Physical and Sensory Characteristics of Fresh Pork Leg Roasts Cooked at Low Temperatures

The effects of oven temperatures of 82, 93, 121 and 163°C were studied using 31 fresh pork leg roasts cooked to 74°C in oven bags. Warmed-over-flavor (WOF) was measured by sensory analysis after holding 3 hr at 68°C and after holding 24 hr at 2°C and then reheating to 68°C prior to serving. Roasts cooked at 82 and 93°C tended to have less WOF after refrigeration and reheating than roasts cooked at 121 and 163°C. Roasts cooked at 93°C had fewer aerobic mesophilic bacteria than those cooked at 121 and 163°C. In general, objective and sensory perception measurements indicated that roasts cooked at 82 and 93°C were of higher quality.     

Differences Between Conventionally Cooked Top Round Roasts and Semimembranosus Muscle Strips Cooked in a Model System

Roasts cooked at 177°C by dry (OR) or moist (OFB) heat to 60°C were compared with muscle strips cooked in a model system to 60°C at a rate similar to oven raosting 1.4-kg roasts at 177°C. OFB roasts were less tender, less juicy, had less rare beef flavor, less red and yellow color, more total cooking loss, and shorter cooking time than did OR roasts. Strips had lower values for Instron measurements of hardness, chewiness, shear cohesiveness, and firmness than did OR or OFB roasts. Although strips were cooked in a moist atmosphere, they were more like OR roasts than like OFB roasts. Variance for a given measurement was similar between roasts and strips.     

Spectra of Pigments Responsible for Pink Color in Pork Roasts Cooked to 65 or 82°C

Undenatured oxymyoglobin and deoxymyoglobin were the pigments responsible for pink color in pork roasts cooked to 65°C. Roasts cooked to 82°C had gray internal color after cooking, but panelists noted development of pink internal color after refrigerated storage. Reflectance spectra of pink slices from roasts cooked to 82°C, then stored for 12 days at 2°C, were characteristic of denatured globin hemo-chromes or related nonnitrosyl hemochromes.     

Oxidative Stability of Restructured Beef Roasts As Affected by Cooking Temperature

Restructured beef roasts (2.5 kg) were cooked in a water bath at 70, 85, and l00°C to an internal temperature of 65°C, then stored at 4°C for 0 and 3 days. Storage increased (p ≤ 0.05) oxidation; after 3 days storage, roasts cooked at higher temperatures had higher (p ≤ 0.05) TBA values. Sensory panelists detected more (p ≤ 0.05) warmedover flavor (WOF) due to storage; however, after 3 days there was less (p ≤ 0.05) WOF in samples cooked at 70°C than in samples cooked at 85 or 100°C. Interaction (p ≤ 0.05) between cooking temperature and storage indicated oxidation proceeded more rapidly with higher cooking temperatures during refrigerated storage. Cook yield decreased as cooking temperature increased and expressible moisture was lower (p ≤ 0.05) at 100°C than at 70°C.     

Palatability and Storage Characteristics of Precooked Pork Roasts

Pairs of boneless pork loins (n=10) were pumped to contain 0.5% tripolyphosphate or water and allotted to three treatments: PVC wrapped, convection oven cookery (CO); vacuum packaged, precooked and reheated in a water bath (PC); and vacuum packaged and cooked in a water bath (VP). Paired loins (n = 30) were injected with tripolyphosphate and allotted to the following treatments and storage (0, 14 or 28 days) conditions: Control (?20°C) [CO]; precooked (?20°C) [PCPR]; precooked (4°C) [PCRF]; vacuum packaged (?20°C) [VPFR]. VP and PC phosphate injected roasts were more tender and had lower cooking losses than CO roasts. After 28 days, all PC roasts had lower microbial counts than other treatments, and PC and VP roasts had improved palatability compared with CO roasts.     

