DISEÑO METODOLÓGICO

All new packaging materials need to be evaluated for their safety and suitability for direct or indirect contact with food. The risk assessment of consumer

exposure to nanoparticles by the oral (food-borne) route is outside the scope of this chapter. The central relevant question asks if there is any migration of nanoparticles into food and, if so, how much (what concentration or number of ENPs) and of what type (size, shape etc) is there?

The establishment of guidelines for migration of ENPs from nanocomposites would be important. The need for such testing has been highlighted by a number of researchers. However, there are only two experimental studies to date. In the first, Avella et al.50measured the migration of the elements Fe, Mg and Si from a biodegradable starch/nanoclay nanocomposite film. Vegetable samples (lettuce and spinach) were placed into bags made of either potato starch, potato starch–polyester blend, and their respective composites with nanoclay. After storage for 10 days at 40 1C, the vegetables were acid-digested, and the migration of minerals determined by atomic absorption spectrometry. There was no increase in Fe and Mg in the vegetables compared to controls but there was an increase in Si – the main component of nanoclay. The con- centrations of Si detected in the vegetables were 16–19 mg kg 1in the case of nanoclay composites of potato starch, and potato starch–polyester blend, compared to 13 mg kg 1for the same polymers without nanoclay, and around 3 mg kg 1in unpackaged vegetables.

A similar approach was taken by Bradley et al. (unpublished)51who studied migration from commercial beer bottles that had a nanoclay composite embedded between PET layers, and commercial polypropylene food containers containing nano-silver (Figure 6.2). In both cases, using ICP-MS analysis, there was no detectable migration of clay minerals. There was a very low silver migration, but the levels were less than the limit of quantification. Also, the

(a) (b)

Figure 6.2 (a) Nanoclay containing PET bottles for beer. (b) Nano silver containing polypropylene storage containers.

97 Nanotechnologies in Food Packaging

presence of ENPs did not cause any significant changes in the migration of non- nano components from the two polymers tested.

Whilst it is the migration of nanoparticles per se that has attracted most concern to date, it must also be recognised that other chemicals are added too. In particular, nanoclays used as fillers are inorganic materials whereas the polymers into which they are incorporated are organic materials with a gen- erally non-polar character. To make the two materials compatible it is usually necessary to modify the surface of the clay with organic chemicals. This is true also for conventional fillers such as glass fibres, titanium dioxide and silicon dioxide. However, because of the very large surface area of the ENPs, a far larger proportion of organic modifier has to be used and it may comprise up to 30% by weight of the ENP. If these organic chemicals remain firmly fixed to the ENP surface then any migration will be in proportion to the ENP migration itself. If, however, there are significant unreacted residues or any modifier not firmly attached, then a higher migration may occur.

Studies of the type described, measuring the migration of all chemical forms, allows an upper limit to be calculated for the migration of ENPs by assuming the worst-case of no migration of soluble and non-nano forms and so with the detection limit calculated for ENPs only. At present there is no alternative approach, since there are not methods available to test foods for low levels of ENPs.

6.10

Summary

In summary, nanotechnology products and applications can potentially revo- lutionise the food packaging sector, and meet many of the industry’s needs in relation to innovative, strong, lightweight and active and intelligent materials. It also seems that, in public opinion, applications of nanotechnology in packaging is perceived as being more beneficial and less problematic than in other food applications.52,53A contributing factor to this seems to be the expectation that, due to the fixed or embedded nature of ENPs in plastic polymers, they are not likely to pose any significant risk to the consumer. A number of possibilities can be seen in the improvement of packaging material properties through the use of nanotechnologies, e.g. in the form of nanocomposites or nanocoatings, both for conventional plastic materials and biodegradable polymers. There are already examples where low levels of nanofillers have been used to increase the mechanical and gas- and light-barrier properties of food packaging materials. Additionally, nanotechnology can be used to introduce completely novel active functionalities to offer innovative packaging solutions. Nanotechnologies can also add other intelligent features to food packaging, e.g. in terms of monitoring the product quality through integrated sensors and indicators as well as estab- lishing the authenticity of the products.

