Understanding the impact of reduced water use beef spray chilling system on beef carcass quality and saleable yield

The objective of this study was to determine the effect of water volumes applied during beef carcass spray chilling on postmortem chilling losses, muscle and surface temperature decline, microbial load, carcass grade attributes, carcass cutability, carcass composition, and beef tenderness. Beef carcasses (N = 1,978) were harvested over 6 weeks at a commercial beef processing facility in Friona, TX and paired sides from each carcass were assigned to one of two spray chilling protocols. One side was chilled with a conventional high water volume spray chilling protocol. This protocol applied 104.1 L of water per sided trough 90 s intermittent sprays occurring every 25 min for a 12 h spray duration (HW). Each paired side was chilled with a reduced water level spray chilling protocol to increase processing sustainability. This spray chilling protocol applied 3.1 L of water per side through 16 s intermittent sprays occurring every 30 min for a 3 h spray duration (LW). Sides were alternatively assigned to chilling protocol to balance the number of left and right sides in each treatment. For each side (n = 1,978 paired sides), hot weight and hot removed kidney pelvic and heart fat weight (KPH) was collected on the harvest floor. Each week, sides (n = 72 paired sides) were monitored for continuous temperature declines of the deep semimembranosus, longissimus, and surface. These sides (n = 72 paired sides) were additionally subjected to pre- and post-chill microbial analysis of aerobic and coliform bacteria. Sides (n = 1,978 paired sides) were weighed and subjected to USDA grading following 28.5 hours of chilling. A subset of the paired carcasses (n = 85) were selected for a full carcass cutout. Carcass sides were fabricated and all carcass components were weighed and compared to initial subprimal weights with a tolerance of ± 1.0% of the initial component for inclusion in the data set weight. A striploin steak was collected from each side (n = 85 paired steaks) for slice shear force and Warner-Bratzler shear force analysis. Paired whole muscle (n = 765 paired samples), trim (n = 510 paired samples), fat (n = 510 paired samples), and external fat (n = 255 paired samples) were collected from each side. These samples were subject to proximate analysis with near infrared spectrometry (NIR) and oven drying moistures. Data were analyzed with the GLIMMIX of SAS (version 9.4, SAS Inst. Inc., Cary, NC). Chilling protocol was observed as the fixed effect and replication as the random effect (α = 0.05). Peak cooked temperature was included shear force models as a covariate (P < 0.001). USDA grade and marbling score distribution of each carcass was accessed with the Freq procedure of SAS (version 9.4, SAS Inst. Inc., Cary, NC). Temperature decay of analyzed tissues were determined in R (version 4.0, R Core Team, Vienna, Austria) using a self-starting Nls Asymptotic Regression (Crawley, 2007). Hot side weights did not differ at prior to chilling(P ≥ 0.53). After chilling, reduced LW increased shrink by 1.07% (P < 0.001) yielding 2.08 kg lighter chilled side weight (P < 0.001) than HW. Temperature decline was not affected in the longissimus (P ≥ 0.12) or at the surface (P ≥ 0.21) by water volumes applied during spray chilling. Conversely, HW produced rounds with lower temperatures after 25 h postmortem (P ≤ 0.03), which was supported by a greater exponential decay factor. Water volumes applied during spray chilling did not influence post chill microbial counts (P ≥ 0.12). Though LW sides possessed lower (P < 0.01) numerical USDA yield grades and HW sides possessed greater marbling scores (P < 0.01), marbling score and USDA grade distribution did not differ (P ≥ 0.43). Though chilling protocols did not impact total cutout subprimal weight (P = 0.34), HW resulted in increased weight of trim (P = 0.03) and fat (P < 0.01). This resulted in LW sides being comprised of a greater percent of subprimals (P < 0.001) and salable yield (P = 0.01) and HW. Oven drying and compositional analysis with NIR determined HW samples possessed a greater percentage of moisture in external fat (P ≤ 0.04) and in fat from four out of the six primals (P ≤ 0.02), respectively. Water volumes applied during spray chilling did not affect instrumental tenderness (P ≥ 0.20). These results determined though high water volumes applied during spray chilling is advantageous at decreasing shrink and postmortem round temperatures, spray chilling water volumes can be reduced without compromising loin temperature decline, carcass grade attributes, subprimal yield and beef tenderness.