Nuclear Magnetic Resonance and Dielectric Spectroscopy as valuable tools to detect Wooden Breast abnormality in broiler chickens

Over the past few years, the poultry industry is facing the occurrence of growth-related breast muscle abnormalities such as Wooden Breast (WB) that strongly impairs the appearance and the quality traits of the meat belonging to fast-growing genotypes. This abnormality is associated with high rejection and downgrading rates, thus resulting in significant economic losses for broiler industry. Thus, the present study aimed at evaluating the effect of WB on water mobility through Dielectric Spectroscopy (DS) in the microwave range and protons’ transverse relaxation time (T2) by Time-Domain Nuclear Magnetic Resonance (TD-NMR) to evaluate the possibility of exploiting this feature to develop sensors which can be implemented on-line to distinguish normal and affected breasts. A total of 124 Pectoralis major muscles was selected from the same flock of fast-growing broilers (males, 42 d and 2.8 kg average live weight) at 3 h post-mortem and classified as unaffected (NORM) or WB (n = 62/group). Samples were then analyzed by DS in the microwave range and TD-NMR to study the properties (i.e., relative intensity and mobility) of the proton populations ascribed to the water within the meat structure as well as its interaction with other components, including ionic molecules (by measuring dielectric constant and loss factor). TD-NMR data were then analyzed by Student’s t-test and considered significant at P<0.05, while DS data were processed using Partial Least Squares Discriminant Analysis (PLS-DA). Compared to NORM, a tendency towards high dielectric constant and loss factor values was found in WB, thus suggesting higher water mobility and a solvate capacity within the abnormal muscles. PLS-DA classified NORM and WB up to 96% of the external validation data set. This outcome was further confirmed by TD-NMR evidencing a significant (P<0.001) increase in the relative intensity of the proton population ascribable to the extra-myofibrillar water along with a reduction (P<0.001) of the proportion occupying the intra-myofibrillar spaces. These outcomes, together with the higher mobility (as depicted by longer T2) of the water observed in WB, may be ascribed to the re-organization of the skeletal muscle structure associated with the onset and progression of the WB abnormality. Based on the above, TD-NMR and DS may represent valuable tools to objectively identify WB meat at slaughter plants after breast deboning and divert them for exploiting them at their maximum potential.