THE EFFECT OF SLICE THICKNESS AND MIXING TIME ON THE PALATABILITY AND COOKING CHARACTERISTICS OF RESTRUCTURED BEEF STEAKS

Restructured beef steaks were made from chuck meat that was flaked (6 mm) or sliced at various thicknesses (2.5, 5.0 or 7.5 mm). Each formulation was mixed for 5, 10, 15 or 20 min, pressed into logs, frozen and cut into steaks. Steaks were evaluated for fat and moisture contents, cooking characteristics, and sensory attributes. Slice thickness had little effect on sensory properties; however, the restructured steaks were significantly more tender and possessed a more desirable texture and flavor than the intact chuck steaks. Restructured steaks made from meat that was mixed for 5 or 10 min were significantly more tender and received higher texture desirability and overall palatability ratings than restructured steaks made from meat that was mixed for 15 or 20 min.     

EFFECTS OF FAT LEVEL AND COOKING METHODS ON PHYSICAL AND SENSORY CHARACTERISTICS OF RESTRUCTURED BEEF STEAKS

Trimmed top rounds from 9 Angus steers were flaked and formed into restructured steaks containing 15, 20, or 25% fat. The steaks were cooked in a microwave oven (MW) on a preheated browning dish or broiled in a conventional oven (CO). Microwave cooking required less time and energy. Decreased time and energy for cooking also related to increased fat levels. Cooking losses and penetration hardness values were greater for the MW steaks. Cooking losses increased and penetration hardness values decreased with increasing fat level. MW steaks appeared more well-done and were harder, less moist, and more resistant to chewing. As fat level increased softness and moistness scores also increased. Consumer panelists found all steaks to be equally acceptable, suggesting the potential for the development of portion- and fat-controlled restructured steaks for microwave cooking.     

EFFECT OF THERMAL PROCESSING ON STRUCTURE AND RHEOLOGICAL PROPERTIES OF CARRAGEENAN/CAROB GUM GELS

Optical rotatory dispersion and rheological studies have been used to investigate changes in carrageenan and carob gels on thermal processing. A synergistic effect was observed on the gel strength of both unprocessed and heat processed carrageenan carob gels when compared to gels without carob, although a lower gel strength was measured after processing. The reduction in strength of gels on heat processing appears to be due mainly to the depolymerisation of the network chains while the crosslinks of the gel are largely unaffected.     

THE EFFECT OF ORGANIC ACID MARINATION ON TENDERNESS, COOKING LOSS AND BOUND WATER CONTENT OF BEEF

Longissimus muscle obtained from beef carcasses was used in this research. Initially, 0.596, 1.0% and 1.5% lactic and citric acid solutions were prepared. Meat was marinated in these solutions (1:4 w/v) in polyethylene bags at 4C for 72h. Bound water, pH, weight gain, cooking loss and Warner Bratzler shear (WBS) were evaluated. Differential Scanning Calorimetry (DSC) was used to determine the bound water content in meat samples. The latent heat of melting (ΔH_m) and bound water were found to be functions of moisture content of marinated meat. There was a significant decrease in pH due to marination. Compared to lactic acid, the samples marinated with citric acid held less water. The WS values in control samples were higher than in marinated samples. Cooking loss was lower in samples marinated with lactic acid compared to citric acid marinated samples.     

EFFECTS OF SOY PROTEIN AND FREEZING TREATMENTS ON COOKING LOSS AND COMPOSITION OF BEEF PATTIES

All-beef and soy-extended patties were frozen to −18°C in either 24, 48, 72 or 96h and stored at −23, −18 or −7°C for 6, 9, 12, 18 or 24 months. The addition of soy resulted in a substantial reduction in cooking loss for patties cooked from the frozen state with a greater retention of moisture in cooked patties. Freezing reduced cooking loss for soy-extended patties, but increased cooking loss for all-beef patties. Faster freezing (-18°C in 24 h vs. −18°C in 96 h) reduced cooking loss and produced higher moisture values in all-beef patties. Patties stored at –7°C lost more moisture during cooking. Increased frozen storage time had a minimal effect on cooking losses, moisture and fat levels. Where it is essential for frozen patties to sustain minimal cooking losses with maximal moisture in cooked patties, the inclusion of soy protein concentrate, faster freezing, and storage at –18°C or colder are suggested.     

EFFECT OF PROTEIN EXTENDERS ON FATTY ACIDS,CHOLESTEROL, SENSORY QUALITY AND COOKING LOSS OF BEEF PATTIES1

Ten different formulations of beef patties were processed to contain 20–50% fat from lean beef containing not more than 7% fat and beef fat consisting of not less than 90% fat and were extended with different levels of textured soy protein (TSP) at 5, 10 and 20% and single cell protein (SCP) at 2.5, 5 and 7.5%. The patties were stored at ?18°C for 6 months. Sensory quality evaluation showed that patties with 80% lean and 20% fat and patties with 40% lean, 40% fat and 20% TSP were the least acceptable, but lower levels of TSP and SCP addition were found to improve panel rating. A 17% increase in protein content and a reduction of about 13.5% in fat content was observed due to TSP and SCP incorporation. An average cooking loss in the different formulations was 33%, addition of protein extenders was found to reduce cooking loss by about 22% while fat loss averages 30.2%. A reduction of 21.1% of 18:1 and a reduction of approximately 18.7% of total FAME and 32% cholesterol were observed due to the addition of TSP and SCP.     

