4 Nano-additives for Food Industries
4.2 Nanomaterial Classifications
Nanomaterials would be mostly used in food formulations and food packaging.
However, researchers have recently reported the beneficial uses of nanomaterials in food processing and food safety issues, as well. Furthermore, nano-sensors can be incorporated into the packaging polymers to provide various smart packaging and enhance the foods’ safety (Chaudhry et al. 2008). Using the nano-filtrations in food processes, such as elimination of detrimental constituents from products, or the nano-fluids for thermal processes of the foods such as sterilization, are some appli-cations of nanomaterials in food processes.
The foods with nanomaterial ingredients mainly offer improved, homogeneous and stable texture, pleasant taste, desired appearance and healthier than convention-ally formulated products without nanomaterial constituents. Nanoemulsions, micro-emulsions, liposomes, nanoparticles, transferosomes, ethosomes and biopolymer-based delivery organizations are some common nutraceutical and sup-plement nano-encapsulating systems in food formulation uses. Nanoencapsulation is the second largest area (after food packaging) of application of nanotechnology in the food industry (He and Hwang 2016; Martirosyan and Schneider 2014). The nano-sized nutraceutical elements of food formulation can change the circulation of the constituents through the body. Thus, if a nano-sized delivery system can carry the bioactive element into the blood flow, its absorption, distribution, digestion and secretion would be different from its conventional forms. However, the broken nano-sized delivery systems, especially at the gastrointestinal region, cannot alter the absorption and distribution of delivered nutraceuticals from their conventional forms (Bajpai et al. 2018; Chaudhry et al. 2008).
According to Nano-forum, ‘Nano-food’ is the food that the nanotechnology pro-cedures or nano-sized compounds are used during their cultivation, manufacture, formulation or packaging (Sekhon 2010; Sozer and Kokini 2009). The nano-food products would be classified into various classes, which are described below.
4.2.1 Inorganic Nanomaterials
Inorganic materials have found various uses in either food formulation, food pack-aging or food processing. For example, calcium, magnesium, selenium and iron nanoparticles can be used in food or beverage systems as a nutrition enhancer or preserver. Gold, silver, iron, silica as well as metal oxide nanoparticles, such as titanium oxide, zinc oxide and iron oxide, with antimicrobial, antioxidant and anti- odorant abilities, can also be used in food packaging constructions, giving effective active packaging. Silver, magnesium oxide and zinc oxide nanoparticles are the most efficient nanoparticles with antimicrobial activity. Titanium dioxide nanopar-ticles can protect the transparent polymers from UV radiations. Titanium nitride nanoparticles can enhance the mechanical strength of the polymeric packaging.
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Thus, the bio-polymers can be used as an alternative for fossil-fuel based polymers in food packaging vector (Palza 2015).
Nanotechnology affords the manufacture of smart packaging, as well as contain-ing metal based nanosensors to give valuable information about their inside pack-aged foods, in which it can sense, detect and visualize the food spoilage compounds (Bajpai et al. 2018; Chaudhry et al. 2008). For instance, TiO2 nanoparticles with light sensibility can be incorporated into oxygen sensing ink, and as a result it can detect oxygen in exposure to UV light. The graphene oxide-TiO2 nanoparticles were also developed as a photocatalyst for UV-activated oxygen detection (Son et al.
2015). Conductive inks based on copper nanoparticles with sizes of 40–50 nm for ink jet printing have also been developed by Park et al. (2007). This attractive and low-cost process is a substitute to expensive conductive metals such as gold.
Nanosensors, inserted into food products as small chips, are imperceptible to the human eye and can also act as microelectronic barcodes (Bajpai et al. 2018;
Chaudhry et al. 2008; He and Hwang 2016). Some inorganic nanoparticles can immobilize the enzymes which are used during food processing in order to improve their dispersion all through the food matrices, increase their activity and re- usability.
For example, the activity, stability and adaptability of porcine triacylglycerol lipase, which are used in the hydrolyzing of olive oil, effectively increased as it immobi-lized covalently on silicon dioxide nanoparticles (Chaudhry et al. 2008; He and Hwang 2016).
4.2.2 Surface Functionalized Nanomaterials
Surface functionalized nanomaterials would be achieved by surface modification of nanoparticles using either hydrophilic or mucoadhesive emulsifiers or biopolymers, leading to a considerable amendment of the zeta potential, hydrophilicity, stability and adhesive and cellular uptake of nanoparticles (Gunasekaran et al. 2014). Surface functionalized nanomaterials are quit advance engineering nanomaterial, which can be used either in food formulation or food packaging uses. They give specific func-tion, such as preservation or antimicrobial activity, to food matrix through oxygen absorption (Anarjan and Tan 2013a; Huang et al. 2010). In food packaging, the surface functionalized nanomaterials can bind to packaging polymers in order to improve their gas barrierity, moisture or volatile components diffusivity and mechanical strength. Despite inert nanomaterials they are able to bond to the poly-mer and are mostly not free enough to migrate from packaging into food matrix, or location into other tissues than the gastrointestinal region (Tsagkaris et al. 2018;
Youssef and El-Sayed 2018). The nano-clay, which is mainly the montmorillonite with nano-scaled layers, is the most suggested nanosystem, which can bind to the packaging polymer matrix, making the organic/inorganic hybrids, and modify the polymer characteristics such as gas barrierity (Youssef and El-Sayed 2018). The antimicrobial activity can also be introduced to the biodegradable packaging using the surface functionalized nanosystems. For example, recently scientists have been
4.2 Nanomaterial Classifications
bonded the benzoic acid to Mg–Al hydrotalcite and combined them into polycapro-lactone, in order to provide an active antimicrobial food packaging (He and Hwang 2016; Sekhon 2010).
