According to a report from market research firm The Freedonia Group, the fastest growth from 2012-2017 will be recorded by the ready-to-eat market as time-pressed consumers seek an expanded variety of prepared food for takeout.
“Gains in the fresh and frozen market will be fuelled by the growing significance of case-ready packaging and MAP (modified atmosphere packaging) to extend the shelf life of, among others, fresh seafood”, states the report.
The keyword for seafood preservation is the MAP-technology. Let’s have a quick look at this technology for seafood, after which I will describe some recent packaging innovation in this field.
MAP packaging for Fish and Seafood
Extending the shelf life of fresh fish and seafood is particularly challenging because of the unique nature of the product and the many types of fish with different characteristics and therefore different requirements for packaging.
The flesh of fish and seafood contains little or no carbohydrate so bacteria present in the gut and gills of fish begin to act on the protein of the tissue very quickly. Enzymes in the flesh also degrade the tissue. The high water content of the tissue of fish and shellfish is at a neutral pH, neither acid nor alkaline, which explains the rapid activity of bacteria and enzymes to cause deterioration, resulting in the production of a range of chemicals that give bad fish its characteristic unpleasant odour.
Fish that have a high content of fat, such as herring and mackerel, are also susceptible to oxidation by the air resulting in rancidity. The key to keeping fish as fresh for as long as possible is to maintain a low temperature, as close to 0°C as possible.
One of the big challenges in choosing a suitable modified atmosphere to prevent the proliferation of bacteria is that some microbes are aerobic, they thrive in oxygen, while others are anaerobic, where the absence of oxygen encourages their growth. Consequently a careful balance is needed.
A proportion of carbon dioxide in the modified atmosphere packaging for raw fish, above 20% and typically around 50%, is effective in inhibiting the growth of common aerobic bacteria. When CO2 dissolves in water it creates a weakly acidic solution and this can slow down the growth of these bacteria. Oxygen also helps to preserve the colour of the flesh. However, in very fatty fish little or no oxygen is best to avoid rancidity. Seafood, such as prawns, is packaged in an atmosphere typically containing only carbon dioxide and nitrogen. In this way, under the correct conditions of refrigeration, shelf life of raw fish and seafood can be doubled or even trebled from a few days to two or three weeks in some cases. (source)
In general terms: fatty fish goes into vacuum packaging and non-fatty goes into, with carbon dioxide and nitrogen, flushed packaging.
Leading South African supermarket Woolworths released two seafood products (salmon and calamari) under its Easy to Cook brand using Sira-Cook Smart-Release, a microwave bag which cooks food in minutes.
The Sira-Cook Smart-Release microwave bag keeps the seafood and sauces separate, sealed into two compartments. The central dividing seal has been designed to rupture in a controlled way, allowing the mixing of the contents of the two compartments. During the cooking process a second vent in the main compartment opens, to maintain pressure in the bag.
The seals will only open at certain temperatures, so the seafood is cooked to absolute perfection in just a few minutes. The venting seals on Sira-Cook Smart-Release can be tuned to meet the cooking requirements of any contents.
Superfresh Salmon Packaging
Nofima, the Norwegian Institute of Food, Fishery and Aquaculture, established a packaging technique that allows salmon to stay fresh for up to 20 days.
Superfresh is a technology to package salmon under vacuum, after placing a CO2 emitting cushion that consists of, among others, citric acid and baking powder, in the packaging.
After the pack is sealed, the cushion develops CO2 gas and it also has absorbent properties. This CO2 emitter has been adapted for the product, so that it does not change the fish’s pH value, and sensory tests have also shown that the fish often has a higher quality than with comparable packaging technologies.
This way salmon can be kept fresh for up to 20 days at a consistently low temperature, or between 10 and 12 days at 4°C.
The initial research focussed on packaging salmon and cod fillet, but the same method could also be used for other fish types.
Nautical Foods created a packaging for frozen, value-added seafood products, of which both the thermoformed tray and the flexible film lidding material is a key element.
The Go-Green tray material, supplied by Coextruded Plastic Technologies, is a five-layer co-extrusion of polypropylene/tie/ethyl vinyl alcohol/tie/PE.
However it is more interesting to see the way in which the trays are thermoformed. In short, and in contrary to the general thermoforming systems using roll-feeding, these trays are cut in blanks and stacked the way flat carton blanks are stacked. Passing first through a pre-heat process said to be crucial to the overall tray making sequence, the blanks are fed into a proprietary thermoforming system.
Coextruded Plastic Technologies claims its trays have a carbon footprint that is 21% smaller than a tray made from conventional roll-fed thermoforming.
Operators place the crab cakes, fish sausages, or salmon burgers into the trays. After filling, the trays are fed into a lidding system from Multivac, in which the trays enter a sealing chamber. Ambient air is evacuated and replaced with a backflush of nitrogen and carbon dioxide before lidding film is heat-sealed to the tray flange.
Supplied by Packall Packaging, the lidding material is a 2.5-mil barrier film that includes reverse-printed 48-ga polyester adhesive laminated to an EVOH/linear low-density PE co-extrusion.
There are some examples to describe, so I will continue this article.