nanotechnology in the packaging industry -...

Nanotechnology in The Packaging Industry:Where Are We Now and Where Can We Go From Here?

Graham Bonwick & Catherine Birch

Current Context – Pressures on the Food Supply Chain

Notes: 1. The significant growth of the Indian and Chinese populations2. The rise of the urban population

Progressive urbanisation and loss of productive lands

Social Change

Single person households

Decline in shared meals

Time poverty

Social Change

Loss of cooking skills

Technological Change

•Centralised Production

•Rapid Distribution (Just in Time)

•The rise of the R2E meal

Food Security

Food Security is the sum of many processes.

The sustainable supply of sufficient food necessary to prevent hunger and maintain a healthy balanced diet to ensure wellbeing.

Requires consideration of the safety and quality of food as well.

Packaging – The Forgotten Contributor to Food Security?

Enhanced Barrier Performance – lighter, stronger, greater internal environment control / external environment protectionSustainability – materials for a circular economySecurity – sensing, reporting, shelf life extension, waste reductionConsumer engagement and communication

The Packaging Wish List

A nanometre is one millionth of a millimetre

80,000 nanoparticles in a row

1 m

Cube

Size

No. of cubes

in 1 cubic

metre

1

Total surface

area

6 m2

1 nm 1027 6,000,000,000 m2 = 6,000 km2

1 cm 1,000,000 600 m2

1 mm 1,000,000,000 6,000 m2

PROPERTIES OF NANOPARTICLES

Conditions: 25oC, pH7, in water

1 nm3

Time to dissolve:SAND

1 mm3 34 million years

1.1 seconds

1st Generation - ‘Hard’ Nanomaterial Applications

Carbon nanotubes and graphene

Nanoparticulate metalshttp://joogroup.cbe.cornell.edu/nanofibers/

Metal nanofibres

‘Hard’ Nanomaterial Applications

Antimicrobial properties of metallic nanoparticles (40 – 100nm)

Effective against Gram+ and Gram- bacteria• Permeate cell walls• Reduce ATP levels• Disrupt DNA replication• High catalytic activity• Induce oxidative stress

Effective against: E coli; Listeria; Salmonella spp;

TiO2 also effective at killing bacteria especially under UV radiation

Engineered ‘Hard’ Nanomaterials

‘Hard’ Nanomaterial Applications - Nanoclay

Tie Lan, 2007

‘Hard’ Nanomaterial Risks• Still largely unknown, initial concerns raised by Gatti et al. (2002)

• FCM silver nanoparticles interfere with DNA replication fidelity (Wang et al., 2009)

• Ingested nanosilver particles re-distributed throughout entire body including brain in rats (Wijnhoven et al., 2009).

• Evidence of transfer of hard nanomaterials from FCMs to food

Natural Nanomaterials

• Milk contains 80% casein and 20% whey proteins. • The phosphoprotein casein is in the form of micelles. • Casein molecules are linked by calcium ions and

hydrophobic interactions. • Kappa-casein molecule tails associate to form a mesh.• Colloidal calcium phosphate nanoclusters also help link

smaller sub-micelles together (deKruiff et al., 2012).

Natural Nanomaterials

Casein micelles can be usedto encapsulate materials.

Enhanced delivery and absorption from the gut.

Also slow release properties.

A safe alternative to ‘hard’ nanomaterialsSustainable sourcesBiodegradable?Greater consumer acceptance?Waste valorisation opportunitiesNanoparticulate materials – anti-oxidants from waste to extend shelf lifeEssential oils as anti-microbialsNanocapsules and fibres for controlled or extended release

Natural ‘Soft’ Nanomaterial Applications

Encapsulation technology involves the formulation of products in the form of micelles, liposomes and encapsulates natural or chemical components

Natural Sources - Variable Composition

Biopolymers for Packaging

26

Chitosan

Has various applications due to its biodegradable and nontoxic properties

chitosan and chitosan nanoparticles are found to be more effective against plant

pathogens like Fusarium solani

The chitosan therefore could be formulated and applied as a natural antifungal agent in

nanoparticles form to enhance its antimicrobial activity (Ing et al., 2012)

Radiation induced

degradation to

produce low

molecular weight

chitosan

Natural Materials – Need for Quality Control

Nanofibres

• Electrostatic spinning (electrospinning) of nanofibers based on the use of natural polymers.

• A simple and versatile manufacturing procedure compared with more complex nanostructure assembly methods.

• Can produce higher level structures based on non-aligned, aligned, woven/patterned fibre networks, enabling 3d structures with high surface areas to be built.

• Applications to sensors, surface coatings

• Can be produced with co-spun encapsulated materials

Electrospinning

Electrospinning

Polystyrene nanofibres – 85% open space, antimicrobial

‘Natural Nano’ – PCL Nanofibres

Structured Nanofibres

Recent electrospinning developments

• Enhanced antimicrobial effects by incorporation of natural materials – nisin, essential plant oils, antioxidants (see Zhang et al., 2017)

• Extended performance due to controlled release from nanofibers – shelf life extension

• Surface coatings or as composite materials within other polymers

Nisin – polycyclic peptide from Lactococcus lactis.Effective against a wide range of Gram positive speciesincluding the food pathogen Listeria monocytogenes

Cellulose Nanofibres (CNF)

Also known as nanocrystalline cellulose or microfibrillated celluloseDiameters 5-25 nm, wood pulp subjected to initial homogenization, milling, heating etc.

