Effects of grass feeding systems on ruminant meat colour and flavour. A review

Grass feeding has been reported to affect several meat quality characteristics, in particular colour and flavour. In this paper we have reviewed some differences in meat colour and flavour between ruminants fed concentrates and animals allowed to graze pasture. The possible factors influencing the differences have been also examined. We have examined a total of 35 experiments which report the effect of pasture vs concentrate finishing systems on beef meat colour. Meat from cattle raised on pasture is reported to be darker than meat from animals raised on concentrates if measured by objective (P < 0.001) as well as subjective (P < 0.05) methods. Several factors, not a specific one are responsible for this difference, variations in ultimate-pH and in intramuscular fat content between animals finished at pasture and those finished on concentrates, seem to play a major role. Diet also affects meat flavour in both sheep and cattle but the components involved seem to be different. In sheep pastoral flavour is mostly determined by the branched-chain fatty acids and 3-methylindole (skatole). An important role seems to be played also by some products of oxidation of linolenic acid and its derivates. In cattle the role of skatole seems to be less important than sheep because of the lack of the branched-chain fatty acids. The pastoral flavour seems to be mostly determined by products of oxidation of linolenic acid and its derivates which derives substantially from grass. grass feeding / meat colour / meat flavour / ruminants Résumé — Effets d’une alimentation à base d’herbe sur la couleur et la flaveur de la viande de ruminants. L’alimentation à base d’herbe est souvent proposée comme un facteur pouvant influer sur la qualité de la viande et notamment ses caractéristiques de couleur et de flaveur. Dans cette revue bibliographique sont regroupées des différences de couleur et de flaveur observées entre viandes de bœufs ou d’agneaux provenant d’animaux alimentés au pâturage ou avec des régimes concentrés (souvent à base de maïs) et les rares éléments d’explication. L’analyse de la couleur de la viande bovine repose sur 35 essais différents. La viande provenant des animaux qui pâturent est plus sombre, quelle que soit la méthode de mesure, objective (luminosité L* mesurée au photomètre P < 0,001) ou subjective (critère visuel P < 0,05). Parmi les principaux facteurs pouvant expliquer cette différence, se trouvent les variations du pH ultime et celles du gras intramusculaire. Le régime alimentaire affecte aussi la flaveur des viandes de bœuf et d’agneau, mais les facteurs impliqués semblent différer entre A. Priolo et al. 186