Beef chilling practices continue to be challenged by today’s incremental increase in carcass size and backfat thickness. Reducing bulk, specifically thick layers of insulating fat, prior to chilling using hot fat trimming (HFT) could improve the ability to chill carcasses and improve quality. The objective of this study was to determine the effect of two levels of HFT on chilling rate, tenderness, marbling score, lean color, and the demand for energy during the chilling process.
Paired sides of beef carcasses (N = 420; n = 105 sides per treatment; 2 replications) varying in weight and backfat thickness were selected on the harvest floor at a commercial processing facility prior to chilling on two separate days. Carcasses were selected hot based on fat thickness to ensure adequate representation of current cattle supply. Alternating left and right sides of the same carcass were assigned to HFT, either minorly trimmed (MT; day 1) or aggressively trimmed (AT; day 2), with the paired side left untouched (negative control; CON). The following measurements were obtained during collection: hot side weight, trimmed side weight, carcass temperature decline, instrumental color, quality, and yield grade factors, as well as an 8 cm section from the anterior end of the strip loin. Temperature probes were inserted to monitor temperature in the deep tissue round, loin, chuck, and surface. Temperature analyses at each location consisted of only matching sides to demonstrate a complete comparison of the HFT sides to the control. Loin sections were aged to 14 d and fabricated into 2.54 cm steak for slice shear force (SSF) and Warner-Bratzler shear force (WBSF) determination with the remaining portion (face steak; approximately 100 g) reserved for sarcomere length analysis. This study was a nested design where carcass side served as the experimental unit nested in carcass, with a significance level set at a = 0.05 for all statistical analysis.
In both MT and AT trimming specifications, HFT sides cooled more rapidly than CON sides, as measured by temperatures monitored in the round, loin, chuck, and surface. Exponential decay models (P < 0.05) showed the greatest difference realized in the chuck and surface, where these areas reached 4°C in 1:29 and 1:22 faster in MT, and 45 and 30 min faster in AT, respectively. Additionally, MT gained a 14 min advantage and AT gained 55 min advantage in time to 4°C over CON in the round. However, because CON and HFT sides were not different in the loin (P≥ 0.10), there was no chilling rate difference. These temperature advantages translated to 0.0113 and 0.0117 savings in tons of refrigeration (TR) over CON in MT and AT sides, respectively. Moreover, tenderness was not affected by either level of HFT as shown by no difference in SSF, WBSF, and sarcomere length in either MT (P ≥ 0.31) or AT (P ≥ 0.58).
Carcasses hot fat trimmed, either minimally or aggressively, had an advantage in temperature decline without affecting tenderness. Of deep tissue monitored locations, the round and chuck displayed the greatest opportunity through HFT. Loin temperatures remained unaffected by minor hot fat trimming and demonstrated a chilling advantage by aggressive hot fat trimming. Additionally, HFT results in lower energy usage and could lead to reduced refrigeration costs over untrimmed sides; if implemented.