Effect of Changes in Intermuscular and Subcutaneous Fat Levels on Cholesterol Content of Raw and Cooked Beef Steaks

Muscle, intermuscular (seam) fat and subcutaneous fat dissected from boneless rib steaks (U.S. Choice quality grade; USDA yield grade 1 to 5) were analyzed for cholesterol content. For raw steaks, the cholesterol content (wet basis) in the fat fractions was greater than 150% of that in the muscle fraction; the difference diminished greatly when steaks were cooked to an internal temperature of 70°C. On an average of all yield grades, cooked intermuscular fat and subcutaneous fat contained about 108 and 122%, respectively, of the cholesterol content in cooked muscle. The percentage of total cholesterol in raw and cooked steaks that was contributed by the combined fat fractions increased significantly with numerical increases in the USDA yield grade. However, the amount of cholesterol per gram of the whole steak was not significantly different among the five yield grades.     

Selected Nutrient Content of Beef Longissimus Muscle Relative to Marbling Class, Fat Status, and Cooking Method

Five ribs (IMPS 103) within each marbling class (practically devoid, traces, slight, small, modest and moderate) were analyzed for nutritional and cooking effect. Subjective marbling classification was effective in categorizing beef for dry matter, fat, protein and caloric density. Steaks were cooked with fat removed or left on either by broiling or microwave exposure. Broiled samples generally had more protein, and less fat and calories. Within cooking method, fat on steaks generally resulted in greater sample weight retention, less protein, less calories, more cholesterol, and higher dry matter. Cholesterol content was greatest in steaks with practically devoid marbling and lowest in steaks with modest and moderate marbling. Each subsequent marbling class added less than 10 Kcal/100g (“as is basis”). There was a small loss in calories available for consumption as a result of the cooking process.     

Oxidative Stability and Sensory Attributes of Prerigor Cooked Beef Steak

Beef sirloin tip steaks from 12 steer carcasses were cooked prerigor and postrigor using three heating methods and stored at 4 °C or ‐20 °C. Prerigor cooked steak had lower cook loss, higher pH, higher shear force, and sensory hardness than postrigor cooked steak. Conventional oven cooking produced the lowest cook loss for prerigor steak. Prerigor cooked steak had lower thiobarbituric acid value than postrigor cooked samples after 2 wks at 4 °C or 3 mo at ‐20 °C. Sensory warmed‐over flavor intensity scores were low and showed no differences between prerigor and postrigor cooked steaks for refrigerated or frozen samples.     

Influence of Postmortem Aging Period on the Fragmentation Index of Bovine Longissimus Muscle

A total of 59 short loins were aged at 2°C for 60, 120, 180, and 240 hr postmortem PM). Following each aging period, steaks were removed for shear force value (SFV) and fragmentation index (FI) measurements. One steak was removed at 60 hr PM for chemical determination. FI was significantly related (r=0.30-0.63) to SFV in 32 comparisons. Variation in FI and SFV for PM aging period and residue fraction drying time (0 and 10 min) was not significant; thus, FI can be accurately determined by omission of the 10 min residue fraction drying time. FI determined on bovine longissimus muscle at 60 hr PM was related (P < 0.05) to SFV of cooked loin steaks from loins aged 60, 120, 180, and 240 hr PM. FI determined at 120, 180 or 240 hr was also related (P < 0.05) to SFV of loin steaks. Simultaneous consideration of five carcass traits (marbling degree, lean color, lein firmness, fat thickness, and carcass weight) accounted for approximately 10% of the observed variation in SFV for cooked steaks from loins aged 60–240 hr, while FI accounted for an additional 15–42%. These data indicate that SFV of cooked loin steaks from A maturity carcasses can be predicted to a significant degree by FI of law muscle determined at 60 hr PM.     

Physicochemical Properties of Rice Steeped in Hot or Warm Water

Prolonged steeping of rice grains in hot or warm water was examined to study the gelatinization process of rice starch. Rice treated at 75°C for 8–18 hr showed the same type “V” X-ray diffraction pattern as that of cooked rice. Rice treated at 50–60°C for 24–72 hr showed a strengthened type “A” pattern. The gelatinization degree of the 75°C treated rice determined by the β-amylase-pullulanase method and Brabender amylography was as high as that of cooked rice. The value of the 50–60°C treated rice was lower than that of raw rice. The gelatinization temperature of rice varied with the two types of treatment.     

