Gordon L. Robertson, adjunct Professor at the University of Queensland and Principal Consultant at Food•Packaging•Environment, reviews recent trends and innovations in food packaging.
Figure 4 LiquiGlide coatings (on right) can offer almost full emptying of viscous condiments, even from narrow aperture packages.
The food packaging industry is vibrant and highly competitive, with food manufacturers always on the look-out for packaging that can provide consumers with increased convenience as well as longer shelf life at a lower cost than their existing packaging. The food industry is well aware that consumers want innovation and value novelty, and therefore the packaging industry must innovate or stagnate. Given the size and diversity of the food packaging industry, this brief overview can only touch on a few of the major trends and innovations.
1. Material substitution Image may be NSFW. Clik here to view.Over the past few decades there have been significant changes in the relative proportions of the packaging materials glass, metal, paper and plastics used to pack food. Most noticeable has been the switch from glass (and to a lesser extent metal) to plastics with, for example, the majority of beverages nowadays packed in polyethylene terephthalate (PET). It is just 40 years since the first PET bottle appeared in the market and its growth since then has been hugely successful. The last great glass markets under threat from PET are wine and beer and recently Sidel created a pasteurisable PET bottle that utilises a ‘champagne’ base traditionally found on glass beer bottles (Figure 1). It also supports a crown cap, which together with the non-petaloid base, gives the appearance of a glass bottle. A 330 mL bottle weighs only 28 g, which is up to 86% less than an average equivalent glass bottle; a 600 mL bottle is also available. The reported shelf life of up to 6 months is based on <1 ppm O2 and <17% CO2 loss which is a requirement of the brewing industry. Another big market for PET bottles is edible oil and recently a 3 L PET bottle with a handle was launched in the USA. Its light weight and convenience are likely to prove popular with consumers.
2. Lightweighting Image may be NSFW. Clik here to view.Lightweighting has been going on for decades, driven primarily by economics but in recent years it has always been trumpeted as being driven by environmental concerns. Just when you think the limit has been reached, a new low is achieved. For example, Krones new PET Lite 9.9 bottle weighs just 9.9 g for a 500 mL carbonated beverage bottle and is 30 to 45% lighter than comparable PET containers on the market. Direct printing onto the bottle means that no label is required and a special neck finish enables a tearoff ring-pull closure to be attached (Figure 2). Another recent example is the Sidel RightWeight PET 500 mL bottle for water that weighs just 7.95 g. To put this into context, the industry average is 12 g and in 1985 the weight of a comparable bottle was 28 g. As well as being lighter, this latest bottle has 32% more top-load performance.
3. Smart labels
The Universal Product Code is a bar code symbology used for scanning packages at point of sale. It has been widely used on food and other packs since its launch in 1974 on a 10-pack of chewing gum. Now a variety of bar code symbologies that can be read by smartphones are appearing on packs. The QR (quick response) is the most common – it can launch exclusive content, update your Facebook status, download coupons, promotions and music and invite your friends to join you. Guinness has unveiled a product-activated QR code printed on a glass that only becomes visible when the glass is full of dark beer. When the glass is empty, or filled with a pale amber beer, it cannot be seen.
4. Sustainability
Although sustainable packaging is widely discussed at conferences and in the packaging media, there is no consensus as to what it is. Many in the packaging industry are confused; consumers are also very confused and the potential exists for unscrupulous companies to market packages as ‘sustainable’ when they are not and thus mislead consumers. However, a single definition of sustainable packaging is unfeasible, as the sustainability of a packaging material intrinsically depends on aspects specific to its life cycle, such as its manufacturing process, the length of its supply chain, its use and finally its disposal options. Many professionals would even argue that there is no such thing as ‘sustainable packaging’. Rather there are improvements that can be made to the packaging’s attributes and its manufacturing process in order to reduce its life cycle impacts and improve the efficiency of the supply chain. This was confirmed in the conclusions to a 2012 report from PwC [1] which found that sustainable packaging was no longer a relevant term today as it is too broad to be useful at a practical level. Furthermore, no one can come up with a single meaningful definition of sustainable packaging. As a consequence, sustainable packaging has been substituted with a more balanced view of efficient packaging: minimum resources, minimising product waste, transport and display efficiency and effective after-use disposal and recycling. UK-based INCPEN defines a sustainable packaging and product supply chain as a system that enables goods to be produced, distributed, used and recovered with minimum environmental impact at lowest social and economic cost.