Palatability and Storage Characteristics of Precooked Beef Roasts

The palatability and storage characteristics of fresh, frozen and precooked beef chuck roasts prepared using added phosphate-salt and vacuum cooking bags were evaluated. Palatability attributes (tenderness, juiciness, beef flavor intensity, and off-flavor intensity) of precooked roasts prepared in vacuum cooking bags with phosphate-salt were as good or better than freshly cooked roasts. Precooked roasts in vacuum cooking bags had the lowest total bacterial counts after storage for 14 and 28 days. A palatable precooked roast beef product was developed that can be stored for 28 days at 4°C.     

Sensory and Chemical Characteristics of Fresh Pork Roasts Cooked to Different Endpoint Temperatures

Pork roasts cooked to various endpoint temperatures were evaluated by sensory and chemical analyses. Increased endpoint temperatures were associated with increased cooking losses; decreased juiciness, pink color, and metallic flavor; increased graininess, brown color, and pork flavor. Increased endpoint temperatures also led to a concentration of lipid, protein and certain fatty acids. Cholesterol levels were not significantly influenced by endpoint temperature. Lipid content was decreased by removal of external fat before cooking. To minimize pink color in some muscles and maximize other sensory characteristics and yield of cooked meat, at least 71.1°C and no more than 76.6°C is recommended as the endpoint temperature for fresh pork roasts.     

Evaluation of 54° and 60°C Holding Temperatures on Aerobic Plate Counts and Coliform Determinations of Control and Post Cooking Contaminated Beef Roast

Fabricated beef roasts were cooked to an internal temperature of 60°C and the surface inoculated with a suspension of Escherichia coli at a level of lo⁶ cells/cm². Roasts were then stored in a warming oven at 54° and 60°C for 1, 2, 6, and 12 hr. Under these conditions the destruction of this strain of E. coli is quite rapid (less than 6 hr) at the 60°C holding temperature. The holding temperatures do allow the growth of thermoduric organisms naturally present in the product to initiate exponential growth after 6 hr at 54°C. The higher holding temperature reduced the rate of multiplication of the thermoduric organisms.     

Oxidative Stability and Textural Quality of Restructured Beef Roasts as Affected by End-point Cooking Temperatures, Storage and the Incorporation of Surimi

Restructured beef roasts containing either 0 or 3.5% surimi were cooked to end-point internal temperatures of 50, 60, and 70°C to assess treatment effects on textural and oxidative quality after 2 and 5 days of refrigerated (4°C) storage. Surimi did not improve binding, cook yield or sensory tenderness and juiciness. The sensory panel was able to distinguish a slightly more pronounced fishy flavor when surimi was added. End-point internal temperature had no effect on tensile strength, however, tenderness increased and juiciness decreased with increased endpoint temperatures. Higher end-point internal temperature enhanced lipid oxidation, which proceeded more rapidly during refrigerated (4°C) storage. Nonheme iron increased with increasing end-point temperature. During storage, phospholipid content decreased while total lipid remained constant.     

Storage and Lipid Quality of Chunked, Formed Roasts Containing Mechanically Separated Lamb

Restructured chunked and formed roasts containing 10 or 30% mechanically separated lamb (MSL) were made with meat from ram or wether lambs. Roasts were either frozen immediately after formulation and stored at -30°C before cooking to 71°C, or precooked immediately to 63°C, chilled and reheated to 71°C before storage at 4 and -30°C. Storage periods varied depending upon treatment. Roasts with 10% MSL contained less total fat and less free fatty acids (FFA) than those with 30% MSL. There was little evidence of extensive lipid oxidation as measured by thiobarbituric acid values and peroxide oxygen values in any of the roasts. There was an indication that pre-cooking and curing prior to storage increased glycerolipid hydrolysis because of increased levels of FFA. Apparently increased hydrolysis occurred in triglycerides since levels of phospholipids did not change.     

