Meat Quality Kinetics during Beef Carcass Chilling

Kinetic models for changes in muscle pH and beef quality, based on press juice and puncture strength, were determined during beef carcass chilling. Changes in quality of Longissimus dorsi muscle during chilling were determined and modeled using reaction kinetics and Eyring's absolute reaction rate theory. The pH and press juice followed first order reaction kinetics while puncture strength did not follow any specific reaction order. Enthalpy and entropy of activation for changes in the quality indices were calculated.     

Comparison of the Effects of High and Low Voltage Electrical Stimulation on Quality-Indicating Characteristics of Beef Carcasses

Electrical stimulation, both high-voltage (HVES; 55OV) and low-voltage (LVES; 35V), resulted in brighter, more youthful appearing color of lean as compared to that of controls (not stimulated). There were no differences attributable to electrical stimulation for marbling or “heat-ring” score. Contrasts were made between LVES-A (35V), LVES-B (60V) and nonstimulated sides. LVES-A resulted in brighter color of lean but lower marbling scores than did LVES-B. LVES-B produced brighter lean color and lower “heat-ring” scores as compared to that of controls. Use of LVES-A resulted in higher marbling scores as compared to that of controls. “Shackled” sides of LVES (both A and B) carcasses had significantly higher incidences of iridescence and two-toning than did the “Free” sides and the controls.     

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.     

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 on Carcass Quality and Meat Palatability Traits of Charolais Crossbred Bulls and Steers

Forty-four Charolais crossbred bulls and steers from a similar background and fed commercially were slaughtered and the right side of each carcass was electrically stimulated. Electrical stimulation reduced lean maturity scores (bulls and steers) and, for steers, lowered lean firmness scores (softer lean) and improved “heat-ring” scores. Electrical stimulation significantly improved most tenderness measurements on steaks from young bulls, but was only effective in decreasing shear force values of steaks from steers. Electrical stimulation was more effective in improving the tenderness of steaks from bulls than those from steers.     

Hot-Fat Trimming and Electrical Stimulation Effects on Beef Quality

We evaluated the effects of hot-fat trimming, low-voltage electrical stimulation (ES) and storage time (3, 7 or 14 days) on quality of beef longissimus dorsi, psoas major, biceps femoris and supraspinatus muscles. Prior to chilling, beef carcasses (n = 32) were either subjected to ES or not stimulated before alternating sides were hot-fat trimmed. Temperature decline, pH, sarcomere length and USDA yield and quality grades were obtained on each carcass side. Muscles were removed from each side and evaluated for quality factors related to storage life and sensory analysis. Generally, no adverse effects of hot-fat trimming, with or without ES, or increased storage time, were observed. Results indicate that hot-fat trimming may be practiced at the industry level without affecting overall quality.     

Tenderness Improvement of the Major Muscles of the Beef Carcass by Electrical Stimulation

Steaks (arm; blade; seven-bone; rib, small-end; top loin; tenderloin; top sirloin; tip, cap-off; and round) from electrically stimulated (ES) and control sides of 20 beef carcasses were cut and frozen at 5 days postmortem. Forequarter muscles that were improved by ES were the longissimus dorsi (rib steak), the subscapularis and supraspinatus (blade steak), and the superficial pectoral (arm steak). Hindquarter muscles that were improved by ES were the longissimus dorsi (top loin steak), the biceps femoris and gluteus medius (top sirloin steak), and the semimembranosus and biceps femoris (round steak). ES, in addition to improving tenderness of the longissimus dorsi, increased tenderness of other major muscles in the carcass.     

宰后浸烫和预冷对白条鸭肉品质的影响

以白条鸭为研究对象,通过响应面法研究宰后因素如浸烫时间(180～220s)、浸烫温度(56～64℃)、预冷时间(40～50min)和预冷温度(10～15℃)对白条鸭肉嫩度的影响,并建立一个高度显著且拟合度良好的二次回归模型。结果表明:当浸烫时间为187s、浸烫温度为64℃、预冷时间为50min、预冷温度为13℃时,白条鸭肉的剪切力为51N。     

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.     

预冷环境及时间对猪胴体冷却损耗的影响

为了解决传统企业在猪胴体冷却过程中干耗较严重的问题,在春季选取若干宰后猪胴体,研究预冷库内不同位置的风速、温度、相对湿度的变化规律,不同冷却时间和冷库内不同位置对猪胴体冷却损耗的影响。结果表明：预冷库内不同位置之间的风速、温度、相对湿度之间差异对猪胴体预冷损耗存在显著影响（P＜0.05）,风速大的位置其胴体周围环境相对湿度高,温度低,胴体冷却损耗小;随着预冷时间的延长,猪胴体损耗逐渐增大,且预冷时间对冷却损耗也有显著影响（P＜0.05）。     

冷却方式和电刺激对牛肉品质的影响

肉的嫩度是肉最重要的食用品质,它决定了肉的商品属性。动物宰前、宰后24h内的技术处理决定了肉的嫩度。本文主要综述了对牛屠宰后的处理方式如冷却方式、电刺激处理等对牛肉嫩度的影响。     

Effects of Certain Electrical Stimulation Parameters on Quality and Palatability of Beef