Effect of Electrical Stimulation and Steak Temperature at the Beginning of Cooking on Meat Tenderness and Cooking Loss

Six steaks from each of 24 loins (from electrically stimulated and control sides of each of 12 steers) were thawed to produce steak temperatures of 2, 7,13,14,18 or 26°C just prior to cooking. After cooking to 70°C steaks with a starting temperature of 26°C were 30% more tender than those with a starting temperature of 2°C. Electrical stimulation increased tenderness of steaks from all treatments (an average of 23%), and no interaction was found between electrical stimulation and starting steak temperature. Tenderness and cooking loss can be optimized by electrically stimulating carcasses and by starting cookery when steaks have high internal temperatures.     

Cooking loss and juiciness of pork in relation to raw meat quality and cooking procedure

The study comprised two experiments with the aim to investigate the influence of raw meat quality and cooking procedure on cooking loss and juiciness of pork. The first experiment determined the cooking loss at 60, 70 and 80 °C centre temperature of 10 raw meat qualities (defined according to ultimate pH, drip loss, breed and rearing conditions) when cooked as steaks on a pan or as a roast in oven at a oven temperature of 90 or 190 °C. The differences in cooking loss between the raw meat qualities and the cooking procedures did decrease as the centre temperature increased and were almost negligble at 80 °C. Low water holding capacity (WHC) and low pH resulted in high cooking loss while no difference in cooking loss was observed between meat having medium or high WHC and pH. In the second experiment four raw meat qualities (standard, Duroc, low pH and heavy carcass weight) chosen from the first experiment to ensure a wide variation in cooking loss, were cooked in oven at 90 or 190 °C oven temperature. Juiciness was assessed three times during the chewing process. The results suggested that juiciness experienced initially in the chewing process depended only on the water content of the meat, whereas juiciness experienced later in the chewing process was determined by a combination of the water and intramuscular fat contents and the saliva production during chewing.     

Marbling, Fat Trim and Doneness Effects on Sensory Attributes, Cooking Loss and Composition of Cooked Beef Steaks

Marbling and fat trim level did not significantly affect sensory attributes of steaks. However, steaks became increasingly tougher and less juicy with increased internal end-point temperature. Cooking losses were greater for steaks with regular trim than those with total trim and increased with degree of doneness. Except for potassium, fat trim levels did not affect mineral content in cooked muscle. Intramuscular fat levels had variable effects on retention of minerals during cooking. Muscle from steaks with slight marbling had higher cholesterol levels than from those with modest marbling, but neither fat trim level nor doneness affected cholesterol content.     

Proximate and fatty acid compositions and sensory acceptability of Hispanic consumers towards rib‐eye steaks from forage‐finished steers

Proximate and fatty acid compositions and sensory acceptability of rib‐eye steaks (fresh and 6 months frozen‐stored) from three forage‐finished steers [S1 (bermudagrass + ryegrass, etc.); S2 (bermudagrass + ryegrass + berseem, etc.); S3 (bermudagrass+berseem+soybean+brown midrib sorghum, etc.)] and one commercial steak (C), cooked by one‐sided and/or two‐sided grilling, were evaluated. All forage‐finished steaks had lower [omega‐6/omega‐3] ratios than C. Sensory liking was assessed by Hispanic consumers. Raw C steak had higher fat and lower protein contents than others (S1, S2 and S3). Concerning raw steaks, S3 had higher liking scores for overall appearance and fat appearance than others. Two cooking methods did not cause significant differences in sensory liking. Juiciness and overall liking of cooked C and S3 (one‐sided grilling) steaks were not significantly different. Purchase intent (after knowing health benefits of forage‐finished steaks) increased from 62.0–73.8% to 69.8–85.7%. Forage‐finished steaks showed a potentially healthier lipid profile than grain‐finished steaks and had market potential towards Hispanic population.     

Heating and Texture Profiles of Packaged Pasteurized Beef Loin Steaks from Precooked Roasts

Precooked beef loin steaks obtained from waterbath cooked roasts, were oasteurized usinge three different temoeratures (65° 85° and 100°C) and rimoved after reaching internal temperatures of 60°, 70° and 80°C. Temperatures of the steaks were monitored at three locations during heating and cooling. Steaks heated to internal temperatures close to the cooking water temperatures had the least differences in temperature between layers. Total cooking losses increased (P<0.05) as internal endpoint temperatures and pasteurization water temperature increased. Texture profiles of steaks cut from precooked roasts were similar to pasteurized steaks.     

