Overview of Nanotechnologies

The main goal of food law is to protect consumers against unreasonable risk to human health and irresponsible manufacture and consumption of food. Food is basically regulated by product class, such as food and food ingredients (fla­voring, additives, enzymes, contaminants).

A. Application of Nanotechnologies in Food

Nanotechnology has emerged as an enabling technology that has opened new horizons in its applications for various industries, including the agriculture and food industry. It has been regarded to have revolutionized the whole agri­food sector from farm to table.^[608] Once known as the “science of the small,” nanotechnology has proved itself superior to conventional food processing technologies in areas such as increased shelf-life, preventing contamination, and enhanced food quality.^[609] This is a technology that deals with manufactur­ing and utilizing materials on a nanometer scale (1—100 nm), which results in nanomaterials that have novel properties.

Based on the dimension of their structural elements, nanostructured materi­als can be categorized into nanofilms and coatings (one dimension), nanotubes and nanorods (two dimensions), and nanoparticles (three dimensions).^[610] Due to their unique features, like a high surface to volume ratio, nanomaterials have been utilized to improve sensory characteristics (i.e. texture, color, and flavor) of food and in food packaging, food processing, dietary supplements, anti­microbial agents, and nanosensors.^[611] The fundamental drivers for most nano­technology applications are the potential improvement in material properties, development of new functionalities, and/or reduction in amount of chemicals used for a function.^[612]

The application of nanotechnology in the food industry captures the whole production chain (Figure 11.1).

The raw materials will be transformed to a finished product after going through a series of processing steps. Food packaging is one of the most important steps in food processing. This is because it protects the food during transporta­tion, distribution, and storage but also serves to attract the buyer’s attention. Then the product is consumed with the perception that it is safe and complies with certain quality standards and legislation. Quality control in food produc­tion is important to check and analyze that all the processes (i.e. raw materials, processing, packaging, etc.) used in producing the food comply with standards and legislation. Hence rapid methods (i.e. sensors, kit detection, etc.) are pre­ferred, as they provide the faster data needed in the dynamic food industry.

Regarding food processing, nanotechnology can be deployed as encapsula­tion and carriers that help to protect aroma, flavor, color, and other ingredients in food and as anticaking agents, which help to improve consistency and prevent lump formation. This will produce better texture and appearance. Additives and nutraceuticals help to improve and enhance nutritional value in food, and gelatine agents help to improve food texture.^[613] Among nanotechnology applica­tions, major contributions are increasingly deployed as additives and ingredients. As additives, nanomaterials can function as preservatives (e.g.

The utilization of nanoscale additives in food processing can improve prod­uct consistency; improve the potency and bioavailability of nutrients in food; maintain palatability and wholesomeness; enhance color and desired flavor; and improve food stability during processing and storage, which extends shelf life and prevents bacteria growth, oxidation, and other chemical changes.^[614] Conventionally, food additives have been used to improve and enhance sensory properties of food (color, flavor, texture, taste). This is done to increase the likelihood of a consumer being attracted to purchase and consume the food.

Figure 11.1 Food nanotechnology from farm to table¹²

Flavor is one of the important sensory characteristics of a food and involves a combination of two human senses: the gustatory and olfactory (i.e. orthona­sal—sniffing of an aroma; retronasal—air pushed out from the back of the nose when we swallow).^{[615] [616] It is retro nasal aromas that are combined with gustatory cues to give rise to flavors. Flavor will increase the enjoyment of a food, but the challenge is that flavors are volatile compounds that can be easily destroyed during processing, storage, and transportation when the food is exposed to heat or a harsh environment. Hence, encapsulation of flavors offers a solution to}

protect against unfavorable environments. Carriers such as carbohydrates (e.g. starch, maltodextrins, and dextrose), gums (e.g.

The usage of nanoencapsulation for flavors can be designed to control the release at the desired time and rate, which gives more flexibility and stability, especially during storage.^[619] It gives sustained release by encapsulating a com­pound in appropriate nanocarriers, which will maintain physical stability under the expected performing conditions and durations.^[620] Therefore, nanoencap­sulation will provide better loading capacity and encapsulation efficiency, enhanced stability, and better control on the flavor release profile.^[621] One of the factors that influences food choice and acceptance is the color of the food. For example, red apples tend to have better acceptance because they are per­ceived to be juicy, crunchy, and sweet. Depending on variety, unripe mangoes are green in color, hence they are perceived to be sour, and their texture is hard and less accepted. Color is one of the most significant factors that directly affects consumers’ food choice and eating desires.^[622] Coloring is used in food processing to restore natural color that was lost during processing and storage, enhance existing color, and strengthen weak color.^[623]

Titanium dioxide (TiO2) is used as coloring agent that can provide optical effects, such as the lightness and brightness of a food, that is, enhancing the white color of certain foods such as doughnuts, candies, desserts, and bev- erages.^[624] It is also used as a flavor enhancer in a variety of foods (i.e. dried vegetables, nuts, seeds, soups, and mustard) and as an antimicrobial agent.^[625] The TiO₂ used in the food industry has a particle size of 100—300 nanometers to increase its light-scattering properties.^[626] Iron oxide nanoparticles are widely used as industrial food pigments to color sweets, olives, or cheese rind.^[627] They can also be used as source of bioavailable iron when food is being fortified with them.

