Nanoparticles used in a variety of sectors are also being used in the processing and packaging of foods. According to a study done by Friends of the Earth, foods which contain nanoscale ingredients and additives are already found on supermarket shelves in Europe and the US. Given the increasing scientific evidence demonstrating the toxicity risks of nanomaterials, this is cause for serious concern.

Firms in Germany producing processed meats like ham and sausage are using already a  nanotechnology-based carrier system using 30nm (1 nanometer = 0.0000001 cm) to encapsulate ingredients such as Vitamins C and E and fatty acids, which can be used as preservatives and processing aids. This nano system is reported to increase the potency and bioavailability of the active ingredients enabling faster processing, better colour of the product and the use of cheaper ingredients without compromising on taste. Nestlé and Unilever are said to be developing a nano-emulsion based ice cream which has a rich creamy texture and flavour but is actually low fat. Low fat ice creams otherwise do not taste as good as those made from full fat milk and cream.

Nanoparticles are now being added to many foods to improve flow properties, for example, how well thick liquids pour, colour and stability during processing, or to increase shelf life. For instance, aluminum-silicates are commonly used to prevent clumping in granular or powdered processed foods,  and a form of titanium dioxide is routinely used as a food whitener in confectionery, cheeses and sauces to brighten up their colour.

Bread, breakfast cereals, beverages and dairy products like yoghurt drinks, ice cream and cheese are being  fortified with vitamins, minerals such as iron, magnesium or zinc, bioactive peptides, and antioxidants. Some of these active ingredients are now being added to foods either as nanoparticles or in nanocapsules to slow their release and make them available for the life of the product.

Nanocapsules in food are used to carry bioactive ingredients like vitamins, isoflavones ( compounds similar to estrogens) , carotenoids, (precursors of vitamin A), essential oils, preservatives and  food colouring substances. These are to improve the taste, appearance and nutritional properties of the food. BASF has produced a Vitamin E nano-solution, especially formulated for drinks like sports beverages and flavored waters which are now very popular among the youth.

Nano-sizing or nano-encapsulating active ingredients in nutraceuticals delivers greater bioavailability, improved solubility and increased potency compared  to when these substances are simply added in powdered or even micro form. Nutraceuticals are new age compounds that aim to provide nutrition and health benefits. (Nutraceuticals: nutra= nutrition + ceuticals from pharmaceuticals).

The greater potency of nanoparticle additives reduces the quantities of additives required, and so benefit food processors by cutting cost. However the high potential for cellular uptake of nanomaterials, coupled with their greater chemical reactivity, could also introduce new health risks.

Apart from nanomaterials being added to food and food packaging, nanoparticles are also created during food processing. Nanoparticles are found in many foods not because they have been added to enhance taste and appearance but because of the technology used to process the foods. Food processing technologies that produce nanoparticles are not new but the rapidly expanding consumption of highly processed foods is increasing the volume of nanoparticles in human diets, resulting in higher exposure to these particles and raising health risks.

Processing techniques which produce nanoparticles are used in the manufacture of ready to eat foods like salad dressings, chocolate syrups, sweeteners and flavoured oils.  Nanoparticles and nanoscale emulsions can be formed as a result of food processing techniques like high pressure homogenisation, dry ball milling, dry jet milling and ultrasound emulsification. It is likely that many food manufacturers particularly in developing countries are unaware that their foods contain nanoparticles. They may have simply licensed a processing technology without being aware of its details and safety implications. Food manufacturers like such processing techniques because the textural changes and flow properties they produce add commercial interest to their products.

In addition to the accidental presence of nanoparticles resulting from processing techniques, they can also enter food as contaminants. Researches have found that many food products contain insoluble, inorganic nanoparticles and microparticles which appear to have contaminated foods unintentionally, for example as a result of the wear and tear of food processing machines or through environmental pollution.