Age-related changes in meat tenderness and tissue pentosidine: effect of diet restriction and aminoguanidine in broiler breeder hens.

The nonenzymatic glycosylation of tissue protein contributes to the formation of crosslinks that leads to structural and functional deterioration in the long-lived tissue protein, collagen. The accumulation of these crosslinks thus contributes to the objectionable toughness of meat from aged animals, decreases its economic value, and limits its use in whole muscle foods. The objectives of this study were to determine the effectiveness of diet restriction and the crosslinking inhibitor, aminoguanidine (AG), on reducing the accumulation of crosslinks, thereby improving meat tenderness in broiler breeder hens. The glycoxidation product, pentosidine, was also measured in skin (Ps) to determine whether changes in its concentrations correlated with the changes in shear value (SV). Chicks (n = 450) were randomly assigned to four treatment groups from 8 to 125 wk after hatch: ad libitum (AL), diet restricted (DR), AL and DR groups supplemented with 400 ppm AG each (AL+AG and DR+AG, respectively). Shear value was measured with an Instron Universal Mechanical Machine. Skin pentosidine was isolated by reverse phase HPLC. There was an age-related, linear increase in SV (P<0.0001, r = 0.96), which correlated (r = 0.86) with the age-related increase in Ps in AL hens. Diet restriction retarded SV (P<0.0001) over the sampling period. In general, SV values for AL+AG were similar to those measured in DR, whereas no additive effect was observed for AG in DR birds. It was concluded that there was a linear increase in meat toughness (SV) with age that correlates with the accumulation of Ps, and that the decline in meat tenderness can be retarded by DR or AG. Secondly, the effect of DR on accumulation of Ps was so pronounced that AG supplementation did not further enhance this effect.