Nanotechnologies, ongoing applications

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shutterstock_73154641New food products and, mainly, packaging materials offering better performances. Nanotechnologies are breaking through even in the food industry, giving rise to concerns for human health and the environment.

New applications do not concern materials only. Nanotechnologies’ use involves also the food industry. Some researchers, however, find the current legislation inadequate, and its updating slow if it is confronted with the continuous development and use of new products and processes involving nanotechnologies.

Latest applications

Nanotechnologies concern the manipulation of substances on a nano-metric scale (10-9 meters). Engineered nanomaterials (Enms), whose size is generally comprised between 1 and 100 nm, offer novel properties called “quantum effects”, which are not present in substances with larger particle size. As yet, there still are very few products and applications, but their number looks set to rise significantly, even in the food industry. Nanotechnologies can foster the development of innovative solutions throughout the whole chain: they can enhance production processes; reduce the use of preservatives; improve nutrition absorbency; control quality, hygiene, authenticity and traceability of products; and improve food preservation. The applications concerning quality control as for instance diagnostic systems, are not involved in safety issues, whereas applications, where nanomaterials or nanoparticles may come into direct contact with food products, are casting doubts on their safety. Several applications of nanotechnologies are already available for the agricultural food sector. As for instance, the improvement of some food properties, as colour, taste and texture; higher absorption and bioavailability of nutrient sources and food supplements; development of new packaging materials with higher barrier or mechanical properties in order to extend the shelf-life of food products. Other applications concern the development of nanosensors for better monitoring packaged food during transport and storage. In agriculture, new nanosensors are being studied for pest detection, and herbicide nanocapsules for slow release and efficient dosage of water and fertilizer, as well as nanofilters for the treatment of water and soil. Food products containing nanoparticles used as ingredients or additives are already on the market; and food products containing nanostructures used as carriers of bioactive compounds or to improve the organoleptic properties of food.  Forms of nanosilver are used for their antimicrobial properties in various applications such as kitchenware and tableware, last generation refrigerators. There is bread enriched with microencapsulated tuna oil, where the microencapsulation masks any fish odour and taste, while preserving its nutritional properties as for instance those derived from omega-3 fatty acids. And again: a nano-selenium enriched tea with antimicrobial properties; food products containing nano titanium dioxide acting as anti-caking ingredient, and so on. And there are nanoemulsions offering the same creaminess of standard food products but lower in calories; and zinc nanoparticles used as taste and palatability enhancers in food products.

shutterstock_209180554Present and future of nanotechnology-based materials

Even the food-packaging sector is in the sphere of nanotechnology-based materials. Nanocomposites are being investigated also by the polymer industry, because they allow the use of conventional matrix material, with significant improvement of properties, even using very small charges; they contribute to enhance mechanical properties and to reduce gas permeability, while increasing solvent resistance and thermal stability. Furthermore, they contribute to reduce the packaging material, because the thickness can be reduced thanks to improved mechanical properties. And they allow the elimination of expensive secondary processes necessary to improve the barrier effect or the surface finish. Clay-based nanocomposites actually reduce the permeability of oxygen and carbon dioxide and considerably enhance the shelf-life of many types of food. This technology is currently used for plastic bottles containing carbonated soft drinks. Several studies investigate the possibility of developing packaging materials that release antimicrobial agents only when necessary; others involve packaging materials containing zinc or magnesium oxide featuring self-cleaning properties, or nanomaterials used to strengthen packages. The presence of nanoparticles allows packages to play a dynamic role in food preservation by releasing or absorbing substances into or from the packaged food or the environment surrounding the food. As in the case of oxygen or ethylene. The presence of oxygen in a package can trigger or accelerate oxidative reactions that result in shorter shelf-life, whereas the formation of ethylene accelerates the ripening of fresh produce. A coating incorporating titanium dioxide nanoparticles on polypropylene film with unlimited microbial activity has been developed to absorb ethylene from a package containing fruits and vegetables. Several nanodevices incorporated in the polymer matrix of the package can monitor the condition of packaged food or the environment surrounding, and can also act as a guard against fraudulent imitation. At NanotechItaly 2015, several studies were presented concerning possible applications of nanomaterials for food packaging. In particular, these studies concern packaging materials with oxygen-scavenging properties; polymeric nanostructures for active packaging developed to extend food shelf-life; packaging materials incorporating nanoparticles allowing considerable material savings; and plasma deposition of a coating layer of less than 100 nm. In fact, atmospheric pressure plasma deposition is a sustainable environmental-friendly technology  that opens up diverse food-approved packaging possibilities; furthermore, it provides a printable, anti-fogging carrier that  offers gas barrier, chemical and microbial protection. Plasma treatment contributes to enhance surface energy of polymers, improving their adhesion and printability; its germ inhibiting effectiveness has been recently demonstrated for food products and packaging materials. Other developments will concern plastic PLA-matrix materials integrating magnesium-aluminium hydrotalcite; the optimization of granulometry to maximize the passive barrier performance and clarity; the study of processes for capturing or adjusting humidity conditions and the scouting of active oxygen scavenging formulations.

