Nanotechnologies in Food

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1 Nanotechnologies in food This submission is meant to provide a brief summary of findings of the studies carried out at Central Science Laboratory (CSL) into the potential applications and implications of nanotechnologies in food. More detailed findings are submitted as two separate reports on the studies that the CSL team has recently carried out for the Food Standards Agency. A number of recent reports and reviews have identified the current and short-term projected applications of nanotechnologies for food and beverages (Bouwmeester et al., 2007; Chaudhry et al., 2008; EFSA, 2008; Food Safety Authority of Ireland, 2008). Like other sectors, nanotechnologies are promising to revolutionise the food sector from production to processing, storage, and development of innovative materials, products and applications. Currently, such applications in the food sector are new emergent, but their number and range is expected to increase in the coming years. Virtually all current applications of nanotechnologies in food are outside Europe, although some supplements and food packaging materials are available in the EU. Also, the global nature of food business means that more products and applications are likely to be available in the EU in the coming years. This also means that there will be a need for regulation of the risks, and establishment of liabilities at the global level. The current and short-term projected applications of nanotechnologies include nano-sized or nanoencapsulated ingredients and additives for food, beverage, and health-food applications. A current niche for such applications is in the areas where there is an overlap between the food, medicines, and cosmetics sectors. For example, some food products are marketed as a means to enhance nutrition for different lifestyles, or as an aid to beauty, health and wellbeing. These hybrid sectors have been the first focus of nanotechnology applications, which have only recently started to appear in the mainstream food sector. Thus the vast majority of the currently available nanotechnology products is in the areas of supplements, healthfoods and nutraceuticals, with only a few products in the food and beverage areas. The main tenet behind the development of nano-sized food ingredients and additives appears to be the enhanced uptake and bioavailability of nano-sized substances in the body, although other benefits such as improvement in taste, consistency, stability and texture etc have also been claimed (Chaudhry et al., 2008). A major application area for engineered nanoparticles (ENPs) is for food packaging. Whilst most nanotechnology applications for food and beverages are currently at R&D or nearmarket stages, the applications for food packaging are rapidly becoming a commercial reality. A contributing factor to such developments 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. Indeed, nanotechnology applications for food contact materials (FCMs) already make up the largest share of the current and short-term predicted nanofood market (Cientifica, 2006). Nanomaterials Relevant to Food Applications The currently available information suggests that nanomaterials used in (health)food applications include both inorganic (metal, metal oxides) and organic materials. In addition to the ENPs, there is a possibility that certain microscale materials used in the food and feed area may contain a nanoscale fraction due to natural size range variation (EFSA, 2008). Based on the available information, the ENP likely to be found in food fall into 3 categories: metal and metal oxide (including alkaline earth metal and silicate), surface functionalised, and organic ENPs. Examples of these include:

2 1. Metal/ Metal-oxides A number of meal/ metal-oxide ENPs are known to used in (health)food products and food packaging applications. These include ENPs of transition metals such as silver and iron; alkaline earth metals such as calcium and magnesium; and non metals such as selenium and silicates. Others ENPs that can potentially be used in food applications include titanium dioxide. Food packaging is the major area of application of metal(oxide) ENPs. Example applications include plastic polymers with nano-clay as gas barrier, nano-silver and nanozinc oxide for antimicrobial action, nano-titanium dioxide for UV protection, nano-titanium nitride for mechanical strength and as a processing aid, nano-silica for surface coating etc. The use of insoluble metal(oxide) ENPs in food applications, especially those that are unlikely to be assimilated in the GI tract, raises a number of concerns. The likelihood of translocation of such ENPs with potentially large reactive surfaces to various cells and tissues in the body may lead to certain risks to consumer health; for example, potential cellular damage and inflammatory reactions due to generation of reactive oxygen radical species (Oberdörster, 2000; Li et al., 2003; Donaldson et al., 2004). ENPs can also adsorb or bind different substances on their surfaces (Šimon and Joner 2008), and thus may carry potentially harmful chemicals and foreign substances into the blood and to various tissues and organs in the body. Certain metal(oxide) ENPs, such as that of silver, magensium oxide and zinc oxide, are known to have strong antimicrobial activity. Especially, there is an increasing use of nanosilver in a number of consumer products, including (health)food and food packaging applications. Indeed, the use of nano-silver as an antimicrobial, antiodorant, and a (proclaimed) health supplement. has already surpassed all other ENPs currently in use in different sectors (Woodrow Wilson, 2008). This has also led to concerns over its safety to human health when ingested orally. Despite this, there is no published research at present on how the intake of nanosilver via food and drinks might affect the cellular function or the gut natural microflora. Nano-silica is known to be used in food contact surfaces and food packaging applications, and some reports suggest its use in clearing of beers and wines, and as a free flowing agent in powdered soups. The conventional bulk form of silica is a permitted food additive (SiO 2, E551), but concerns have been raised over the safety of nano-silica because it is likely to remain undigested in the GI tract and thus may pose a risk due to greater uptake and translocation in the body. In this regard, a commercial product Slim Shake Chocolate, available in the USA, is understood to incorporate nano-sized silica particles (between 4 to 6 nm in diameter) that are coated with coco to enhance the chocolate flavour through the increase in surface area that hits the taste buds. Titanium dioxide, in conventional bulk form, is an already approved additive for food use (TiO 2 E171), but there is a concern that the conventional form may also contain a nano-sized fraction. Nano-titanium dioxide is used in a number of consumer products (e.g. paints, coatings) and its use may extend to foodstuffs. For example, a patent by Mars Inc. (US Patent US ) describes nano-scale inorganic coatings applied directly on food surface to provide moisture or oxygen barrier and thus improve shelf life and/or the flavour impact of foods. The materials used for the nano-coatings, applied in a continuous process as a thin amorphous film of 50 nm or less, include titanium dioxide. The main intended applications described in the patent include confectionary products. 2. Surface Functionalised Nanomaterials Surface functionalised nanoparticles are the 2 nd generation nanoparticles that add certain functionality to the matrix, such as antimicrobial activity, or a preservative action through absorption of oxygen. For food packaging materials, functionalised ENPs are used to bind with the polymer matrix to offer mechanical strength or a barrier against movement of gases,

3 volatile components (such as flavours) or moisture. Compared to inert materials, the use of this category of ENPs in food applications is likely to grow in the future. They are also more likely to be react with different food components, or become bound to food matrices. Examples include organically-modified nano-clays that are currently used in food packaging to enhance gas-barrier properties. The nanoclay mineral is mainly montmorillonite (also termed as bentonite), which is a natural clay obtained from volcanic ash/ rocks, and has a natural nano-scaled layer structure. 3. Organic Nanomaterials A number of organic nano-sized materials are used (or have been developed for use) in food products. These include vitamins, antioxidants, colours, flavours, and preservatives. The main principle behind the development of nano-sized organic substances is the greater uptake, absorption and bioavailability in the body, compared to conventional bulk equivalents. However, a greater uptake and bioavailability of certain compounds, such as certain preservatives, can also be detrimental to consumer health. Also developed for use in food products are nano-sized carrier systems for nutrients and supplements. These are based on nanoencapsulation of the substances both in liposomes and micelles as well as protein based carriers. Such nano-carrier systems are used for taste masking of ingredients and additives, and their protection from degradation during processing. They are also claimed for enhanced bioavailability of nutrients/ supplements, antimicrobial activity and other health benefits. There is a wide range of materials available in this category, for example, food additives (e.g. benzoic acid, citric acid, ascorbic acid), and supplements (e.g. vitamins A and E, isoflavones, ß-carotene, lutein, omega-3 fatty acids, coenzyme-q10). The concept of nano-delivery systems has essentially originated from research into targeted delivery of drugs and therapeutics. The use of similar technology in foodstuffs is interesting in the sense that whilst it can offer increased absorption, uptake and bioavailability, it also has the potential to alter tissue distribution of the substances in the body. For example, certain water-soluble compounds (such as vitamin-c) have been rendered fat dispersible through nano-carrier technology. Vice versa, certain fat-dispersible compounds (e.g. vitamin- A) have been rendered water dispersible. It is hoped that these nano-carriers are completely broken down and their contents are released in the GIT. As such, the encapsulated compounds will not be any different from their conventional equivalents. However, if a nanocarrier system is capable of delivering the encapsulated substance to the bloodstream, its absorption, tissue distribution and bioavailability may be drastically different from the conventional forms. This raises the concern that some nano-carriers may act as a Trojan Horse and facilitate translocation of the encapsulated substances or other foreign materials to unintended parts of the body. It is also worth mentioning that there are many other nanomaterials that are used for other applications but their use in food/ food packaging is uncertain or unlikely. Examples include certain carbon-based materials (such as fullerenes, carbon nanotubes). Although, recent studies have linked carbon nanotubes with potential harmful effects in biological system, they are not likely to be used in food applications. This is because functionalities that carbon nanotubes offer mainly derive from their enhanced tensile strength and electrical conductivity, which are of little relevance to potential use in food, although there may be some applications in the packaging area. Consumer safety concerns It is known that the conventional physicochemical rules are not fully applicable at the nanometer scale, and that there can be some fundamental shifts in physicochemical properties, behaviour, and interactions of ENPs compared to their bulk equivalents. For example, quantum effects may have a much greater influence on the properties of ENPs,