It is also imperative, however, that the development of such packaging innovations is steered carefully with all the safety considerations in respect to consumers and workers, as well as the environment. In this regard, the available

information is currently very sparse in terms of experimental data on the tox- icology of ENPs that are (or can be) used to develop new food contact materials to provide a basis for adequate risk assessment. The risk is, however, dependent on both hazard and exposure – where the absence of one means no risk. Therefore, in the absence of hazard information, the focus is on the estimation of potential exposure. The results of migration testing (Bradley et al., unpublished), and the estimates of potential migration through modeling54do provide some reassurance in the safety of nanotechnology-derived food contact materials. However, more testing on other types of materials is needed to build a broader picture in regard to the migration patterns for other nanocomposites that may be used in food packaging. Detailed toxicological studies are also needed to determine the potential effects of those ENPs that may get into food through packaging. These studies need to particularly focus on the health consequences of the long-term exposure to potentially low levels of ENPs via food and drinks.

References

1. Cientifica, Nanotechnologies in Food Industry, published August 2006, http://www.cientifica.eu/.

2. S. V. Lei, S. V. Hoa and M.-T. Ton-That, Compos. Sci. Technol., 2006, 66, 1274–1279.

3. T. Joseph, and M. Morrison, www.nanoforum.org, April 2006.

4. http://www.foodproductiondaily.com/news/ng.asp?n¼78025-nanotechnol- ogy-plastics-molecules.

5. Additives for polymers, April 2008, 2–3. 6. Additives for polymers, 2006, 2.

7. Additives for polymers, 2007, 3.

8. D. R. Paul and L. M. Robeson, Polymer, 2008, 49, 3187–3204. 9. Plastic additives & compounding, 2005, 7, 18–21.

10. Z. Ke and B. Yongping, Materials Lett., 2005, 59, 3348–3351.

11. G. Qian, D. Jarus and V. Zabrocki, PCT Patent WO 2007/106671 A1. 12. Z. Akbari, T. Ghomashchi and A. Aroujalian, in the Food and Health

Food Industries’ Conference, organised by Institute of Nanotechnology, 25–26 October 2006, Amsterdam.

13. D. A. Pereira de Abreu, P. Paseiro Losada, I. Angulo and J. M. Cruz, Eur. Polym. J., 2007, 43, 2229–2243.

14. Plastic Technology, www.plastictechnology.com/articles/200508fa1.html. 15. Plastics Technology Newsletter, http://www.ptonline.com.

16. Additives for polymers, 2008, 1, 5–6.

17. A. Sorrentino, G. Gorrasi and V. Vittoria, Trends Food Sci. Technol., 2007, 18, 84–95.

18. V. P. Cyras, L. B. Manfredi, M.-T. Ton-That and A. Va´zquez, Carbohydr. Polym., 2008, 73, 55–63.

19. S. Tang, P. Zou, H. Xiong and H. Tang, Carbohydr. Polym., 2008, 72, 521–526.

99 Nanotechnologies in Food Packaging

20. P. Mangiacapra, G. Gorrasi, A. Sorrentino and V. Vittoria, Carbohydr. Polym., 2006, 64, 516–523.

21. Plastic Addit. Compounding, 2005, 7, 13.

22. J. H. Johnston, T. Borrmann, D. Rankin, M. Cairns, J. E. Grindrod and A. Mcfarlane, Curr. Appl. Phys., 2008, 8, 504–507.

23. J. Vartiainen, M. Ra¨tto¨, U. Tapper, S. Paulussen and E. Hurme, Polym. Bull., 2005, 54, 343–352.

24. J. Vartiainen, M. Ra¨tto¨ and S. Paulussen, Packaging Technol. Sci., 2005, 18, 243–251.

25. K. S. Tammaji B. Harish, Patent Application, US 2006/0069197 A1. 26. P. E. Share and K. R. Pillage, Patent US 7,244,484 B2.

