High pressure/thermal treatment effects on the texture of beef muscle

The effects of high pressure (to 800 MPa) applied at different temperatures (20-70 °C) for 20 min on beef post-rigor longissimus dorsi texture were studied. Texture profile analysis showed that when heated at ambient pressure there was the expected increase in hardness with increasing temperature and when pressure was applied at room temperature there was again the expected increase in hardness with increasing pressure. Similar results to those found at ambient temperature were found when pressure was applied at 40 °C. However, at higher temperatures, 60 and 70 °C it was found that pressures of 200 MPa caused large and significant decreases in hardness. The results found for hardness were mirrored by those for gumminess and chewiness. To further understand the changes in texture observed, intact beef longissimus dorsi samples and extracted myofibrils were both subjected to differential scanning calorimetry after being subjected to the same pressure/temperature regimes. As expected collagen was reasonably inert to pressure and only at temperatures of 60-70 °C was it denatured/unfolded. However, myosin was relatively easily unfolded by both pressure and temperature and when pressure denatured a new and modified structure was formed of low thermal stability. Although this new structure had low thermal stability at ambient pressure it still formed in both the meat and myofibrils when pressure was applied at 60 °C. It seems unlikely that structurally induced changes can be a major cause of the significant loss of hardness observed when beef is treated at high temperature (60-70 °C) and 200 MPa and it is suggested that accelerated proteolysis under these conditions is the major cause.     

Modelling the yield and texture of comminuted pork products using color and temperature. Effect of fat/lean ratio and starch

Practices to control the processing of finely comminuted meat products are proposed. The objective was to test the practical value of both temperature and light reflection measurements made during emulsification as potential indicators of cooking losses and resulting gel texture in pork sausages emulsified within a wide range of temperatures and starch and fat levels. Prior to cooking, pork batters were chopped for different times to ensure final emulsion temperatures ranging from 5 to 50°C. The effects of the fat/lean ratio (0.25 and 0.67) and starch addition (0.8 and 3.2% w:w) on temperature and optical reflection were also investigated. The chopping increased the temperature and decreased the light reflection of fresh meat emulsion. There was no relevant loss of emulsifying capacity at emulsion temperature below 30°C and lightness values over 70 CIE units. The losses and textural parameters of cooked emulsions could be predicted by means of non-linear regression equations based on the temperature and color of the raw emulsion. The determination coefficients obtained ranged from 0.89 to 0.99. The prediction models needed to be fitted to each batter formulation, especially in the presence of reduced levels of gelation agents (meat protein and starch). Lightness was a better predictor than chromaticity, since it decreased constantly with chopping in the range of final emulsion temperatures studied (5-50°C). This confirms previous studies that lightness could be used for monitoring emulsion stability in meat batters.     

SENSORY CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES FORMULATED WITH WAXY HULL-LESS BARLEY

Texture characteristics and acceptability of 90/10 (percentage lean/percentage fat) ground beef patties formulated with 10% hydrated, cracked waxy hull-less barley were profiled by two types of sensory panels. A panel trained in ground beef texture analysis found beef-barley patties to be more juicy and soft, and less chewy and crumbly than 90/10 and 80/20 samples. An untrained consumer panel rated the beef barley samples as acceptable in appearance, flavor, and texture as an 80/20 formulation, and more acceptable in all three attributes than 90/10 ground beef patties.     

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。     

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.     

Effects of added connective tissues on the sensory and mechanical properties of restructured beef steaks

To quantify objectionable levels of connective tissues, restructured beef products were made with 2·5 and 5% added tendon; 5 and 10% added epimysium, gristle, or peri/endomysium; and a control. Initial tenderness (IT), residual connective tissue (CT), and overall texture (OT) were evaluated by a sensory panel. Panelists adversely scored IT, CT, and OT for 2·5 and 5% tendon and CT and OT for 10% epimysium and gristle. CT and OT scores correlated with hydroxyproline content and Lee-Kramer peak shear force for uncooked steaks with added tendon, gristle and epimysium but not peri/endomysium. Acceptable products can be made when raw materials are free of tendons and contain only limited amounts of epimysium.     

