High technology for fish packaging

Fish and seafood have a high nutritional value but are at the same time sensitive, perishable foods. Packaging protects the products from harm and contributes towards reducing losses during transport, storage or at the retailer’s. The functions that packaging has to fulfil are accordingly diverse. And requirements are constantly growing, for the materials used to produce it are today expected to be as sustainable and recyclable as possible.

In the past fishmongers wrapped fish in newspaper before handing it over the counter to the customer but today it is sealed in high tech non-drip, odour proof, insulated packaging. Without these useful packaging options for purpose- and product-specific wrapping of packed goods “normal” commercial life would simply no longer be conceivable. What is true for products in general applies to fish and seafood in particular. Packaging maintains product quality, offers protection, and facilitates movement of goods and handling. Because there is a different packaging solution for almost every need and application, fish products are often repacked several times on their journey from source to the finished product. Producers and exporters tend to prefer bulk packaging from shatterpack to interleaved that is robust enough to withstand the demands of global seafood trade and at the same time guarantee that the products arrive at the customer’s undamaged and in optimal quality. Although the requirements of product packaging in wholesaling and retailing are basically similar further functions are necessary at the retailer’s. There, packaging has to appeal to the final customer, it should offer specific information, and also serve as a buying incentive.

Whether for frozen or cook-in-the-bag products there is a suitable plastic film for nearly every application.

The wide range of packaging solutions for the retail trade is quite overwhelming, particularly in the self-service section. Vacuum packs or MAP, skin packs or sealed plastic trays, traditional folding cartons and tins – not every packaging is right for every product. Fresh fish is packed differently from frozen fish, and the packaging for smoked products or ready-to-cook convenience differs from that used for marinades. Some products are not only packed once but several times, for example MAP smoked salmon which is additionally placed into a cardboard slipcase. A lot of packaging today is elaborately designed, colourfully decorated and equipped with windows for viewing the contents, and other clever details. Sometimes it is even possible to gain the impression that the producer has put more effort into the packaging than the actual product. Customer response to all this effort is not always good: consumers react with increasing annoyance, and for many of them packaging is a necessary evil that can necessitate complicated disposal once it has fulfilled its task of carrying the product the short journey to the domestic kitchen. And their annoyance is even greater if the packaging makes access to the product difficult, i.e. when the ring-pull, zipper closure, easy-peel or other “easy opening” solutions that packaging technologists thought up don’t work as intended. Who, in such situations has not asked themselves whether all this effort is really needed, whether less might not sometimes be better? But what is the right measure, how much packaging do we really need in self-service trade in its current form? And what alternatives would the producers have?


Primary, secondary and tertiary packaging functions

In fact, where some products are concerned companies have different packaging options to choose from. However, the desire for less packaging waste is only one of numerous decision criteria. It must also be considered that the packaging has to meet very high requirements with regard to food safety, moisture stability and hygiene. Apart from that, packaging is exposed to various mechanical stresses, for example during stacking in the warehouse, during transport, and at the retailer’s, for some customers like to touch and press products when considering whether to buy them. In spite of this, the packaging should not in any way suffer from this treatment since it has to be presented in the supermarket in such a way that will be a buying incentive. Packaging has so many functions that they are often grouped for clarity into three categories. The primary functions are geared towards the technical requirements of packaging, for example protection of the contents against external influences during transport, handling and storage. The material used has to be robust, stable and resistant, it should protect the product as far as possible from fluctuating temperatures, moisture and dirt. This function category also includes protection against loss, damages and theft.

The secondary functions of packaging are primarily to serve the retail section for they include the communicative aspects. Packaging should promote sales and make the buying process as rational as possible. Appearance, feel, smell, even the acoustics of the package should appeal to the senses of the consumer, arouse emotions and stimulate them to buy. Printed information on the labels informs shoppers about the ingredients, shelf life, intended usage, correct preparation and particular properties of the product. Product-specific EAN codes enable fast recognition by the scanner at the cash desk. The guarantee function if for consumer protection and product liability. It enables specific product recalls or the acceptance of returned goods by the retailer as long as the freshness seal is still intact. Tertiary functions of packaging comprise its possible additional uses. For example, cartons can be printed with figures to cut out, cups and buckets can be used as storage boxes or toys once they have fulfilled their main purpose, or they can be recycled.

Foods in glass jars or thin sheet metal cans are among the oldest packaging and storage types for fish and seafood.


