Effects of Beef Carcass Electrical Stimulation, Hot Boning, and Aging on Unfrozen and Frozen Longissimus dorsi and Semimembranosus Steaks

Ninety-six sides from 48 beef carcasses were used to study the effects of hot boning (HB), electrical stimulation (ES), a combination of electrical stimulation and hot boning (ESHB), and steak storage treatments on longissimus dorsi and semimembranosus steaks. Steak storage treatments were: unfrozen (aged until 6 days postmortem) or frozen (ES, HB, and ESHB frozen 24 hr and controls 48 hr postmortem). ES did not improve taste panel ratings or consistently lower shear force values when compared with control counterparts. Storing carcasses at 5°C for the first 24 hr postmortem and freezing ES steaks at 24 hr versus 48 hr postmortem for the control possibly diluted the effectiveness of ES. However, ES did eliminate any toughening due to HB.     

Effects of Electrical Stimulation and Hot Boning on Functional Characteristics of Preblended Beef Muscle in Model Systems

Thirty beef carcasses were used to determine the effects of electrical stimulation (ES) and hot boning on the emulsifying capacity (EC) and thermal emulsion stability (TES) of preblended Triceps brachii (TB) muscle (long head) from sides assigned to one of four treatments: (1) conventionally boned after chilling at 2–8°C until 48 hr postmortem (CB); (2) hot boned at 1 hr postmortem (HB); (3) ES during bleeding and conventionally boned at 48 hr postmortem (ESCB); and (4) ES during bleeding and hot boned at 1 hr postmortem (ESHB). HB preblended samples had greater EC and TES values than CB preblended samples in both nonstimulated (P < 0.05) and stimulated carcasses. When compared to nonstimulated sides, ES decreased (P < 0.05) these values in both ESHB and ESCB sides.     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Muscle Display Color of Polyvinylchloride Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine the effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM) steaks packaged in polyvinylchloride film. LD from HB was mostly visually darker, had less oxymyoglobin, and more metmyoglobin than other treatments as was the SM, but SM had fewer differences between HB and ESHB. ES and ESHB muscles were visually similar, suggesting ES minimized the darkening effect of HB. Regardless of treatment, muscle color was acceptable at 0, 1, 3 and 5 days of display.     

Biochemical and Quality Characteristics of Ovine Muscles as Affected by Electrical Stimulation, Hot Boning, and Mode of Chilling

The combined effects of electrical stimulation and carcass holding temperature were evaluated on some biochemical and quality characteristics of intact and hot-boned ovine muscles. Twenty-four lamb sides were randomly assigned to four treatments. Electrical stimulation was performed within 15 min postmortem (350 V with 10 Hz) for 4 min. Electrically stimulated and slowly chilled (5 hr at 14 ± 2°C) sides significantly exhibited more rapid pH decline in the longissimus dorsi (LD) muscle, less cold shortening in the semitendinosus (ST) muscle and greater tenderness in both LD and ST muscles than sides chilled at 2°C. None of the treatments had any effect on cooking loss in ST and LD muscles, lean color of LD muscle during a 4-day retail display, and solubility of different protein fractions as well as the swelling factor of the stroma protein of LD muscles.     