Effects of chopping time, meat source and storage temperature on the colour of New Zealand type fresh beef sausages

The colour stability of finely chopped fresh sausages made from post-rigor, pre-rigor salt added (1.5% w/w) or pre-rigor no salt added beef mince was evaluated using a Hunter Miniscan (L (?) a (?) b (?)) and sensory colour panel. Batters were chopped for various times and sausages stored at -1.5 °, + 4.0 ° and + 8.0 °C. Regardless of meat source or chopping time, colour stability was greatest at -1.5 °C. Panellists found the colour of all sausages stored at -1.5 °C acceptable for at least six days. Sausages made from unsalted pre-rigor mince had markedly better colour stability than those made from the other meats, especially when stored at 4 °C or 8 °C.     

The effect of whey protein concentrates and hydrocolloids on the texture and colour characteristics of chicken sausages

The effects of fat reduction by increasing water content and the addition of whey protein and hydrocolloids on the instrumental texture profile, microstructure and water holding capacity of low‐fat chicken sausages were analysed. Low‐fat sausages were prepared with fresh breast chicken meat; in all formulations, a 3:7 ratio guar/xanthan gum was used. A factorial design with three levels of added fat (0%, 1.98% and 4.96%), two levels of whey protein concentrate (0.64% and 1.94%), and two levels of the hydrocolloids (0.13% and 0.32%) was applied. Samples were heat‐processed (73 °C final internal temperature) and, after cooling, chemical composition of the sausages was determined and scanning electron microscopic images were obtained. Colour was measured with a tristimulus reflectance colorimeter. Texture profile analysis of sausages was performed and the results were related to sample formulations. Extra‐lean products with a fat content lower than 0.5 g/100 g product showed very good quality attributes determined by a sensory panel.     

The effect of cooking temperature on mechanical properties of whole meat, single muscle fibres and perimysial connective tissue

The structural changes in beef semitendinosus caused by cooking were studied by performing tensile tests of the isolated meat components (i.e. single muscle fibres and perimysial connective tissue) and related to the toughness of the whole meat. Whole meat toughness was found to increase in two separate phases upon cooking from 40-50°C, and again from 60 to 80°C with a decrease in meat toughness between 50 and 60°C, in agreement with previous studies. The changes in whole meat toughness at temperatures below 60°C were found to correspond to changes in the mechanical properties of the perimysial connective tissue, whereas changes of whole meat toughness at temperatures above 60°C were found to correspond to increased breaking strength of single muscle fibres. The myofibrillar component explained approximately 47% of the variation in whole meat toughness upon cooking whereas inclusion of the connective tissue component increased the goodness of fit.     

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.     

EFFECTS OF DRY AND MOIST HEAT ON SELECTED HISTOLOGICAL CHARACTERISTICS OF BEEF SEMIMEMBRANOSUS MUSCLE

ABSTRACT— Samples of raw and heat-treated beef semimembranosus muscle were examined histologically to determine how deep-fat frying, oven roasting, oven braising and pressure braising to 70°C affected histological characteristics of the muscle. A panel of three persons used an ocular micrometer to measure muscle fiber width, observed color and type of connective tissue and distribution of fat and estimated quantity of connective tissue of 475 histological sections. Differences among heat treatments in muscle fiber width and relative proportion of straight and wavy connective tissue were not significant. However, there was a significantly (P<0.05) larger quantity of granular tissue in deep-fat fried, pressure braised, and oven braised samples than in oven roasted samples. Intact fat cell walls were observed in both raw and heated samples.     

Ohmic Cooking of Processed Meats and its Effects on Product Quality

ABSTRACT: A basic bologna emulsion (lean and fatty pork meat, sodium chloride, sodium erythorbate, and sodium nitrite) was cooked in 1-kg portions, either in a smokehouse (180-min cycle; to 70 °C at core) or by ohmic heating (64 to 103 V; 3.9 °C/min to 10.3 °C/min; to 70 °C to 80 °C), and the finished products were compared for color, texture, pH, drip, Eh, and rancidity. Heating rates, final temperatures, and a 20-min holding time had little influence on the quality of ohmic sausages. In addition, ohmic sausages were always found to be similar to smokehouse products except for texture, which was significantly softer (P > 0.05) in ohmic products but could be hardened by use of binders.     