SENSORY AND RHEOLOGICAL PROPERTIES OF K-CARRAGEENAN GELS MIXED WITH LOCUST BEAN GUM, TARA GUM OR GUAR GUM

Mixed gels of _K-carrageenan (C) and a galactomannan gum, viz., locust bean (L), tara (T), and guar (G) in ratios of 7:3 and 1:1 (total concentration 1%), were examined for their rheological properties and by a sensory evaluation. Texture, creep and rupture were measured, and the semantic differential method (SD) was employed. _K-Carrageenan alone could not form a gel at the concentration of 0.5%, while C-L and C-T but not C-G mixtures in the ratio of 1:1 formed gels. The mixed gels of C-L were hard, very elastic and not perceived as smooth by the sensory evaluation. The values for the gels comprising T were intermediate between the C-L and C-G gels in instrumental measurements and sensory characteristics, indicating that the C-T mixture performed well as an edible gel. This difference is attributed to the synergistic effect between _K-carrageenan and the gums.     

EFFECT OF PRESSING ON MOISTURE LOSS AND SENSORY PROPERTIES OF BEEF

Paired halves of top round (Semimembranosus and Adductor muscles) sub-primals were removed from each of ten, USDA Choice, approximately 272 kg steers, freezer wrapped, frozen, and stored at -24° C for approximately 1 month. Following freeze-tempering, each primal was divided longitudinally with one half being pressed at 344 Newtons/cm² to a specified shape in a Bettcher Model 70 Press, while the other half served as nonpressed control. Moisture loss and sensory properties were determined for 2.54 cm thick steaks. No significant differences were found in juiciness, flavor or Kramer shear values between pressed and non-pressed top round steaks, however, sensory tenderness scores were lower (P < 0.05) for steaks that were pressed than for those that were not pressed. Holding steaks at 2° C for 0, 1, 2, or 3 days did not significantly alter Kramer shear or sensory panel evaluations. Cooking loss, drip loss and total loss were not affected by pressing. Drip loss was lower (P < 0.05) and cooking loss was higher (P < 0.05) for steaks held one day at 2° C than for steaks held 2 or 3 days at 2° C. When drip loss and cooking loss were combined (total loss) there was no difference among the four storage times. Drip loss following portion cutting could result in a problem in fresh merchandising of freeze-tempered cuts.     

RHEOLOGICAL STUDY OF O/W EMULSIONS CONTAINING DRIED WHOLE EGG AND LOCUST BEAN GUM

The influence of sucrose addition and type of salt (NaCl; Morton Lite salt: 50% NaCl and 50% KCl, and Mineral salt: 65% NaCl, 25% KCl and 10% MgSO₄) on the rheological properties of O/W emulsions containing locust bean gum was analyzed. Flow curves over the range 0.1 to 100 s⁻¹ and transient flow curves at 0.2 s⁻¹, at 20 and 30C were obtained for 12 different emulsions, containing 30% (w/w) of sunflower oil. The K and n power law parameters and the hysteresis loop area (HL) were evaluated from the flow curve. So were the Hahn parameters from time-dependent stress decay fitting. Rheological behaviour of emulsions was affected by the type of salt and the presence of sucrose. Changes in solvent properties of the continuous phase in the emulsions on the macromolecules present could be responsible for the different behaviour. The ageing effect on flow behaviour parameters and on the hysteresis loop area was also studied. Evolution of rheological parameters during emulsion storage suggests that increase of ionic strength and polar solutes concentration decrease the stabilizing properties of locust bean gum.     

EFFECTS OF LIQUID SMOKE ON LIPID OXIDATION IN A BEEF MODEL SYSTEM AND RESTRUCTURED ROASTS

Commercially available liquid smokes were added to a meat model system and to a restructured beef product to assess their ability to suppress lipid oxidation. Aqueous hickory smoke was the most effective smoke in suppressing oxidation as reflected in 2-thiobarbituric acid reactive substances (TBARS) of microsomal lipids. Phenol was not antioxidative in the model system. Addition of liquid smoke had no significant effect on "stale, cardboardy, painty" flavor or aroma of restructured beef roast slices stored at 4C. The aroma and flavor of sliced beef deteriorated over the 7-day storage regardless of liquid smoke addition. Hexanal in the control roasts increased during storage from ∼0 to >3 ppm; those containing aqueous liquid smoke contained little (< 0.5 ppm) hexanal. Smokes, but not the phenol mix, kept TBARS near day zero (0.2 mg/kg) levels through 7 days.     