Grain-finished steers and heifers (n=390) were slaughtered in a commercial plant and assigned to one of five groups: (a) electrical stimulation (ES) immediately after exsanguination, (b) ES immediately before evisceration, (c) ES immediately after evisceration, (d) ES immediately after splitting, and (e) untreated (not ES). ES consisted of either 150 or 550 volts for either 1 or 2 mm. Electrically stimulated carcasses had more youthful, brighter colored lean and less “heat-ring” than untreated (not ES) carcasses. Steaks from electrically stimulated carcasses had (P<0.05) lower shear force values, were more tender, had less panel-detectable connective tissue and higher overall palatability ratings than did steaks from untreated (not ES) carcasses. Steaks from carcasses receiving 550-volt ES usually had more youthful, brighter colored lean and lower shear force values, were more tender, had less panel-detectable connective tissue and higher overall palatability ratings than steaks from carcasses that received 150-volt electrical stimulation. Quality and palatability traits of carcasses electrically stimulated for 1 mm were not different from those of carcasses receiving 2 mm of electrical stimulation. Electrical stimulation at different stages in the slaughter-dressing sequence did not evoke differential responses in quality or palatability factors.     

Effects of Electrical Stimulation, Hot Boning and Chilling on Bull Semimembranosus Muscle

Taste panel, Warner-Bratzler shear force (WBS) and cooking loss characteristics of semimembranosus (SM) muscles from thirty electrically stimulated and hot-boned (ESHB) or control young bull sides were evaluated. At 2 hr postmortem, muscles were excised from electrically stimulated sides and chilled in a tray or in a cardboard box. All control sides and ESHB muscles were chilled at 5–7°C until 24 hr postmortem; then 2–4°C for 24 hr. At 48 hr postmortem, steaks were cut, vacuum packaged and aged (2–4°C) for 4 days. Beef flavor was more intense for control steaks than for steaks from either ESHB chilling treatment. No other differences were noted.     

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.     

电刺激对牛肉成熟和牛肉超微结构的影响

对宰后牛胴体进行电刺激 ,跟踪检测牛肉在不同成熟时间的 p H值、剪切力值和超微结构的变化。试验结果表明 ,电刺激可加速牛肉成熟速度 ,提高牛肉嫩度 ,促使肌原纤维小片化 ,减少牛肉在预冷过程中发生的寒冷收缩     

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.     

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.     

Physical and Compositional Characteristics of Beef Carcasses Selected for Leanness

Ten muscles and muscle groups were excised from each of eight typical (average yield grade 2.99) and eight lean (average yield grade 1.73) steer carcasses and analyzed to determine differences between carcass types. Lean carcasses (raw basis) were higher (P<0.05) in moisture and protein and lower (P<0.05) in fat, cholesterol and calories in comparison to typical carcasses. Typical carcasses (cooked basis) were higher (P<0.05) in fat and caloric content than lean carcasses. No differences (P>0.05) were found between carcass types (cooked basis) for moisture, protein, cholesterol, dry matter cholesterol, cooking loss or shear force value. Semitendinosus muscles from typical carcasses were rated higher (P<0.05) for juiciness and tenderness than from lean carcasses. Differences (P<0.05) were found among muscles for all traits measured.     

Effect of Carcass Chilling on the Palatability Traits and Safety of Fresh Red Meat

Chilling procedures have been widely used in livestock abattoirs since the development of refrigeration systems. The major criteria when applying chilling regimes is not only complying with regulations, but economic concerns, and also meat safety and quality assurance requirements. Given recent developments, an updated review is required to guide the industry to choose the best chilling method and to inspire the development of new approaches to chilling. Thus in this paper, the quality and microbial safety of beef, lamb, pork, venison, and bison resulting from different chilling treatments has been reviewed, as well as the underlying mechanism(s) for the different impacts on meat quality traits as a result of different chilling regimes. The effect of fast chilling on the tenderness of beef and lamb is a focus, as some new findings, have recently been reported, while multistep chilling is highlighted as it incorporates the advantages of fast chilling to reduce carcass weight loss, resulting in similar quality improvements as found with slow chilling. It is, suggested, that if spray chilling can be combined with the second phase of multi‐step chilling, it will benefit the meat industry in terms of both meat quality and safety. Future studies should focus on combinations of chilling methods with new technologies, such as medium voltage electrical stimulation, muscle stretching, or ultrasound and so on, to move meat quality and safety to a new level.     

Characteristics of Beef Batters as Influenced by Electrical Stimulation and Postmortem Salting Time

Changes were evaluated in functional and textural properties of beef batters altered by mincing, postmortem salting time and electrical stimulation. Histological examinations showed raw batters from non-stimulated (NS) meat exhibited uniform fat dispersal throughout the protein matrix regardless of salting time; however, fat channeling, increased fat and gel-water release, lower hardness and gel strength along with reduced apparent viscosity were observed in electrically stimulated (ES) meat when salting was delayed. Changes in amounts of salt-soluble protein were not consistent. Effects of pH on water-holding capacity and myofibrillar swelling accounted for most changes observed in batters from ES muscles. However, increases in apparent viscosity and hardness may have been a consequence of rigor onset.