 CFU/100 ml reduction
- 160 mJ/cm2–0.75 ±0.26 CFU/100 ml reduction
- 200 mJ/cm2–0.49 ±0.47 CFU/100 ml reduction
Parameter 2 Population of L.monocytogeneson treated breasts (sprayinoculation)
- 80 mJ/cm2–1.31 ±0.35 CFU/100 ml reduction
- 160 mJ/cm2–1.04 ±0.17 CFU/100 ml reduction
- 320 mJ/cm2–0.96 ±0.33 CFU/100 ml reduction
- 640 mJ/cm2–0.97 ±0.23 CFU/100 ml reduction