4.2.3 Organic Nanomaterials
The organic nanosystems, such as nano-sized vitamins and antioxidants, can also be designed to be used in food sectors in order to increase their cellular uptake and bio- absorption and enhance their bioavailabilities, compared to conventional bulk equivalents. It was predicted that if the food additives, such as preservations (e.g.
citric acid, benzoic acid phosphoric acid) or nutraceuticals (e.g. vitamins A, D and E, carotenoids, poly-unsaturated fatty acids, and Co-Q10), colorants etc. would be available as nano-sized, and their functionality can be considerably increased (Sekhon 2010). For example, in our previous research, the astaxanthin (a carotenoid with high antioxidant activity) nanodispersions have been formulated using various stabilizers. It was concluded that the gained nano-sized astaxanthin showed very increased cellular uptake as well as antioxidant activities than their micro-sized equivalents (Anarjan et al. 2012). The similar results have been reported for other nano-sized functional lipid compounds’ nanoparticles. Recently, the nanoparticles, such as fullerenes and carbon nanotubes, have also been used in food processes as an absorbent to remove the undesired odor, colour, pesticide residuals as well as to clarify them. These nano-absorbents showed considerable efficiency in absorbing the organic materials due to their great surface area, resulting from their size reduc-tions into nano-ranges (Hou et al. 2014; Paszkiewicz et al. 2016).
Furthermore, the organic nanoparticles, such as carbon nanotubes, can also be incorporated into the food packaging matrix in order to improve their mechanical strength and elasticity, flexibility, gas barrierity or adjust their electrical conductivi-ties. The essential oil nanoparticles with antioxidant and antimicrobial activities can also be incorporated into packaging materials to give various active packaging. If the nanosensors (nanobiosensors), such as immobilized enzymes, are incorporated to the packaging polymer, it offers smart packaging (Bajpai et al. 2018; He and Hwang 2016; Martirosyan and Schneider 2014).
4.2.4 Nanoencapsulated Compounds
Nanoencapsulation is the technique to pack the constituents in order to protect them against environmental destructing stresses, cover their undesired characteris-tics, such as odor or reactivity, and control their release. It can be organized in nanocomposite, nanoemulsions, liposomes and nano-blended forms (de Souza Simões et al. 2017; Katouzian and Jafari 2016). Thus the protection, activity enhancement and stabilization of bioactive compounds, such as proteins, lipids,
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polysaccharides, vitamins and antioxidants, can be attained using nanoencapsula-tion processes (Prakash et al. 2018). The different processes are suggested to pro-vide these compounds’ nanocapsules in various studies, including high or low energy input techniques (Anarjan et al. 2011b). Thus, based on novel nanoencapsu-lation and control release techniques, different delivery systems can be designed to increase the cell absorption of valuable health promoting compounds and, conse-quently, decreases the amount of needed ingredient. Therefore, nanoencapsulation can give considerable savings in which the nano-sized compounds had significant increased surface- based characteristics, such as solubility, conductivity and colo-rant activity etc., in comparison to their micro-sized form (de Souza Simões et al.
2017; Prakash et al. 2018).
Several synthetic or natural surface active compounds, in either small molecular or polymer forms, have the potential to be used as emulsifiers, covering molecules and stabilizers in the nanoencapsulation of nutraceuticals. Thus, the proteins and polysaccharides are desired to be used in nanoencapsulation formulations (Anarjan et al. 2017; Anarjan and Tan 2013b). The protein–carbohydrate conjugations with improved stability, water-solubility and emulsifying properties, increased antioxi-dant activity and reduced allergenicity. They have been used in oil compounds’
nanoencapsulation like essential oils fish oils and polyunsaturated fatty acids (Augustin et al. 2006; Shah et al. 2012).
It was confirmed that the nanoencapsulation of essential oils could enhance their antimicrobial activities and, consequently, their preservation efficiency in the food system. For example, nanoencapsulated terpenes and D-limonene, Mentha piperita, Cardamom, thymol and carvacrol essential oil showed better antibacterial activity against various foodborne pathogens than their micro-sized equivalents (Prakash et al. 2018).
The volatile compounds, which provide the food’s flavor, taste, odor and aroma greatly affect their desirability by consumers. However, they have a tendency to decline because of evaporation, oxidation and degradation. Thus, their retention techniques are interesting for food scientists. Nanoencapsulation of these com-pounds can protect them and control their releases, effectively meeting the food industry challenges about the extension their shelf life, freshness, long lasting flavor and organoleptic features (Katouzian and Jafari 2016). Contrary, some healthy com-ponents, such as fish oil, have an undesirable taste or odor. Nanoencapsulation tech-niques can also resolve this problem by masking the unpleasant tastes and odors.
The nanoencapsulated essential oil can be released by diffusion, wall material deg-radation or bursting the nanocapsules by swelling (Osorio-Tobón et al. 2016).