PS9-6. Exploratory Lipidomics Reveals Factors Affecting Tenderness and Intramuscular Fat Variation in Nellore Beef.

Abstract Small molecules such as lipids provide insights into biological and metabolic processes in organisms. Considering the central role of lipids in muscle structure, energy metabolism, and biochemical signaling, lipidomics has emerged as a promising approach to investigate the molecular basis of meat quality traits. This study investigated lipid species associated with variations in beef tenderness and intramuscular fat (IMF). Samples of Longissimus thoracis muscle were collected from 280 Nellore bulls to determine Warner-Bratzler shear force (WBSF) and IMF. Based on these traits, samples were classified into four groups: −WBSF−IMF (6.21 ± 0.14 kg and 0.76 ± 0.03%), +WBSF+IMF (8.26 ± 0.17 kg and 2.35 ± 0.15%), −WBSF+IMF (5.68 ± 0.18 kg and 2.54 ± 0.15%), and +WBSF−IMF (8.41 ± 0.10 kg and 0.85 ± 0.08%). Six samples/group were selected for exploratory lipidomics by multiple reaction monitoring using Agilent 6410 triple quadrupole mass spectrometer. The relative intensities of the ions were loaded into Metaboanalyst 6.0 (https://www.metaboanalyst.ca/) for univariate and multivariate statistical analyses. Lipid profiles were compared across three contrasts: +WBSF−IMF vs. −WBSF−IMF, +WBSF+IMF vs. −WBSF+IMF, and +WBSF+IMF vs. +WBSF−IMF. In low IMF, the +WBSF group showed lower abundance of acylcarnitines (CAR; 14:0) and greater abundance of phosphatidylcholine species compared to the −WBSF group. In high IMF, −WBSF group exhibited greater abundance of cholesteryl esters (19:0), CAR (22:5), and L-carnitine. In samples with similar tenderness (+WBSF), a high IMF was associated with greater abundance of CAR and diacylglycerols and reduced free fatty acids (15:0, 16:0) and sphingomyelins. In conclusion, tenderness and IMF content of Nellore beef appear to be related to lipid class distribution and remodeling, which influence postmortem metabolism and proteolysis. Funding from the São Paulo Research Foundation (FAPESP): 2022/10240-8, 2023/16301-1, and 2023/16127-1.