Effects of Heating System, Temperature and Rate of Heating on Sensory Characteristics of Beef

Sensory scores for appearance and texture of oven-roasted beef semitendinosus were compared with those of samples heated in glass tubes in a water bath. Roasts heated in 93 and 149°C ovens appeared to be less done and were moister than water bath samples heated at comparable rates. Samples heated to 60°C in both systems appeared to be less done and were moister and less mealy than samples heated to 70°C. Few differences in sensory scores for textural parameters were attributed to heating system, endpoint or heating rate. Correlations between scores for intact roasts and objective measurements for the small samples were not always of the same direction or strength as were the relationships between scores and objective values for roast samples.     

Correlations of Sensory and Instrumental Evaluations of Roast Beef Texture

Beef semitendinosus roasts heated to endpoint temperatures of 60°, 70°, and 80°C were evaluated by a taste panel and by instrumental tests of shear, penetration, and compressive force. Correlations were found between sensory parameters of chewiness, hardness and tenderness and between these parameters and shear parameters of firmness and cohesiveness. Compression-hardness was related positively to panel scores for moisture and negatively to mealiness scores. Compression-cohesiveness was related only to panel scores for oiliness while compression-springiness and penetration hardness were not related to any of the sensory parameters evaluated.     

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.     

来自牛半腱肌肌束膜和肌内膜胶原蛋白热力学特性分析

探讨牛半腱肌肉肌束膜和肌内膜胶原蛋白热力特性的热诱导变化。牛半腱肌肉分别采用水浴和微波加热到内部终点温度分别为20、40、50、60、70、80℃和90℃,用示差扫描量热法研究肌束膜和肌内膜胶原蛋白热力特性(起始、最高和最终热收缩温度)在热处理过程中的变化。结果表明：牛半腱肌肉肌束膜和肌内膜胶原蛋白的热收缩温度在两种热处理方式间都存在显著差异,在两种热处理方式中,内部终点温度60℃是影响肌束膜和肌内膜胶原蛋白热收缩温度的关键加热温度。热诱导的肌束膜和肌内膜胶原蛋白热力特性的变化是水浴和微波加热牛肉胶原蛋白热收缩温度存在差异的主要原因。     

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.     

Effect of Heating Temperature and Muscle Type on Porcine Muscle Extracts as Determined by Reverse Phase High Performance Liquid Chromatography

Samples from porcine longissimus muscles were heated to temperatures ranging from 40–80°C to reach endpoint temperatures (0 min) or held at endpoint temperature for 30 min. Proteins in water-soluble extracts of these samples were separated and quantified by reverse phase high performance liquid chromatography (RP-HPLC). After heating to 60°C for 0 min or to 55°C and holding for 30 min, lactate dehydrogenase (LDH), pyruvate kinase (PK) and myoglobin appeared to comprise the bulk of the remaining soluble protein. RP-HPLC analysis of water soluble extracts from longissimus dorsi, serratus ventralis and psoas major muscles from barrows and sows indicated differences in proportions of LDH and myoglobin.     

TENSILE PROPERTIES OF BEEF SEMITENDINOSUS MUSCLE AS AFFECTED BY HEATING RATE AND END POINT TEMPERATURE

The effects of heating rate and end point temperature on tensile properties of beef semi-tendinosus muscle were studied. Samples of meat heated in glass tubes in a water bath to simulate oven roasting at 93 °C had lower (P < 0.01) shear values than those heated to simulate oven roasting at 149 °C. Samples heated to 60 and 70°C had lower (P < 0.001) shear values than samples heated to 50°C. Instron breaking strength values varied (P < 0.001) with end point temperature, but were not significantly affected by the rate of heating. Significant (P < 0.001) interactions between the end point temperature and heating rate, as well as between the end point temperature and fiber direction suggested that Instron breaking strength measurements may be more sensitive to changes in tenderness than Warner Bratzler shear measurements.     

Ohmic Heating Maximizes Gel Functionality of Pacific Whiting Surimi

Surimi without enzyme inhibitors containing 78% moisture and 2% NaCl was heated conventionally and ohmically to 90°C after holding at 55°C for 0, 1, 3 and 5 min. Gels heated slowly in a water bath exhibited poor gel quality, while the ohmically heated gels without holding at 55°C showed more than a twofold increase in shear stress and shear strain over conventionally heated gels. Degradation of myosin and actin was minimized by ohmic heating, resulting in a continuous network structure. Ohmic heating with a rapid heating rate was an effective method for maximizing gel functionality of Pacific whiting surimi without enzyme inhibitors.     

