MPUVL Applications in the Food Industry

1. MPUVL Applications in the • Food Industry Dr. Montserrat Ortoneda Pedrola Dr. Jeff Cullen Prof. Ahmed Al-Shamma’a RF and Microwave Group

2. Summary • Description of the system • Microorganisms of interest • Results obtained with the MPUVL • Other applications

3. I. Description of the system MPUVLMicrowave Plasma UV lamp UV Plasma Tuneable Microwave Cavity Magnetron 2.45 GHz 0-200 W Reflected Power Coaxial cable Power in Compressed Gas inlet Gas + ozone outlet

4. I. Description of the system Original Panasonic microwave Portable model Static model 2 New lamps built There is no cavity and the microwaves are coupled directly from the magnetron onto the lamp. Microwave controls (time and power) work.

5. II. Microorganisms of interest Food pathogens • E. coli (pathogenic E. coli O157:H7) • Found in healthy cattle. Also in meat (minced). • Infection occurs when con taminated meat is eaten undercooked. • Also in vegetables irrigated with contaminated water. • Pseudomonas sp. is a common spoilage agent in foods due to its ubiquitous nature. It can survive at low temperatures.

6. II. Microorganisms of interest Fried-Rice cooking process Boil rice Kills all the B. cereus living cells but at the same time it stimulates the spores to germinate Refrigerate If Temp is not low enough, spores will germinate, grow and produce toxins Fry Doesn’t destroy the heat-stable toxin • B. cereus is commonly found in rice and other cereals, and the spores can resist very extreme temperatures, and therefore survive the cooking process. • Causes the “fried rice syndrome” • S. aureus (MRSA) strains can produce heat stable enterotoxins • Food can get contaminated during handling, (carriers) bacteria will reproduce and produce toxins if food is left “warm”.

7. II. Microorganisms of interest Fish pathogens Of special concern in fisheries, because of the high density of fish. • Aeromonassalmonicidais a gram-negative bacterium which grows optimally at 22-25°C. • It causes furunculosis in fish. • Lactococcusgarvieae is a gram-positive cocci. • It causes Lactococcosis (hyperacute and haemorrhagic septicaemia). • It is an emergent disease which affects many fish species and causes important economic losses both in marine and freshwater aquaculture when water temperature increases over 16 °C in summer months. Large boil caused by A. salmonicida

8. III. Results Results (Food pathogens) • NOT very effective for these morganisms, • especially for the spores • 6 log kill after 30 seconds exposure for vegetative cells • 4 log kill after 1 minute exposure for spores • Very effective for these morganisms • 5-6 log kill in 2 seconds exposure • up to 7 log kill in 5 seconds B. cereus spores S. aureus 6 log kill B. cereus 5-6 log kill E. coli 4 log kill P. aeruginosa

9. III. Results Results (Fish pathogens) Plates inoculated with fish pathogens and exposed to UV light for 2, 5 and 8 seconds. 6 log kill 5 log kill Aeromonassalmonicida Lactococcusgarvieae

10. IV. Other applications Application for the sterilisation of water in fisheries • Beakers with L. garvieae. • Microorganism non-detectable after 60 seconds. • It could be used to keep the numbers of bacteria low in the tanks with fish. • Improved by: • changing the distance between lamp and water • immersion of the lamp