Intramuscular fat (IMF) corresponds to the amount of fat found between muscle fiber bundles within muscles. The amount of IMF, i.e. IMF content, varies between species, breeds and muscle types. IMF content plays an important role in various quality traits of pork. It is generally accepted that a higher IMF content has a positive effect on sensory quality traits of pork, for example, juiciness, tenderness, and flavor. Since it is strongly related to carcass quality, IMF content is also a useful tool to make genetic improvement in selection programs for carcass quality in the pork industry.
IMF content is normally determined by chemical extraction of lipid from muscle samples (Folch et al., 1957). Chemical extraction is time-consuming, labor-intensive and destructive, which makes it not suitable for industrial application. In the pork industry, another quality trait, i.e. the marbling score, is widely used to estimate the IMF content of muscles. Marbling refers to the visible IMF of muscles. Marbling scores are visually assessed by experienced assessors by comparing marbling levels of meat with a standardized chart system (NPB, 2002). However, visual and subjective