EFFECT OF INDIVIDUAL MUSCLES AND CONNECTIVE TISSUE LEVELS ON THE SENSORY AND SHEAR PROPERTIES OF RESTRUCTURED BEEF STEAKS

Restructured steaks were made from slices of forequarter muscles known to be different in tenderness. Additional steaks were made from pieces that were sorted to contain either epimysium, intramuscular connective tissue sheets or no visible connective tissue. Texture panels and shear force values could discriminate between steaks from some of the different muscles. High correlations ( P < 0.05) existed between connective tissue amounts and the sensory evaluations of residual connective tissue toughness and instrumental shear force values.     

EFFECTS OF PAPAIN,FICIN AND SPLEEN ENZYMES ON TEXTURAL,VISUAL, COOKING AND SENSORY PROPERTIES OF BEEF BULLOCK RESTRUCTURED STEAKS1

Twelve blends were formulated from young bullocks to contain 0, 0.125, 0.250 or 0.375% spleen extract, papain or ficin enzymes. All blends were analyzed for chemical, sensory and visual properties. Control blends were superior to all enzyme treated restructured steaks for flavor desirability and overall satisfaction ratings. Type and level of enzyme significantly decreased fat and increased moisture percentages, and the enzymatic degradation of the myofibril caused emulsion instability. Cooking loss and cooking time were longer for blends made with enzymes as the protein matrix was denatured extensively. Storage time was reduced significantly with the addition of spleen enzymes and all restructured steaks were undesirable for raw appearance ratings. Restructured steaks formulated with these enzymes had reduced connective tissue amount; however, the proper level of these enzymes needs to be studied further in order to minimize the problems in binding and sensory properties.     

EFFECT OF POLYSORBATE-60 ON THE STABILITY OF O/W EMULSIONS STABILIZED BY PROPYLENE GLYCOL ALGINATE AND XANTHAN GUM

The effect of polysorbate-60 in improving the stability of model oil-in-water emulsions formulated with xanthan gum and propylene glycol alginate was studied at two levels of the surfactant; 0.15% and 0.30%. Creep measurements and steady shear measurements as well as surface tension and oil droplet size measurements were conducted to relate rheological and surface properties to improved stability. Higher polysorbate-60 concentration resulted in lower surface tension values which shifted the oil droplet size distribution to a smaller size range; this distribution was a function of aging time at 0.15% weight concentration PS-60. The decay in rheological parameters, particularly Newtonian viscosity, was slower at 0.30% surfactant concentration.     

EFFECT OF COOKING OIL TYPE ON FINAL CHOLESTEROL CONTENT AND FATTY ACID COMPOSITION OF GROUND BEEF

The purpose of this study was to compare three oils for extraction of cholesterol when used to cook ground beef and to determine the effect of oil type on fatty acid composition of the ground beef. Ground beef (30 % fat) was cooked in 1 L of corn, canola or palm oil at 100–110C and then rinsed with 500 ml of boiling water, which significantly decreased ether-extractable fat. Control hamburger was skillet-fried without any added oil. Total lipids were extracted and analyzed for fatty acid composition and cholesterol content. Changes in fatty acid composition of residual fat on the meat after cooking reflected those of the oils used for cooking. Cholesterol was significantly lower in all oil-cooked hamburger than in the control. In conclusion, cooking ground beef in any of the three vegetable oils will extract cholesterol, and the lipid remaining after a boiling water rinse will contain fatty acids characteristic of the cooking oil.     

EFFECT, DEVELOPMENT AND OPTIMIZATION OF MIXING TEMPERATURE, TIME AND PARTICLE REDUCTION IN THE MANUFACTURE OF RESTRUCTURED BEEF STEAK

Restructured beef steaks were processed from USDA Select chuck muscles without the use of additives, and three processing variables were utilized at three different levels: -2, 0, +2C for mixing temperature, 12, 18, 24 min for mixing time and 1, 2, 3 passes through a kidney plate for particle size reduction. A sensory panel composed of 149 untrained consumer panelists evaluated the 27 treatment combinations for five sensory attributes. Instrumental determinations were also made. Increasing mixing temperature and decreasing particle size significantly decreased sensory tenderness, flavor and overall acceptance and increased instrumental hardness and springiness of the restructured beef steaks. Increasing mixing time had a significant effect on sensory appearance and on instrumental cohesiveness and gumminess. The means for sensory scores were used for a response surface analysis (RSM) to optimize the three processing variables. Significant models were found for tenderness (P<0.05), overall acceptance (P<0.05) and flavor (P<0.15). Using a sensory score of 6.00 (like slightly) as an acceptable score, optima for the processing variables were determined. To obtain an acceptable product, the meat should be ground by two passes through the kidney plate then mixed at a maximum temperature of 0.67C for 12 min.