Variations in Internal Color of Cooked Beef Patties

Seventeen commercially prepared patty formulations were cooked to internal temperature 71°C. Pink cooked color occurred in eight of the products and was due to incomplete denaturation of myoglobin. Although there was some relation between pH and cooked color, other factors seemed to be involved. When products were re-analyzed after 1 yr storage at -27°C, sixteen products were red/pink when cooked to 71°C. This increase in redness after frozen storage could not be explained. Cooking to internal temperatures between 81 and 87°C was necessary for complete disappearance of red/pink color. Premature browning, where a product looks well-done at temperatures lower than 71°C, occurred in one formulation.     

USDA MATURITY INDICES AND PALATABILITY OF BEEF RIB STEAKS1

In a population of 195 beef carcasses, as maturity increased (by whole USDA groups) from A to B, flavor, tenderness and overall palatability ratings for rib steaks decreased (P < .05); further increases in maturity (B vs. E) resulted in subsequent decreases (P < .05) in tenderness and overall palatability. Subdivision of whole maturity groups into thirds and subsequent data analyses supported precepts in USDA grade standards of declining palatability with advancing maturity, but the declines, when they occurred, were nearly linear through the extremes (from A^? to E⁺) and did not support the concept, in USDA grade standards, of a precipitous decline in eating satisfaction at or near the B⁺/C^? maturity line. Among seven carcass maturity indices, all were similarly and singularly related (P < .05) to palatability of rib steaks, with some measure of skeletal maturity (the best of these was color/shape of the rib bones) plus some measure of muscle maturity (the best of these was color of the longissimus muscle) combining (by means of multiple regression analyses) to predict tenderness (panel ratings and shear values) with maximum precision. Neither total pigment concentration (a chemical measure of muscle color), amount of ether-extractable lipid (a chemical measure of intramuscular fatness) nor marbling score (a visual measure of intramuscular fatness) was able to explain more than about 7% of the observed variability in palatability ratings for cooked beef steaks. Data suggest that more attention should be paid to appearance of rib bones in a carcass (to better assess effects of maturity) and that less attention could be paid to differences between SLIGHT, SMALL and MODEST in marbling in the ribeyes, in attempting to predict, via USDA grading, the palatability of beef rib steaks.     

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.     

Effects of Electrical Stimulation, Boning Temperature, Formulation and Rate of Freezing on Sensory, Cooking, Chemical and Physical Properties of Ground Beef Patties

The effects of electrical stimulation vs nonstimulation, temperature of boning (hot vs cold), formulation (USDA Choice chucks with USDA Choice plates vs imported cow lean with USDA Choice plates) and rate of freezing (fast = -50°C vs slow = -20°C) were determined on sensory, cooking, chemical, and physical properties of ground beef patties. Sensory panel ratings for tenderness were highest in patties from formulations processed with either nonstimulated beef, hot-boned beef or Choice chucks. The substitution of imported cow lean for Choice chucks generally reduced cooking losses and changes in patty height during cooking. Fat losses during cooking were higher in patties made from electrically stimulated than nonstimulated beef, while moisture losses during cooking were greater for patties from nonstimulated than stimulated beef. Of the factors involved in this study, hot boning produced the most beneficial results in beef patties. Boneless chucks and plates from electrically stimualted Choice carcasses appear to be suitable raw materials for production of ground beef patties.     

Sodium Alginate Plus Modified Tapioca Starch Improves Properties of Low-Fat Beef Patties

Sodium alginate (A) in combination with modified tapioca starch (T) was evaluated in low-fat beef patties cooked by broiling or grilling to 68 or 74°C. Added water was used with AT formulations at 7% (AT7) or 14% (AT14) levels. In comparisons with all-beef patties (8 and 20% fat), AT provided improvements in tenderness, juiciness and cooking yields without increasing fat retention or affecting beef flavor. In sensory comparisons with 14 commercially processed, low-fat beef patties, AT7 and 14 patties received the highest ratings. Combined use of A and T would provide improved acceptability of low-fat patties over that from using single fat replacers.     

