NANOTECHNOLOGY IN FOOD PACKAGING (FOOD TECHNOLOGY)

NANOTECHNOLOGY IN FOOD PACKAGING

1. NANOTECHNOLOGY IN FOOD PACKAGING M.Tech Department of Food Engineering & Technology : .

2. Content Introduction History Synthesis of nanomaterials Importance (Why Nanotechnology?) Application of Nanomaterials Polymer Nanocomposites Nano-co atings Surface biocides Active packaging Intelligent Packaging Commercial uses Advantages & Disadvantages Safety issues References

3. Introduction Nano denotes nanometer (1nm=10 -9 m) Nanotechnology is the ability to work on a scale of about 1-100nm in order to create, characterize and use material structure, devices and system with new properties derived from their nanostructures. Nanotechnology

4. History Father of Nanotechnology - Richard Feynman 1959 – introduced the concept of nanotechnology 1974 - "nano-technology” term coined by Norio Taniguchi

5. Synthesis of Nanomaterials There are two approaches: 1)Top-Down Approach : size reduction of bulk material by grinding, laser abrasion 2) Bottom-up Approach : allows nanostructures to be built from individual atoms or molecules

6. Why Nanotechnology ? Fig. : Importance of Nanotechnology in Food Packaging

7. Applications of Nano-materials 4. Active packaging 2. Nano-coatings 3. Surface biocides 1. Polymer Nano composites 5. Intelligent Packaging 6. Bio-plastics ( Bradley, E.L. 2011)

8. 1. Polymer Nano-composites Incorporating nanomaterials into the packaging polymer to improve physical performance, durability, barrier properties, and biodegradation . (Bradley, E.L. 2011) Polymer Matrix + Nanomaterials= PNCs

9. Production of Nanocomposites

10. (Vijay Kumar Thakur, 2020) Fig. Production of Nanocomposites

11. Polymer nano composites(PNCs) PNCs are created by dispersing an inert ,Nanoscale filler through out a polymeric matrix. Fillers are Silica Organo-clay Polysaccharide nanocrystals Carbon nanotubes Cellulose based materials (fibres, crystals) Chitosan And other metal nanoparticles (ZnO 2 , Colloidal Cu etc. ) (Li R. et al., 2011)

12. Nanoclays are nanoparticles of layered mineral silicates. Examples : montmorillonite, bentonite, hectorite etc. Nanoclay was the first material to appear on the market among the polymer of nano-composites and has been the most commonly used nanomaterials in food packaging . It is commonly used for improving the physical properties of plastic packaging and its barriers to gas and moisture. Nanoclay is generally recognized as an essential filler for bio-based polymer reinforcements as it can enhance barrier properties, creep resistance and provide mechanical strength of bio-polymer with very low clay content while biodegradability remains intact. Nanoclay

13. Fig. : (a) Gas Permeation in polymer (b) Gas Permeation in polymer-nanoclay matrix

14. The pattern of nanoclay dispersion in the polymer matrix is classified into one of three categories : I. TACTOID The tactoid arrangement is a compact, face-to face stacking. A tactoid structure in a nano-composite rare find due to its poor affinity with polymers. The agglomeration of clay platelets with a tactoid structure leads to a low barrier structure. II. INTERCALATED The intercalated pattern allows only a moderate dispersion level of the clay into the polymer matrix. III. EXFOLIATED Exfoliated nanoclay clusters readily lose their tendency to agglomerate, And are separated into single flakes, There by facilitating dispersion of the nanoparticles in a polymer ma trix.

15. Morphologies of nanoclay in polymer matrix Fig. : Nanoclay Morphologies in the Polymer matrix

16. Nylon Polymer / Nano clay hybrids (NCH) Clays or other silicate materials Popularity is due to Low cost, High stability & Effectiveness. Montmorillonite(MMT) [(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2.nH2O)] Only 1.6 wt% clay silicate layers loading,its strength, modulus, and heat distortion temperature were much higher than those of neat nylon 6.

