A comparison of water distribution and protein oxidation between poultry and rabbit meat

In the last years, proton Nuclear Magnetic Resonance (NMR) relaxometry has been successfully applied to study water mobility and distribution in porcine meat. In addition, although neglected for decades, the impact of protein oxidation on meat quality traits has been recently reviewed. Within this context, considering the incomplete knowledge on water distribution and mobility in white meats and the lack of information concerning protein oxidation, this study aimed at provide reference values on poultry (chicken and turkey) and rabbit meat. For this purpose, rabbit (L. lumborum muscles from 11 weeks-old males slaughtered at 2.7 kg), chicken (P. major muscles from medium-size 44 days-old male broiler slaughtered at 3.0 kg) and turkey (P. major muscles from 20 weeks-old male birds slaughtered at 21 kg) meat samples (n=8/specie) were selected 24 h post-mortem and used to assess ultimate pH, colour (L*a*b*), NMR relaxation properties and protein oxidation. In detail, proton transverse relaxation (T2) decay curves were recorded, at the operating frequency of 20 MHz, with a Bruker (Milan, Italy) Minispec PC/20 spectrometer, while protein carbonylation was assessed following a novel 2,4-dinitrophenylhydrazine (DNPH)-based method. Overall, ultimate pH values and colour were consistent with previous studies. If compared to both chicken and turkey, rabbit meat exhibited a remarkably higher proportion of the extra-myofibrillar water fraction (2.4 and 2.8 vs. 8.4%; P<0.001) and a consequent decrease in the intra-myofibrillar one (93.7 and 93.3 vs. 88.5%; P<0.001). However, although increased, the extra-myofibrillar water in rabbits appeared to be more tightly bound (lower T2) in comparison to both chicken and turkey meat (130.3 vs. 286.3 and 210.6 ms; P<0.001). These dissimilarities might be related to the different muscle fibre characteristics (e.g. type, size, post-mortem acidification behaviour, etc.). As for protein oxidation, significantly higher carbonyls content were found in turkey and rabbit in comparison with chicken meat (3.10 and 3.60 vs. 1.11 nmol/mg of protein; P<0.001). The lower protein oxidation level observed in chicken meat might be likely related to its lower iron content if compared to both turkey and rabbit meats. In conclusion, providing reference values, this study improved the current knowledge concerning poultry, turkey and rabbit meat quality characteristics.