Cooking Temperature and Hold Time Affect Beef Brisket Textural Properties and Cooking Yield

Product selection

Raw USDA Choice briskets (n = 96) selected at random from 2 commercial lots were trimmed to 6 mm external fat thickness at a commercial processing plant (Table 1). These lots were restricted to be domestic, USDA Choice, and weight range of 2.9 to 7.1 kg. Deckle fat was removed, and sternum and external fat were trimmed to 6 mm before being vacuum packaged and shipped to College Station, TX for cold (4°C) storage of no more than 1 wk.

Cookery and yield determination

Briskets were weighed and sorted into batches with weights ± 1.1 kg (n = 6 briskets per batch with 2 batches for each of 8 temperature/hold time combinations) to monitor the ending temperature more accurately. The treatments were assigned to stratified batches for one “light weight” and one “heavy weight” batch to prevent brisket weights from confounding the treatments. Each batch of 6 briskets was randomly assigned a final internal temperature of 75, 80, 85, or 90°C and a hold time of 0 or 3 h at that internal temperature, respectively (n = 12 briskets per time-temperature treatment).

A 50 g piece of lean from the surface of the flat and point were collected for raw analysis prior to cooking. Raw weight, temperature, brisket length from the anterior to posterior point, and flop dimensions (see Figure 1) were recorded. Briskets were placed on the middle racks of a smokehouse truck, spaced evenly, and cooked in an Alkar (Model 1000 with Jumo Controls, Alkar, Middleby, Lodi, WI, USA) smokehouse according to a standard brisket smokehouse schedule (see Table 2) in randomly assigned batches. The temperature of the product (placed in the thickest point of the heaviest brisket for each batch) and the house conditions were monitored using standard smokehouse probes. Upon completing the hold time, temperature, cooked weight, and brisket length were recorded. In addition to cooked flop measurements, briskets were probed with a TMS-Pro (Food Tech Corp, Rockland, MA) fitted with a custom 2.5 cm spherical probe. Each brisket was placed beneath the spherical probe which was attached to a vertical load cell. Each brisket was probed perpendicular to the surface of the brisket in triplicate at the each of the point, flat, and the center seam that attaches the two muscles. The probe traveled a vertical distance of 10 mm after contact with the brisket at a speed of 400 mm/min. Peak force was recorded for each. Briskets were chilled at 4°C overnight, and piece weights were collected. The flats and points were then sliced using a deli slicer (Avantco model SL312, Lancaster, PA) perpendicular to the muscle fibers. Slices from areas subjected to probing were sliced to 2.5 cm thick for WBSF analysis. The rest of the piece was sliced 8 mm thick, with those serially cut next to the WBSF slice designated for slice shear force (SSF) and sensory analysis. Slices were labeled, vacuum packaged individually, and stored in cold storage (4°C; no more that 2 wk) until sensory analysis.

Figure 1.

Cooked briskets were measured by distance A and B. The angle designated (*) was calculated using trigonometric properties. Cooked briskets cooked to (C) 75°C with 0 h hold, (D) 85°C with 0 h hold, and (E) 90°C with 3 h hold that could not flop (CNF).

Warner-Bratzler and slice shear force

Shear force techniques are described in AMSA (2016). Briefly, slices (2.5 cm thick) were placed in a single layer on a plastic tray with PVC overwrap and stored at refrigerated temperature until coring. The 2.5 cm slices were trimmed to expose muscle fiber orientation, and 6 cores were removed from each portion parallel to the muscle fibers. The cores for WBSF were sheared once perpendicular to the muscle fibers using a TMS-Pro (Food Tech Corp) fitted with the WBSF blade moving at 200 mm/min. Peak force was recorded.

This SSF slice was reheated along with the sample for trained sensory panel in a sealed vacuum bag to 63°C in a water bath. The slice was cut, avoiding fat and connective tissue depots, to a 1.3 × 5 cm portion. The trimmed sample was sheared once perpendicular to the muscle fibers using a TMS-Pro (Food Tech Corp) fitted with the SSF blade at 200 mm/min. Peak force was recorded.

Trained sensory panel

A five-member sensory panel was trained on the descriptive spectrum of texture attributes, including cohesiveness, cohesiveness of mass, muscle fiber tenderness, connective tissue amount, and moisture release. References for attributes are provided in Table 3. Intensity scores (0 = none; 15 = extreme) were recorded for each panelist prior to discussion among panelists to provide a consensus score (AMSA, 2016). Individually vacuum-packaged sample slices were reheated in a water bath to an internal temperature of 63°C using sous vide. Slices were cut into 1.3 x 1.3 x 0.6 cm portions and served to panelists. After assessing a warmup sample of brisket similar to what would be evaluated during testing, the panel evaluated 16 samples per 2-h session with a 10-min break after the first 8 samples. The 16 samples represented duplicate samples of 4 temperatures and 2 hold times during each panel session. The panel was provided with double-distilled water, saltless crackers, and fat-free cottage cheese to cleanse their palettes. All sensory analyses were approved by the Texas A&M Institutional Review Board IRB# 2019-1001M.

