Analytical screening studies on irradiated food packaging. Dr Malcolm Driffield

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1 Analytical screening studies on irradiated food packaging Dr Malcolm Driffield

2 Introduction Food irradiation is a processing technique that exposes food, usually pre-packaged to avoid further contamination, to high-energy ionising radiation Types of food irradiated:

3 Why irradiate food? Prolong shelf life by preventing food borne diseases Delay ripening and aging in fruit and vegetables Stop vegetables from germinating and sprouting Disinfect grain, dried fruit, nuts and vegetables by killing invading insects Improve re-hydration of foodstuffs

4 Irradiation and polymers Effect of irradiation on basic polymers has been studied e.g. polyolefins energy. O 2 OO. OOH unstable O O O OH OH O H H H + other hydrocarbons + other hydrocarbons H H

5 Irradiation and plastic packaging Foods are generally irradiated in their packaging to avoid further contamination Food packaging materials contain additives Adhesives, inks, plasticisers, photoinitiators, lubricants, catalysts, surfactants, antioxidants... Irradiation of food packaging may pose problems not evident from studies on basic polymers

6 Project Analytical screening studies on irradiated food packaging Investigate finished plastic packaging systems before and after irradiation adiolytic products Identification Estimated quantification Effect on radiolytic products upon changing irradiation parameters Irradiation type Irradiation dose Irradiation dose rate

7 Experimental set-up 15 materials selected to cover a range of: Plastic types Packaging types Foodstuffs Irradiation experiments arried out by Synergy Health (formerly Isotron, UK) Scoping study Vials, caps and septa all tested first Dosimeters in empty vials to allow correction factors to be calculated

variety of compounds with different chemical and physical properties

8 Analytical screening of packaging Samples tested before and after irradiation ombination of techniques to allow detection of a wide variety of compounds with different chemical and physical properties Direct analysis by headspace G-MS Solvent extraction followed by G-MS and L-TOF-MS

9 Effect of irradiation - Identification of compounds by G-MS PV packaging dichloromethane extract Abundance Abundance ontrol Electron beam Gamma m/z--> 0 Time--> Library match to 2-decenal Peak formed upon irradiation

10 Effect of irradiation - Identification of compounds by L-TOF-MS PV packaging acetonitrile extract x ontrol ontrol x Gamma 1 1 x Electron beam Gamma Electron beam ounts vs. Acquisition Time (min) Peak formed upon irradiation

11 Effect of irradiation - Identification of compounds by L-TOF-MS PV packaging acetonitrile extract x [M+NH4] [M+Na] Formula alculated mass Mass error (ppm) Score 24H40O [M+H] [M+K] ounts vs. Mass-to-harge (m/z) Software to carry out data comparison and determine statistical significance e.g. MassProfiler (Agilent)

12 Effect of irradiation Potential migration levels at 10 kgy PP tray Number of peaks by HS-G-MS prior to irradiation 16 Number of peaks affected by irradiation 8 Number of additional peaks after irradiation 4 oncentration range of peaks formed after irradiation (mg/kg in packaging) (mg/kg) # # Worse case migration assuming total transfer and using actual food/packaging ratio Non-intentionally added substances (NIAS) Additional substances detected above level of interest for NIAS

13 Effect of irradiation Summary Irradiation induced degradation of packaging Products from phosphite additives detected Plasticiser compounds present after irradiation Irradiation effecting polymer structure to allow easier release Many more radiolytic products present by G-MS than L-TOF-MS PV, PE and PP largest number of radiolytic products

14 Effect of irradiation type and dose rate Gamma ray vs. electron beam (10 kgy) Quantities of oxidative compounds generally higher by gamma irradiation Intense electron beam at higher dose rate reducing oxygen levels so fast it cannot be replenished fast enough by diffusion from surrounding air Dose rate gamma irradiation at 0.4 kgy/hour and 1.85 kgy/hour No major differences detected in the effects of any substances (over a wide concentration range) measured by any of the analytical techniques

15 Effect of irradiation dose No change in concentration PP packaging HS-G-MS analysis Abundance Time--> 10 kgy 7 kgy 3 kgy 1 kgy ontrol Substance may be radiolytically stable Irradiation dose may not be high enough to induce change 13 alkane

16 Effect of irradiation dose Decrease in concentration PV packaging HS-G-MS analysis Abundance kgy 7 kgy ompounds may be breaking down due to the high energy irradiation Time--> 3 kgy 1 kgy ontrol ompounds may be participating in radiolytically induced reactions with other compounds heptanal

17 Effect of irradiation dose Increase in concentration PP packaging HS-G-MS analysis Abundance 1.5e e e e e+07 1e Time--> 10 kgy 211 mg/kg PP 7 kgy 193 mg/kg PP 3 kgy 79 mg/kg PP 1 kgy 27 mg/kg PP ontrol - ND Larger compounds may be breaking down due to the high energy irradiation ompounds may be forming in radiolytically induced reactions 1,1-Diethoxy-ethane

18 Summary Analytical screening using state-of-the-art technologies on finished food packaging before and after irradiation adiolytic products detected Detection of substances indicative of breakdown of packaging materials Estimated worse case migration concentrations for NIAS up to 8 ppm Levels of oxidative compounds generally higher by gamma irradiation Irradiation dose effects extent of radiolytic product formation/loss

19 Acknowledgements Fera Emma Bradley Nick Harmer Irene Leon Liam Lister Dennis Speck Laurence astle Food Standards Agency Funding for Project A03068 Edward Potter Full details will be given in the paper for the conference issue of FA Thank you for your attention!

The identification and implications of reaction and breakdown products from starting substances used to produce food contact plastics

The identification and implications of reaction and breakdown products from starting substances used to produce food contact plastics Dr Malcolm Driffield malcolm.driffield@fera.gsi.gov.uk Presentation