The objective of the current study was to evaluate the influence of bone and subcutaneous fat on yield, physicochemical traits, and color stability of dry-aged beef from grass-fed Nellore bulls. Paired bone-in loins (from the 10th thoracic vertebra to 6th lumbar vertebra) from 8 carcasses were collected and cut in half, and the sections from each carcass were assigned to 4 treatments (
Brazil is a major exporter and the second largest producer of beef in the world, with 2.2 million metric tons (carcass weight equivalent) exported and 10.2 million tons (carcass weight equivalent) produced in 2019 (
Tenderness is the most important sensorial attribute for beef consumption (
Compared to wet aging, dry aging is more expensive (
It is well known that the lean tissue expresses greater evaporation loss compared to fat tissue (
Most beef produced in Brazil is from grass-fed Nellore cattle with thin subcutaneous fat; therefore, knowledge of the impact of both subcutaneous fat and bone on dry-aged beef is important to increase yield and achieve a consistent and less costly product. In this sense, to evaluate the feasibility of dry-aged beef produced from grass-fed Nellore bulls, this work assessed the combined effects of bone (bone-in and boneless) and subcutaneous fat (with or without fat) on yield and physicochemical traits of dry-aged beef from grass-fed Nellore bulls.
Paired bone-in loins (from the 10th thoracic vertebra to 6th lumbar vertebra) from 8 grass-fed Nellore bulls (approximately 30 mo old; on average 290 ± 36 kg of carcass weight; 6.0 ± 0.4 mm of fat thickness, measured at the 9th/10th rib interface at three-fourths of the length of the ribeye from its chine-bone end; marbling score: traces) were collected at a commercial beef plant at 2 d postmortem. The loins were packed in plastic bags (not vacuumed or sealed), placed in a portable cooler with ice, and transported to the meat lab at the University of Campinas.
At the laboratory, each pair of bone-in loins was cut in half, providing 4 half-loin sections per carcass (2 anterior and 2 posterior sections). Then, the half-loin sections from each carcass were balance assigned into the 4 treatments in a predetermined design to avoid an effect of anatomical position. The treatments were bone-in with subcutaneous fat, bone-in without subcutaneous fat, boneless with subcutaneous fat, and boneless without subcutaneous fat. The sections assigned to boneless treatments were deboned (bones were weighed), and sections for treatments without subcutaneous fat had the fat removed (fat was not weighed, since the aim was to simulate carcasses with little or no fat), following the natural connective tissue seam.
After fabrication, the loin sections were aged for another 21 d in an aging chamber (VN50R model, Metalfrio 2010 ©, Brazil) adapted with a humidifier to control the relative humidity of the chamber. The aging condition was 2°C, 70% ± 5% relative humidity, and 2.5 m/s of air speed.
For the bone-in treatments, either with or without subcutaneous fat, each loin section was weighed (initial weight) and then dry-aged for 21 d. After aging, the bone-in loin sections were reweighed (post-aging weight), and the evaporation loss was calculated according to following equation: [([initial weight − post-aging weight] / initial weight) × 100]. Then, the bone-in loin sections were deboned, and the dried crust was trimmed. Afterward, bone (bone weight), trimmings (trimming weight), and the loin section (final weight) were weighed. The trimming loss was determined by [(trimming weight / initial weight) × 100]. Furthermore, the yield was calculated by [(final weight / initial weight) × 100].
Similarly, evaporation, trimming loss, and yield of the boneless treatments, either with or without subcutaneous fat, were determined according to the following steps. First, each loin section assigned to the boneless treatment was deboned. Bone (bone weight) and loin sections (initial weight) were weighed. Subsequently, the boneless loin sections were dry-aged for 21 d. After aging, boneless loin sections were reweighed (post-aging weight), and the evaporation loss was calculated by [([initial weight − post-aging weight] / initial weight) × 100]. Then, boneless loin sections were trimmed. The trimmings (trimming weight) and loin sections (final weight) were weighed. The trimming loss was determined by [(trimming weight / initial weight) × 100]. The yield was calculated by [(final weight / [initial weight + weight of bone]) × 100].
Following the fabrication process, the loin sections were cut into steaks, without trimming any of the subcutaneous fat. The steaks were sequentially assigned to the analyses, following the respective order (anterior to posterior): pH and moisture content (2.0 cm thick), thiobarbituric acid-reactive substances (TBARS; 1.0 cm thick), Warner-Bratzler shear force and pressed juice percentage (2.5 cm thick), and instrumental color (1.5 cm thick).
The water activity (aW) was measured on the surface of dry-aged samples. A 2-mm-thick sample was cut out from the dried surface of each loin section and placed in a container for aW analysis. Then, aW was determined using a water activity meter (Decagon, Brazil, Aqualab 4TE). The pH was determined in non-aged and aged steaks. To determine the pH, the probe (Mettler Toledo, Brazil, MP125 pH meter) was first calibrated with buffer solutions of 4.01 and 7.00 pH, at 5°C. Then, the pH probe previously calibrated was introduced directly into each steak in 2 different positions, measuring the pH in duplicate.
The moisture content was measured in non-aged and aged samples. Each steak assigned to the moisture content analysis had the fat removed, and the internal lean beef was ground. Approximately 10 g of each ground steak was dried in a forced air convection oven at 105°C for 20 h, in triplicate, according to AOAC (
The pressed juice percentage and Warner-Bratzler shear force were both analyzed using the same steaks. Immediately after aging and fabrication, the steaks were prepared for cooking. Steaks (2.5 cm thick) were weighed and cooked in an electric convection oven (Fritomaq, Brazil) at 170°C, until the internal temperature reached 71°C. After cooking, the steaks were reweighed to determine the cooking loss.
