The meat of Lueyang black-bone chickens is delicious and nutritious, and has the value of medicine and food therapy, which has a special flavor. However, there are few studies on its flavor substances, especially the lack of systematic sensory flavor analysis. This study provided the theoretical basis for the selection of marketing time of Lueyang black-bone chickens by analyzing the body size traits in the growth and development and comparing the flavor differences of breast muscles.

The experiment selected 30 Lueyang black-bone chickens randomly, and the body weight and body sizes at the age of 3, 6, 8, 10, 13, and 16 weeks were measured to analyze dynamic growth and development process. At 13 and 16 weeks of age, 10 chickens were randomly selected for slaughter for collecting the chest muscle and analyzing their volatile flavor substances by comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC-TOF MS) combined with multivariate data.

The growth rate of Lueyang black-bone chickens was faster before 13 weeks, and there was a significant difference in body weight and body size (P < 0.05), while the growth rate slowed down after 13 weeks, there was no significant difference in body weight between 13 and 16 weeks (P > 0.05). Body size indexes (chest width, chest depth, keel length, etc.) also tended to be stable after 13 weeks (P > 0.05). The results of the meat quality analysis showed that there was no significant difference in pH, shear force and dripping loss between 13 and 16 weeks (P > 0.05), indicating that the 13 weeks had reached physiological maturity. The results of flavoromics analysis showed that 642 and 660 flavor substances were identified in the chest muscle of 13 and 16 weeks Lueyang black-bone chickens respectively, among which alcohols, aldehydes, esters and hydrocarbons were the main components. Sensory analysis showed that the breast muscles of 13 weeks Lueyang black-bone chickens were significantly better than those of 16 weeks in aroma note types of sweety, green and fruity, and this difference was closely related to fatty acid composition. 43 key differential flavor substances were further screened, and Phenol, Pyrazine, 2-Cyclopenten-1-one, 3-methyl- and Trichloromethane were found to be the main volatile compounds responsible for the flavor difference between 13 and 16 weeks chest muscles. Correlation analysis showed, 1H-pyrrole,2-methyl-, 2-Cyclopenten-1-one,3-methyl-, 2-Hexene,3,5,5-trimethyl-, 2(3H)-Furanone,5-butyldihydro-, Ethanone, 1-(4,5-dihydro-2-thiazolyl)-, Formamide, N, N-dibutyl-, Phenol, Pyrazine, Pyrazine, methyl- and Trichloromethane (green and fruity substances) were significantly negative correlation with the total amount of fatty acids, and 1-Heptanol,2-propyl- and Biphenyl (lipid fragrance precursor substance) were significantly positive correlation with the total amount of fatty acids (|r| > 0.5, P < 0.05).

The chest muscle at 13 weeks had a more obvious floral, fruity, and sweety aroma. The higher fatty acids content in the chest muscle at 16 weeks might be richer after cooking. Considering the growth rate, flavor characteristics and breeding cost, it was possible to market the Lueyang black-bone chickens at 13 weeks of age in advance.