Formalization and validation of the notion of "grain of meat" to predict the quality of Charolais meat Formalisation et validation de la notion de « grain de viande » comme prédicteur de la qualité des viandes chez le bovin Charolais En Fr

Résumé En Fr

The assessment of the meat “grain” size is an empirical method used by some butchers in France to predict prematurely the tenderness of meat. The first aim of this study was to formalize this empirical notion by building a scoring scale of grain of meat. A group of 16 criteria were identified on the carcass as effective to anticipate overall “grain of meat” score. The second aim was to characterize the main muscles used by the experts to realize the appreciation of the GDV (rectus abdominis, longissimus thoracis, longus colli and diaphragma muscles) and to establish the link between their physico-chemical properties and the score of meat “grain” size. In the rectus abdominis muscle, the shear force needed to cut a broiled sample was significantly higher for “coarse grain” carcasses than for “fine grain” ones (7.06 vs 5.78 daN; p=0.0397). The total collagen content in the coarse grain group was significantly higher than those from the fine grain group both in m. diaphragma and longissimus thoracis (8.80 vs 7.48 mg / d DM, p=0.0198 and 4.33 vs 3.59 mg /g MS, p=.0.0307 respectively). In diaphragma and longissimus thoracis muscles, the samples of the coarse grain group had a significantly higher cytochrome-c oxydase activity than those of the fine grain group (p=0.0270 and p=0.0410 respectively). At the same time, the LDH activity was found to be higher in longissimus thoracis muscle from the coarse grain group than in those from the fine grain group, arguing for both a more oxidative and a more glycolytic in m. longissimus thoracis metabolism. The last aim was to establish the relation between the score of meat grain estimated on the carcass and tenderness of the longissimus thoracis muscles estimated by sensory evaluations. Coarse grain samples having a slight higher content in intramuscular fat, meat flavor intensity was also slightly higher for coarse grain samples than for fine grain ones. No significant relation appeared between grain of meat and tenderness (initial: p=0.58; overall: p=0.50), nor shear force (p=0.33) nor collagen content and collagen solubility (p=0.23; p=0.33).

L'évaluation du « grain de viande » est une appréciation subjective, utilisée par certains chevillards et bouchers sur la coupe primaire des carcasses (demi-carcasses et ART8), permettant de sélectionner et d’orienter les carcasses, un grain extrêmement fin étant recherché. Trois études successives, menées sur les bovins Charolais, ont eu pour objectifs 1) de formaliser la notion de grain de viande (GDV), 2) de caractériser les principaux muscles utilisés par les experts pour apprécier le GDV et 3) de valider la relation entre GDV et qualité sensorielle des viandes. Pour mettre au point une grille, pratique et répétable, de notation du grain de viande, seize critères ont été définis. Les observations se font sur la demi-carcasse entière, mais aussi sur l’ART8. Pour chaque critère, un score croissant (de 1 à 5) avec l’amélioration favorable du GDV est attribué par les experts 48 heures post mortem. L’analyse a montré que l’évaluation du GDV était reproductible dans le temps et répétable entre experts (coefficients de concordance de Kendall > 0,60 ; p0,49) entre les muscles des deux lots.