17. USES OF NANOCLAY In Biopolymers such as polylactic acid (PLA), polycaprolactone (PCL), and poly(butylene succinate) (PBS) Nanoclay has been recognized as major reinforcement filler for biobased polymer. (Rhim, 2013) characterized bio-composite films prepared with Agar and nanoclay and showed that tensile strength, water vapor permeability, and hydrophobic behavior of agar films are greatly influenced by nanoclay. BIOPOLYMERS BIO-COMPOSITE FILMS

18. Liu and Berglund (2015) developed nanopaper which is composed of montmorrilonite nanoclay, nanofibrillated cellulose and chitosan. Due to the molecular clay platelet, this nanocomposite paper showed low oxygen transmission rate, excellent mechanical properties and fire retardancy. NANOPAPER

19. The first successful example of a polymer–clay nano-composite(PCNC)was a nylon 6MM T hybrid material developed by the Toyota Corporation in 1986. (Kawasumi, 2003)

20. Properties of PNCs 1.Enhance polymer barrier properties 2.Stronger than normal polymer 3.More flame resistance 4.Possess better thermal properties (Melting point, degradation and glass transition temperatures, than the control polymers which contain no nano scale filler) 5.Alterations in surface wettability and hydrophobicity

21. Current Migration Research (PNCs) Avella, et al.(2005), investigated the migration of nanoclay from starch-based materials. Composite films were prepared with potato starch and 4% ( w/w ) clay and immersed in distilled water at 40 ºC for 10 days. The results showed that weight loss depended on the sample’s pre-conditioning processes. The composite films that were pre-conditioned by drying under a vacuum retained their weight for 10 days in water. In contrast, the composite film without any preconditioning presented a weight loss of approximately 15% after 10 days immersion. However, this study did not provide sufficient data as to whether the weight loss was caused by loss of moisture or inorganic compounds from MMT.

22. Schmidt, et al.(2009) investigated and determined the total migration of MMT from a PLA nano-composite. The simulant for fatty food, which is a mixture of 95% ( v/v ) ethanol and distilled water, was prepared according to the European Committee for Standardization . Film samples were completely immersed into the simulation solution at 40ºC for 10 days. The unidentified nanoparticles of 50 to 800 nm in radius were detected in food simulant. However, the signal for clay components was not detected by ICP-MS, and therefore this study concluded that the clay nanoparticles were stable and did not migrate from the composite film. Current Migration Research (PNCs)

23. 2. Nano-coatings Nanocoatings are ultra thin layers of the nanoscale. They are used to impart a particular chemical or physical function(s) to a surface as gas-barrier coatings, hydrophilic/hydrophobic or oleophobic properties, improve corrosion resistance and enhance insulating or conductive properties. Several types of nanocoatings are known in food packaging applications such as: nanocoating inside package, outside package, sandwiched as a layer in laminated multilayer packaging films.

24. . Depending on the desired function, nanocoating uses some nanomaterials as in the case of antimicrobial coatings containing silver, titanium dioxide, zinc oxide, some organic bioactive agents as polysaccharides, proteins, spice and herb extracts as essential and vegetable oils, bacteriocins (ex: Nisaplin®, nisin, pediocins), organic acids for food packaging. Vacuum-deposited aluminium coatings on plastic films are commonplace as barrier materials for packaging snack foods, confectionery and coffee. The aluminium coating can be about 50 nm thick.

25. Production of Nanocoatings Layer by Layer method : The films are formed by depositing alternating layers of oppositely charged materials .

26. Fig. : Layer-by-layer (LbL) technique by (A) dipping and (B) spraying (Langmuir, 2009)

27. Electrospinning method : High voltage electricity is applied to the liquid solution & a collector.

28. . Other methods : Sol-gel method Solution casting Extrusion Surface immobilization Photografting Biological methods Plasma nanocoating

29. Preparation of Nanocoated material Naamani et al, 2016 done research on Chitosan-zinc oxide Nanoparticle Composite Coating for Active Food Packaging. They coated package surface as follow:- Polyethylene (PE) films were cleaned with 70 % ethanol solution and dried at room temperature (26 °C). The dried PE films were then treated using a plasma instrument (Pressure: 0.2mBar, O 2 :3 -4 standard cm 3 per minute, Power:50 %). Plasma treatment was used to provide a hydrophilic property to the PE surface in order to result in a better attachment of chitosan to the PE surface. After plasma treatment, 6 ml of previously prepared chitosan-ZnO nanocomposite solution was sprayed on the PE surface (10 x 15 cm) and allowed to dry at room temperature (26 °C). PE films coated with 2 % chitosan were used for comparison, and uncoated PE was used as a control.