shutterstock_200821727Regulations, environment, and health

Materials and articles intended to come into contact with food are regulated by the EU Regulation No. 10/2011 of the European Commission, dd.January 14, 2011, which requires, inter alia, that the direct inclusion as food contact material shall not cover substances present in form of nanoparticles; furthermore, for nanocomposites the functional barrier concept does not apply. However, the regulation does not prohibit the use of nanofillers in polymers in contact with food products. It points out that nanoparticles should be authorized as new food product before their use in the manufacture of or in contact with food. Their safety, as that of other novel food products, shall be assessed by Efsa, the Food Safety Authority. Applicants shall demonstrate also that latest test methods have been implemented for checking the compliance of engineered nanomaterials for which they are asking the authorization. Several nanofillers already achieved certification, and are included in the EU list. As in the case of carbon black (FCM 411), silicon dioxide (FCM 504), titanium nitride (FCM 807 – only in PET and up to 20 mg/kg). Other nano-substances have been added to the positive list with (EU) Regulation 174/2015. It is the case of kaolin (FCM 410); size smaller than 100 nm and contents < 12% in EVOH, with functional barrier), and three different co-polymers: (butadiene, ethyl acrylate, methyl methacrylate, styrene) copolymer crosslinked with divinylbenzene (FCM 859); (butadiene, ethyl acrylate, methyl methacrylate, styrene) copolymer not cross-linked (FCM No 998); and (butadiene, ethyl acrylate, methyl methacrylate, styrene) copolymer cross-linked with 1,3-butanediol dimethacrylate (FCM No 1043).  The Authority has no safety concern in case those substances are used at a maximum combined weight percentage of 10 % w/w in non-plasticised polyvinyl chloride in contact with all food types at ambient temperature or below, including long-term storage, and when used individually or in combination as additives, and when the diameter of the particles is larger than 20 nm, and for at least 95 % by number the diameter is larger than 40 nm.  There are still many concerns about the potential risk from nanoparticles for health and environment. If released into the air, they can be inhaled by humans or by the animals we eat. If they deposit to soil or water, they can be absorbed by fruit and vegetables, or enter the feed chain of marine animals, such as fish, for which they might be toxic. The level of biodegradability of nanoparticles is still  unknown, just like the reaction of the human body to uncontrolled ingestion, since the behaviour of nanoparticles significantly differs from those of larger scale. Due to their small size, nanoparticles are particularly reactive from the chemical point of view; they can pass through cell membranes; they are not recognised by the human immune system; they can cross the blood-retinal and placental barriers. All these factors team with the difficulty of knowing the real behaviour of the investigated nanoparticle, and the complexity of the toxicological analysis. All this making it even more difficult to make a correct assessment of the risk, for which the application of the sole precautionary principle might be insufficient, if there are no secure indications on the properties and behaviours of nanomaterials and nanomaterial-based products. Although deficient in a number of crucial respects, there is a European legislation on nanotechnologies and nanomaterials used in the food industry, and it is in continuous evolution. This is not the case for other world economies, which have no specific regulations on nanomaterials used in food and in contact therewith. It is therefore extremely difficult to quantify the number of products already using these nanomaterials.

 

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