In order to understand meat packaging, it is important to understand the needs of the beef product being marketed. Research has shown that meat color is a primary factor affecting consumer purchase decisions and the most favorable meat color is red.
Beef can naturally exist in many colors; including red, purple and brown as well as yellow and green. Meat contains the protein myoglobin, which is responsible for meat color and a change in myoglobin results in a change in meat color. Within its structure, myoglobin contains iron and a binding site for various biochemical components to attach. The state of the iron and the nature of the components attached to the binding site determine the color of meat. U.S. consumers associate bright red beef with wholesomeness and any deviation from this color could be detrimental to the marketing of fresh beef to consumers. However, once developed, the red beef color is not permanent.
The amount of time beef maintains its bright red appearance in the grocery store is referred to as color shelf-life or case-life. Case-Life Consumers have several indicators available to determine beef freshness and quality. In addition to color and odor changes associated with the end of case-life, code dates are included on fresh beef packaging labels. Code dates indicate when a package should be sold by or consumed by to ensure freshness. Case-life is limited because exposure to oxygen is required for beef to become red in color. Once exposed to oxygen, a natural process of chemical reactions begins, which is called oxidation. Oxygen in the air is transformed and begins to affect lipids and proteins in the meat. This results in chemical changes that adversely affect the color, odor and taste of meat products.
Oxidized meat products are brown in color, have a tendency to smell like cardboard and taste rancid. The best indicator of oxidation in meat products at the point of purchase in a retail store is the development of brown spots on the lean surface. Another factor limiting the case-life of beef is the growth of spoilage bacteria. These bacteria are classified as spoilage bacteria because they contribute to the spoilage of beef products, but do not cause illness like pathogenic bacteria. Beef products contain low levels of spoilage bacteria after processing. Bacteria must grow and reproduce to substantial numbers to cause a decrease in case-life.
Typically, the bacteria responsible for the spoilage of meat are those that find the environmental conditions favorable for growth. Environmental conditions that affect the growth of bacteria can include storage temperature, moisture availability, initial bacteria levels, nutrient availability and the physical state of the meat product (ground beef vs. beef steaks). Spoilage bacteria that find conditions most favorable will begin to grow even at refrigerated temperatures.
Meat is an BEEF FACTS • Product Enhancement Beef Packaging excellent source of the nutrients that spoilage bacteria need to survive and grow. Beef is also high in moisture and protein. Once the low levels of glucose in meat are consumed by the bacteria, beef proteins will be targeted. Bacteria use the proteins for growth which results in the development of by-products. These by-products then react with myoglobin causing beef to turn brown, yellow or green in color. It should be noted that the growth of spoilage bacteria is slow at refrigerated temperatures and oxidation usually results in discoloration before the development of by-products from bacterial growth.