30. Nano-Silica Coated High Oxygen Barrier Films Nano-silica material is coated on base plastic films such as PET, OPP, Nylon etc. Food Packaging Applications : Processed Meat products (Beef Jerky, Rare Meat, Sausage, Ham etc.) Fresh Food like Rare fish, Sushi, Dried Fish etc. Processed milk products (Cheese) Bakery & Confectionery (Soft cake, Sandwich, Snack, Candy etc. ) Nut Products with high fat (Smolanderand choudhary, 2010)

31. . Features Excellent Oxygen and moisture barrier, shelf life of packaged food increases, and hence the production cost can be decreased. Aroma Preservataion, Transparent, Good printablility and Laminating machinability, Eco-friendly Excellent mechanical and optical property (Retains the properties and characteristics of base films).

32. Fig. : Nano-Silica Coated High Oxygen Barrier Nylon (OPA) Films

33. 3. Surface Biocides Incorporating nanomaterials with antimicrobial properties on the packaging surface of packaging material. Used to maintain the hygienic condition of the food contact surface by preventing or reducing microbial growth. Common in some reusable food containers such as boxes and crates and the inside liners of refrigerators and freezers also.

34. . Have a very high ratio of surface area to mass. Chemicals commonly used are : a)Nano silver ( in the form of metallic silver(Ag) , AgNO3, etc.) b)Zinc oxide c)Titanium dioxide (TiO2) d)Magnesium oxide

35. Nanomaterial with Silver nanoparticle Silver has long been used as an antimicrobial agent for food and beverage storage. In 2009, the United States Food and Drug Administration (USFDA) regulated the use of silver nitrate as a food additive for antimicrobial activity in bottled water with a maximum concentration of 17 microgram/kilogram . Silver ions are fatal to many microorganisms including bacteria, algae, fungi, and possibly some viruses. Jeong, et al . reported that about 650 disease causing pathogens can be killed by silver molecules.

36. Antimicrobial mechanismof AgNPs AgNPs surfaces serve as vehicles for the delivery of ions (Ag+) to the interior of the microorganisms causing DNA damage. AgNPs can adhere to the cell surface and degrade lipopolysaccharides, consequently forming a pit in the cell membrane.

37. Fig. : Antimicrobial activity of Ag nanoparticles of different size range (5-100nm) ( Carbone et al., 2016)

38. Migration Research (AgNPs) Song, et al. (2011), studied the migration of silver from AgNP–polyethylene composite food packaging film, which is produced by Anson Nanotechnology Co., Ltd. (Zhuhai, China). The results showed that the amount of silver that migrated into the food simulants 3% ( w/v ) aqueous acetic acid and 95% ( v/v ) aqueous ethanol- slightly increased with time prior to reaching a steady-state. The migration of AgNPs into the acetic acid was mainly influenced by temperature , while the migration into the ethanol was independent of temperature. Migration was evaluated at 20, 40, and 70 ° C, and the maximum extent of migration was 1.70%, 3.00% and 5.60% into acetic acid and 0.24%, 0.23% and 0.22% into ethanol, respectively.

39. Huang, et al. (2011), investigated the migration of silver from AgNP–polyethylene food fresh bags produced by Sunriver Industrial Co., Ltd. (Fujian, China). Four standard food simulants were used in these experiments: ultrapure water, 4% ( v/v ) acetic acid, 95% ( v/v ) ethanol, and hexane. After washing the sample bags with ultrapure water and drying, each bag was filled with 200 ml of food simulant. Samples were stored for 15 days at room temperature, 40 °C, or 50 °C. The amount of silver migration was analyzed at 3, 6, 9, 12, and 15 days by using scanning electron microscope to confirm the migrated AgNPs. The migration of AgNPs increased with storage time and temperature. This study concluded that the dimension of migrated AgNPs in food simulants was less than 300 nm, which is the threshold at which micro-organisms can survive. Migration Research (AgNPs) .

40. Cushen, et al. (2013), investigated the migration behavior of AgNPs from PVC film into poultry products. This experiment was conducted with skinless and boneless chicken breast. Chicken meat samples were wrapped with 120 cm 2 of AgNP–PVC composite films and were covered with aluminum foil to eliminate any possible variations due to the impact of light. Samples were then stored at 6.6, 7.2, 19.9, or 24.1 ° C and sampled at 1.1, 2, 3.1, or 4 days. The highest rates of silver migration resulted in approximately 8.85 mg/kg or 0.84 mg/dm 2 . However, this concentration of silver was lower than the allowance of European Union (EU) legislation, which allows no more than 60 mg/kg, or 10 mg/dm 2 (2002/72/EC ). Migration Research (AgNPs) .

