Why is chicken breast white and dark meat dark? 聽It all has to do with different kinds of muscle. 聽Dark meat is a result of the predominant presence of slow oxidative muscle fibres used for sustained activity by active muscles such as found in the legs and thighs. 聽These fibres have a continuous rich supply of oxygen and generate low levels of force over long periods of time. 聽They contain high levels of a protein called myoglobin that helps facilitate oxygen transport from the blood. 聽This iron-rich, red-pigmented protein, when cooked, turns into metmyoglobin and is what gives dark meat its colour. 聽By contrast, fast glycolytic muscle fibres are mainly found in chicken breast and other muscle regions that are not used actively. 聽These muscle fibres lack myoglobin but are capable of generating a large force over a short time span.