Sensory Characteristics, Shear Values and Cooking Properties of Ground Beef Patties Extended with Iron- and Zinc-Fortified Soy Isolate, Concentrate or Flour

Ground beef patties made from 100% beef or beef extended with 20% rehydrated soy isolate, concentrate, or flour, with or without iron and zinc fortification, were evaluated for sensory, shear and cooking properties. With the exception of patties formulated with soy isolate, soy-added patties were rated as more tender (P <0.05) than all-beef patties. Soy isolate imparted textural characteristics to patties that were more similar to those of all-beef patties than to those of soy concentrate or soy flour extended patties. Patties made with soy flour had the highest cooking yields. Also, patties extended with soy flour had lower incidences of rancid flavor, but higher incidences of soy flavor compared with all other beef-soy formulations. Iron and zinc fortification produced a higher frequency of rancid flavor when used with soy isolate and concentrate.     

Cooked Color in High pH Beef Patties as Related to Fat Content and Cooking from the Frozen or Thawed State

Beef patties were processed from high pH (>6.0) beef to contain 5, 10, 15, 20 or 25% fat. Patties were cooked to 71°C from the frozen or thawed state before evaluating color. Neither fat content nor state of patties when cooked exerted any major influence on color, but linear effects (p<0.01) in association with increased fat content included higher L* values and hue angles and lower a* values (15.2% reduction). Higher values for L*, b* (but not for 5% fat patties), and hue angles were observed for patties cooked thawed rather than frozen. The use of high pH beef lessened the effects of increased fat and cooking from the thawed state on increased brown color in cooked patties.     

MODIFIED PREGELATINIZED POTATO STARCH IN LOW-FAT GROUND BEEF PATTIES

Effects of modified pregelatinized potato starch (MPPS) in 5 and 20% fat ground beef patties were evaluated. In formulas containing starch, MPPS comprised 3.0% and added water 5.0% of the raw mixture. Use of 20% rather than 5% fat in the ground beef improved sensory tenderness measured early in chewing, while lowering many Instron measurements. The 20% fat patties had more intense beef flavor. MPPS increased tenderness, but reduced juiciness and beef flavor. The addition (1% of formulation) of concentrated butter flavor to ground beef with MPPS produced beef flavor equivalent to all-beef patties. The use of MPPS increased cooking yields and moisture content following cooking and reduced fat retention of 20% patties. MPPS increased heating rate while retaining substantial moisture during cooking. Inclusion of MPPS in beef patty formulations offers improvements in tenderness and cooking yield, while reducing fat retention during cooking.     

RELATIONSHIPS AMONG CHEMICAL, COOKING AND COLOR PROPERTIES OF BEEF PATTIES COOKED TO FOUR INTERNAL TEMPERATURES

A study involving five laboratories and nationwide sampling of ground beef was undertaken to determine cooking and color properties of patties cooked to 52.7, 65.6, 71.1 and 79.4C. The design of the study included purchase location (local, distant) and patty handling prior to cooking Pesh, thawed either as patties or bulk ground beef). Purchase location was not a statistically significant influence on cooking and color properties. Patties processed from bulk thawed product had a higher amount of brown cooked color. A strong relationship existed between visual and instrumental measures of red color in cooked patties. However, correlations among other cooking properties were low. Patties with higher fat content were associated with shorter cooking times, lower cooking yields and more brown cooked color. The low relationships between raw and cooked patty properties limits the use of raw ground beef properties as predictors of food safety in cooked beef patties. This further supports the use of instant read meat thermometers in cooking beef patties to at least 71C.     

The Fate of Glucose in Strains S288C and S173-6B of the Yeast Saccharomyces cerevisiae

Intracellular metabolic flux has been investigated in two strains of Saccharomyces cerevisiae grown into stationary phase under both glucose-repressed and glucose-derepressed conditions. By employing a variety of simple methodologies (manometry, enzymatic analysis and colorimetric analysis) we have been able to identify and quantitate carbon flow from glucose without the need for isotopically labelled substrate. We can account for 88–98% (depending on strain and growth conditions) of the carbon products of glucose metabolism under both glycolytic and oxidative conditions as ethanol (27–40%), carbon dioxide (15–26%), acetate (2–3%), glycerol (5–11%), glycogen (5–13%) and trehalose (9–39%).©1997 John Wiley & Sons, Ltd.