Antioxidant status and odour profile in fresh beef from pasture or grain-fed cattle

The main goal of the present work was to determine the overall antioxidant status in fresh meat from animals fed different diets and to differentiate them through their odour profiles. Attributes were evaluated in beef from pasture or grain-fed animals with (PE and GE) or without supplementation (P and G) with vitamin E (500UI/head/day). Fresh meat produced on pasture (P and PE) had higher total ferric reducing antioxidant power (FRAP) levels than meat from grain fed-animals (G and GE) (P<0.05). However, no differences were found on their ability to reduce ABTS(+) (2,2'-azino-bis-(3-ethylbenz-thiazoline-6-sulfonic acid)), indicating that total antioxidant activity was preferentially due to the reduction potential than to the quenching capacity of tissue homogenates. Two-fold glutathione (GSH and GSSG are the reduced and oxidised forms, respectively) levels were found in the P+PE group respect to G+GE meat (P<0.001). In addition, meat from pasture-fed animals presented a higher glutathione redox potential compared to grain-fed animals (-156.1±6.1 and -158.1±6.5 vs. -148.1±13 and -149.8±14.6 for P, PE G and GE, respectively), showing that the antioxidant status in fresh meat was affected by diet. Enzymatic activity of catalase and glutathione peroxidase were equivalent for all dietary groups. Only superoxide dismutase activity was slightly higher (P<0.05) in the P+PE group than in G+GE samples. Odour profile analysis was performed in relationship to antioxidant parameters. Significant linear correlation coefficients (P<0.05) were found for a set of sensors and the FRAP values. E-nose methodology successfully discriminated the odour characteristics of samples corresponding to pasture- or grain-based diet. Hence, it was possible to describe an analytical relationship between the odour profile and the antioxidant power of fresh meat.