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.     

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.     

Analysis of Warner-Bratzler shear pattern with regard to myofibrillar and connective tissue components of tenderness

Force-deformation curves from the Warner-Bratzler (WB) shear device were used to evaluate specific changes in the myofibrillar (WB M-force) and connective tissue component (WB C-force) of tenderness in samples from beef semitendinos. Cores were heated in a water bath to end point temperatures of 60°C and 80°C by using combinations of slow and fast heating rates. Increasing the end point temperature from 60°C to 80°C was found to increase the WB M-force and to decrease the WB C-force, whereas the WB peak force was least affected. Comparisons between different heating rate combinations to samples heated to 80°C showed that the WB M-force was affected by a heating rate both below and above 60°C, while the WB C-force was most influenced by a heating rate above 60°C. Slower heating rates and higher endpoint temperatures resulted in greater cooking losses and increased solubility of collagen. The WB M-force and WB C-force were found to be more significant estimators of sensory evaluations of tenderness and collagen solubility in this experiment than the usually measured WB peak force.     

Prediction of Pork and Lamb Meat Quality Characteristics

A two-factor central composite rotatable design and corresponding response surface analysis were successfully applied to data from pork and lamb loin roasts, using cooking temperature and endpoint temperature as the two independent variables. Heating rate (°C/min), evaporation loss, cooking time, total moisture, and chromaticity coordinate (z) were found to be significantly affected (p ≤ 0.10) by different combinations of cooking temperatures and endpoint temperatures in pork and lamb. Additional significant variables for pork were total nitrogen, remaining protein fraction and sensory panel juiciness; and for lamb, heating rate (°C/g), drip loss, total cooking loss, expressible moisture index, total nitrogen, chromaticity coordinate (×), saturation index, and sensory panel doneness and color. Response surfaces were useful in evaluating results.     

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.     

Rapid Heating of Alaska Pollock and Chicken Breast Myofibrillar Proteins as Affecting Gel Rheological Properties

Surimi seafoods (fish/poikilotherm protein) in the U.S.A. are typically cooked rapidly to 90+°C, while comminuted products made from land animals (meat/homeotherm protein) are purposely cooked much more slowly, and to lower endpoint temperatures (near 70 °C). We studied heating rate (0.5, 25, or 90 °C/min) and endpoint temperature (45 to 90 °C) effects on rheological properties (fracture, small strain) of washed myofibril gels derived from fish (Alaska pollock) compared with chicken breast at a common pH (6.75). This was contrasted with published data on gelation kinetics of chicken myosin over the same temperature range. Heating rate had no effect on fracture properties of fish gels but slow heating did yield somewhat stronger, but not more deformable, chicken gels. Maximum gel strength by rapid heating could be achieved within 5 min holding after less than 1 min heating time. Dynamic testing by small strain revealed poor correspondence of the present data to that published for gelling response of chicken breast myosin in the same temperature range. The common practice of reporting small‐strain rheological parameters measured at the endpoint temperature was also shown to be misleading, since upon cooling, there was much less difference in rigidity between rapidly and slowly heated gels for either species.     

牛半腱肌肉结缔组织胶原蛋白热力特性热诱导变化DSC分析

探讨牛半腱肌肉结缔组织胶原蛋白热力特性的热诱导变化。牛半腱肌肉分别采用水浴和微波加热到内部终点温度分别为40、50、60、70、80℃ 和 90℃,研究结缔组织滤渣和热力特性在热处理过程中的变化。结果表明：结缔组织滤渣含量随着热处理温度的升高而增加,当加热温度分别为60、70℃ 和 80℃时,结缔组织滤渣含量在两种热处理方式间存在显著差异(P＜0.05)。在两种热处理方式中,40℃至60℃的内部终点温度是影响结缔组织胶原蛋白热收缩温度的关键加热温度。热诱导的结缔组织胶原蛋白热力特性的变化是水浴和微波加热牛肉胶原蛋白热收缩温度存在差异的主要原因。     

