Postmortem Temperature Research Articles

Ascorbic acid, alpha-tocopherol, and oregano supplements reduce stress-induced deterioration of chicken meat quality

In order to ameliorate a negative effect of stress on meat quality characteristics, chickens were fed a diet supplemented with a combination of ascorbic acid (1,000 ppm) and alpha-tocopherol (200 ppm) or oregano (3%), which has a high content of antioxidants. Chickens were slaughtered by cervical dislocation in the stable (no stress) or after transport and electrical stunning at the slaughter plant (stress). Activities of antioxidative enzymes (catalase, superoxide dismutase, and glutathion peroxidase) in pectoralis major (PM), iliotibialis (IL), and liver were unaffected by supplementation. However, erythrocyte stability, which is a more complex model system for determining oxidative status, increased with ascorbic acid-alpha-tocopherol supplementation and tended to increase after oregano supplementation. In nonstressed birds, this improved antioxidative status was reflected in decreased TBA-reactive substances (TBARS) in PM and liver of ascorbic acid-alpha-tocopherol-supplemented chickens and likewise in liver from oregano-supplemented chickens compared to that of nonstressed control birds. However, postmortem temperature, pH, and water-holding capacity were not affected by supplementation. Drip loss from oregano-supplemented chickens showed increased protein oxidation in specific bands, but this did not relate to water-holding capacity or antioxidative status. When exposed to stress, the concentration of TBARS in the control animals increased in PM and IL. Ascorbic acid-alpha-tocopherol supplementation protected IL, and oregano supplementation protected PM from stress-induced increases in TBARS. This differential effect between muscles may indicate differences in protection mechanisms. In conclusion, ascorbic acid-alpha-tocopherol and oregano supplements to chickens protect against stress-induced increase in TBARS, in different muscles.

Maintaining muscles at a high post-mortem temperature induces PSE-like meat in turkey

The aim of the present study was to validate an experimental model which surely generates pale, soft, exudative (PSE) turkey meat. Immediately after exsanguination, Pectoralis major ( n=15) were kept at various temperatures (4, 20 or 40 °C) for 6 h. All the muscles were then stored at 4 °C for 9 days. They had the same rate of pH fall. L ∗ values were higher in the 40 °C treatment muscles than in the two other treatment muscles between 1 and 9 h. Drip loss of the 40 °C treatment muscles was higher than in the two other treatment muscles. However, thawing and cook loss were not significantly different between treatments. Cooked meat from the 40 °C treatment muscle was tougher than the two other treatment muscles. Napole yield was lower for these muscles. Myofibrillar protein extractability was lower in the 40 °C treatment muscle whatever the considered time. We showed that the 40 °C treatment muscles were similar to PSE muscles.

Combination of low voltage electrical stimulation and early postmortem temperature conditioning on degradation of myofibrillar proteins in Korean native cattle (Hanwoo)

The combination effect of low voltage electrical stimulation (LVES) and early postmortem (PM) temperature conditioning (2, 16, and 30°C until 3 h PM) on degradation of myofibrillar proteins were determined from Korean native cattle (Hanwoo). Myofibrils were removed at 1, 2, 3, 7, and 14 days of PM storage (2°C) and analyzed for titin, nebulin, desmin, and troponin-T by SDS-PAGE and by Western blot analysis. Degradation rate of myofibrillar proteins was affected by the combination of LVES and temperature conditioning. LVES-30°C treatment resulted in faster degradation of titin, nebulin, desmin, and troponin-T during PM storage than the other treatments. Degradation of titin took place more slowly than nebulin, desmin or troponin-T.