Nanocellulose developments

• Surface modification of the nanofibers and attachment of biomolecules e.g. antibodies/aptamers

• Applications to paper and board manufacture –enhance bond strength and reinforcement/strengthening of materials e.g. other natural polymer matrices such as polylactides. A safer alternative to carbon nanotubes?

• Improved barrier properties (oxygen) when used as a coating

• Oil resistance – grease proof papers

• Smoother surfaces for printing / improved glossiness

Nanopolymers and Packaging

• Antimicrobial nanopolymers from natural sources –food grade ingredients and edible film usage

• Chitosan from crustaceans is the primary material presently (also non-allergenic)

• Antimicrobial activity is the primary focus for packaging• Renewable natural sources explored include starch,

cellulose, alginate, carrageenan, soy protein, corn zein, wheat gluten, gelatin, collagen.

• Nisin is easily degraded on contact with food materials and so nanoencapsulation strategies are also being explored e.g. nanoencapsulated nisin in nanoliposomesin hydroxypropylmethylcellulose film or chitosan films

Edible films

• Desire to move away from petroleum based materials such as PE and PP

• Edible and biodegradable natural polymers are desirable alternatives although complete replacements also considered acceptable

• Biopolymers (carbohydrate or protein-based) also need to provide a barrier to control gas/water diffusion, also act as carriers of food additives, flavours, antioxidants and exhibit antimicrobial activity.

• Most biopolymers are water soluble and so inclusion of essential oils is problematic due to low solubility / poor non-uniform film distribution. Nanoemulsions appear to provide a solution –ultrasonication of essential oils in methylcellulose to provide an edible film (Otoni et al. 2014)

• Nanosilver has performed well when incorporated into biopolymers (although concerns exist in relation to this material)

Edible Films

• Chitosan frequently used, however, efficacy is diminished by inclusion of other materials such as proteins or oils to enhance barrier properties.

• Nanoencapsulation of active components or use of nanoparticulate materials in conjunction with chitosan films appears to overcome these issues

• E.g. Abugoch et al. 2016 demonstrated that nanoencapsulated thymol in a chitosan / quinoa protein blend inkjet printed onto surfaces demonstrated enhanced antimicrobial activity compared to chitosan alone for Gram positive & negative bacteria (Listeria innocua, S. aureus, S. typhimurium E. coli, P. aeruginosa Enterobacter aerogenes)

Bionanosensors

• Metal nanoparticles (NPs)

• Magnetic NPs

• Nanowires

• Nanofibres

• Carbon nanotubes (CNTs)

• Nanoscopic gold tube

• Nanocrystalline silicon

• Quantum dots (QDs)…and many more

The type of nanomaterial exploited depends on the type of sample and the analyte to be detected

NP-based Detection Systems

Antibodies

• Engineering – nanogold support

Blue lines – clustered nanogold antibody complexes

Nanogold-antibody complexes for rapid detection

Nanogold antibody complexes observed with polarized light (Wong et al. 2013)

Antibodies

• Large molecules (160 kDa) adapted to physiological conditions• Antigens <1000 Da not immunogenic• No conformational change or other response on binding target

molecules (antigen)• Protein based, no sequence information, binding site not

modelled• Cannot be chemically synthesized, limited/no opportunity to

engineer antigen binding site

Aptamers• High affinity single stranded nucleic acid molecules (DNA/RNA)

• Production by chemical synthesis

• Can be targeted to bind different molecular targets

Aptamer complexed with vitamin B12 (http://aptamer.icmb.utexas.edu/index.php)

Aptamers - Selective Pathogen Binding

Bacterial cells incubated with FAM-labelled aptamers (50 pmol)

Nanomaterials and QS Inhibition?

• Quorum sensing (QS) in microorganisms mediated by small molecules

Nanotechnology Advantages

• Improved barrier resistance• Incorporation of active components for functional

performance• Sensing and reporting of internal and external

environment conditions• Prior developments indicate likelihood of

successful exploitation e.g. • Materials with improved barrier properties or

antimicrobial effects• Nanosensors

Smart Packaging – A great futureCombining and integrating active & intelligent packaging concepts

-Monitor changes in product or environment and to respond appropriately to changes via feedback mechanisms?

Nanotechnology & Packaging - Some Observations

Packaging and Nanotechnology – Next Steps?

• Improved barrier resistance• Incorporation of active components for functional

performance• Sensing and reporting of internal and external

environment conditions• Prior developments indicate likelihood of

successful exploitation e.g. materials with improved barrier properties or antimicrobial effects

• Nanosensors

Nanotechnology & Food Packaging Publications

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Frequency Based on Key Words in Publication Titles

Packaging Food Packaging Meat Packaging

• Nanotechnology is an important tool to overcome challenges currently faced in relation to food security and sustainability

• Advancement continuing opportunities for enhanced shelf-life; quality & safety, consumer information and protection

• More research needed on migration characteristics and potential toxicity

• Challenge: Finding scalable cost-effective production methods using natural materials

• Precautionary principles must be applied!

Nanotechnology & Packaging - Some Observations

Thanks for your attention!