Isoelectric variants of actin in raw and cooked meat

Isoelectric focusing of myofibrillar proteins from raw meat gave one major and several minor actin bands. Extending the time, or raising the temperature, of a heat treatment progressively increased the proportion of variants of isoelectric point lower than the primary component. Because of the concomitant release of ammonia on heating, it was concluded that these variants arose from the hydrolysis pf amide groups of asparagine and/or glutamine. Determination of the relative proportion of deamidated actin components may provide a measure of the severity of heat treatment given to a sample of cooked meat.