Food packaging and use of stabilizers ADVANCED BIO-FRIENDLY POLYMERS Food packaging and use of stabilizers Györgyi Szarka

Packaging materials Paper Metal Plastic: -PP -PET box -PS -PVC -Polyesthers foil -PE light, transparent, unbreakable, minimal use of material, good gas and aroma closing, valuable raw material http://www.foodpackagingforum.org/Food-Packaging-Health/Food-Packaging-Materials C. Silvetre et. al. Prog. Polym. Sci., 36, 2011, 1766.

Polymer additives FUNCTIONAL PROTECTING TYPICAL STABILIZERS Plasticizer Lubricant Antistatic Filler Foaming / Crosslinking Colorant Flame retardant PROTECTING Heat stabilizer Light stabilizer Antioxidant TYPICAL STABILIZERS Primary stabilizers/ antioxidants: Hindered phenols, aromatic amines Secondary stabilizers / peroxide decomposers: Organic thioesters, phosphites and metal-thiocarbamates Chelating agent/metal deactivator: Organic phosphites and hydrazides

Problem related to food packaging Migration of additives Chemical changes during processing Health problem due to synthetic stabilizers FOOD FOOD

Strategies to avoid migration Macromolecular stabilizer grafting by chemical decomposition of 1,2,2,6,6-pentamethyl-4-piperidyl-acrylate (PMPA) Connect the stabilizer to the polymer (grafting / copolymerization ) 1. time antioxidant used in copolymerization with olefin under Ziegler-type conditions M. L. Binet, S. Commereuc, P. Lajoie, J. Lacosta, J. Photochem. Photobiol. A: Chem., 137, 71, (2000) T.L. Pattorn, J. T. Horeczy, D. E. Brown (to Esso Research and Engineering Co.) U. S. 3,477,991 (1969) T. Iwata, J. Sasaki (to Mitsui Petrochemical Co., Ltd), Canadian 876,769 (1971)

Changes during processing Manufacturer should guarantee not only the safe use of the additive but the product(s) of them after processing There are some health concern in relation to BHT, the quinone form causes lung cancer in mice. Human health problem has not been proved yet.

Natural materials in packaging Environmental and health problem due to synthetic stabilzers Natural antioxidant: lignin, carotin, quercetin Radical scavenger: vitamin E carotin vitamin E quercetin BIODEGRADABLE POLYMERS: PHA, PHB, PLA (Ecoflex, Ecovio) Brocca, D.; Arvin, E, Mosbaek, H: Water Res., 36, 3675-3680, 2002 Pataki P., Imra B., Földes E., Pukánszky B., Műanyag és Gumi, 2012, 1

1935/2004/EC regulation This Regulation covers all materials and articles that are intended to come into contact with food: all types of packaging, bottles (plastic and glass), cutlery, and even adhesives and inks for printing labels. They must under no circumstances transfer substances to the food with which they are in contact in quantities likely to: endanger human health; bring about an unacceptable change in the composition of the food; or bring about a deterioration in the organoleptic characteristics thereof. Active materials and articles: intended to come into contact with food: materials and articles that are intended to extend the shelf-life or to maintain or improve the condition of packaged food. They are designed to deliberately incorporate components that would release or absorb substances into or from the packaged food or the environment surrounding the food. Intelligent materials and articles intended to come into contact with food: materials and articles which monitor the condition of packaged food or the environment surrounding the food. 2023/2006 EK GMT helyes gyártási gyakorlat

Active and intelligent material Oxygen absorbents: ascorbic acid, metal-sulfides, glucose oxidase, catalase enzyme, amorphous polyamide Oxygen exclusion: ethylene/vinyl alcohol closing coating with Fe-compound Water vapour absorbents: molecular sieve, silica, CaO, Al coating Moisture controller: salts Antimicrobial packaging: sorbic acid, Ag

Summary The use of plastics is rapidly expanding in food packaging industry The new products are more sophisticated and fit better to the improved claims with special polymers and active additives These materials should improve not only the physical, chemical but the health safety properties of the package (EU) due to - reducing migration - and full controll of all the used materials and evolved products during processing

