Fresh fruit and vegetables must be picked and packaged with care to ensure that produce arrives at the final destination in the most pristine and saleable condition possible, which may be many thousands of miles away.
The packaging of fruit and vegetables can be challenging. Soft fruit such as blackberries would require a different approach to packaging and printing than oranges and apples. However, if one packaging structure were to be singled out for its versatility and popularity it would be corrugated fiberboard, which may be used on its own or, as with other paper board material employed as the main container for transport with smaller, fragile container units nested within.
Printing, which includes coding and marking is critical in imparting brand and product information. Packaging units destined to be displayed in the retail environment for purchase by the consumer receive the most attention with regard to graphic design, colour, logo and informational content.
Retailers only have a short window of opportunity to shift products off the shelf. Shelf life even with laminated, coated or multi web barrier packaging material is not limitless.
Packaging technologists, produce buyers and (especially) consumers may refuse or avoid containers if packaging is torn, dented, scored, or shows sign of collapse. Packaging material must be clearly labelled, incorporating information about the product including point of origin, harvesting date, shipper and size/weight of produce.
Clamshell packaging, a form of rigid plastic packaging is an option when packing premium priced high quality produce including single serve, single product items such as avocado or pre-cut melon. Often the hinge of the clamshell is sealed by the label, which incorporates an aggressive adhesive.
￼￼￼￼Products with high water content and a short shelf life are sometimes subjected to shrink wrapping; this helps to prevent the spread of microbial contamination and functions as a receptive surface for labels.
When providing a presentation sample or colour match it is important to use the same substrate as will be printed on. Printing one colour on Kraft, mottled or even clay-coated sheets that have the same surface appearance will yield a wide range of shades from the same colour. The reason for this is that the sheets with a high level of absorption produce a weaker colour due to the ink being absorbed into the substrate; those sheets with a lower absorption however, will produce stronger colours, and if clay-coated sheets are used the ink will not penetrate the surface.
When printing on clay-coated board, insufficient coverage or poor trapping may well be associated with poor ink adhesion due to the materials in the ink having a combined surface tension that is higher than that of the substrate. This produces an effect whereby inks tend to shy away from some areas of the substrate surface to produce an uneven appearance to the final print. Inks with a higher level of polymeric additives and incorporating water can be added to great effect. In this instance, the water is often added at the press side to reduce viscosity for faster drying and faster press speeds. Care has to be exercised as too much water causes an ink imbalance that will affect rub resistance and gloss. A diluting vehicle can be used to maintain ink balance.
The FlexiProof 100/UV, from RK Print Coat Instruments, is ideal for situations such as the colour matching of pre-printed liner, typically associated with premium quality, high value goods; trialling new jobs, inks and substrates. The K Printing Proofer (also from RK Print Coat Instruments), on the other hand is an option for organisation with multi-print processes. This device can proof using gravure, gravure-offset and flexo inks. It can also undertake wet or dry laminating sampling.