USDA Quality Grade Research Articles

Effect of Electrical Stimulation on Carcass Quality and Meat Palatability of Beef from Forage- and Grain-Finished Steers

Twenty forage-fed (FF), 20 limited grain-finished (LGF) and 19 grain-finished (GF) steers were slaughtered in a commercial meat packing firm. A randomly selected side from each carcass was electrically stimulated (ES) within 1 hr of exsanguination. All sides were chilled in a 0 C cooler, ribbed at 18 to 21 hr postmortem and evaluated for USDA quality and yield grade factors. Five short loin steaks (2.5 cm thick) were removed after 60, 120, 180 and 240 hr postmortem aging for determination of force value (SFV) and after 240 hr for palatability assessment. Quality scores for the longissimus muscle of non-ES (NES) sides of carcasses from GF steers were higher (P<.05) and more desirable for color, firmness, texture and marbling than were scores for NES sides from FF or LGF steers. Across all carcasses, ES sides had higher (P<.05) lean color, firmness and texture scores and less (P<.01) “heat-ring” than NES sides. ES had no (P>.05) effect on marbling score for longissimus muscles from FF or LGF carcasses, but increased (P<.10) marbling scores for GF beef. Steaks from FF carcasses were less (P<.05) tender and had a less desirable “moderately-dairy or grassy” flavor than loin steaks of carcasses from GF steers, which had a “slightly- to moderately-intense” beef flavor. FF and LGF loin steaks differed (P<.05) in flavor but were similar (P>.05) in all other physical, chemical and histological traits studied. ES improved (P<.05) the tenderness ratings of steaks from FF carcasses but did not (P>.05) change palatability of steaks from LGF and GF carcasses. ES decreased SFV and reduced by 5 days the cooler aging time necessary to achieve satisfactory tenderness for loins from FF, LGF and GF beef. Variability in SFV was decreased (P<.05) by ES. In general, ES increased lean quality and tenderness without creating undesirable characteristics.

Nutritional effects of beef connective tissue characteristics and eating qualities (1981)

We compared taste panel and connective tissue characteristics of beef fed a high energy diet with beef fed grass. The high energy diet produced higher USDA quality and yield grades, more rapid weight gain, and increased connective tissue collagen synthesis arid breakdown. But, it did not consistently improve taste panel and shear characteristics over grass-feeding.

QUALITY‐INDICATING CHARACTERISTICS OF BEEF AS AFFECTED BY ELECTRICAL STIMULATION AND POSTMORTEM CHILLING TIME

ABSTRACTEffects of electrical stimulation on quality‐indicating characteristics of beef were evaluated in two studies involving a total of 402 carcasses. Electrical stimulation (550 volts, 5 amps, 60 cycles per set) was administered shortly after the carcasses were split and consisted of 17 impulses of 1.8 set each with a 1.8 set interval between impulses. In Study 1, one side of each carcass (n=222) was electrically stimulated (ES) and the opposite side served as an untreated control (C). Both sides of each carcass were ribbed and evaluated at 24 hr postmortem. Study 2 included carcasses (n=180) in which (a) neither side was stimulated, (b) both sides were stimulated, or (c) one side was stimulated and the opposite side was not stimulated. Postmortem chilling time prior to ribbing also was varied to permit evaluations to be made of the effects of electrical stimulation on carcasses chilled for 24, 48, or 72 hr. In Study 1, ES sides were more desirable (P &lt; 0.0001) than C sides in all quality‐indicating characteristics (marbling, USDA quality grade, lean maturity, lean color, lean firmness, and incidence of “heat‐ring”). In Study 2, optimum chilling time for maximizing marbling score and USDA quality grade was 48 hr for both ES and C sides. ES sides usually were more youthful (lean maturity) than C sides, especially at 24 hr postmortem. Control sides chilled for 48 hr had more marbling and higher USDA quality grades than did ES sides chilled for 24 hr. Nothing in the present study indicates that electrical stimulation results in a higher‐than‐justified quality grade.

FLAVOR PROFILE ANALYSES OF COOKED BEEF LOIN STEAKS

ABSTRACTShort loin steaks selected from beef carcasses representing wide ranges in USDA maturity score (A, B, C, and E) and marbling level (high=moderate0 0 to moderately abundant5 0, medium=slight6 7 to modest9 0 and low=practically devoid5 0 to slight3 3, were subjected to flavor profile analyses. Beef from E maturity carcasses had higher aroma and flavor amplitudes and a greater predominance of “grassy” flavors than did beef from carcasses of other maturity groups. “Astringent” aftertaste was common to most samples. Analyses obtained in our study agree with earlier flavor profile studies conducted on beef of various USDA quality grades. Flavor profiles were developed for steaks from the same carcasses that had provided steaks previously identified as “desirable” or “undesirable” in flavor by two separate panels using hedonic flavor rating scales. “Sweet” and “browned” were typical flavors of steaks previously classified as desirable in flavor, while “grassy” and “astringent” were frequently noted flavors of steaks previously classified as undesirable in flavor. Marbling and fat content were higher in steaks previously classified as desirable in flavor, than in steaks classified as undesirable in flavor.