27. J. H. Johnston, J. E. Grindrod, M. Dodds and K. Schimitschek, Curr. Appl. Phys., 2008, 8, 508–511.

28. Nanomaterials News, 2007, 3(17), 2.

29. C. A. Poland, R. Duffin and I. Kinloch, et al., Nature Nanotechnol., 2008, 3, 423–428.

30. R. Ahvenainen and E. Hurme, Food Addit. Contam., 1997, 14, 753–763. 31. T. Mattila-Sandholm, R. Ahvenainen, E. Hurme and T. Ja¨rvi-Ka¨a¨ria¨inen,

European Patent, 0666977, 1998.

32. D. Perlman and H. Linschitz, US Patent, 4526752, 1985.

33. Y. Yoshikawa, T. Nawata, M. Goto and Y. Kondo, US Patent, 4349509, 1982.

34. R. Ahvenainen, T. Pullinen, E. Hurme, M. Smolander amd M. Siika-aho, PCT International Patent Application, WO 9821120, 1997.

35. A. Mills and M. J. McGrady, Photochem. Photobiol., A, 2008, 193, 228–236.

36. M. Smolander, in Novel Food Packaging Techniques, ed. R. Ahvenainen, Woodhead Publishing Ltd, Cambridge, 2003, pp. 127–143.

37. M. Smolander, E. Hurme, M. Koivisto and S. Kivinen, PCT International Patent Application, WO 2004/102185, A1, 2004.

38. M. Smolander, in Smart Packaging Technologies, Wiley, Wiltshire, UK, 2008, pp. 111–127.

39. http://www.psivida.com/application/other.asp.

40. S. D. Minteer, B. Y. Liaw and M. J. Cooney, Curr. Opin. Biotechnol., 2007, 18, 228–234.

41. F. Davis and S. P. J. Higson, Biosens. Bioelectron., 2007, 22, 1224–1235. 42. M. Smolander, H. Boer, M. Valkiainen, R. Roozeman, M. Bergelin,

J.-E. Eriksson, X.-C. Zhang, A. Koivula and L. Viikari, Enzyme Microb. Technol., 2007, 2008, 43, 93–102.

43. M. Strange, D. Plackett, M. Kaasgaard and F. C. Krebs, Sol. Energy Mater. Sol. Cells, 2008, 2008, 92, 805–813.

44. Nanomaterials News, 2007, 3(17), 6.

45. A. D. Albert, M. F. Becker, J. W. Keto and D. Kovar, Acta Mater., 2008, 56, 1820–1829.

46. B. K. Park, D. Kim, S. Jeong, J. Moon and J. S. Kim, Thin Solid Films, 2007, 515, 7706–7711.

47. I. Willner, R. Baron and B. Willner, Biosens. Bioelectron., 2007, 22, 1841–1852.

48. M. Han, X. Gao, J. Z. Su and S. Nie, Nat. Biotechnol., 2001, 19, 631–635. 49. S. P. Patel and N. K. Thanawala, PCT Patent, WO 2007/015261, 2007. 50. M. Avella, J. J. De Vlieger, M. E. Errico, S. Fischer, P. Vacca and M. G.

Volpe, Food Chem., 2005, 93, 467–474.

51. E. L. Bradley, L. Castle and Q. Chaudhry, Nanoparticles in food contact materials and articles, 2009, in preparation.

52. M. Siegrist, M.-E. Cousin, H. Kastenholz and A. Wiek, Appetite, 2007, 49, 459–466.

53. M. Siegrist, N. Stampfli, H. Kastenholz and C. Keller, Appetite, 2008, 2008, 51, 283–290.

54. P. Sˇimon, Q. Chaudhry and D. Bakosˇ, J. Food Nutr. Res., 2008, 47(3), 105–113.

55. A. Garland (ed.), Nanotechnology in Plastics Packaging: Commercial Applications in Nanotechnology, Pira International Limited, UK, 2004, 14–63.

56. M. Alexandra and P. Dubois, Mater. Eng. Res., 2000, 28, 1–63.

57. Advance Magazine, Feb 2004, www.azonano.com/details.asp Article ID-1317.

101 Nanotechnologies in Food Packaging

CHAPTER 7

Potential Benefits and Market