Susceptibility of dry-cured tuna to oxidative deterioration and biogenic amines generation: I. Effect of NaCl content, antioxidant type and ageing.

This study aimed to assess lipid oxidation and biogenic amine (BA) development in "muxama", a dry-cured tuna muscle product, as affected by salt content, antioxidant type and ageing time. Overall, BA contents decreased with NaCl level (2785.1mgkg-1, 1148.1mgkg-1 and 307.7mgkg-1) and increased with ageing time (366.2mgkg-1, 1711.8mgkg-1 and 2959.2mgkg-1 in the final product (T0), and after 1 (T1) and 3 (T3) months of ageing, respectively). Regardless of the test conditions, the most concentrated BA was always tyramine. For the ageing periods considered in the present study, malondialdehyde formation was affected by the NaCl level, with the saltiest samples exhibiting lower content. Rosemary and sage extracts represented promising technological options for preserving muxama from oxidation and to minimize the presence of a fishy flavour and odour, but this treatment may cause the colour to lose some of its redness and become less appealing.

Concentration of antioxidants in two muscles of mature dairy cows from Azores.

This study evaluated the concentrations of α-tocopherol, ß-carotene, creatine, carnosine, anserine and coenzyme Q10 in Longissimus dorsi (Ld) and Gluteus medius (Gm) muscles of culled dairy cows and the impact of age, production status before slaughter (dry-off vs lactating) and carcass weight on them. The effects of applying a finishing feeding regimen before slaughter were also examined. Gm muscle presented higher levels (P<0.001) of α-tocopherol (5.14 vs 3.61 µg · g(-1)) ß-carotene (0.36 vs 0.27 µg · g(-1)), anserine (59.24 vs 43.25 mg · 100 g(-1)) and coenzyme Q10 (3.33 vs 1.73 mg · 100 g(-1)), and by contrast lower (P<0.05) creatine concentration (502.40 vs 527.28 mg · 100 g(-1)) than Ld. Dry-off and lactating cows differed significantly in α-tocopherol level (P<0.001) but not in the concentrations of the other compounds (P>0.05). The finishing feeding promoted higher mean concentrations of anserine and creatine but lower carnosine values (P>0.05) than directly slaughtered dry-off cows. The variation between muscles and from animal-to-animal makes it difficult to exactly define the antioxidant status of the dairy cow's meat.