Predicting temperature profiles to determine degree of doneness for beef biceps femoris and longissimus lumborum steaks.

The degree of steak doneness is an important factor in providing consumers with a satisfying eating experience. Endpoint temperature and cooking rate are the determinants of degree of doneness. Our objectives were to predict internal temperature profiles and cooking times for longissimus lumborum and biceps femoris steaks. Each biceps femoris and longissimus lumborum steak was cooked individually in a gas-fired, forced-air-convection oven at 163 °C until the center temperature of each steak reached 70 °C. Temperature profiles were recorded by a Doric temperature recorder and the recorded time and temperature data were imported into a spreadsheet. A prediction method was then implemented to predict cooking times and temperature profiles. No significant differences (p<0.05) were found in cooking times between experimental and predicted values for either longissimus lumborum or biceps femoris steaks. Good agreement was found between experimental and predicted temperature profiles for the longissimus lumborum muscle. However, predicted temperature profiles were consistently higher (except for the beginning of the cooking cycle) than the experimental values up to 65 °C in the cooking cycle for biceps femoris steaks. A highly positive linear relationship was found between experimental and modeled temperature profiles for longissimus lumborum (R(2)=0.99), whereas a high quadratic (R(2)=0.99) relationship was found for biceps femoris steaks. Our method for predicting temperature profiles of steaks for a specified cooking time to attain a given degree of doneness should increase consumer satisfaction by reducing variation in meat sensory traits related to an expected degree of doneness.

Beef longissimus lumborum, biceps femoris, and deep pectoralis Warner-Bratzler shear force is affected differently by endpoint temperature, cooking method, and USDA quality grade.

Effects of endpoint temperature, cooking method, and quality grade on Warner-Bratzler shear force (WBSF) of beef longissimus lumborum (LL), biceps femoris (BF), and deep pectoralis (DP) muscles were evaluated. Eighteen of all three subprimals were selected from USDA Select and 18 from USDA Choice (Certified Angus Beef) carcasses for the respective muscles. Muscles were vacuum packaged and held at 1 °C for 14 days, frozen (-29 °C), sawed into 2.54-cm thick steaks, vacuum packaged, and stored frozen until cooking. Thawed steaks were cooked by either a Magikitch'n(®) electric belt-grill (BG) at 93 °C, or a water-bath at 93 °C, to one of nine endpoint temperatures: 40, 45, 50, 55, 60, 65, 70, 75, or 80 °C. Belt-grill cooking was much faster and resulted in distinctly less cooking loss than water-bath cooking. Water-bath cooking resulted in higher (P<0.0001) Instron(®) WBSF (31.92 N) than BG (28.25 N) for LL. The combination of Select quality grade and higher endpoint temperatures resulted in higher (P<0.05) WBSF for LL. Two distinct phases of tenderization/toughening occurred for BF. Between 40 and 60 °C, WBSF decreased from 43.95 to 38.16 N (P<0.01), whereas between 60 and 70 °C, WBSF increased from 38.16 N to 44.44 N (P<0.05). Water-bath cooling resulted in higher (P=0.0001) DP WBSF (71.12 N) than BG (59.25 N). The DP had a distinct (P<0.0001) decline in WBSF between 45 and 65 °C, irrespective of the cooking method, followed by an increase between 65 and 80 °C (P<0.01).

In situ investigation of the calcium-induced proteolytic and salting-in mechanisms causing tenderization in calcium-enhanced muscle.

The objective of this experiment was to explore the mechanism(s) of calcium-induced tenderization in calcium-enhanced beef muscle. At 72 h postmortem, beef strip loins (n=15) were injected (9% by weight) with 0.0, 0.05, 0.1, 0.2, or 0.4 M calcium chloride (CaCl(2)) with and without 0.05 M zinc chloride (ZnCl(2)), and aged until 15 days postmortem. Warner-Bratzler shear force peak values indicated that addition of ZnCl(2) drastically inhibited tenderization; however, enhancement with CaCl(2) still tended to reduce shear values (P=0.07; 0.55 kg) when ZnCl(2) was present. In the absence of ZnCl(2), the 0.2 and 0.4 M CaCl(2) treatments were 18.9 and 32.1% more (P<0.05) tender than the 0.0 M CaCl(2) treatment. SDS-PAGE indicated that addition of zinc reduced breakdown of troponin-T into ∼31 and ∼28 kDa components. Transmission electron micrographs indicated that addition of CaCl(2) without ZnCl(2) caused more frequent Z-line fractures and increased lateral spreading of myofibrils. These results suggest that both calcium-activated enzymatic activity and a non-enzymatic salting-in effect contributed to tenderization of calcium-enhanced muscle. However, the enzymatic mechanism reduced toughness 2.9- to 7.5-fold more than the non-enzymatic mechanism. Calcium-activated enzymatic degradation appears to be the major tenderization mechanism and non-enzymatic salting-in of calcium ions appears to be a minor tenderization mechanism, even at high calcium concentrations.