Influence of Rate and Length of Cookery upon Product Attributes of Pre- and Post-Rigor Beef

Paired sides of 15 steer carcasses were used to determine the effects of low temperature, long duration cooking upon muscle (semimembranosus, SM; semitendinosus, ST) shortening, cooking and tenderness attributes of beef roasts that were removed 1 hr (hot-boned, HB) and 48 hr postmortem (cold-boned, CB). The cooking treatments were: (1) 1st hr at 47°C then raised 5.6°C/hr through the 5th hr (69°C); (2) 1st hr at 52°C then raised 5.6°C/hr through the 4th hr (69°C); and (3) 1st hr at 58°C then raised 5.6°C/hr through the 3rd hr (69°C) and thereafter at 80°C until an internal temperature of 66°C was reached. Shear values and panel ratings showed HB roasts to be slightly less tender than CB roasts. Cooking yields were higher for HB than CB roasts.     

Cholesterol and Selected Attributes of Pork Tenderloin Steaks Heated by Conventional, Convection, and Microwave Ovens to Two Internal Endpoint Temperatures

Six treatment combinations for determination of cholesterol and selected quality attributes of pork tenderloin steaks were studied with three oven types (conventional, convection and microwave) and two internal endpoint temperatures (71°C and 77°C). In general, pork tenderloin steaks heated in the microwave oven had lower evaporative loss and higher drip loss. Cholesterol (wet weight basis) of the pork steaks was not affected by oven type; however, heating to the higher internal endpoint temperature (77°C) increased (concentrated) the cholesterol. On a dry weight basis, microwave-heated steaks contained more cholesterol when compared to conventional and convection-heated samples.     

Changes in texture, cooking losses, and myofibrillar structure of bovine M. semitendinosus during heating

Vacuum-packed slices of bovine semitendinosus (ST) muscle were retorted to internal temperatures of 50, 60, 70, 80, 90, 100, and 121°C. Changes in texture of the meat were evaluated by measurements of Texture Profile Analysis (TPA) parameters. Changes in microstructure were evaluated using a Scanning Electron Microscope (SEM) and measuring fibre diameter and sarcomere length. Cooking losses were also estimated. During heating the TPA parameters changed independently of each other. They reached a maxima at different endpoint temperatures of the meat and then decreased. A decrease in fibre diameter was observed in samples heated to 60 and 121°C. Sarcomere length decreased continuously in the range 50-121°C. Cooking losses increased with increased heating temperature. Relationships between changes in sarcomere length and cooking losses and between springiness and fibre diameter were found.     

Scanning Electron Microscopy, Proteolytic Enzyme Activity, and Acceptability of Beef Semitendinosus Cooked by Microwaves and Conventional Heat

Beef semitendinosus muscles cooked by conventional heat and microwave energy to endpoint temperatures of 40, 50, 60, and 70°C were evaluated for structural (scanning electron microscopy, SEM) changes, enzyme activity, and shear value. The 70°C samples were evaluated by sensory panel. As endpoint temperature increased, there were concomitant increases observable in SEM in intermyofibrillar spaces, fiber fragmentation, and occurrence of nonfibrous connective tissue. At 70°C, microwave samples were more fragmented, flattened, and coagulated than the conventional samples. Generally, enzyme activity of the muscle and drip decreased as end-point temperature increased. Conventional samples received higher sensory scores than microwave samples.     

Effects of Sodium Tripolyphosphate on Physical and Sensory Properties of Beef and Pork Roasts

Six paired beef round and pork loin roasts were used to determine the effects of sodium tripolyphosphate (STPP) on fresh and reheated roasts. Roasts were pumped 10% of their weight with distilled water (control) or with distilled water containing 4.75% STPP. Roasts were cooked to internal temperatures of 70°C (beef) or 75°C (pork) and evaluated after 0, 1 or 3 days (roasts were reheated to cooked temperatures). This study indicates that phosphate in pork and beef roasts allowed them to be reheated after 1 and 3 days of refrigeration with minimal losses of juiciness, tenderness or flavor intensity, Phosphate injection reduced warmed-over flavor in reheated pork roasts but was not successful in decreasing the incidence of warmedover flavors in reheated beef roasts.