Effect of temperature of comminution on the stability and eating quality of 'English' sausages

Sausages were prepared after equilibrating the ingredients to temperatures in the range 2° to 37°C. Following comminution for 6·5 min the temperatures of the batters ranged from 15 to 33°C and their pHs from 6·25 to 6·48. During storage at -20°C sausages prepared from the high temperature batters lost more weight than those made from batters prepared at the lower temperatures (0·3% compared to 1·2%). Increasing temperature of comminution led to increased cooking losses, softening in texture and darkening in colour. However, even at the highest temperatures complete emulsion breakdown did not occur as cooling losses were still only about 20%. Subjective assessment indicated that at least up to comminution temperatures of 25°C the sausages were acceptable. At temperatures above 30°C off-flavours developed. It is suggested that comminuted meat products can be manufactured in situations where refrigeration is not available, provided a preservation system can be devised to inhibit microbial and chemical spoilage.     

Thermomechanical properties of beef muscle

Differential scanning calorimetry (DSC) was used to follow the three major endothermic transitions (T(1), T(2) and T(3)) of beef muscle during heating. Borchardt and Daniels reaction kinetics were used to predict the three time and temperature treatments required to sequentially eliminate each transition. Longissimus dorsi and semimembranosus muscles were removed from beef carcasses suspended by Achilles tendon or pelvis. Samples prepared by heating for 5 min at 57°C (I), 70°C (II) and 81°C (III) were assessed by sensory panel for tenderness, juiciness and residual connective tissue. Weight loss, Warner-Bratzler (W-B) shear and microstructure using transmission electron microscopy (TEM) were also determined. The I treatment showed a significant difference in tenderness and residual connective tissue between muscles, but not between contraction states. The II treatment produced collagen shrinkage and a significant drop in W-B shear and residual connective tissue, coupled with increased tenderness in semimembranosus muscle. An increased W-B value, decreased juiciness, increased weight loss and a reduction in sarcomere and A-band length accompanied the III transition. Muscles from carcasses that had been suspended by the pelvis were found to be significantly more tender than the same muscles from Achilles hung carcasses. It is concluded that DSC is capable of determining amount of protein denaturation and, hence, degree of cooking.     

Antioxidant activity of carrot juice in gamma irradiated beef sausage during refrigerated and frozen storage

The antioxidant activity of carrot juice in gamma irradiated beef sausage was studied. Four batches of beef sausage were prepared, in which the first batch was formulated with water as the control. The other batches were formulated with unconcentrated carrot juice, carrot juice concentrated by 35% and 60%, respectively. Samples were irradiated at doses of 0, 3 and 4.5 kGy. Then the extent of oxidation in raw sausages was determined during refrigerated and frozen storage through the determination of peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) for lipid oxidation and carbonyl content for protein oxidation. The raw sausages were sensory evaluated during storage for colour, appearance and odour, while the grilled samples were sensory evaluated for their colour, odour, taste, texture and juiciness post-treatment only. Irradiation and storage significantly increased the PV, TBARS and carbonyl content in the samples formulated with water. The carrot juice significantly decreased the oxidative processes in the samples proportionally to the juice’s concentration. Furthermore, the sausages that were formulated with carrot juice had a high acceptable sensory scores as compared with the control samples.     

The effect of conditioning on the strength of perimysial connective tissue dissected from cooked meat

Tensile tests were carried out on ribbons of perimysial connective tissue dissected from slices of bovine semitendinosus muscles that had been conditioned or not conditioned and then cooked to a range of temperatures. A consistent reduction in the strength of the perimysia was seen in the conditioned samples, both in the raw meat and meat cooked to 50°C. At higher cooking temperatures (60-80°C), no effect of conditioning was seen. The content of collagen or total protein of mechanically extracted perimysia and the collagen content of the test pieces from conditioned and unconditioned muscles was not significantly different. It was concluded that conditioning decreases the breaking strength of the perimysial connective tissue in raw meat or in meat which is subsequently cooked to 50°C, but not in meat cooked to the temperatures normally employed by consumers. The tenderization observed in conditioned meat cooked to 60°C and above is, therefore, due to the weakening of muscle fibres within the fibre bundles.     

