Future packaging trends affecting taints

4.13 Future packaging trends affecting taints

  New technology is continually being applied to food packaging. Some developments that are likely to emerge in the next few years are discussed below.

4.13.1 Cationic inks

  Although lower odour compared to UV radical curing is sometimes claimed for cationic inks, lower odour is not the principal reason that will drive this technology forward.A mature technology, UV radical curing is quite capable of achieving a low odour product. At present cationic technology accounts for no more than a few per cent of the radiation curing technology used in packaging. Cationic-cured inks offer the advantage of high gloss and less shrinkage than conventional free radical UV-cured inks with better adhe- sion on metal surfaces. Cationic inks can provide high grease resistance on packaging such as pet food bags and garlic bread bags.

  The UV light is used to initiate the cationic curing process. Once the cure has been initiated, curing continues in the dark. The photoinitiator does not itself take part in the curing process. The photoinitiator is used to produce strong acids such as hydrofluoric acid, which cause the actual curing. The development of the technology has been held up by the lack of commer- cially available photoinitiators at competitive prices. The most widely used photoinitiators for food packaging applications have been triaryl sulfonium salts. Diphenyl sulfide (highly odorous) can be produced as a by-product in the polymerisation process of some cationic inks. Following concerns over the possibility of benzene being produced during curing, non-benzene- producing initiators have been introduced. An excellent review of cationic inks is provided by Crivello and Dietliker (1998).

4.13.2 Digital printing

  Computer technology has now developed to the point where artwork can

  be designed on a PC and sent straight to the printer, without the need for

  a plate or roller to transfer the image. The inks are transferred to the paper or plastic using processes somewhat similar to a photocopier. The inks are usually powders that are fused by a heater onto the surface. The use of this technology is likely to expand in the future particularly for short print runs

  108 Taints and off-flavours in food and items such as labels. The reasons for this are the speed with which an

  image can be designed, and reviewed and printed, or transmitted. The image can be sent anywhere in the world to be printed. Storage and reuse of the images is much easier. Considerable development and investment in the technology, however, is required for it to compete with the line speed and costs achieved with conventional flexo or gravure printing. The advantage as far as taint risk is concerned is that the printing process is solvent free.

4.13.3 In-store printing

  The advantage of in-store printing technology is the flexibility it provides, for example to enable a store to add promotional designs onto small batches of product. The technology could potentially involve additional risk as far as taint is concerned. The printing may not be carried out under tightly monitored and controlled conditions.

4.13.4 Co-extrusions

  The continued shift towards co-extrusion structures and away from lami- nates manufactured using solvent-based adhesives will reduce the risk of taints. Layered structures are produced by extruding a whole series of layers on top of each in a molten form. As it cools the layers fuse, forming a single structure without the use of any adhesive.

4.13.5 Smart and active packaging

  Smart and active packaging technology has more to do with the prevention of off-odour and taste as a result of food spoilage than taint occurring as a result of a packaging interaction. However, taint scavengers are being developed for incorporation into packaging to trap potentially tainting compounds from the packaging components within the packaging. These scavenging compounds are often crystalline powders such as xeolites, which have a cage-like molecular structure that can trap a range of tainting com- pounds. An example of an application is ‘bag in a box’-type packaging for drinks. The problem with these taint scavengers is their lack of specificity. Taste scalping can therefore be a problem, with flavour compounds being removed from the food. The result can be an imbalance of flavours which manifests itself as a taint.