Colour is the Decision-Making Parameter for Consumers When Selecting Meat

Colour plays a central role in consumers’ perception of meat quality and freshness. As one of the most visible attributes at the point of purchase, it often determines whether a product is selected or rejected. For meat manufacturers, maintaining a consistent and appealing colour throughout shelf life remains a challenge, as colour changes are closely associated with oxidative reactions and, to some extent, microbial activity.^1,3

Retail data indicate that visual discolouration significantly contributes to product discounting and removal from display, particularly in fresh meat categories.¹² While colour is a key driver of initial purchase decisions, flavour consistency and sensory quality influence repeat buying behaviour. As a result, colour stability has both economic and quality‑related implications across the meat supply chain.¹

Myoglobin chemistry and meat colour

Myoglobin is the primary organic substance responsible for meat pigmentation. Its concentration varies between animal species and within individual muscles, influenced by factors such as age, genetics, diet, and physical activity. Beef generally contains higher levels of myoglobin than lamb, pork, or poultry, which explains its darker red appearance.³

These forms continuously interconvert depending on oxygen availability, storage time, and environmental conditions. Fresh meat surfaces exposed to oxygen favour oxymyoglobin formation, whereas prolonged oxidative exposure increases the proportion of metmyoglobin. Consumers generally perceive this shift toward brown colouring as an indicator of declining freshness.^3,5

Colour changes during processing and storage

Several factors influence colour stability during processing and storage, including oxygen exposure, temperature, light, and packaging systems. In fresh meat, surface exposure to oxygen promotes the formation of oxymyoglobin, producing the bright red colour preferred by consumers. Over time, however, oxidative reactions can shift pigment balance toward metmyoglobin, leading to visible browning.^3,5

Packaging conditions play a key role in managing these colour changes:³

• Vacuum or low‑oxygen packaging limits oxidative discolouration but may result in a darker or purplish appearance due to deoxymyoglobin predominance.
• Oxygen‑permeable packaging systems can support a red surface colour initially but may accelerate oxidation during prolonged storage or retail display.

Processing steps further modify meat colour. Grinding increases surface area and oxygen interaction, enhancing susceptibility to oxidation.⁶ In cured meats, nitrite reacts with myoglobin to form nitric oxide myoglobin, which is responsible for the characteristic pink colour and shows greater thermal stability compared with fresh meat pigments.⁴ Cooking denatures myoglobin, producing the typical brown or grey colour observed in cooked meat products.³

Role of antioxidants in meat colour and oxidative stability

Oxidative reactions are among the main factors influencing both lipid stability and meat colour deterioration during processing and storage. Several naturally derived ingredients commonly studied in meat systems act through complementary antioxidant mechanisms, contributing to colour stability either directly, by interacting with myoglobin, or indirectly, by limiting lipid oxidation and secondary reaction products.⁶

Plant extracts rich in phenolic compounds

Plant‑derived extracts such as rosemary (Rosmarinus officinalis), green tea (Camellia sinensis), and olive (Olea europaea) have been widely investigated for their antioxidant activity in meat applications. Their effectiveness is largely attributed to their phenolic composition, which enables free‑radical scavenging and metal‑chelating activity.⁶

• Rosemary extract
  Rich in phenolic diterpenes such as carnosic acid and carnosol, rosemary extract is known for its ability to inhibit lipid peroxidation. By slowing lipid oxidation, it can indirectly support colour stability, as lipid‑derived oxidation products contribute to myoglobin oxidation and metmyoglobin formation.⁶

• Green tea extract
  Green tea contains catechins, including epigallocatechin gallate (EGCG), which exhibit strong antioxidant activity. These compounds act primarily as radical scavengers and have been studied for their capacity to reduce oxidative reactions in raw and processed meat systems.⁶

• Olive extract
  Olive‑derived extracts contain phenolic compounds such as hydroxytyrosol and related derivatives. These compounds have been associated with antioxidant effects in meat matrices, particularly through their ability to limit oxidative chain reactions and interact with pro‑oxidant metal ions.⁶

Ascorbic acid and acerola cherry derivatives

Ascorbic acid plays a distinct role in meat colour stability due to its reducing properties. It can delay discolouration by helping maintain the heme iron of myoglobin in its reduced (Fe²⁺) state, thereby slowing the conversion to metmyoglobin.⁴

Acerola cherry (Malpighia emarginata) is a natural source of ascorbic acid and has therefore been studied as an alternative way to introduce reducing activity into meat formulations. By supporting redox balance, ascorbic acid and its naturally derived sources may contribute to improved colour stability during storage and retail display.⁴

Complementary antioxidant mechanisms

In addition to radical scavenging and reducing activity, some formulation components contribute to oxidative stability through metal ion chelation. Chelating agents such as citric acid can bind pro‑oxidant metals, thereby reducing their catalytic role in oxidation reactions.⁶

Taken together, these complementary mechanisms highlight how ingredient selection can influence oxidative reactions, lipid stability, and meat colour during processing and storage. A science‑based understanding of antioxidant function supports informed formulation strategies aimed at maintaining visual quality across shelf life.

References

1. Smith, G.C., Belk, K.E., Sofos, J.N., Tatum, J.D., Williams, S.N. (2000). Economic implications of improved color stability in beef. In E.A. Decker, C. Faustman & C.J. Lopez‑Bote (Eds.), Antioxidants in Muscle Foods: Nutritional Strategies to Improve Quality (pp. 397–426). Wiley Interscience, New York.

2. Carr, M.A., Miller, M.F. (1998). Improvement of retail case life of pork – Phase I. National Pork Producers Council, Des Moines, Iowa, pp. 101–107.

3. Feiner, G. (2006). Meat Products Handbook: Practical Science and Technology. CRC Press, Boca Raton, Florida.

4. Belitz, H.‑D., Grosch, W., Schieberle, P. (2009). Food Chemistry. 4th revised and extended edition. Springer.

5. Mancini, R.A., Hunt, M.C. (2005). Current research in meat color. Meat Science, 71, 100–121.

6. Pegg, R.B., Shahidi, F. (2012). Off‑flavors and rancidity in foods. In L.M.L. Nollet (Ed.), Handbook of Meat, Poultry and Seafood Quality (2nd ed., pp. 127–139). Wiley & Sons, Ames, Iowa.