4 especially of those in the lower nanometer size range, compared to their bulk equivalents. In some cases, such changes in physicochemical properties may also lead to a change in the effects and impacts on biological systems. Some studies have suggested a deviating toxicity profile for some ENPs compared to their conventional equivalents (Donaldson et al. 2001; Nel et al An important aspect to consider in relation to potential harmful effects of ENP is their increased ability to penetrate cellular barriers (Geiser et al., 2005; Oberdörster et al., 2004). This adds a new dimension to particulate toxicology, as ENPs can potentially reach new targets in the body where entry of larger particulates is restricted (Jani et al. 1990; Carr et al. 1996; Hillyer and Albrecht 2001; Hoet et al. 2004; Florence 2005; des Rieux et al. 2006; De Jong et al. 2008). ENPs are also known to adsorb or bind different compounds and moieties on their surfaces (Šimon and Joner 2008), and may act as a carrier of potentially harmful chemicals and foreign substances into the blood and different tissues and organs in the body. Depending on the surface chemistry, systemically introduced ENPs have been found to interact with various biological entities, such as e.g. plasma proteins, platelets and cells (Nemmar et al. 2002; Šimon and Joner 2008). Such interactions may have a substantial effect on the distribution and excretion of an ENP (Dobrovolskaia 2007). In this regard, there is emerging evidence to suggest that ENPs become coated with certain biomolecules, especially proteins, and these coatings can direct them to specific locations in the body (Lynch and Dawson 2008). For example, coating with apolipoprotein E has been associated with their transport to the brain (Michaelis et al. 2006). The protein corona is, however, also reported to be changeable in different surroundings (Cedervall et al. 2007). This suggests that ENPs can undergo complex and dynamic interactions in biological environments, and studies carried out on neat ENPs under artificial conditions may not represent their true behaviour and effects in real-life situations. Nanomaterials that are likely to dissolve/ solubilise either in the food matrix or in the GI tract are not likely to raise health concerns as, once digested or dissolved, they are not likely to behave any differently from the conventional bulk equivalents. One example is that of nanoselenium, which is being marketed as an additive to a tea product in China for a number of (proclaimed) health benefits. However, nano-selenium is likely to solubilise in food or in the GI tract. Another example is that of a mayonnaise (currently under development) which is composed of nano-micelles that contain nano-droplets of water inside. The mayonnaise is being developed to offer taste and texture attributes similar to the full fat equivalent, but with a significant reduction in the amount of fat intake by the consumer. It is also worth highlighting that currently there are a number of major knowledge gaps in regard to the behaviour, interactions, fate and toxicological effects of most ENPs in the GI tract. It is possible that the ENPs added (or migrated) to food will not remain in a free form (and hence not available for translocation) because of agglomeration, binding with food components, reaction with stomach acid or digestive enzymes. Furthermore, much of the available toxicological information relates to in vitro studies, or to exposure through inhalation of ENPs, and full extent of hazard, exposure, and risk from the ingestion of ENPs via food and drinks are therefore largely unknown. References - Chaudhry, Q., Scotter, M., Blackburn, J., Ross, B., Boxall, A., Castle, L., Aitken, R. and Watkins, R. (2008) Applications and implications of nanotechnologies for the food sector, Food Additives and Contaminants 25(3): Bouwmeester, H., Dekkers, S., Noordam, M. Hagens,W., Bulder,A, de Heer, C., ten Voorde, S.,Wijnhoven, S., Sips,A. (2007) Health impact of nanotechnologies in food production. Report RIKILT Institute of Food Safety,Wageningen UR and National Institute of Public Health & the Environment; Center for Substances and

