title: Heat-induced changes in the proportion of types I and III collagen in bovine Longissimus dorsi.
abstract: Intramuscular collagen (IMC) was isolated from the Longissimus dorsi of six Simmental bulls, 17 months of age, to evaluate the effect of heating on the proportion of types I and III collagen. Cyanogen bromide (CNBr) peptides were prepared from unheated IMC and the soluble and insoluble fractions of IMC heated to 70°C for 70 min or 90°C for 140 min. Percentage of type III collagen was determined by densitometric scans of the CNBr peptides, αl(I)CB8 and αl(III)CB8, as resolved by SDS-PAGE. Percentage of collagen solubilized was greater (P < 0·05) at 90°C than at 70°C. The 70°C and 90°C insoluble IMCs were similar (P > 0·05) for percentage of type III, but both had a greater (P < 0·05) percentage of type III than unheated IMC, indicating that type I is more heat labile than type III. Heat-soluble IMC contained both α and β components and the CNBr peptides of 70°C soluble IMC were mostly type I. These results indicated that heating intramuscular collagen from bulls mainly solubilized type I collagen. Improved tenderness associated with increased heat solubility of collagen may be more closely related to heat-induced solubilization of type I than of type III collagen.
authors: Meat Science Section, Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506, USA.
authors: D E
authors: DE
authors: Burson
authors: M C
authors: MC
authors: Hunt