Sodium lactate and storage temperature effects on shelf life of vacuum packaged beef top rounds

Cooked, vacuum-packaged beef top rounds containing up to 4% sodium lactate (NaL) in the final product were stored at 0, 4, 10 or 16°C for 1, 7, 14 or 21 days. Aerobic plate counts (APCs) were lower for roasts containing 3 or 4% NaL and stored at 10°C for 7 days. At higher temperatures and longer storage times, only those treated with 4% NaL were lower than controls. Lipid oxidation, Hunter L* and b* values decreased and Hunter a* values, cooked yields and Ph increased with NaL addition. Beefy odor decreased with storage but was higher in roasts containing NaL. Roasts with added NaL had lower rancid odor scores.     

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.     

Thiamin Retention and Other Characteristics of Cooked Beef Loin Roasts

Beef loin roasts were prepared by three procedures that simulated home, foodservice or commercial methods for precooking meat prior to vacuum packaging. Roasts were prepared by conventional electric (176.5°C), cook-in-package waterbath (70°C water), or smokehouse (ambient temperature) heating. Yield, thiamin, fat, water content, and Instron tenderness of roasts were determined. Raw roasts had higher (P<0.05) water and free water content. All cooked roasts were significantly lower in thiamin content (dry, fat free basis) and thiamin retention (true and dry, fat free basis) than raw roasts (P<0.05). No differences were observed between cooking procedures evaluated (P>0.05), suggesting that most heat processing treatments used for precooking packaged meat result in similar quality products.     

Influence of Storage Times After Cooking on Warner-Bratzler Shear Values of Beef Roasts

Fifty longissimus and 49 biceps femoris roasts were cut from five Choice-grade steer carcasses and used to evaluate differences in Warner-Bratzler shear values at different times after cooking. Five longissimus roasts and four or five biceps femoris roasts were cut from both sides of each carcass. Roasts were cooked to an internal temperature of 71°C then wrapped in aluminum foil and chilled (4°C) for 2, 24, 48, 72 or 168 hr prior to shear analysis. No differences in shear values by carcass side or by length of chill after cooking existed for biceps femoris roasts. Longissimus roasts were more tender when taken from the left side and when chilled for 2 hr vs longer chill periods. Roasts chilled for 24, 48, 72 or 168 hr had similar shear values. Cores taken from the medial portion of the longissimus roasts had lower shear values than cores taken from the central or lateral portions. Longissimus roasts were always more tender than roasts from the biceps femoris muscle and they were less variable in tenderness.     

Processing Ingredients Affecting Oxidative and Textural Stability of Restructured Beef Roasts

Restructured beef roasts containing 0.3% sodium tripolyphosphate (STP) and 1% soy protein isolate (SPI); or STP only; or SPI only; or no STP or SPI were cooked at 70 or 100°C to an internal temperature of 65°C, then stored at 4°C for 0 and 3 days. In control roasts, the higher cooking temperature resulted in higher (p ≤ 0.05) TBA values. STP and SPI inhibited oxidation but the effect was not detected sensorially. Significant interactions (p ≤ 0.05) indicated that STP was more effective at higher cooking temperatures and SPI at lower temperatures. Total moisture of the cooked product was significantly greater with STP but no differences in juiciness and tenderness were detected sensorially.     

Evaluation of Microwave Cooking Procedures and Ovens for Devitalizing Trichinae in Pork Roasts

Pork roasts from pigs experimentally infected with Trichinella spiralis were cooked in five microwave ovens. Twenty-nine procedures, generally recommended by the oven manufacturers or pork interest groups, were used. Infective trichinae were present after cooking in 50 of 189 roasts. Factors affecting infectivity included procedure used, use or nonuse of post-cooking standing or temperature holding, weight of roast, and internal temperatures attained. Five visually well done roasts contained infective trichinae including one in which all five temperatures taken exceeded 76.7°C. One other infective roast, with a small red spot, also had all temperatures at or above the 76.7°C level. Recommendations are made to minimize the potential that trichinae may survive in microwaved-cooked pork.     