41. Silver migration in food Higher temperature and lower pH increased the rate of silver ion discharge. The result also showed that the amount of silver migration at 70 ᵒ C for 2 hours was gradually reduced with an increasing number of cycles. The possible mechanism was explained with a two-phase scenario: first cycle caused nearly complete AgNP release from the encapsulated silver within the sample surface layers. second migration took place; silver ions were discharged from an unstable AgNP via an oxidation reaction between remaining nanoparticles and the simulant.

42. Film Effect Reference LDPE film by coating with nano-TiO2 They reported that their film can inactivate E. coli under fluorescent and UV light irradiation. suggest that nano-TiO2 coated films can be applied to food and hygienic packaging in near future. Othman, et al. (2014) TiO2-coated polypropylene (PP) plastic film antifungal activity for fruit packaging Thin layer of TiO2 coating initiated a photocatalytic reaction against Penicillium expansum on lemon peel. Maneerat and Hayata(2006) TiO2 composite films High scavenging activity and fast oxygen reduction in the presence of ethanol due to the photocatalytic redox reaction. Peiró, et al.(2006) Table : Nanomaterials with TiO2

43. Film Effect Refe- rences PVC film with nano-ZnO powder to preserve and prolong the quality of fresh-cut Fuji apples Li, et al.(2011) nano-ZnO composite film with polyethylene prepared and characterized a nano-ZnO composite film with polyethylene and reported the potential to protect food from bacterial contamination Tankhiwale and Bajpai(2012) LDPE-ZnO nano-composite Inhibition of Lactobacillus plantarum for orange juice Emamifar, et al(2011) Table : Nanomaterials & their properties

44. Nanomaterial Types of food Effect References TiO2-coated oriented-polypropylene Lettuce 2 log reduction of E. coli Chawengkijwanich and Hayata, 2008 Absorbent pads containing Ag nanoparticles (NPs) Poultry meat Effective against E. coli and S. aureus Fernandez et al., 2009 Ag montmorillonite NPs Fresh fruit salad Inhibited the growth of spoilage microorganisms and preserve the sensory Quality Costa et al., 2011 Fresh cut carrots Inhibited the growth of spoilage microorganisms and enhanced the shelf life of carrot by more than 2 months stored under 4 Costa et al., 2012 Polyvinyl chloride (PVC) with ZnO NPs Sliced apples Fruit decay rate was significantly lowered Li X. et al., 2011 Low density polyethylene(LDPE) films loaded with Ag and ZnO NPs Orange juice Increased the shelf life of orange juice up to 28 days and inactivate Lactobacillus plantarun Emamifar et al., 2011

45. Nanomaterial Types of food Effect References Cellulose Ag nanoparticles (AgNPs) Kiwi and melon juices 99.9% reduction of total viable count of bacteria and yeast Lloret et al., 2012 Poultry and beef samples 90% reduction of total viable count of lactic acid bacteria Ethylene vinyl alcohol (EVOH) with AgNPs Chicken, pork, cheese, lettuce, apples, peels, eggshells 2 log reduction of bacterial (Salmonella spp., L.monocytogenes) count in low protein food and 1 log reduction in bacterial count in high protein food Martinez-Abad et al., 2012 Low density polyethylene with Ag and ZnO Meat Inhibited the growth of E. coli, P. aeruginosa and L. monocytogenes Panea et al., 2013 Polyethylene with Ag, TiO2 Fresh apples, white slice bread, fresh carrots, soft cheese, atmosphere packaging milk powder, fresh orange juice Inhibited the growth of Penicillium and Lactobacillus spp. Metak and Ajaal, 2013

46. Nanomaterial Types of food Effect References Nanoclays with matrix of polyamide 6 Beef Enhanced O2 barrier properties, capability to block UV and improved stiffness of packaging Picouet et al., 2014 Sodium alginate with CaCl2 and AgNPs Fior di Latte cheese Increased the shelf life upto 10 days and inhibit the proliferation of Pseudomonas spp Mastromatteo et al., 2015 Isotactic polypropylene (iPP) with CaCO3 nanofiller Apple slice Increased the shelf life up to 10 days Volpe et al., 2015 Ag/TiO2 nanocomposite Bread Enhanced the shelf life of bread Cozmuta et al., 2015 Polyethylene with Ag and TiO2 NPs Fresh apples, white sliced bread, fresh carrots, pre-packed soft cheese, MAP milk powder and orange juice Fruit decay rate was significantly lower than in the control sample upto 10 days Metak, 2015

47. 4. Active Nano-packaging Nanomaterials are employed in packaging to directly react with the contained food or its environment to ensure better protection and extend shelf-life of the food. Different properties of nanomaterials as a active food packaging : 1. Antimicrobial property : agents like AgNPs, magnesium oxide, copper and copperoxide, zincoxide, chitosan and carbon nanotubes are used.