Glass, tin or plastic

The packaging classic is the tin can, timeless since its development 200 years ago and it has lost none of its popularity. Cans are robust, protect the contents very effectively and convince users through their long shelf life. Nutritional value, flavour and aroma are optimally preserved. No special temperatures are necessary during storage. These are advantages that pay off for producers, retailers and consumers alike. Canned fish plays a significant role in the global seafood market. One just has to think of canned tuna from Asia that is traded in Europe and North America. Fruit and vegetables account for the major share of canned products; more than one quarter of all canned foods (26%) contain fish or other seafood. High-quality products are often preserved in screw top jars that allow a view of the products they contain. Although glass is chemically inert, tasteless and fully approved for food and can in addition also be recycled easily glass jars only account for a small proportion of fish preserves. One explanation for this is probably that glass jars often have to be filled by hand so that the contents are visually appealing. This considerable effort leads to additional costs that raise the price of the mass product.

Instead of glass, producers of preserved products mostly resort to tinplate or aluminium sheet, the “tin” that is known worldwide as the typical canned fish. Metal packaging is also 100% recyclable without quality losses and can thus be re-used after appropriate treatment. Europe-wide, however, only just under two thirds of such cans are recycled at present – estimates speak of slightly more than 60% recycling. And cans rarely consist of pure metal, for on the inside they are today usually coated with plastic based on polyesters, epoxy resins or organosols. This ultra-thin coating prevents direct contact of the contents with the metal of the can which could lead to undesired chemical reactions and alter the taste. Such plastic coatings are criticised by consumer organisations because they can give off substances such as bisphenol A to the contents of the can. Although the quantities released are extremely low it is warned that these substances can act like hormones and are said to be harmful especially to small children. In January 2015 the European Food Safety Authority (EFSA) therefore published a new report on possible health risks arising from bisphenol A. According to this report the substance does not pose a risk to human health in the concentrations concerned.

In spite of such concerns the use of plastics in the canning sector is increasing. There are already cans in which the can body is made of metal and the lid of plastic. To close the can securely the materials are connected using an elaborate folding technique. The plastic lids are relatively light-weight and usually transparent which reduces the weight of the fish preserve and allows a view of the contents. Some of these products are even suited to preparation in the microwave because the plastic lid allows electromagnetic radiation to pass through. Another variant are plastic lids made of PE (polyethylene) which are additionally slipped over the standard sealed can. This means that the can be reclosed after the standard ring-pull or easy peel lid has been removed. In the meantime there are even containers that are completely made of plastic, something which was long thought to be technically impossible, for cans are subjected to temperatures of at least 75°C during pasteurisation or, in the case of fully preserved products, temperatures of above 120°C during sterilisation. This places extremely high requirements on the plastic material used which also has to have good barrier properties against oxygen and other gases. Not just for a few days but over the product’s full lifetime. The immense progress in polymer chemistry and the development of coextruded multilayer plastic film have now made such containers possible, however. In spite of this, products in plastic boxes are likely to remain the exception in the foreseeable future.

The upper film of the skin pack wraps itself snugly around the product, fixes it on the base, and prevents excessive leakage of liquid.


Inexpensive and resilient, temperature and moisture stable

In many areas, however, plastics are indispensable and are considered a universal and cost-effective packaging material. Plastic film, bags and pouches, crates, tubs, buckets and barrels, canisters and pails – plastic packaging can be tailored to use for almost any purpose. Thermoplastics are moisture stable and light-weight and at the same time mechanically resilient and relatively break-proof. They can be thermally formed, coloured as one wishes, and printed on. Some plastic materials are suited to deep freezing, others can even endure oven heat. This versatility opens up ever new application fields in the packaging industry.

Flexible plastic film, for example, is available in different hardnesses and thicknesses. It can be used for wrapping fish, for interleaving packed products, or for plastic bags, carrier bags or sacks. Temperature stable film that can withstand up to 200°C are used to produce cooking bags that are suited to the preparation of foods in the oven, in the microwave or in “sous-vide” techniques. Some of them are equipped with several chambers to enable the separate heating of fish, sauces and other side-dishes. This kind of film mostly allows the passage of any resulting water vapour to enable excess pressure to escape. Cardboard packaging can be coated with a thin film to render it impervious to liquids and to hold in flavour and aroma. Since the development of modern coextruded film which as a rule consists of three to nine laminar layers the application range of “plastic film” has expanded significantly. It is often specifically tailored to its intended use. Hot soups and dried fish, fresh or frozen products, delicatessen salads, seafood mixes and ready meals, almost anything will keep well and maintain its quality in packs made of coextruded film.


Stand-up pouches, MAP-sealed trays, vacuum and skin packs

The success of fresh and smoked fish products in the self-service retail sector was not possible until packaging in modified atmosphere (MAP) was developed.

