Abstract

Marbling refers to the appearance of white flecks of fatty tissue between muscle fibre bundles. The whiteness and opacity of the fat is important for visual assessment of marbling and depends on the crystallisation of the triacylglycerols within the fat cells. In the living animal, fat is in a liquid state. With chilling, the triacylglycerols undergo phase changes (solidify) and become opaque. The temperature at which this occurs is largely dependent upon the melting points of the individual fatty acids. Marbling fat can comprise a diverse range of fatty acids and each has an individual melting point (e.g. palmitoleic melts at 0°C; stearic melts at 70°C). The visual appearance of marbling will thus depend on the melting points of the constituent fatty acids at chiller temperature. The high melting point stearic acid can vary significantly in content across groups of cattle and has a major influence on the physical properties and visual appearance of marbling fat. The effects of nutrition, seasonal and climatic variation are reviewed and linked to marbling appearance and fat hardness.