48. Fig. : Active packaging and its association with nanotechnology (Mihindukulasuriya and Lim, 2014)

49. . 2. Oxygen Scavenging property : Food deterioration by indirect action of O 2 includes food spoilage by aerobic microorganisms Oxygen scavenger films were successfully developed by Xiao et al .(2004) ,by adding Titania nano particles to different polymers.

50. 5. Intelligent Packaging They are able to respond environmental changes inside the package (Temperature , humidity and level of oxygen exposure) Nano sensors communicate the degradation of product or microbial contamination. (Bouwmeesteretal.,2009) • Also give the history of storage conditions and period of storage. Incorporating nanosensors to monitor and report on the condition of the food.

51. Fig. : Intelligent packaging concept and its association with nanotechnology (Mihindukulasuriya and Lim, 2014)

52. Nanomaterial Types of food Effect Oxygen indicator Uncooked bacon Change in sensor color indicate exposure to O 2 Carbon nanotubes Meat Detection of pathogens in food Xanthine and hypoxanthine chemical indicator Canned tuna Checked the freshness of food sample Table : Nanomaterials for intelligent packaging

53. 6. Bio-Plastics Bioplastics are plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, woodchips, sawdust, recycled food waste etc. Bioplastic can be made from agricultural by-products and also synthesized by using microorganisms.  Examples Starche based : polylactic acid, polybutylene adipate terephthalate, polybutylene succinate, polycaprolactone, and polyhydroxyalkanoates Cellulose-based :  cellulose acetate, nitrocellulose Protein-based : gelatin films, corn zein films Some aliphatic polyesters : polyhydroxyalkanoates like the poly-3-hydroxybutyrate, polyhydroxyvalerate and polyhydroxyhexanoate Other : Polyhydroxyalkanoates, Polyamide 11, Chitin, Chitosan

54. .   Among the bioplastics, polyglycolic acid (PGA) has excellent barrier properties thus it’s one of the most promising new commercially available barrier polymers.  Fig. : Starch based peanut packaging Fig. Blister packaging from Cellulose acetate

55. Table :

56. Manufacturer Application & properties SongSing Nano Technology Food cling wrap treated with ZnO NPs; tea pot treated with Ag NPs Sharper Image and BlueMoonGoods Fresher Longer Miracle Food Storage Containers and Plastic Storage Bags Baby Dream Ag NPs baby milk bottle A-DO Global Ag NP-coated cutting board Nanocor Branded with Imperm. Used in multi-layer PET bottles for food and beverage packaging to minimize the loss of CO2 from the drink and the ingress of O2 into the bottle Honeywell Branded with Aegis® OX. Resin composed of nylon and MMT NPs, enhance barrier properties for retaining CO2 and keeping O2 out. Used in PET bottles such as beer, fruit juice and soft drinks Bayer Branded with Durethan® KU2-2601. Hybrid plastic comprises polyamide and layered silicate barriers. The plastic incorporates Nanocor’s MMT to produce a film with increased barrier properties, enhanced gloss and stiffness Table : Commercially available packaging materials using nanotechnology

57. Advantages Biodegradable nanosensors (monitoring of time, temperature & moisture) Used to preserve the food (improvement in barrier properties, antimicrobial, antioxidant) Improve mechanical & thermal properties (Strength, creep resistance, melting point etc.) Cost effective (required in lesser amount) Eco-friendly (Biodegradable & Edible coatings) Other advantages : light in weight, fire resistance, improve appearance etc.

58. Disadvantages Food safety & quality and impact on consumers Environmental impact Safety Issues

59. POTENTIAL RISKS, HEALTH SAFETY FEATURE OF NANOPARTICLES Nanoparticles enter into the body through inhalation, ingestion or exposure (Maisanaba et al., 2015). Chithrani et al. (2006) reported that the smaller NP(s) exhibit more toxicity than larger ones. Nanoparticles may unintentionally come in GIT contact via leaching/migration of NPs from nanopackaging to food commoditie s (He and Hwang, 2016). NP will inevitably come into contact with a huge variety of biomolecules (proteins, sugars, and lipids) which are dissolved in body fluids such as the interstitial fluid between cells, and blood (Farhoodi, 2016). Liver and spleen are mainly responsible for distribution of nanoparticles , mediating their passage from intestine to the blood circulation (Dimitrijevica et al., 2015).