Applications for plastic film are to be found practically everywhere. Self-adhesive household film protects food in the fridge, cartons on pallets are wrapped and secured by film, shrink film bundles product batches in the warehouse, barrier film seals MAP trays of fresh fish at the retailer’s. Some plastic packaging such as tubs, trays or blister packs are already delivered ready formed and can thus be filled immediately. This type of packaging includes stand-up pouches, flexible bags with a firm base that are in the meantime replacing traditional cans for some seafood products. In contrast to tin cans the stand-up pouches are often equipped with devices that allow the bag to be closed again (e.g. reclosable zippers, retortable press to close). Other packaging varieties are thermoformed in the required size immediately before filling. An example of this method is sealed trays in which fish is packed under protective atmosphere (MAP). MAP usually requires two different films: a relatively rigid lower film that can be thermoformed into a tray, and a flexible film lid which closes the tray and maintains the quality and freshness of the fish under modified atmosphere. Both materials – the upper and lower film – must have high barrier properties and be reliably combinable with one another. There is also peelable film that sticks on uncoated aluminium and so can be used for materials other than thermoforming grade bottom films.

The main advantages of deep drawing during the packaging process include the fact that producers can react quickly to current market trends that frequently demand new packaging solutions. By exchanging the forming tools they can vary the shape and size of the trays, for example, or include several chambers or portion packs. Intelligent MAP trays are also fitted with absorbent pads that soak up any liquid from the fish fillet and at the same time release CO2 that inhibits the development of harmful bacteria and prevents enzymatic spoilage processes. This can often extend the shelf life of the products by several days.

Film that is used for vacuum package of fish products must also have high barrier properties. In the case of MAP the protective atmosphere should remain in the sealed tray, in the case of vacuum packed products the air should in contrast be fully evacuated as far as possible and kept out until the pack is opened. A special form of vacuum packaging are the skin packs where the upper film wraps itself around the product like a second skin. Skin packs constitute high technology in the packaging sector. Sometimes the shrink process of the high-tech lid film is additionally supported by a vacuum but mostly it is already enough to soften it through the effect of heat. In what almost seems like a magical process the film then wraps itself around the product like a second skin. This takes place so gently and carefully that the soft product is neither squeezed nor constricted. To perfect the protection of the product the film is joined over a large area to the cardboard on which the product was arranged. In the past it was often difficult to free the skin film from the cardboard and the contents again when opening but in the meantime this problem has been solved and today’s improved film can be peeled off easily. Like almost all packaging, skin packs also serve as protection and enable a longer shelf life of the packed products. Apart from that, they maintain moisture within the product and enable a visually appealing presentation at the retailer’s.


Sustainability is gaining importance in the packaging sector

Vacuum packaging prevents fat oxidation and the development of aerobic, i.e. O2-dependent pathogens, through air removal.

The technical, aesthetic and economic requirements of packaging are today already very high but now sustainability has become an important issue, too. Since more and more seafood companies have committed themselves to sustainable usage of resources the topic has moved more strongly into public awareness. Sustainability seals such as ASC and MSC communicate a producer’s values and philosophy and have become an important marketing tool. Viewed holistically it is not only the products that should be considered, however, for the packaging is equally important. But how does one determine the sustainability of packaging?  Particularly since it is not only a question of the material used but also of its design, the colours used for printing, the transport paths and methods, the weight and also its recyclability. The problem is extremely complex and so it is difficult or even impossible to find a simple answer. A cardboard carton made of recycled cellulose that is flown from the other end of the earth to Europe can be less sustainable than a light-weight plastic packaging that has a big CO2 footprint during its production from crude oil but which will be used again several times.

When assessing the sustainability of packaging similar rules apply as to the fish products themselves. From their origin to the final product their path has to be fully traceable. Although such lifecycle considerations are controversial among experts this is at present presumably the simplest way to determine the ecological footprint of packaging within a reasonable time. Direct comparison of materials is difficult, for their resource and energy consumption varies depending on the application. Cardboard can be more expensive than plastic, the production of tin sheet costs even more but is very economical in the overall balance because it can be recycled and once in the can hardly anything spoils. Some plastics can also be down cycled and re-used. In the eco-balance glass is more advantageous than plastic but only if the transport distances are less than 50 km. No packaging material is per se “good” or “bad” or superior to another. And this also applies to packaging materials made of paper, which are allegedly particularly ecological. But they are often coated with a plastic film as a moisture protection, as in the “coffee to go” mugs.