Effect of USDA carcass maturity on eating quality of beef from fed steers and heifers that have been classified into maturity groups using dentition

Abstract

Objectives were to compare sensory properties of LM steaks from A maturity and B maturity or older carcasses that were produced by grain finished steers and heifers classified as less than and greater than 30 months of age at the time of slaughter by dentition. Carcasses were selected to represent 2 dentition groups, 2 maturity groups, and 3 marbling categories within each dentition x maturity group resulting in 12 dentition x maturity x marbling subclasses; each subclass consisting of 50 carcasses. Dental age groups consisted of carcasses classified as less than or 30 months of age (MOA) or 30 MOA or older by dentition. Maturity groups consisted of carcasses classified by USDA graders as either A⁰⁰ to A⁹⁹ overall (A) maturity or B⁰⁰ to D⁹⁹ overall (B-D) maturity; marbling categories consisted of carcasses with instrument marbling scores of Slight (SL), Small (SM), or Modest ⁰⁰ to Moderate ⁹⁹ (MT-MD). Carcasses were selected in pairs so that each carcass selected to represent the B-D maturity group was paired with an A maturity carcass of the same sex and similar marbling score (± 50 marbling units.) Strip loin (LM) steaks were obtained from both sides of each carcass. After a 14-d aging period, 1 LM steak was evaluated for Warner-Bratzler shear force (WBSF) and slice shear force (SSF). The other LM steak was used for sensory analysis by a trained descriptive attribute panel. No differences (P > 0.05) were detected in WBSF, SSF, or sensory panel ratings for tenderness juiciness, or flavor between LM steaks from carcasses classified as A maturity vs. steaks of carcasses classified from B-D maturity. Sex class influenced (P < 0.05) WBSF and sensory panel tenderness. As degree of marbling increased, sensory tenderness, juiciness, meaty/brothy flavor, and buttery/beef fat flavor increased (P < 0.05) while bloody/serumy flavor, WBSF and SSF decreased (P < 0.05). There was a significant interaction between dental age group and marbling category for SSF and panel tenderness ratings, where cattle classified as 30 MOA or older with a slight degree of marbling produced the toughest (P < 0.05) LM steaks. Within the SM and MT-MD marbling categories dental age had no effect. Results from this study suggest that USDA quality grades could be effective at determining eating quality differences to grain-finished cattle with a dental age less than 30 mo old at the time of slaughter if the A and B-D maturity groups were combined and quality grades were assigned only by marbling. In grain-finished cattle 30 mo or older at the time of slaughter the evidence was not sufficient to make conclusions.