Collagen determination

The collagen amount was determined following the method described in Hill (1966) and modified by Cross et al. (1973). In summary, raw and cooked samples from the point and flat segments of each brisket were frozen in liquid nitrogen, powdered, and weighed out (4.0 to 4.1g) in duplicate. A ¼ strength Ringer’s solution was added to each sample, agitated in a warm bath (80°C) for 60 min, cooled, and separated into phases via centrifugation (1,500 x g for 15 min). The pellet and supernatant from each sample were cooked for 16 h with 7 N sulphuric acid. Samples were filtered before 2 mL was oxidized and exposed to a color reagent in a 60°C water bath alongside a hydroxyproline solution standard gradient. The final solution was pipetted in triplicate, and the absorbance was read at 558 nm using a spectrophotometer (Gen5, BioTek, Winooski, VT).

Statistical analysis

Data were analyzed using ANOVA with a significance level of 0.05 for a 4 (75, 80, 85 and 90°C temperatures) by 2 (0 or 3 h holding time) factorial arrangement of a completely randomized design. Random effects included in the models were replication for cook yield, sensory and shear force, and batch for flop measurements. Muscle pH was used as a covariate in determining both hot and chilled cook yield. Raw weight was used as a covariate for data analyzed for poke force measurement using the spherical probe. For significant (P < 0.05) main effect and two-way interactions, students’ t-tests were used to separate least-squares means. Pearson’s coefficients for correlation were evaluated to determine relationships among the variables. All statistical analyses were performed using JMP (SAS Institute, Inc., Cary, NC).

Cookery, yield, and flop determination

The cook times in hours are reported in Table 4. No significant differences were reported in cook time among time and temperature treatments (P > 0.05). As expected, briskets cooked to 75°C and held for 0 h had the highest (P < 0.001) hot and chilled cook yields, whereas briskets cooked to 90°C and held for 3 h had the lowest (P < 0.05) chilled cook yields. Within each internal temperature treatment, holding briskets for 3 h instead of 0 h resulted in lower (P < 0.05) hot and chilled cook yields. Harris et al. (2017) reported cook yield of 62.6% when cooked on a professional barbecue pit to an internal temperature of 85°C, which is nearly identical to the value for yield in the present study when briskets were cooked to 85°C. Boles and Shand (2001) reported a 67% cook yield of the point half cooked to a final internal temperature of 73°C.

The change in length measurements corresponded to the shrink of the flat and was used for calculating the angle of the flop (Table 5). The greatest (P < 0.05) change in length (measured by the difference between raw length and cooked length) occurred in briskets cooked to 85°C and held for 0 h, while the smallest (P < 0.05) change was observed in briskets cooked to 80°C and held for 3 h or cooked to 90°C and held for 3 h (4.1 and 2.6, respectively; which were similar; P > 0.05). The cooked flop angle degree was greatest (P < 0.001) for briskets cooked to 75 and 80°C, regardless of hold time, and those cooked to 85°C and held for 0 h (>50° angle and >30° change. Briskets cooked to 90°C and held for 3 h lost structural integrity enough to result in breaking across the point of flop. These briskets were designated as “could not flop” (CNF). This is a novel measurement for determining the change in texture and connective tissue amount and thus has not been investigated other than in the present study.

The present study’s findings underscore the relationship between cooking conditions and the physical properties of beef briskets, which in turn affect consumer satisfaction and marketability. The results demonstrated that cooking to a lower internal temperature of 75°C and not holding the briskets post-cooking yielded the highest hot and chilled cook yields (73.22% and 70.24%, respectively). Conversely, cooking to a higher internal temperature of 90°C and holding for 3 h significantly reduced (P < 0.05) the chilled cook yields (55.97% and 55.19%, respectively) compared to other cook and hold times. This pronounced yield reduction at higher temperatures and longer holding times can be attributed to increased moisture loss and structural breakdown of the meat, which is critical for optimizing cooking processes in commercial settings.

Data from Harris et al. (2017) and Boles and Shand (2001) further contextualize these findings. Harris et al. reported a cook yield of 62.6% when cooking to 85°C on a professional barbecue pit, while Boles and Shand noted a 67% yield for briskets cooked to 73°C. These variations in cook yield underscore the importance of temperature control and cooking methods in achieving desired meat qualities. The present study also introduced novel measurements such as the change in length and the angle of the flop to evaluate the structural integrity of cooked briskets. The greatest change in length was observed in briskets cooked to 85°C and held for 0 h, indicating significant shrinkage. This metric, along with the cooked flop angle, provides valuable insights into the texture and connective tissue changes during cooking. Briskets cooked to 90°C and held for 3 h exhibited the smallest change in angle and, in some cases, lost structural integrity to the extent that they were designated as CNF.