Macrostabilizer strategy Compatibilizer Hyperbranched polymer Stabilizers

Acknowledgement HUSK /1101/1.2.1/0209 Hungarian Academy of Sciences Research Centre for Natural Sciences Institute of Materials and Environmental Chemistry Department of Polymer Chemistry

Packaging Barrier protection - A barrier from oxygen, water vapor, dust, etc., is often required. Permeation is a critical factor in design. Some packages contain desiccants or Oxygen absorbers to help extend shelf life. Modified atmospheres or controlled atmospheres are also maintained in some food packages. Keeping the contents clean, fresh, and safe for the intended shelf life is a primary function.. Convenience - Packages can have features which add convenience in distribution, handling, stacking, display, sale, opening, reclosing, use, and reuse.

Macromolecular stabilizers Advantages Very low migration to the surface Long and predictable effect Properties (eg. solubility, miscibility) can be easily modified by molecular weight and functionality Disadvantages Further functionalization reactions, which are often expensive and time consuming

INTERPACK 2011

Other additives Antiaging additives: BHT has been cleared by the FDA

MULTIFUNCTIONAL HYPERBRANCHED POLYMERS Dendrimers: repetitively branched molecules start-up of one well defined central core low viscosity high chain-end funcionality developing of generations can be made by only expensive, difficult and time consuming methods and reactions Hyperbranced polymers: no special main chain statistical distribution of branch points The branched polymers have all the beneficial properties of dendrimers. Synthesis: different one-step reactions Polycondenzation of ABn-type monomers Sequential grafting INIMER POLYMERIZATION Self-grafting of polymers 18

ONE NEW CANDIDATE FOR BIO-FRIENDLY STABILIZER: HYPERBRANCHED POLYGLYCEROL Properties Synthesis: cationic or anionic Ring Opening Polymerization of glycidol Well defined product (Mn, PD, number of OH-groups) Good solubility in water OH-groups can be functionalized easily Biocompatible does not induce an immune response oligomers are FDA approved for food and pharmaceutical additives

THE TARGET STABILIZER

Effect of antioxidant Stabilization of chain-breaking antioxidants Stabilization by preventive (secondary) antioxidants phosphites, organic sulfides

Effect of heat stabilizer The processing temperature is about 180-200 °C. ROOH + Mn+ ROO. + M(n-1)+ + H+ ROOH + M(n-1)+ RO. + Mn+ +OH- 2ROOH ROO. + RO. + H2O Much more efficient inhibition is achieved by using metal deactivators, together with the antioxidants. Mn+/M(n-1)+ Main function is to retard effectively metal-catalyzed oxidation of polymer.

Effect of light stabilizer Small amounts of impurities or chromophores can be sufficient to induce photooxidaiove degradation even in the absence of appreciable UV absorption by a polymer. Types: UV absorbers: absorption of harmful UV radiation and it dissipation that does not form heat. Need a thickness. Hxdroperoxybenzophenones and hydroxyphenyl benzotriazoles. Quenchers of excited states: light stabilizers able to take over energy absorbed by the chromophores present in the plastic and to dispose of it efficiently to prevent degradation. Hydroperoxide decomposers: metal complexes of sulfur-containig compounds such as dialkyldithiocarbamates, dialkyldithiophosphates and thiobisphenolates. Free radical scavengers: n-butylamine-nickel-2,’2-thio-bi-(4-tert.-octylphenolate) nickel-bis(3,5-di-tert.-butyl-4-hydroxybenzol-phosphonic acid monobutylester). Hindered amine typelight stabilizers: bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate. Light stabilizer are chemical compounds capable of interfering with the physical and chemical processes of light-induced degradation. Most important classes: 2-hydroxybenzophenones, 2-hydroxyphenyl benzotriazoles, hindered amines and organic nickel compounds. Radiation between 295 and 400 nm initiates degradation.

Food packaging and use of stabilizers Györgyi Szarka, Béla Iván Department of Polymer Chemistry Institute of Materials and Environmental Chemistry  Research Centre for Natural Sciences, Hungarian Academy of Sciences