nanotechnology in the packaging industry -...
TRANSCRIPT
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!