Effects of Electrical Stimulation, Boning Time and Cooking Method on Beef Roasts

Sixteen steer carcasses were selected to study effects of electrical stimulation, boning time and cooking methods on palatability traits, cooking loss and chemical composition of beef biceps femoris muscle. Eight carcasses were electrically stimulated and eight carcasses served as controls. The biceps femoris muscle was removed from one side of each carcass within 2 hr of exsanguination and from the remaining side following a 48-hr chill. Muscles were subdivided and cooked in either a convectional electric or a microwave oven. Electrical stimulation resulted in longer (P < 0.01) sarcomeres for cooked product but did not affect palatability traits, cooking loss or chemical content. Hot boning reduced (P < 0.01) cooking loss and tenderness, resulted in less (P < 0.05) total, soluble and insoluble collagen and increased the juiciness score and moisture percentage when compared with 48-hr boning. Microwave cooking produced a greater (P < 0.01) cooking loss and a higher shear force value than convectional electric cooking.     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Display Color of Unfrozen Vacuum Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), and hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM), vacuum packaged steaks. HB muscles frequently were visually brighter purplish-red than other treatments. Compared to ESHB, ES LD was not different, but ES SM was duller purplish-red in color. Reflectance indicators of reduced myoglobin and metmyoglobin were essentially the same across treatments in both muscles. Vacuum packaged fresh beef steaks from all treatments were acceptable in color at 0, 3, 7, and 14 days of display. Vacuum packaging appears suitable for steaks from any of these carcass treatments but is especially useful for steaks from hot boned cuts.     

Effects of Electrical Stimulation and Hot Boning on Color Stability of Aerobic and Vacuum Packaged Restructured Beef Steaks

Color stability of restructured beef steaks processed from beef boned 4 hr postmortem (HB) and 96 hr postmortem (CB) was determined using a Hunter color difference meter and a semi-trained color evaluation panel. Steaks were formulated using ground tenderized (2.5 cm) restructurable meat (75% of formulation), salted preblended meat (3% NaCl + 0.267% BHA, 25% of formulation) and enough ground fat to form steaks of 10% fat. Steaks were aerobically wrapped and vacuum packaged. Hunter L, a, b, a/b values and color panel scores during a 7-day retail display revealed that HB steaks had superior color stability. This was attributed to the ability of NaCl to inhibit glycolysis in the HB preblended meat and to act as a prooxidant of myoglobin in the CB preblended meat.     

Vitamin A, Electrical Stimulation, and Chilling Rate Effects on Lysosomal Enzyme Activity in Aging Bovine Muscle

Means of enhancing the rate of aging of bovine meat were investigated to provide some understanding of the tenderization process. Vitamin A was administered to finishing steers, carcasses were electrically stimulated, and longissimus dorsi muscle samples chilled at 2 different rates. Liver cathepsin D, beta-glucuronidase and hexosaminidase were increased (P < 0.05) with vitamin A supplementation but muscle enzymes were not affected. Chilling rate, electrical stimulation and time significantly (P < 0.05) affected cathepsin D distribution patterns, meat color, Warner-Bratzler, myofibrillar fragmentation index and collagen data. Troponin-T degradation was enhanced by aging. Thus, vitamin A can modify liver catheptic enzyme activity but does not affect muscle enzymes at these levels.     

Processing Properties of Beef Semimembranosus Muscle as Affected by Electrical Stimulation and Postmortem Treatment

Semimembranosus muscles from paired sides-electrically stimulated (ES) and not-stimulated (NES)-of mature cows were used to determine effects of certain postmortem treatments (state of rigor/temperature) and of ES on processing properties. ES decreased (P<0.05) pH values for prerigor, prerigor/frozen and postrigor/frozen muscles, but did not affect (P>0.05) values for total protein or juice loss during cooking. State of rigor/temperature treatment affected pH and salt-soluble protein (SSP) values more than did ES treatment. pH values differed (P<0.05) between each state of rigor/temperature treatment for both ES and NES samples. Salt-soluble protein values were higher (P<0.05) for NES prerigor than for NES postrigor/frozen samples and higher (P<0.05) for NES postrigor than for NES postrigor/frozen samples. SSP values for ES muscles were higher (P<0.05) for ES postrigor samples than for ES postrigor/frozen samples but were not different for other comparisons. Regardless of ES treatment, freezing of semimembranosus muscles increased pH values (P<0.05) and decreased SSP values (P<0.05) in three of four comparisons.     