Transient Kinetics during the Isothermal Reduction of NO by CO on Rh(111) As Studied with Effusive Collimated Molecular Beams

The transient kinetics of the reaction between NO and CO on clean Rh(111) surfaces have been studied using molecular beams in conjunction with mass spectrometry detection. The changes in the partial pressures of the reactants (CO and NO) and products (N2 and CO2) as a function of time have been used as a measure of the evolution of the uptake and desorption rates, respectively, for temperatures between 350 and 1000 K and for NO:CO mixture ratios between 4:1 and 1:99. Post-mortem temperature programmed desorption (TPD) and CO titration experiments were also performed in order to estimate the surface coverages of atomic nitrogen and oxygen left on the Rh(111) surface by the gas mixture. Systematic variations were observed during the transition from the clean surface to the steady-state catalytic regime that correlate well with the overall reaction rates in the latter. Specifically, there is a time delay in the production of molecular nitrogen because of the need to build up a threshold atomic nitrogen cover...

Muscle metabolism and PSE pork

Pale, soft, and exudative (PSE) pork is primarily caused by an accelerated rate of postmortem glycolysis resulting in low muscle pH while carcass temperature remains high, thus causing protein denaturation. Numerous factors influence the rate of postmortem metabolism and may be responsible for the rapid pH decline characteristic of PSE pork during the 1st h postmortem. Release of high levels of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm triggers an accelerated rate of postmortem glycolysis and is responsible for the high incidence of PSE observed in halothane pigs. Because total muscle ATPase activity is closely associated with rate of glycolysis, differences in myosin ATPase activity may explain in part the accelerated glycolysis in PSE development. Although important in determining the overall rate of glycolysis, differences in glycolytic enzyme activities have failed to explain discrepancies in postmortem metabolism between PSE and normal muscle. Elevated muscle glycogen content and an extended duration of postmortem glycolysis can also result in PSE-like characteristics, as seen in RN – pigs. Shifts in muscle fiber type toward higher proportions of glycolytic fibers may help explain the incidence of PSE. Inherent differences in mATPase activity, Ca 2+ regulation, glycolytic enzyme profiles, and glycogen content between muscle fiber types integrate various mechanisms responsible for the abnormal postmortem glycolysis in PSE muscle. In an effort to delineate potential mechanisms responsible for PSE, models to artificially induce PSE, such as retarding temperature decline and electrical stimulation, provide useful tools. The value and limitations of these models stem from their abilities to alter postmortem temperature and pH declines and to effectively simulate the protein denaturation typical of PSE pork.

Rigor mortis development at elevated temperatures induces pale exudative turkey meat characteristics

Development of rigor mortis at elevated post-mortem temperatures may contribute to turkey meat characteristics that are similar to those found in pale, soft, exudative pork. To evaluate this effect, 36 Nicholas tom turkeys were processed at 19 wk of age and placed in water at 40, 20, and 0 C immediately after evisceration. Pectoralis muscle samples were taken at 15 min, 30 min, 1 h, 2 h, and 4 h post-mortem and analyzed for R-value (an indirect measure of adenosine triphosphate), glycogen, pH, color, and sarcomere length. At 4 h, the remaining intact Pectoralis muscle was harvested, and aged on ice 23 h, and analyzed for drip loss, cook loss, shear values, and sarcomere length. By 15 min post-mortem, the 40 C treatment had higher R-values, which persisted through 4 h. By 1 h, the 40 C treatment pH and glycogen levels were lower than the 0 C treatment; however, they did not differ from those of the 20 C treatment. Increased L* values indicated that color became more pale by 2 h post-mortem in the 40 C treatment when compared to the 20 and 0 C treatments. Drip loss, cook loss, and shear value were increased whereas sarcomere lengths were decreased as a result of the 40 C treatment. These findings suggested that elevated post-mortem temperatures during processing resulted in acceleration of rigor mortis and biochemical changes in the muscle that produced pale, exudative meat characteristics in turkey.