5. Biobased but not biodegradable plastics
Sustainable means to maintain or keep going continuously and the word has been used in connection with forest management for over a century. To be sustainable, consumption of resources must match their rate of renewal and therefore the use of non-renewable resources, such as petroleumbased plastics (and metals), is unsustainable. This has led to a focus on renewable biobased plastics. Nature produces 170 billion metric tonnes per year of biomass by photosynthesis yet only 3-4% of this material is used by humans for food and non-food purposes [2]. Biomass carbohydrates are the most abundant renewable resources available (75% of this biomass) and are currently viewed as a feedstock for the green chemistry of the future (including bioplastics).
Bioethylene can be produced by the catalytic dehydration of bioethanol produced by the fermentation of carbohydrates, followed by normal polymerisation to produce polyethylene (PE) as shown in Figure 3. It is not biodegradable and has the same properties, processing and performance as PE made from natural gas or oil feedstocks. The major producers are in Brazil and use sugar from cane as the starting material. Current applications by multinationals include yogurt cups (Danone), fruit juice bottles (Odwalla) and plastic caps and closures for aseptic paperboard cartons (Tetra Pak)
Such developments have led to the new paradigm for sustainable food packaging: biobased but not biodegradable [3]. This is further evidenced by Coca-Cola’s PET Plantbottle® where the ethylene glycol and the terephthalic acid are derived from plant-based sugars and agricultural residues. Although the 100% biobased bottle was released in Milan in June 2015, it will be five to eight years before it is available in commercial quantities and it will not reach price parity (equalling the price of producing current Coca-Cola PET bottles) until 2018. Heinz and Danone will also have access to this bottle.
A very exciting development undertaken by Avantium in The Netherlands has resulted in a new polyester: polyethylene furanoate (PEF), an analogue of PET. [4] The main building block in PEF, 2,5-furandicarboxylic acid (FDCA), is derived from plant-based carbohydrates and can be used as a replacement for terephthalic acid. PEF could replace PET in typical packaging applications, such as films and in particular bottles, as it outperforms PET in many areas, particularly barrier properties. Specifically, PEF’s O2 barrier is ten times better than that of PET, the CO2 barrier is four times better and the H2O barrier is two times better. Pilot-scale production is currently underway. Of course sustainably managed forests have an assured future supplying paper and wood-based packaging materials. Earlier this year Carlsberg announced its ambition to develop the world’s first fully biodegradable woodfibre (moulded pulp) bottle in conjunction with EcoXpac, which owns the rights to an energy saving, impulse-drying technique that it is claimed will ‘disrupt the market for moulded fibres.’ All parts of the bottle — including the cap — are to be manufactured using only biobased and biodegradable materials ‘so they can be responsibly discarded and degraded.’
This raises the question as to why biodegradation is so popular among the general population and in the media. To many consumers biodegradation appears ‘natural’ – it is what nature does so it must be good! They believe biodegradable packaging will solve the solid waste problem plus the litter problem although few cities are able to collect and compost green waste. Biobased, biodegradable plastics have even been classed as ‘sustainable packaging’ by some people and organisations. But converting a solid material to a gas via biodegradation or composting cannot be sustainable. It is much better to recycle or recover the embodied energy through incineration. There is a need to close the resource loop and make the most out of the material rather than simply use it once.
Life Cycle Assessment (LCA) quantifies the resource and energy use as well as the environmental burdens over the entire life cycle of a package and is used to show how, for example, lightweighting and material changes lower environmental impacts. However, the conclusions cannot be extrapolated to provide universal generalisations as the results are specific to the precise system under study. There are a number of software packages available to perform LCAs and a recent study [5] found that results from four LCA software systems disagreed on which package had the greatest environmental impact. Of real concern was the finding that some results were more than an order of magnitude different between software packages and discrepancies occurred in all four impact categories. In addition, all four software systems disagreed with each other at multiple points in the comparisons.
Pawelzik et al. [6] reported that while internationally agreed LCA standards (ISO 14040 and 14044) provide generic recommendations on how to evaluate the environmental impacts of products and services, they do not address details that are specifically relevant for the life cycles of biobased materials. In particular, treatment of biogenic carbon storage is critical for quantifying GHG emissions of biobased materials in comparison with petroleum-based materials.
Innovations
Invention is the creation of a new idea, concept, device or process, while innovation is turning a new concept into commercial success — the introduction of change via something new. It follows that it is not an innovation until a customer says it is! In short, innovation = invention + exploitation. While the patent literature is full of inventions, few ever qualify as innovations. Drivers for packaging innovation include invention, fastchanging social trends, profitability, differentiation, environmental awareness and sustainability.