60. . Studies on titania and silver nanoparticles revealed that these materials may enter blood circulation and their insolubility leads to accumulation in organs (Rhim et al., 2013) Inhalation of very high doses of nano-TiO 2 has been associated with incidence of lung tumors . ZnO NP(s) displayed genotoxicity in human epidermal cells , even if the bulk ZnO is non-toxic, implying the role of particle diameter (Sharma et al., 2009) . Inhaled MgO NP(s) can make their way to the olfactory bundle under the forebrain via the axons of olfactory nerve in the nose and can also travel to other parts of the brain through systemic inhalation . Nanoparticles that finds their way to blood stream may influence the blood vessel lining and their function, may lead to blood clotting , or may even contributes toward cardiovascular diseases . Overall data available concludes that more research is warranted before NPs may be tagged as toxic or safe .

61. NMs & applications Size & physical description Experimental evidence of toxicity TiO2, used as antimicrobial and UV protector in food packaging ( very high doses (10 mg/m3) 20 nm Destroyed DNA 30 nm, mix of rutile and anatase forms Produced free radicals in brain immune cells NPs, mix of rutile and anatase forms DNA damage to human skin cells when exposed to UV light Four sizes 3–20 nm, mix of rutile and anatase form High concentrations interfered with the function of skin and lung cells. Anatase particles 100 times more toxic than rutile ones 25 nm, 80 nm, 155 nm 25 nm and 80 nm particles caused liver and kidney damage in female mice. TiO2 accumulated in liver, spleen, kidneys and lung tissues Table : Toxicity of nanomaterials based on their size

62. NMs & applications Size & physical description Experimental evidence of toxicity Zn and ZnO, used as antimicrobial in food packaging 20 nm, 120 nm ZnO powder 120 nm particles caused dose-effect damage in mice liver, heart and spleen 20 nm particles damaged liver, spleen and pancreas 19 nm ZnO Toxic to human and rat cells even at very low concentrations 58±16 nm, 1.08±0.25 μ m Zn powder Test mice showed severe symptoms of lethargy, vomiting and diarrhea NP dose produced more severe response, killed 2 mice in first week, and caused greater kidney damage and Anemia Greater liver damage in microparticle treatment SiO2, particles nano form touted for use in food packaging 50 nm, 70 nm, 0.2 μ m, 0.5 μ m, 1 μ m, 5 μ m 50 nm and 70 nm particles taken up into cell nucleus where they caused aberrant protein formation and inhibited cell growth Caused the onset of a pathology similar to neurodegenerative disorders

63. NMs & applications Size & physical description Experimental evidence of toxicity Ag, used as antimicrobial in food contact materials 15 nm Highly toxic to mouse germ-line stem cells 15 nm, 100 nm Highly toxic to rat liver cells 15 nm Toxic to rat brain cells

64. References Bambang  Kuswandi, Nanotechnology in Food Packaging, Nanoscience in Food and Agriculture 1 (151-181), 2016   Bambang Kuswandi and Mehran Moradi, Improvement of Food Packaging based on Functional Nanomaterial, Chapter 16 (309-344), 2019   Cornelia Vasile, Polymeric Nanocomposites and Nanocoatings for Food Packaging, Multidisciplinary Digital Publishing Institute, 2018 Kolasinska, M., Krastev, R., Gutberlet, T. and Warszynski, P. (2009). Layer-by-layer deposition of polyelectrolytes. Dipping versus spraying, Langmuir 25:1224–1232 Sneha Mohan, Oluwatobi S. Oluwafemi, Nandakumar Kalarikkal, Sabu Thomas and Sandile P. Songca, Biopolymers – Application in Nanoscience and Nanotechnology, 2016 Wan Akmal Izzati Wan Mohd Zain, Yanuar Z. Arief, Zuraimy Adzis, Mohd Shafanizam, Partial Discharge Characteristics of Polymer Nanocomposite Materials in Electrical Insulation: A Review of Sample Preparation Techniques, Analysis Methods, Potential Applications, and Future Trends, The Scientific World Journal, 2014 Bioplastic – Wikipedia