Fat structure determines fat-holding capacity of meat.

The loss of fat has a significant effect on the cooking yield of meat and poultry products. Meat fats are usually solid at room temperature. But once the product temperature exceeds the fat melting point, the fat can move out of the meat matrix.

The fat-holding capacity (FHC) of meat is the maximum amount of fat bound in the meat after a given heat treatment. Scientists at Michigan State University wanted to determine the FHC of ground beef as a function of temperature, time and the product's initial fat content. It appears that the FHC depends on the physical structure of the fat. So, it is necessary to study the interactions that occur among meat proteins, moisture and fat during cooking. This information can be useful in developing mathematical models that optimize cooking processes.

In their tests, the researchers determined the FHC of ground beef at 5.6% and 15.0% fat. Samples, which were about 3.5 g each, were loaded into brass tubes that were 7.9 mm in diameter and 12 mm in length. Then they were heated in a water bath ranging from 30 C to 90 C and held isothermally for 2 minutes, 5 minutes, 10 minutes or 15 minutes. The researchers closed the bottom of the tube with a stopper. Then they fitted the top with a nylon mesh above the water line.

After the tubes and samples were heated, the samples were centrifuged with the mesh side down at 25 C and 1000 g for 15 minutes. After centrifuging, the released fat was separated from water and weighed. The investigators found that the FHC was significantly affected by the initial fat content and temperature. The FHC was inversely proportional to heating temperature. The largest change in the FHC occurred between 40 C and 55 C. However, investigators could not find any definite relationship between FHC and time.

Further information. Bradley Marks, Department of Biosystems and Agricultural Engineering, Michigan State University, 210 Farrall Hall, East Lansing, MI 48823; phone: [phone]; fax: [phone]; email: [e-mail].