Dynamical Changes of Beef Intramuscular Connective Tissue and Muscle Fiber during Heating and their Effects on Beef Shear Force

Changes of meat shear force and its characteristics during cooking have been extensively studied, but great variability existed due to the cooking method among different studies. This study was designed to focus on the dynamic changes of beef intramuscular connective tissue (IMCT) and muscle fiber during water-bath heating and their effects on beef shear force. At 4 d postmortem, beef semitendinosus muscles were divided into 11 steaks and then cooked respectively to an internal temperature of 40, 50, 55, 60, 65, 70, 75, 80, 85, and 90°C (the remainder was not cooked as control). Collagen content and its solubility, transition temperature of perimysia and endomysia, fiber diameter, and Warner–Bratzler shear force values (WBSF) were determined. The results showed that fiber diameter decreased gradually during cooking, concomitant with the increases in filtering residue and WBSF. The maximum transition temperature (T _max) of endomysial components was lower than that of perimysial components (50.2 vs. 65.2°C). Muscle fiber and IMCT (especially perimysia) shrank during cooking, resulting in the increase of WBSF when the internal temperature was lower than 75°C, but further cooking led to the disintegration of perimysial structure, lowing up the increase of WBSF between 75 and 90°C. For beef semitendinosus muscle, the internal temperature of 65°C is a critical cooking point where meat gets tougher.     

Physical analysis of friction cooked RTE snacks

Extrusion is widely applied for production of ready to eat snacks. The existing technology is capital intensive and requires preconditioning the raw grains before extrusion, dedicated drying after extrusion and post extrusion addition of fat and sugar where required. A novel technology, friction cooking, has been developed to greatly lower capital costs and overcome the limitations of conventional extrusion. The production conditions (temperature and moisture content) and resulting physical properties from eight friction cooked raw grains were compared to the equivalent properties of conventionally extruded products from these grains. Properties were expansion ratio, bulk density, hardness and colour. Friction cooking temperatures were lower (60–98 °C versus about 150 °C), and products were softer but with a lower expansion ratio and higher densities. In friction cooking colour differences between raw grains and cooked product were minor. Many of these differences were attributed to lower temperatures and moisture contents in the friction process.     

Effect of Trim Level, Cooking Method, and Chop Type on Lipid Retention, Caloric Content, and Cholesterol Level in Cooked Pork

The effect of external fat trim on fat, caloric, and cholesterol content of pork lean was investigated. Paired top-loin chops (TL), rib chops (RC) and blade steaks (BS) were obtained and trimmed free of all subcutaneous fat before (NF) or after (SF) cooking. Cuts were cooked to 71°C by roasting, pan-frying, braising or microwaving. Lean from TL chops having SF contained more fat and calories and similar amounts of cholesterol compared with NF chops, regardless of cooking method. Few differences were observed in fat and caloric content of RC and BS cooked with SF versus NF, perhaps due to seam fat. Eliminating external fat prior to cooking reduced fat and caloric content of pork lean.     

EFFECTS OF END-POINT TEMPERATURE AND FAT LEVEL ON THE RESIDUAL CHOLESTEROL IN GROUND BEEF PATTIES1

Patties of lean ground beef with 2% fat (L2PF) and 6% fat (L6PF) were used to study the fat and cholesterol composition of raw and cooked ground beef and to determine how the end-point cooking temperature affects the amount of fat and cholesterol in a lean ground beef patty as it would be eaten by the consumer. The two patty types were obtained from the longissimus muscle of steers with marbling scores associated with “Standard” to “Select” and “Select” to “Choice” U.S. carcass grades of beef, respectively. All steers were fed a diet of roughage and concentrates to ensure fat deposition over the 12th and 13th ribs; longissimus muscles between the 7th and 10th ribs were removed, trimmed of all external fat, ground and formed into three 130-g patties. One patty was fried to an internal temperature of 60C, another to 71C and the third was uncooked. After frying, the patties were measured for drip loss, moisture and total fat. The fat extract was used for cholesterol analysis. The cooked L2PF sample had significantly less fat than the cooked L6PF samples, but there was no difference between the L2PF and L6PF in cholesterol. End-point temperature had no effect on the fat and cholesterol contents for either L2PF or L6PF samples, but the higher end-point temperature resulted in a significant loss of moisture.     