In the primary production of food, application of nanotechnology in agri­culture has the following benefits, including increasing productivity by utilizing nanopesticides and nanofertilizers, improving the quality of the soil by utilizing nanozeolites and hydrogels, stimulating plant growth by utilizing nanomateri­als (SiO2, TiO2, and carbon nanotubes), and smart monitoring by utilizing nanosensors and wireless communication devices.^[631] Nanotechnology has also contributed to formulating nanoscale carriers that enable the delivery of agri­culture chemicals, that is, fertilizers, pesticides, and fungicides, that show ben­eficial effects over conventional ones.^[632] Encapsulation of chitosan has been used as the delivery of pesticides, micronutrients, and fertilizers, which reduced the required dosage for efficacy and ensured controlled delivery.^[633] This reduction will help to address environmental issues (i.e. heavy metal pollution) raised by these agricultural chemicals. Controlled delivery mechanisms will allow the active ingredients to be slowly taken up to reduce the amount used and mini­mize the input and waste.^[634] Upon harvesting, these agriculture products will be further processed, as they are used as raw materials in the making of value- added products.

B. Safety of Nanomaterials in Food

The use of nanomaterials in food raises concerns of whether conventional risk assessment will continue to apply to nanofood.^[635] Unique characterization of substances used in food as compared to other food formulated at the micro­scale level, such as the determination of maximum permissible limit of daily intake for food based on weight in additives, contaminants, natural intoxicants, and dietary supplements are among the major problems facing the regulatory authorities.

With substantially different physiochemical and biological properties com­pared to their conventional form, the usage of nanomaterials can possibly create unpredictable hazards.^[636] Little is known about the bioavailability, biodistribu­tion, and routes of nanomaterials and the ultimate toxicity upon exposure to them.^[637] Humans are likely to be exposed to nanomaterial toxicity via skin, gas­trointestinal tract, lung, nasal cavity, and eyes, which are likely to redistribute or migrate it to other organs.^[638] There are several potential mechanisms as a result of nanoparticle toxicity.^[639] It is expected that there will be interference with nor­mal gastrointestinal tract (GIT) function in which the presence of nanoparticles in gastrointestinal fluids could interfere with normal GIT functions. Concerns regarding high levels of nanoparticles (inorganic or some indigestible organics) could reduce the rate of digestion, whereas some types of inorganic nanopar­ticles may physically disrupt structures within the GIT (i.e. microvilli), which alters normal nutrient absorption and the protective function of the epithelium cells.^[640] The presence of nanoparticles can stimulate an immune response, which could have adverse effects on human health. Accumulation within specific tis­sues, particularly the possibility of absorption of nanoparticles into the cells which are metabolized and transferred out of or accumulate within the cells may also occur. Accumulation of nanoparticles within specific tissues may lead to long-term problems if they exhibit toxic effects above a certain accumula­tion threshold.^[641] This mechanism is most important for inorganic nanoparticles that are not normally digested or metabolized in the gastrointestinal tract.

Another possible effect is cytotoxicity and cellular malfunction, where inor­ganic nanoparticles generate reactive oxygen species (ROS) (i.e. singlet oxy­gen, superoxide, hydrogen peroxide, and hydroxyl radicals) and contribute to their toxicity.^[642] ROS can cause damage to cell membranes, organelles, and nucleus when interacts with lipids, proteins, or nucleic acids.^[643] As a result, many biochemical functions required to maintain cell viability (i.e. adenosine triphosphate production, DNA replication, and gene expression) are adversely affected.^[644] This mechanism is important for inorganic nanoparticles that are absorbed by the intestinal cells, since most organic nanoparticles are digested before being absorbed.

Nanoparticle toxicity may also lead to altered location of bioactive release. The encapsulation of bioactive agents such as dietary supplements or nutra­ceuticals in nanoparticles may alter the location of their release and absorption within the gastrointestinal tract. This will upset the normal function of the digestive system, which could lead to gastrointestinal problems, whereas for enhancement of oral bioavailability, the biological effect of the bioactive agent will depend on exposure levels in the blood and specific tissue. If it is too low, the bioactive agent has little effect, but if it is too high, then it might be toxic. It is system dependent where it depends on the toxicity profile of the bioac­tive agent. For example, Vitamin E is essential for maintaining human health at a specific dosage, but consumption at a high dosage will lead to chronic diseases.^[645] This may also give rise to the enhancement of pesticide bioavail­ability: this mechanism is likely to be for foods containing lipid nanoparticles (nanoemulsions) that are consumed with foods containing high levels of hydro­phobic pesticides or hormones. Finally, it would also cause interference with gut microbiota: As a result of the interaction of nanoparticles with colonic bacteria, it will alter the microflora and its surroundings. Hence, any change in the bacteria populating the human colon will have an effect on human health. It is likely that nanomaterials may enter our body during food production that may lead to DNA damage, cell membrane disruption, and cell death.^[646]

III.