Warner-Bratzler and slice shear force

Probe brisket peak force (N; Table 6) was more variable (a lower R² value indicating less of the variation being accounted for by the model, data not shown in tabular form) when observed at the flat than the point or center region of the brisket (R²_adj = 0.36, 0.54, 0.60, respectively). This is due to the geometric and flat thickness differences of the briskets. A greater range of values was observed for the center than the point region (91.1 N vs. 43.1 N, respectively). Accordingly, the center region would be a more sensitive measure for determining doneness. In the center region, the greatest (P < 0.001) peak force was recorded for briskets cooked to 75°C and held for 0 h and decreased with an increase in temperature and hold time until briskets reached 90°C, where they were similar, regardless of hold time, to briskets cooked to 85°C and held for 3 h.

Brisket flats cooked to 90°C and held for 0 h had the lowest (P < 0.001; Table 7) peak WBSF (N). As temperature and hold time increased from 75°C and 80°C with 0 h hold time, shear force decreased (P < 0.001) until 85°C, at which the values became similar between 0 and 3 h hold and those cooked to 90°C and held for 3 h. The slight increase (P < 0.05) in brisket flats cooked to 90°C and held for 3 h reflects the yield loss, for these briskets yielded less than 56%. By tenderness certified claim requirements, all of the cooked briskets achieved “certified tender” claim thresholds (ASTM, 2011). Only the point of the briskets cooked to 90°C and held for 3 h was able to achieve the delineation of “certified very tender” by SSF value under 45.1 N (Figure 2).

Figure 2.

Final internal temperature main effect on Warner-Bratzler shear force and slice shear force values (N) in the point portion of the briskets.

In general, the brisket muscles are considered to be tough in comparison to other muscles (Boles and Shand, 2001), and the point half is tough regardless of USDA quality grade (Fletcher et al., 2021) and is even immune to shockwaves (McDonnell et al., 2021). Nevertheless, the briskets in the present study had low WBSF measurements even at an internal temperature of 75°C when compared to these other studies. One of the challenges in comparing the shear force values to other published values is that most other studies used an oven roast method rather than a commercial smokehouse, as a smokehouse generally takes a longer time to complete the cook cycle and includes a step for the addition of natural smoke.

Trained sensory panel

Cohesiveness was greatest (P < 0.001; Table 8) in briskets cooked to 75°C and held for 0 h for both the flat and point (12.0 and 13.5, respectively). Similar scores for cohesiveness were observed in the flats of briskets cooked to 75°C and held for 3 h, 80°C, and 85°C and held for 0 h. The lowest (P < 0.001) flat cohesiveness scores were in briskets cooked to 85°C and held for 3 h or cooked for 0 or 3 h to 90°C (6.2, 6.3, and 7.0, respectively). Similarly, the points of briskets cooked to 85°C and held for 3 h and cooked to 90°C for either 0 or 3 h hold times were the least (P < 0.001) cohesive (6.3, 5.1, and 5.3, respectively). Cohesiveness of mass is defined as the degree to which the brisket forms a mass as it is chewed. Briskets cooked to 75°C and held for 0 h scored the greatest (P < 0.05) cohesiveness of mass for both the flat and point (9.7 and 11.3, respectively). Generally, the cohesiveness of mass scores decreased (P < 0.05) with increased temperature and hold time. Points of briskets cooked to 90°C regardless of hold time scored the least cohesive (6.2 and 6.3 for 0 and 3 h hold, respectively; P < 0.05). Muscle fiber tenderness scores increased (P < 0.02) as the temperature rose above 75°C for 0 h, then maintained tenderness scores until briskets were cooked to 90°C and held for 3 h. At this point, the scores for the point decreased slightly, presumably in response to the severe decrease in yield as the briskets began to dry out. Detectable connective tissue amount decreased (P < 0.05) with increased temperature and increased past 75°C 0 h hold time for the flat until temperatures passed 85°C. The greatest (P < 0.05) connective tissue amount was detected in briskets cooked to 75°C and held for 0 h. The least connective tissue amount was detected in briskets cooked to 90°C and held for 0 h, which was similar (P > 0.05) to flats cooked to 85°C and held for 3 h.