Electrical Stimulation and Hot Boning: Cooking Losses, Sensory Properties, and Microbial Counts of Ground Beef

Six batches of ground beef, approximately 10, 15, or 20% fat, were fabricated from flanks (lean and fat trim) of electrically stimulated-hot boned (ESHB) or conventionally chilled (CC) beef sides. Patties (2.5 × 7.6 × 8.2 cm) from each batch were modified broiled for 35 min at 177°C. Generally, ESHB and CC products were comparable in cooking and sensory properties and in microbial counts of raw products. ESHB products had slightly higher cooking losses, more intense beef flavor, and were slightly juicier than CC products. Small differences between ESHB and CC products more often were attributable to fat content than to processing treatment (ESHB or CC).     

Electrical Stimulation and Hot Boning: Color Stability of Ground Beef in a Model System

Lean and fat trim of flanks from electrically stimulated, hot boned (ESHB) or conventionally chilled (CC) beef sides were used to fabricate six batches of ground beef with three levels of fat (ESHB 10, 15, or 20% fat; CC 10, 15, or 20% fat). Raw samples were evaluated for color stability in a model system, pH, and microbial counts. After 4 hr exposure to radiant energy, percentage reflectance for 630 – 580 nm, HunterLab spectrophotometer a values, HunterLab a/b ratios, and visual color scores indicated the ESHB samples were more (P < 0.05) sensitive to metmyoglobin formation, had slightly lower pH, and had lower microbial counts than did CC samples.     

Processing Properties of Pork as Affected by Electrical Stimulation, Post-Slaughter Chilling and Muscle Group

Left sides of 30 slaughtered pigs were electrically stimulated (ES); right sides were not stimulated (NES). Sides were placed in a conventional cooler (24 hr) or blast freezer (3 hr) or showered with a brine solution (15.8% salt, -5.6°C for 3 hr). Twenty-four hr postmortem, picnic shoulders were removed, dissected into four muscle groups and determinations made for certain processing properties. ES decreased (P < 0.05) pH values for predominantly white muscles, increased (P < 0.05) juice loss during cooking for shank muscles and decreased (P < 0.05) percentages of salt-soluble protein (SSP) for both predominantly red and shank muscles. Other muscle properties were not affected by ES. Rapid initial chilling did not affect (P > 0.05) processing properties of muscle groups.     

Chemical and Physical Characteristics of Beef Chuck Muscles: Effect of Electrical Stimulation, Hot Boning and High Temperature Conditioning

Chucks from 12 electrically stimulated steer carcasses were randomly assigned to one of 3 treatments: (1) cold boned [CB], (control), (2) hot boned [HB], and (3) hot boned/time conditioned [HB/TC], (5 hr at 18°C). Infraspinatus, Serratus ventralis, Subscapularis, Supraspi-natus, Teres major, and Triceps brachii were excised from each chuck according to treatment conditions. No differences (P > 0.05) were noted among treatments for muscle yields, cooking loss, proximate composition, or collagen content; however, differences (P<0.05) were found among muscles. Differences (P < 0.05) were found among treatments and muscles for ultimate pH, sarcomere length, Warner Bratzler shear values, and Hunter color ‘a’ values. Sarcomere length of muscles assigned to CB treatment were longer (P < 0.05) than HB and HB/ TC treatments.     

Effects of Electrical Stimulation, Temperature of Boning and Storage Time on Bacterial Counts and Shelf-Life Characteristics of Beef Cuts

Strip loins and eye of rounds from 16 beef carcasses were used to study the effects of electrical stimulation (ES), no stimulation (NS), hot-boning (HB), and cold-boning (CB) on bacteriological and shelf-life evaluations. Following 7 days of vacuum-packaged storage, coliform counts were higher in the drip fluid from strip loins and lean surfaces of eye of rounds from ES compared to NS carcasses. A major advantage for HB in this study was the additional time required in retail display before the occurrence of lean surface discoloration. A previously identified benefit of lighter lean color with ES beef in carcass and primal cut form was also found in this study during display of retail cuts.     

