Effect of broiler breast abnormality and freezing on meat quality and metabolites assessed by 1H-NMR spectroscopy

Abstract

The present study aimed at investigating the impact of the current growth-related abnormalities (White-Striping-WS, Wooden Breast-WB, and Spaghetti Meat-SM) affecting broilers Pectoralis major muscles on the main quality traits, the oxidative stability of both the lipid and protein fraction as well as the water mobility assessed in fresh and frozen/thawed meat. In addition, Nuclear Magnetic Resonance spectroscopy (1H-NMR) was applied to quantify free amino acids, histidine-containing dipeptides and metabolites involved in energy-generating pathways. Overall, the occurrence of WS, WB, and SM abnormalities remarkably affected the quality traits (pH, color, and water holding capacity) and oxidative stability of the meat, with the WB condition leading to the most detrimental effects. However, overall, freezing and subsequent thawing only partially worsened the aforementioned traits. Significant variations in free amino acids and histidine-containing dipeptides were found between abnormal muscles and their unaffected counterpart by 1H-NMR spectroscopy and, aside from the occurrence of muscular defects, their content was remarkably reduced in frozen/thawed meat. The findings obtained by analyzing the metabolites through 1H-NMR spectroscopy allowed to advance the knowledge concerning the impact of freezing and subsequent thawing on meat quality traits and provided useful information concerning the underlying mechanisms responsible for the development of WS, WB, and SM abnormalities in broilers.

Keywords: NMR; free amino acids; freezing; muscular abnormality; oxidative stability.

Figure 1

Sampling procedure adopted to assess quality traits, oxidative stability, and main metabolites (free amino acids, histidine-containing dipeptides, and metabolites involved in energy-generating pathways) in fresh and frozen/thawed broilers P. major muscles.

Figure 2

Effect of the occurrence of WS, WB, and SM abnormalities on yellowness (b*) assessed in both fresh and frozen/thawed P. major muscles (N = 96; 12 muscles/group/treatment).

Figure 3

Effect of the occurrence of WS, WB, and SM abnormalities on lightness (L*) assessed in both fresh and frozen/thawed P. major muscles (N = 96; 12 muscles/group/treatment).

Figure 4

Effect of the occurrence of WS, WB, and SM abnormalities on carbonyls content assessed in both fresh and frozen/thawed P. major muscles (N = 96; 12 muscles/group/treatment).

Figure 5

Representative 600 MHz ¹ H-NMR spectrum displaying the assignment of the compounds. The spectra were acquired using the cpmgpr1d pulse sequence.

Figure 6

Schematic representation of the metabolic pathway that through the removal of 2 methyl groups from betaine results in the formation of N,N-dimethylglycine and glycine (having N-methylglycine as an intermediate product). Then, glycine can be subsequently converted resulting in the synthesis of serine and methionine.

Figure 7

Principal component analysis of the metabolites (free amino acids, histidine-containing dipeptides, and metabolites involved in energy-generating pathways) assessed through ¹ H-NMR in fresh and frozen/thawed broilers' P. major muscles affected by WS, WB, and SM abnormalities. Plot of the first 2 principal components score vectors (a). Plot of the variables (free amino acids, histidine-containing dipeptides, and main metabolites) having the highest discrimination power and resulting significantly different (P < 0.001) among the groups according to the 2 principal components loading vectors (b).