The pressed juice percentage was determined according to Lucherk et al. (
After cutting the samples for the pressed juice percentage method, the samples were saved at room temperature for approximately 30 min to cool and then they were overwrapped in polyvinyl chloride film and kept at 4°C overnight before proceeding with the Warner-Bratzler shear force method, following the American Meat Science Association (
Color stability during storage was evaluated using a colorimeter (CM 508-d, Hunter MiniScan TMXE, Hunter Associates Laboratory, Inc., Reston, VA). Each steak assigned to color display was placed in a polystyrene tray, then wrapped with a polyvinyl chloride film and kept in a refrigerator at 4°C, with no lights, for 9 d. Color was determined every day following the American Meat Science Association (
Sixteen bone-in loins, from 8 beef carcasses, were used in this experiment. The bone-in loins were cut in half and then balanced across to the treatments (8 half-loins per treatment,
No interactions (
Effects (mean ± SEM) of bone (bone-in and boneless treatments) and subcutaneous fat (with and without subcutaneous fat treatments) on evaporation loss, trimming loss, and yield (
Trait | Treatments | ||||||
---|---|---|---|---|---|---|---|
Bone | Subcutaneous Fat | ||||||
Bone-in | Boneless | With | Without | Bone | Fat | Bone × Fat | |
15.63 ± 0.76 | 22.76 ± 0.96 | 16.58 ± 0.88 | 21.81 ± 1.23 | <0.0001 | <0.0001 | 0.249 | |
8.16 ± 0.55 | 18.18 ± 0.65 | 11.70 ± 1.21 | 14.64± 1.53 | <0.0001 | <0.0001 | 0.127 | |
49.77 ± 1.15 | 40.79 ± 1.42 | 48.92 ± 1.46 | 41.64 ± 1.46 | <0.0001 | <0.0001 | 0.749 |
Boneless samples showed higher evaporation and trimming loss and consequently lower yield compared to bone-in samples (
Thus, bone and subcutaneous fat were considered important factors during the dry-aging process, reducing evaporation and trimming loss and increasing yield.
No interactions (
Effects (mean ± SEM) of bone (bone-in and boneless treatments) and subcutaneous fat (with and without subcutaneous fat treatments) on pH, TBARS, moisture content, surface aW, cooking loss, pressed juice percentage, and WBSF (
Trait | Treatments | ||||||
---|---|---|---|---|---|---|---|
Bone | Subcutaneous Fat | ||||||
Bone-in | Boneless | With | Without | Bone | Fat | Bone × Fat | |
5.44 ± 0.01 | 5.45 ± 0.01 | 5.46 ± 0.01 | 5.43 ± 0.01 | 0.326 | 0.069 | 0.912 | |
0.19 ± 0.02 | 0.20 ± 0.02 | 0.21 ± 0.02 | 0.19 ± 0.02 | 0.691 | 0.588 | 0.325 | |
74.06 ± 0.23 | 72.97 ± 0.21 | 73.63 ± 0.26 | 73.40 ± 0.26 | <0.05 | 0.469 | 0.091 | |
0.9409 ± 0.0020 | 0.9324 ± 0.0021 | 0.9396 ± 0.0020 | 0.9336 ± 0.0024 | <0.05 | <0.05 | 0.177 | |
16.66 ± 0.58 | 14.06 ± 0.56 | 16.49 ± 0.39 | 14.23 ± 0.74 | <0.05 | <0.05 | 0.322 | |
33.19 ± 0.67 | 32.67 ± 0.87 | 33.06 ± 0.72 | 32.79 ± 0.83 | 0.645 | 0.811 | 0.292 | |
36.03 ± 1.98 | 36.46 ± 3.08 | 37.97 ± 3.14 | 34.52 ± 1.78 | 0.905 | 0.342 | 0.113 |
aW, water activity; MDA, malondialdehyde; TBARS, thiobarbituric acid-reactive substances; WBSF, Warner-Bratzler shear force.
The presence or absence of bone did not affect the pH or TBARS values (
Subcutaneous fat had no effect on the pH, TBARS, or moisture content values (
No interactions (
Bone-in samples had higher cooking loss values compared to boneless (
Regardless of the presence of bone and subcutaneous fat, the treatments were considered very tender, as the WBSF values were lower than 38.2 N (
No interaction (
Additionally, there was a bone-by-time interaction (
Effects of bone and time interaction on CIE
Pictures illustrating the development of color discoloration on bone-in and boneless steaks during display.
Meat discoloration is influenced by many biochemical mechanisms, including metmyoglobin reducing ability and oxygen consumption (
In this study, the steaks assigned for the color analysis were refrigerated at 4°C without light exposure. In a supermarket display, discoloration could occur faster, due to the temperature fluctuations and light exposure. Lower temperature could increase display color life; however, retail display temperature is frequently up to 7°C (
The data from the current study indicate that dry-aged beef from grass-fed Nellore bulls resulted in a very tender product. However, further sensory studies should be performed to investigate consumers’ acceptance of dry-aged beef from grass-fed Nellore bulls in the Brazilian market. Furthermore, the results show that both bone and subcutaneous fat had a similar protective effect on lean beef, reducing evaporation loss and increasing yield of dry-aged beef. Therefore, considering these results and taking into account that dry-aged beef is an expensive product mainly due to the weight lost during its production, the use of bone-in loins with thicker subcutaneous fat to produce dry-aged beef is highly recommended.
The authors have no conflict of interest to declare. The current research was funded by the São Paulo Research Foundation (FAPESP - Project: 2016/02853-9) and financed in part by the Coordination of Superior Level Staff Improvement (CAPES - Financial Code 001). The authors would like to thank the National Council for Scientific and Technological Development (CNPq) for providing scholarship support