Electrical Stimulation of Mature Cow Carcasses

Mature cows (n = 95) were slaughtered and assigned to one of three treatment groups: (1) electrical stimulation (ES) of unsplit carcasses, before evisceration, (2) ES, after splitting, of sides, and (3) untreated (not ES) control carcasses or sides. Electrical stimulation consisted of either 150 volts or 550 volts for 1 (16 impulses) min or for 2 (32 impulses) minutes. Carcasses were ribbed at 24 hr postmortem and USDA quality grade factors, lean-color score and “heat-ring” incidence were evaluated. Sections of longissimus muscle (10 to 11th ribs) were used for shear force determinations. Electrical stimulation, irrespective of carcass form, ES voltage or ES duration, improved (P<.05) lean-maturity score, improved (P<.05) lean-color score and decreased (P<.05) shear force value when treated (ES) carcasses and steaks were compared to control (not ES) carcasses and steaks. Use of 550 volts, irrespective of carcass form or ES duration, improved (P<.05) lean-color score and decreased (P<.05) “heat-ring” incidence compared to the use of 150 volts; advantages for 550 vs 150 volts were more evident for carcasses (P<.05 differences in lean-color score and shear force value) than for sides (no significant differences). Stimulation for 2 min, rather than for 1 min, did not affect (P>.05) carcass characteristics or shear force value at either voltage (150 or 550 volts). ES can be performed on mature beef carcasses with expectations in terms of improved quality and increased tenderness proportionately similar to those achieved in electrical stimulation of young beef carcasses.

Tenderness Variations among Beef Steaks from Carcasses of the Same USDA Quality Grade

Tenderness Variations among Beef Steaks from Carcasses of the Same USDA Quality Grade

BEEF QUALITY AND PALATABILITY AS AFFECTED BY ELECTRICAL STIMULATION AND COOLER AGING

ABSTRACTFifty light‐weight heifers were slaughtered and selected sides were electrically stimulated with 50 impulses of 1.0 set duration (machine setting = 100 volts, 5 amps, 50–60 cycles per set: producing a 440 volt potential difference between electrodes). Treatment groups consisted of certain combinations of electrical stimulation (ES) and/or paired control (C) sides stored for 7 or 21 days postmortem. In the treatments involving ES vs C, ES had a significant effect on lean maturity and overall maturity (more youthful) and in one group resulted in higher marbling and final USDA quality grade than the C sides. Lean color was significantly improved and incidence of “heat‐ring” was reduced by the ES treatment. Significant decreases in shear force were observed for 21 day ES vs 21 day C; 21 day C vs 7 day C and 7 day ES vs 21 day C. These data suggest that electrical stimulation could be utilized to improve certain quality‐indicating characteristics and allow carcasses to be graded sooner than normally processed carcasses. In addition, the ES treatment could substantially reduce the time of cooler aging needed to assure optimum tenderness.

Performance and carcass characteristics of Chianina-X steers

Chianina-X steers gained consistently during a 151-day finishing test and produced high yielding carcasses with 0.06 in. fat and 1.71 square of loin per hundred pounds of carcass. Average USDA quality grade was between high good and low choice.

Everyman's meat

Carcasses (n=20) were selected from two commercial packing plants, one in the Texas Panhandle and the other in Nebraska, by trained Texas A&M University personnel. Ten USDA Choice and 10 USDA Select, yield grade 2 and 3 carcasses were selected to reflect the approximate distribution found in the U.S. beef supply. Thirteen cuts (in sets of four) were fabricated and assigned to one of four treatments: (1) 0.3 cm external fat trim, raw; (2) 0.0 cm external fat trim, cooked; (3) 0.3 cm external fat trim, cooked; and (4) 0.6 cm external fat trim, cooked. Retail cuts assigned to the cooked treatment were braised, broiled or roasted. Both the cooked and raw cuts were dissected into separable lean, external fat, seam fat, and waste (heavy connective tissue and bone). USDA quality grade or trim level did not significantly affect the cooking yields of most cuts. Retail cuts that were braised had lower cooking yields than cuts that were roasted or broiled. Dissection data suggested that percentage separable lean increased as cuts were trimmed progressively of external fat cover. Cooked USDA Choice retail cuts had a higher percentage of seam fat than Select retail cuts. Arm roasts had the least separable lean, as well as the most seam fat and waste, even if all the external fat was removed before cooking. These data will be a potential source of information to be used by USDA in Agriculture Handbook 8-13 and the National Nutrient Data Bank, the most widely used resource for nutritional information in the U.S.