Harris et al. (2017) concluded that briskets smoked and prepared using a Texas-style barbecue method scored highly by consumers, with the flat half scoring higher in overall palatability. They suggested that marketing the two brisket muscles separately may be more valuable. However, Fletcher et al. (2021) reported that—while consumers could not distinguish among USDA quality grades of the point portion of smoked briskets—point samples, regardless of quality, scored higher than flat portions. They furthermore found that consumers had a greater willingness to pay for what they perceived as superior eating quality. This may indicate that if flavor were the same for each brisket and tenderness could be maximized, then consumers may be willing to pay more for perceived tenderness.

Collagen determination

Total collagen (mg/g) and collagen solubility (%) did not differ (P > 0.05) among raw briskets (Table 9). Total collagen also did not differ (P > 0.05) for the flats of cooked briskets. The greatest concentration of collagen (mg/g) in the point was in briskets cooked to 80°C and held for 3 h (16.16), which was similar to 85°C and 90°C held for 0 h, whereas briskets cooked to 75°C and held for 0 h or cooked to 90°C and held for 3 h were similar (P > 0.05; 11.51 and 9.76, respectively). The difference in total collagen concentration may be a function of cook yield. Briskets cooked to lower temperatures had greater moisture content to dilute the collagen concentration, and briskets cooked to greater temperatures lost collagen with greater fat melting duration and protein denaturation. Collagen solubility (%) of both the point and flat increased (P < 0.001) with an increase in temperature and hold time, reaching the greatest solubility at a temperature of 85°C with a 3 h hold and 90°C with a 0 or 3 h hold. Moreover, the change in solubility (%) from raw to cooked upon application of temperature and hold treatment resulted in the same outcome. The flat and point of briskets cooked to 75°C and held for 0 h resulted in a 10.35% and 7.07% change (P < 0.001), respectively, whereas flat and point regions of briskets cooked to 85°C and held for 3 h or cooked to 90°C and held for 0 or 3 h showed the greatest (P < 0.001) percentage change in collagen solubility (more than 34% and 26%, respectively).

Purslow (2005) described the overall characteristics of connective tissue in meat and its effects on meat quality. He reported that cooking increases intramuscular connective tissue strength in the temperature range of 25 to 50°C and decreases strength at higher temperatures. Additionally, connective tissue forms a background toughness that little can be done to alleviate at low temperatures that most whole muscle products are cooked to (Sentandreu et al., 2002). Perimysial intramuscular connective tissue has been reported to have a much larger influence on background toughness than endomysial connective tissue and that the perimysial layer is so strong and so dominant that it is considered to be the most important fraction of collagen in muscle (Carroll et al., 1978; Purslow, 1985, 2005).

The calculated cook angle had a positive, moderate correlation (r = 0.40; P < 0.05) to cohesiveness and a negative, moderate correlation (r = −0.42; P < 0.05) to collagen solubility (%) for both the flat and point (Table 10 and 11). Flat trained sensory panel muscle fiber tenderness had a moderate, negative correlation (P < 0.05) to WBSF, SSF, cohesiveness, cohesiveness of mass, and yields and had a strong, positive correlation (r = 0.81; P < 0.05) to connective tissue. Strong, positive correlations (P < 0.05) were observed between cook yields and poke force at center as well as sensory cohesiveness. Cook yields also had negative, moderate correlations (P < 0.05) to muscle fiber tenderness and connective tissue amount for both the flat and point. Poke force at the center showed a positive, moderate correlation (P < 0.05) to WBSF and SSF of the flat and point. Center poke force also had a strong, positive correlation (P < 0.05) to yield outcomes.

Table 10.

Correlation coefficients for brisket quality measurements on the flat half (pectoralis profundis)

Table 11.

Correlation coefficients for brisket quality measurements on the point half (pectoralis superficialis)

Moisture release had no correlation (P > 0.05) to the other sensory attributes except for a positive, weak correlation (P < 0.05) to cohesiveness and cohesiveness of mass in the point of the brisket. Cohesiveness and cohesiveness of mass had a negative, moderate correlation (P < 0.05) in both the flat and point to muscle fiber tenderness and connective tissue amount. Strong, positive correlations (P < 0.05) were established between muscle fiber tenderness and connective tissue amount as well as between cohesiveness and cohesiveness of mass.

In determining the contribution of connective tissue to sensory tenderness, Jeremiah et al. (2003) reported that insoluble collagen was moderately correlated to sensory traits of briskets, but that soluble and total collagen content had no relationship with sensory traits or sensory desirability. Fletcher et al. (2021) found no relationship between total collagen and consumer acceptability or willingness to pay for smoked briskets. Additionally, Purslow (2005) emphasized that the structural integrity of muscle fibers and the degree of cross-linking in collagen also affect meat tenderness. These studies collectively indicate that, while insoluble collagen contributes to tenderness, the overall collagen content and its solubility do not significantly impact consumer perception or market value of beef products. Understanding these distinctions can help in developing meat processing techniques that enhance tenderness without altering collagen content.