EFFECTS OF PHYSIOLOGICAL MATURITY OF BEEF AND MARBLING OF RIB STEAKS ON EATING QUALITY

SUMMARY— Selected characteristics of beef rib steaks representing three physiological maturity levels and two marbling levels were investigated. Paired steaks at the 1lth thoracic vertebra were used to obtain cooking time and losses, palatability scores, Warner-Bratzter shear values, and selected histological data. In addition, steaks from the left 7th and right 8th thoracic vertebrae positions were used to measure cooking time and losses, Warner-Bratzfer shear values, waterholding capacity, pH, color-difference, and total moisture. Ether extract was obtained for raw longissimus dorsi at the 12th thoracic vertebra. Maturity and marbling affected told moisture (P < 0.001), quantity of fat in raw muscle (histological measurement, P < 0.01). ether extract (P < 0.001). and dripping losses (7th and 8th thoracic vertebrae P < 0.001). Other factors were not affected significantly. Maturity and marbling, at levels represented, had little effect on palatability of the steaks, although generally, measurements for fat content were higher and those for moisture lower at the higher marbling level. Most correlation coefficients for overall acceptability and histological measurements were low. Tenderness had more influence on the overall acceptability of the meat than flavor or juiciness. Moderate to high relationships occurred between cooking time and both initial weight of steaks and cooking losses. Generally, waterholding capacity was not related to pH, total moisture, or cooking losses. Correlation coefficients for pH vs. shear value and pH vs. color-difference were low.     

Thiamin, Riboflavin and Niacin Retention in Cooked Cowpeas as Affected by Kanwa Treatment

Retention of three water soluble B-vitamins in dry cowpeas cooked with a local tenderizer, named “kanwa,” were investigated. Results showed cooking (100°C) in kanwa or sodium bicarbonate decreased levels and retention of vitamins compared to controls cooked in water. Levels of vitamins in kanwa-cooked cowpeas were not significantly different from those in NaHCO₃ cooked samples. Retention in the alkaline cooking processes ranged 15–20% (thiamin), 26–49% (niacin) & 53–64% (riboflavin). Soaking followed by boiling at 100°C or pressure cooking (121°C) increased levels and retention of vitamins.     

Effect of Cooking on Cholesterol Content of Patties Containing Different Amounts of Beef, Textured Soy Protein and Fat

Ground beef patties were prepared to contain 0, 10, 20 or 30% rehydrated textured soy protein (TSP) and 8, 16 or 27% fat. Patties were cooked from the frozen state on a rack in a preheated oven at 177°C to an endpoint internal temperature of 75°C. The cholesterol content of raw ground beef patties decreased as the amount of TSP increased and also decreased as the fat content decreased from 27 to 16 or 8%. At initial fat levels of 8 and 16%, there were no significant differences in cholesterol retention (per-patty basis) during cooking among patties with initial TSP (rehydrated) levels of 0, 10, 20 and 30%; at an initial fat level of 27%, however, patties containing TSP (10, 20 or 30%) retained substantially higher (P < 0.05) amounts of cholesterol when cooked than did those without TSP.     

EFFECTS OF FAT TRIM ON THE COMPOSITION OF BEEF RETAIL CUTS – 2. FAT AND MOISTURE CONTENT OF THE SEPARABLE LEAN

Thirty beef carcass sides varying in USDA quality and yield grade were fabricated into various steaks and roasts. The retail cuts were assigned serially to the following treatments: (A) raw, trimmed to 0.6 cm external fat; (B) trimmed to 0.6 cm external fat, cooked; (C) trimmed to 0.0 cm external fat, cooked. The 0.0 cm and 0.6 cm, cooked treatments were prepared by appropriate cookery methods, and the separable lean and separable fat were analyzed for chemical fat and moisture content. Regression analyses were used to predict values for the percentage chemical fat and moisture content at each treatment as influenced by marbling and USDA yield grade. Retail cuts that were braised had the lowest (P < 0.05) predicted moisture content of the separable lean, while roasted cuts had the highest (P< 0.05) predicted percentage moisture content of the lean. Trimming retail cuts to 0.0 cm external fat before cooking decreased the predicted percentage chemical fat of the lean as compared to retail cuts trimmed to 0.6 cm before cooking.     

Functional, Sensory, and Microbiological Properties of Restructured Beef and Emu Steaks

Beef and emu steaks were restructured with 5% fibrinogen/0.25% thrombin (F), 0.5% algin/0.5% calcium lactate (A), or 0.5% phosphate/1.5% salt (P). P and A treatments had higher cooked binding strengths and cook yields than the F treatments (P < 0.05). The pH and cook yields of restructured emu were higher than beef (P < 0.05). Binding strength of emu was lower than beef in all binding systems (P < 0.05). F solution had an aerobic plate count (APC) of 39,000/g and increased the microbial count in restructured emu steaks from 940 to 7500/g (P < 0.05). Cooking to 60°C reduced APC to < 250/g (P < 0.05) with progressively greater bacterial kill after cooking to 66°C or 75°C.     

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.