THE EFFECT OF VARIOUS LEVELS OF ADDED SODIUM CHLORIDE AND POTASSIUM CHLORIDE ON THE CHEMICAL,PHYSICAL AND SENSORY CHARACTERISTICS OF PRECOOKED,RECOMBINED BEEF CHUCK ROASTS1

Commercial beef chuck tenders were processed into recombined roasts utilizing salt or Morton's® Lite Salt (43% NaCl, 57% KCl) according to treatment (100% salt, 70% salt—30% lite salt, 30% salt—70% lite salt or 100% lite salt). Roasts were cooked to an internal temperature of 68°C. Percentages of water and protein were relatively constant across treatments and as fat percentages increased (P < 0.05) so did caloric content. As the level of lite salt increased, the percentage extractable potassium also increased. Cooking loss was not affected by treatment. Treatment 1 (100% salt) was harder and less tender (P < 0.05) than the other treatments; while juiciness, flavor and overall palatability were not affected by treatment. Results of this study suggest the feasibility of substituting lite salt for salt in these types of value added, precooked products.     

SELENIUM AND TOCOPHEROL CONTENT OF COOKED PORK ROASTS1

The content and the retention of the antioxidant nutrients, selenium and tocopherol (vitamin E), in boneless Chef's Prime^TM pork loin roasts cooked by different methods to 71 and 82C internal temperatures were determined. Roasts were cooked at 163C by roasting, braising, and in an oven cooking bag. Yield, moisture, and crude fat measurements were similar for all treatments. The only form of vitamin E in the sample was α-tocopherol. Selenium and vitamin E content as well as true retention values were similar in pork cooked to the two internal temperatures by the three household methods with one exception; the selenium content was significantly higher in pork cooked in the bag and roasted than in those prepared by braising. Overall, the selenium and vitamin E content of the cooked pork was 101.8 ± 0.5 μg/100g (X?± SEM) and 0.144 ± 0.006 mg α-TE/100g, respectively. Over half of the vitamin E but little to none of the selenium in the pork was lost during these household cooking procedures.     

Microbiological, Sensory and Chemical Characteristics of Vacuum-Packaged Cooked Beef Top Rounds Treated with Sodium Lactate and Sodium Propionate

Cooked, vacuum-packaged beef top rounds containing 3% sodium lactate (NaL) or 3 or 4% NaL in combination with 0.1 or 0.2% sodium propionate (NaP) were stored for up to 84 days at 4°C. Addition of any of the treatments greatly reduced total Aerobic Plate Counts (APC). Positive flavor notes associated with fresh beef were enhanced by ingredient addition and tended to be highest in roasts with 3% NaL + 0.2% NaP. Cooked roast beef color was enhanced by addition of NaL alone or in combination with 0.1% NaP. Lipid oxidation and water activity were decreased by addition of NaL with NaP and pH and cooked yield were increased with any level or combination of ingredients.     

Oxidative Stability of Restructured Beef Steaks Processed with Oleoresin Rosemary, Tertiary Butylhydroquinone, and Sodium Tripolyphosphate

Antioxidant activities were evaluated in raw restructured beef steaks stored at ?20°C six months and in cooked steaks at 4°C six days. During refrigerated storage, thiobarbituric acid-reactive substances (TBARS) and sensory scores indicated sodium tripolyphosphate (STPP) provided (p<0.01) protection against warmed-over flavor development. No significant differences existed between OR (0.10%)/STPP and TBHQ/STPP, due probably to STPP. During frozen storage, a linear concentration effect of OR existed (p<0.01) for both TBARS values and sensory scores indicating OR was an effective antioxidant which combined with STPP produced an additive protective effect during frozen storage. Hexanal content and phospholipid fatty acid profiles also changed during frozen storage. Correlation coefficients between TBARS values and sensory scores were generally nonsignificant.