Fresh-Meat Colour

Myoglobin concentration and chemical state create purple, bright red or brown appearances. Species, muscle, animal age and exercise affect the starting pigment level.

Deoxymyoglobin, oxymyoglobin and metmyoglobin can interconvert as oxygen availability changes. Blooming, vacuum packaging and high-oxygen packs therefore create different normal colours.

Postmortem pH decline, chilling, protein denaturation and water loss alter light scattering and pigment stability. PSE and DFD conditions produce characteristic but not perfectly diagnostic appearances.

Grinding exposes more surface area and distributes oxygen and enzymes, accelerating colour change. Salt, cure, freezing, thawing and light also influence the later response.

Brown colour can develop in sound meat, while contaminated meat can retain an attractive colour. Colour must be interpreted with odour, surface condition, pack integrity and time-temperature history.

Specify acceptable raw-material colour by species and pack type, standardise viewing conditions and investigate deviations without using colour as a standalone release test.