Biochemistry and morphological characterization of intra muscular connective tissue of two contrasting bovine muscles

Résumé En

Beef meat tenderness depends on biochemistry factors as collagen and cross-link contents and muscle fibres characteristics. Tenderness could also depend on structural characteristics of intramuscular connective tissue (perimysium and endomysium). This study aims to develop an image analysis method able to measure some intramuscular connective tissue characteristics that reflect the specificity of two contrasting muscles. We used Longissimus thoracis (LT) and Biceps femoris (BF) muscle from 42 young bulls. Picro-Sirius red method applied on histological muscle cryosections stained intramuscular connective tissue in red and muscle fibres in yellow. Our image analysis procedure was based on this contrast. The computer algorithm (Visilog 6.7, Noesis, France) calculated automatically the intramuscular connective tissue area, length, width, optical density and connection points. Collagen (total and insoluble) and cross-link contents were determined, respectively by hydroxy-proline and pyridinoline measurements, on muscle powder. Statistical correlations between morphological and biochemical parameters were evidenced. Area and optical density of BF intramuscular connective tissue were higher than in LT. BF connective tissue network was longer and wider and was more ramified. Total and insoluble collagen contents and cross-link level were higher in BF than in LT. This confirms that morphological parameters are different from muscle to another and that our algorithm is able to highlight them. BF collagen content and solubility were positively correlated with endomysium characteristics. No correlation between morphological and biochemical parameters appeared in LT muscle, neither between perimysium characteristics and biochemical characteristics. BF and LT show different relationships between biochemistry and morphological characteristics.