5 Integrated Risk Assessment. Available at F58C-47EB-A0AA 23CB9956CE18/54352/R pdf, 95 pp. - EFSA (2008) Draft Opinion of the Scientific Committee on the Risks Arising from Nanoscience and Nanotechnologies on Food and Feed Safety, Endorsed for public consultation on 14 October Food Safety Authority of Ireland (2008) The Relevance for Food Safety of Applications of Nanotechnology in the Food and Feed Industries, Published by Food Safety Authority of Ireland, Abbey Court, Lower Abbey Street, Dublin 1, pp Woodrow Wilson International Centre for Scholars (2008) The Nanotechnology Consumer Inventory Available at: accessed 16 September Cientifica Report Nanotechnologies in the Food Industry published August Available: Accessed 24 October Li et al. (2003) Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage, Environmental Health Perspectives 111(4): Geiser et al. (2005) Ultrafine particles cross cellular membranes by nonphagocytic mechanisms in lungs and in cultured cells, Environmental Health Perspectives 113 (11): Oberdörster G, Sharp Z, Atudorei V, Elder A, Gelein R, Kreyling W & Cox C (2004a). Translocation of inhaled ultrafine particles to the brain. Inhalation Toxicology 16: Oberdörster G (2000) Toxicology of ultrafine particles: in vivo studies. Phil. Trans. R. Soc. London A. 358: Donaldson K, Brown D, Clouter A, Duffin R, MacNee W, Renwick L, Tran L, and Stone V. (2002). The pulmonary toxicology of ultrafine particles. J Aerosol Med 15: Šimon P, Joner E (2008) Conceivable interactions of biopersistent nanoparticles with food matrix and living systems following from their physicochemical properties. Journal of Food and Nutrition Research 47, Nel A, Xia T, Madler L, Li N (2006) Toxic potential of materials at the nanolevel. Science 311, Donaldson K, Stone V, Clouter A, Renwick L, MacNee W (2001) Ultrafine particles. Journal of Occupational Environmental Medicine 58, Carr KE, Hazzard RA, Reid S, Hodges GM (1996) The effect of size on uptake of orally administered latex microparticles in the small intestine and transport to mesenteric lymph nodes. Pharmaceutical Research 13, De Jong WH, Hagens WI, Krystek P, Burger MC, Sips AJ, Geertsma RE (2008) Particle size-dependent organ distribution of gold nanoparticles after intravenous administration. Biomaterials 29, des Rieux A, Fievez V, Garinot M, Schneider YJ, Preat V (2006) Nanoparticles as potential oral delivery systems of proteins and vaccines: a mechanistic approach. Journal of Control Release 116, Donaldson K, Stone V, Clouter A, Renwick L, MacNee W (2001) Ultrafine particles. Journal of Occupational Environmental Medicine 58, Florence AT (2005) Nanoparticle uptake by the oral route: Fulfilling its potential? Drug Discovery Today: Technologies 2,

6 - Hillyer JF, Albrecht RM (2001) Gastrointestinal persorption and tissue distribution of differently sized colloidal gold nanoparticles. Journal of Pharmaceutical Sciences 90, Hoet P, Bruske-Hohlfeld I, Salata O (2004) Nanoparticles - known and unknown health risks. Journal of Nanobiotechnology 2, Jani P, Halbert GW, Langridge J, Florence AT (1990) Nanoparticle uptake by the rat gastrointestinal mucosa: quantitation and particle size dependency. Journal of Pharmacy and Pharmacology 42(12): Nemmar A, Hoet PHM, Vanquickenborne B, et al. (2002) Passage of inhaled particles into the blood circulation in humans. Circulation 105, Dobrovolskaia M (2007) Immunological properties of engineered nanomaterials. Nature Nanotechnology 2, Lynch I, Dawson KA (2008) Protein-nanoparticle interactions. Nano Today 3, Michaelis K, Hoffmann MM, Dreis S, Herbert E, Alyautdin RN, Michaelis M, Kreuter J, Langer, K (2006) Covalent linkage of Apolipoprotein E to albumin nanoparticles strongly enhances drug transport into the brain. J Pharmacol Exp Ther 317, Cedervall T, Lynch I, Foy M, Berggard T, Donnelly SC, Cagney G, Linse S, Dawson, KA (2007). Detailed identification of plasma proteins adsorbed on copolymer nanoparticles. Angew Chem Int Ed Engl 46,

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