Electrical Stimulation Effects on Myoglobin Properties of Bovine Longissimus Muscle

Beef longissimus steaks from 40 bull carcasses were used to study the effects of electrical stimulation (ES) on meat color mechanisms and myoglobin properties. Total pigment concentration and ratios of myoglobin forms for ES and control (C) samples were not different. Color panel and several spectrophotometric measurements indicated ES produced a lighter, brighter-red color in displayed steaks. Disappearance of reduced myoglobin during blooming was similar in unaged C and ES steaks, but reduced myoglobin decreased faster during blooming of ES steaks aged 6 days. ES decreased anaerobic metmyoglobin reducing activity and induced more metmyoglobin formation when steaks were in a 1% oxygen atmosphere.     

Effects of Electrical Stimulation and Delayed Chilling of Beef Carcasses on Carcass and Meat Characteristics

A 2x2 factorial experimental design with 2 replications was used to study the effects of a combination of electrical stimulation and delayed chilling of carcass on meat characteristics. Twenty Standard or Good grade beef cattle were slaughtered and 10 sides were assigned to each of the 4 treatments. Meat characteristics were evaluated subjectively (sensory panel evaluation) and objectively (W-B shear device). Electrically stimulated carcasses cooled faster in the first hour postmortem; thereafter the order of further cooling was reversed. The 24 hr postmortem weight loss in the electrically stimulated with delayed chilling did not differ (P > 0.05) from those receiving electrical stimulation plus immediate chilling nor those not stimulated but chilled immediately. For delayed chill carcasses, 24 hr postmortem weight loss was lower (P < 0.05) in electrically stimulated than in nonstimulated groups. Electrical stimulation reduced (P < 0.05) cooking losses. The difference in sarcomere lengths among the 4 treatments was not significant (P > 0.05). At the microstructural level, an open triad and T-system were observed immediately following electrical stimulation. As early as 24 hr postmortem, considerable Z-line degradation was observed in the electrically stimulated and delayed chilled samples.     

Effects of Electrical Stimulation on the Functional Properties of Lamb Muscle

One side from each of eleven lamb carcasses was electrically stimulated (60 Herz alternating current at 240v followed by 420v) within 45 min postmortem. Three carcasses (stimulated and respective control sides) were rapidly chilled (1°C), three carcasses received a delayed chill (12°C until pH 6.0 was attained, then excision and 1°C), and three carcasses were slowly chilled (12°C). Measurements beginning at 44 hr postmortem showed that stimulation increased the sarcomere lengths but had few consistent or significant effects on water-holding capacity, protein solubility, emulsifying capacity, gel strength, cooking loss, or binding strength. The remaining two carcasses were rapidly chilled and their meat was manufactured into frankfurters. The emulsion stability was slightly improved by stimulation but smokehouse weight loss, Warner-Bratzler shear force, penetration force, cooking loss, and sensory characteristics were unaffected.     

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.     

Electrical Stimulation and 48 Hours Aging of Bull and Steer Carcasses

Bull (n = 30) and steer (n = 30) carcasses were measured for meat quality in the longissimus muscle after 48 hr on electrically stimulated (ES) sides or after 6 days on their unstimulated counterparts. Electrical stimulation and 48 hr aging had the same tenderizing effect as a 6 day aging period on both bulls and steers. Compared to meat from steers, that from bulls was tougher and had higher ultimate pH values and collagen contents. On an overall quality basis however, ES meat aged for 48 hrs was equivalent to nonstimulated meat aged for 6 days.     

Effect of Electrical Stimulation and Postmortem Boning Time on Sensory and Cookery Properties of Ground Beef

Ground beef was prepared from electrically stimulated and nonstimulated sides of 24 U.S. Utility grade carcasses that were boned 1, 3 or 24 hr postmortem. Postmortem electrical stimulation had no negative effects or, the physical, sensory or cooking properties of ground beef patties. Time of boning had significant effects on percent height change during cooking, total cooking loss, tenderness, and juiciness. As cooning time increased, the effects on the traits were negative.