Packaging is particularly important for meat and meat products. Raw and cooked meats are commonly sold in tray and lidding formats, usually packed in a modified atmosphere combination of oxygen, carbon dioxide and nitrogen. Correct combination of gases can extend microbiological shelf life and appearance of the product. High oxygen MAP promotes the bright colour of raw red meat (oxymyoglobin) but may have an effect on eating quality. Low oxygen MAP, typically used with cooked meat products, replaces oxygen within the pack, most commonly with carbon dioxide, which inhibits growth of some bacteria and moulds, and nitrogen, an inert filler gas which prevents pack collapse.
The recent revival of vacuum skin packing (VSP) involves sealing the product between a base film, coated card or preformed tray and a heat softened top film, which is vacuum drawn onto the top of the meat surface to give a skin type pack. Retailers and manufacturers are increasingly opting for this packaging format in an effort to extend shelf life and reduce supply chain waste. This gives an attractive presentation of the product, a reduction in drip loss and easy open options.
To maintain quality of the product, barrier properties need to be adequate to prevent oxygen ingress. Any stretching over the product may thin the top film and affect the barrier properties and strength of the material. Measuring the barrier properties following packing is advised.