Among recent innovations that are finding application in the food packaging area are polymer-clay nanocomposites, plasma-enhanced
chemical vapour deposition (used to deposit hydrocarbon films - sometimes referred to as amorphous carbon – on different substrates using, for example, acetylene in a plasma) and atomic layer deposition, all of which canimprove the barrier properties of plastic and (in some cases) paper packaging. Space only permits a discussion of the latter.
Atomic Layer Deposition (ALD)
ALD was invented in 1974 by Dr Tuomo Suntola at the University of Helsinki. It is a surface-controlled, layer-by-layer, thin-film deposition process based on self-terminating gas-solid reactions. In packaging applications, metal oxides such as Al2O3, SiO2 and ZnO are applied and a 10 nm oxide layer typically decreases the oxygen transmission rate by a factor of 10. Recently, water vapour transmission rate (WVTR) of ~6 x 10-3 g m-2 day-1 for PET using atmospheric ALD at a deposition temperature of 50˚C was reported and when this invention is commercialised it will have a significant impact on food packaging structures. [7]
LiquiGlide
Founded in 2012 from research at MIT, LiquiGlide coatings allow viscous liquids to move easily due to permanently wet slippery surfaces. The coatings consist of two layers: a porous solid layer and an impregnating liquid layer. The first consumer products with LiquiGlide coatings are expected to hit shelves in late 2015, with likely products including mayonnaise and ketchup (Figure 4). Benefits include reducing waste, increasing consumer value and eliminating the need for complicated pump modules and dispensing/closure systems.
Serac’s Roll N Blow
Invented by Agami and commercialised by Serac, Roll N Blow uses an innovative tubular thermoforming technology to produce cups or bottles from plastic reels of polystyrene or polypropylene. Sizes range from 100 to 500 mL. The innovation lies in a vertical thermoforming process that first forms the plastic sheet into a pipe before heating and blowing the bottle into a mould. As a consequence, bottle designs are not limited to large necks and small heights and can be shaped totally round. Such bottles also show a better resistance to vertical compression than with flat thermoforming.
Amcor’s LiquiForm™ Bottle
LiquiForm™ uses the consumable liquid instead of compressed air to hydraulically form and fill the PET container on one machine simultaneously. This simplifies the manufacture of rigid plastic containers and significantly reduces cost and waste. It differs from traditional blow moulding and filling operations in that when the preform is placed in the mould the actual beverage is forced at high pressure into the preform, moulding it into the bottle shape. This results in a filled bottle, ready for capping and labelling. Amcor and Sidel own 50:50 in a joint venture that is commercialising this invention.
Gordon L. Robertson, Ph.D., is an adjunct Professor at the University of Queensland and Principal Consultant at Food•Packaging•Environment, 6066 Lugano Drive, Hope Island, QLD 4212, Australia. He will be running a workshop on Plastic Packaging & Shelf Life at Campden BRI in October 2015. Email: gordonlrobertson@gmail.com Web: www.gordonlrobertson.com
References
[1] Robertson G.L. 2013. Food Packaging Principles and Practice. 3rd edn. Boca Raton, Florida: CRC Press, 728 pp.
[1] Robertson G.L. 2014. Biobased but not biodegradable: a new paradigm for sustainable food packaging? Food Technol. 68(6): 61-70.
[1] Speck R., Selke S., Auras R., Fitzsimmons J. 2015. Choice of life cycle assessment software can impact packaging system decisions. Packag. Technol. Sci. 28: 579-588.
[1] Pawelzik P., Carus M., Hotchkiss J., Narayan R., Selke S., Wellisch M., Weiss M., Wicke B., Patel M.K. 2013. Critical aspects in the life cycle assessment (LCA) of bio-based materials—reviewing methodologies and deriving recommendations. Resour. Conserv. Recyl. 73: 211-228.
[1] Hirvikorpi T., Laine R., Vähä-Nissi M., Kilpi V., Salob E., Li W.-M., Lindfors S.,Vartiainen J., Kenttä E., Nikkola J., Harlin A., Kostamo J. 2014. Barrier properties of plastic films coated with an Al2O3 layer by roll-to-roll atomic layer deposition. Thin Solid Films 550: 164–169.
[1] Koopmans R.J. 2014. Polyolefin-based plastics from biomass-derived monomers. Chpt. 14 in Bio-Based Plastics: Materials and Applications, ed. S. Kabasci, pp. 295-310. John Wiley & Sons Ltd., Chichester, England.
