Packaging Methods To Preserve Meat, Poultry and Fish

The major goal of any packaging way for fresh muscle foods is to prevent or delay undesirable changes to the appearance, flavor, odor, and texture which is so called decomposition. Deterioration in these qualities leads economic losses due to consumer rejections of the product. Interms of consumer purchase mentality appearance of fresh muscle foods greatly affects the decision.

During the storage of raw muscle foods like fresh meat, fin fish, fresh chicken etc… at chiller temperatures, various enzyrnemediated and non-enzymic chemical reactions will affect the flavor, odor, and texture of the tissues. Some of these changes caused by enzymic reactions are desirable – such as, the increased tenderness of aged beef. Nevertheless, most of the changes led by enzymic activities are undesirable. Therefore, a preservative packaging should ideally applied to inhibit undesirable enzymic activities, but not interfere with, or inhibit, activities that are beneficial.

Considering above, there are basically four categories of preservative packaging that can be used with raw muscle foods like fresh meat, chicken, poultry, fish… These are vacuum packs, high oxygen modified atmosphere packs (MAP), low oxygen modified atmosphere packs (MAP), and controlled atmosphere packs (CAP).

Type	Packaging Gases	Film Gas Permeability	Atmosphere
Vacuum Pack	Residual Air	Low	Anaerobic
High O2 MAP	O2, CO2, N2	Low	Aerobic
Low Q2 MAP	CO2, N2, Residual O2	Low	Anaerobic
Controlled Atmosphere Pack (CAP)	CO2, N2	Anaerobic	Anaerobic

Vacuum packs comprise evacuated bags, in which a film of low gas permeability is closely applied to the surface of the product. Preservative effects are achieved by the development of an anaerobic environment within the pack.

High O2 modified atmopshere packs (MAP) contain atmospheres of oxygen and carbon dioxide and, often, nitrogen. Only oxygen and carbon dioxide have preservative effects. However, carbon dioxide is highly soluble in both muscle and fat tissues, while oxygen may be respired by tissues and bacteria at high initial concentrations, will tend to be lost through the packaging film. Consequently, nitrogen is often included in high O2 MAP atmospheres as an inert filler, to guard against pack collapse.

Low O2 modified atmosphere packs (MAP) contain atmospheres of carbon dioxide and nitrogen usually with some residual atmospheric oxygen remaining in the pack at the time of closure. As nitrogen has no preservative function in low O2 MAP atmospheres, the initial volüme of the pack atmosphere need only be sufficient to allow for dissolution of carbon dioxide in the product without pack collapse and crushing of the product.

Controlled Atmopshere Packs (CAP) contain atmospheres that do not change during storage of the product. To achieve this, the films used for such packaging must have very low, preferably immeasurable, gas permeability. CAP atmospheres may contain carbon dioxide and/or nitrogen. If carbon dioxide is used, the initial gas volume must be sufficient to allow for dissolution of carbon dioxide in the product. The specific attributes of different raw meat tissues determine which of these various packaging systems is best suited for preservation.