Production of squid emulsion sausages using pork skin and coconut powder mixture as fat replacers

How to improve the inferior properties of squid products is a big challenge for producers. Pork skin and coconut powder (PSCP) mixture were assessed as fat replacers in squid emulsion sausages. The modified treatment containing 100% PSCP had 62.58% less fat, 4.82% more protein and 8.79% more moisture than those of the control (P < 0.05). High PSCP concentration resulted in lower cooking loss, higher emulsion stability and better textural properties. Texture profile analysis (TPA) showed that the addition of PSCP significantly (P < 0.05) increased the hardness, cohesiveness and chewiness of the sausages. The three‐dimensional network structures of the sausages containing PSCP were more compact and homogeneous. Sensory evaluation results produced by a sensory panel comprised of 100 panellists indicated that the sausages had an excellent flavour and overall acceptability when the substitution was 60%. Therefore, pork skin and coconut powder can be used to replace the pork back fat in the squid emulsion sausage without sacrificing the quality.     

Effects of electrical stimulation and temperature on beef quality and tenderness

Beef carcasses were stimulated with either 50 or 500 V and exposed to three chilling temperatures during the first 3 to 9 h post mortem. Both high (HV) and low voltage (LV) electrical stimulation (ES) treatments improved lean maturity scores, lowered the pH values at 2 h through 12 h and reduced the time required for the ATP level to reach minimum values. Both HV-ES and LV-ES treatments influenced firmness, fragmentation and connective tissue (CT) residue as measured by sensory panel and reduced Instron shear value (ISV) of loin steaks. The 30°C temperature treatment had an adverse effect while the 20°C temperature treatment had a beneficial effect on ISV and panel ratings for firmness and CT residue. There was an interaction between conditioning treatments and ES for ISV and sensory panel traits. The LV-ES-20C treatment resulted in the lowest ISV and superior panel ratings; however, the LV-ES-30C treatment had ISV and sensory panel ratings that were similar to the NES-2C (control) group.     

SENSORY AND OBJECTIVE EVALUATION OF A RESTRUCTURED BEEF PRODUCT

A study was undertaken to determine the effect of connective tissue, flake size and NaCl level on the texture of restructured beef steakettes; to examine the effect of these factors on the acceptability of restructured steakettes; and to develop sensory and instrumental texture profiles of the product. Restructured beef steakettes were manufactured with two levels of connective tissue (high, low), three flake sizes (3 mm, 6 mm, 13 mm) and three NaCl levels (0.25%, 0.50%, 0.75%). The textural attributes of these products were measured by a trained sensory panel and by objective measures of compression texture profile analysis, Warner-Bratzler shear and three tensile tests. Most sensory texture attributes could be predicted accurately using instrumental methods. Reduction of the sensory attributes by Principal Components Analysis revealed two underlying dimensions of connective tissue and bind strength. A consumer panel rated steakettes manufactured with 6 mm flakes and 0. 75% NaCl at either connective tissue level to be the most acceptable of the 18 products manufactured for this study.     

Potassium chloride, potassium lactate and glycine as sodium chloride substitutes in fermented sausages and in dry-cured pork loin

Salt is essential in the elaboration of dry meat products, contributing to their texture and flavour development. The effect brought about by substituting NaCl with KCl (0-60%), potassium lactate (0-100%) and glycine (0-100%) on the texture, flavour and colour characteristics of fermented sausages and dry-cured pork loins was evaluated. Texture profile analysis and a sensory analysis were performed. Important flavour defects were detected with substitutions above 40% for the three substituents in both products, and with substitutions above 30% for glycine in dry-cured loin. A loss of cohesiveness was detected by the sensory analysis in fermented sausages at substitution levels higher than 30% with potassium lactate (K-lactate) and higher than 50% with glycine. Although the instrumental analysis detected texture changes in dry-cured loin, the sensory analysis did not detect any substitution effect on texture.