Effects of cooking method, reheating, holding time, and holding temperature on beef longissimus lumborum and biceps femoris tenderness.

Effects of cooking method, holding temperature, holding time, and reheating on Warner-Bratzler peak shear force (WBPSF); Warner-Bratzler myofibrillar force (WBM-F), Warner-Bratzler connective tissue force (WBC-F) and cooking loss were investigated. Two muscles (longissimus lumborum and biceps femoris) from USDA Choice beef carcasses were used. Water-bath cooking resulted in higher WBPSF, WBM-F, and WBC-F than belt-grill cooking for longissimus lumborum. The biceps femoris muscle tenderness improved more with holding time after cooking on a belt than the longissimus lumborum due to its higher collagen content. Cooking biceps femoris steaks to 54 °C by a belt grill and holding them at 57 °C in a water bath for 15 min and subsequent reheating to 70 °C (best treatment combination) produced a 25% reduction in WBPSF, a 37% reduction in WBC-F, and a 12% reduction in WBM-F as compared to the control (cooking steaks directly to 70 °C without holding). Water-bath cooking resulted in lower WBPSF than belt-grill cooking for biceps femoris without any holding time, but further tenderization did not occur with holding. Water-bath cooking resulted in higher cooking losses than belt-grill cooking for both muscles.

Effects of cooking beef muscles from frozen or thawed states on cooking traits and palatability.

Biceps femoris and longissimus lumborum steaks were cooked from either a frozen or thawed state on an electric belt grill (TBG-60 MagiKitch'n Inc., Quakertown, PA) at 93 °C to the endpoint temperature of 70 °C. Cooking loss, cooking time, Warner-Bratzler shear force (WBSF), and color (Illuminant A, L(∗), a(∗), b(∗)) were evaluated. Trained panelists (n=6) evaluated palatability attributes on an eight-point scale for myofibrillar tenderness, juiciness, flavor, overall tenderness, and connective tissue amount (1=extremely tough, dry, bland, tough, and abundant; 8=extremely tender, juicy, intense, tender, and none). L(∗), a(∗), WBSF, juiciness, flavor, connective tissue amount, and overall tenderness did not differ (P>0.05) between steaks cooked from frozen and thawed states. However, thawed steaks cooked faster and had lower cooking losses than frozen steaks. The biceps femoris had higher WBSF values than the longissimus lumborum and was rated less tender by trained panelists. L(∗), a(∗), or b(∗) values did not differ (P>0.05) between muscles. The biceps femoris needed more time to cook and had greater cooking losses than longissimus lumborum. Dimensional changes of steaks cooked to either 60 or 70 °C were studied. The width of biceps femoris steaks decreased 12.2%, and width of longissimus lumborum decreased 6.3%. Longissimus lumborum steaks became shorter (P<0.01) than biceps femoris steaks. Thickness of biceps femoris steaks decreased 25.6%, and thickness of longissimus lumborum steaks decreased 23.3%. Muscle type had a more pronounced effect on dimensional changes of steaks than endpoint temperature.

Evaluation of electric belt grill, forced-air convection oven, and electric broiler cookery methods for beef tenderness research.

Five muscles from USDA Select beef carcasses were cooked on an electric belt grill at three temperatures (93, 117, and 163°C), in a forced-air convection oven, and on an electric broiler to determine effects of cooking treatment and muscle on Warner-Bratzler shear force values, cooking traits (cooking loss, cooking time, and endpoint temperature), and repeatability of duplicate measurements. All cooking treatments allowed shear force differences to be detected (P<0.05) among the five muscles, although the differences were inconsistent. Neither longissimus lumborum nor semitendinosus shear values differed among the five cooking treatments; however, shear values for biceps femoris, deep pectoralis, and gluteus medius differed (P<0.05) among cooking treatments. Belt grill cooking resulted in the highest shear force repeatability (R=0.70 to 0.89) for the longissimus lumborum. All cooking methods provided acceptable repeatability (R⩾0.60) of shear values for the biceps femoris and semitendinosus. The electric broiler was the only cooking treatment that resulted in acceptable repeatability of shear force measurements for all five muscles. It is not recommended to use the gluteus medius to test treatment effects on shear force values. Belt grill or electric broiler cooking are recommended for shear force evaluations.