Effects of post-mortem time before chilling and chilling temperatures on water-holding capacity and texture of turkey breast muscle

Two studies were conducted to determine 1) the effect of post-mortem time before chilling on hot boned prerigor breast muscle water-holding capacity (WHC), and 2) post-mortem temperature effect on sarcomere length and drip loss of uncooked breast, and shear force and WHC of turkey breast muscle that is hot-boned, marinated, and cooked. In Study 1, the turkey breast muscle was excised immediately after slaughter and chilled at 0 C. The effect of post-mortem time (15, 30, 45, 60, 90, and 120 min) before chilling on muscle pH, drip loss, and WHC (measured by homogenate cooking yield) was determined. In Study 2, hot boned prerigor breast slices were held at either 0 or 12 C and then at 3 h post-mortem stored at 2 C. Sarcomere length and drip loss of uncooked breast, and the shear force and WHC (measured by cooking yield) of cooked breast muscles with water, salt, and sodium tripolyphosphate were determined. Results indicated that pH on Day 1 post-mortem and cooking yield of water homogenates were not influenced by the post-mortem time before chilling. Drip losses increased as the post-mortem time before chilling was increased. Cooking yield of homogenate with water, salt, and sodium tripolyphosphate was decreased when breast muscle was chilled after 60 min post-mortem. Drip loss of breast was less at 0 C than at 12 C, but cooking yield and shear force were not affected by post-mortem chilling temperature. It was concluded that the post-mortem time before chilling has an influence on uncooked and cooked muscle WHC, but the differences found in uncooked muscle drip loss were not reflected in WHC or shear force of cooked muscle with water, salt, and sodium tripolyphosphate added.

Effects of postmortem temperature and time on the water-holding capacity of hot-boned turkey breast and thigh muscle

Turkey breast and thigh muscles were excised immediately after slaughter and held from 0.25 to 4 h postmortem at 0, 12 or 30 °C to determine postmortem time and temperature effect on muscle pH, drip loss, sarcomere length, homogenate supernatant weight, salt-soluble protein and cooking yields. Higher temperature and longer storage time induced greater drip losses in breast. Longer storage time induced greater drip losses but the least drip loss occurred at 12 °C in thigh muscle. High temperature increased the supernatant weight in breast but decreased that in thigh. Storage time increased supernatant weight and supernatant salt soluble protein levels in both muscles. Homogenate cooking yields of breast containing water, salt and phosphate (HWSP) were higher for 0 and 12 °C compared with 30 °C, and increased with storage. The low postmortem temperature (0 °C) decreased homogenate cooking yields in thigh. These findings indicate that lower postmortem temperatures (0 and 12 °C) and shorter storage time (24 h) produced the greatest water-holding capacity in turkey breast muscle, whereas high and low postmortem temperatures (30 and 0 °C) and longer storage (168 h) produced the least water-holding capacity in raw turkey thigh muscle.

Ostrich Slaughter and Fabrication: 1. Slaughter Yields of Carcasses and Effects of Electrical Stimulation on Post-Mortem pH

A commercial ostrich slaughter protocol was developed. Ostriches (n = 7 males and n = 7 females) averaged 95.54 kg live weight and yielded 55.91-kg carcasses. By-product yields were measured. The most significant by-products by weight were full viscera (8.29 kg), hide (6.71 kg), full gizzard and crop (5.80 kg), and abdominal fat (4.11 kg). Sex had no effect on slaughter yields. Post-mortem temperature declines were measured on five separate muscles and showed that chilling for 24 h was sufficient to adequately chill the deep muscle temperature to under 4 C. The effect of electrical stimulation on post-mortem pH decline also was investigated and had no effect.

The effect of high post-mortem temperature on the development of pale, soft and exudative pork: Interaction with ultimate pH

The effects of post-mortem temperature and ultimate pH (pH u, 24 h post mortem) on the development of the pale, soft and exudative (PSE) characteristics in pig longissimus dorsi muscle were studied. Ten out of the 13 pigs used received pre-slaughter injections of adrenaline in order to deplete muscle glycogen stores. The two muscles from each pig were held at 12 or 35°C during rigor mortis development. Results from covariance analysis, using pH u as covariate, showed that a high temperature (35°C) resulted in a dramatic increase in internal light scattering (FOP) 24 h post mortem and a significant decrease in water- and salt-soluble proteins. Cooking loss, sarcomere length and drip loss did not vary significantly with rigor temperature. Interaction between temperature and pH u was estimated by assessing the relationship between pH u and the difference between the two rigor temperatures for selected traits. The best predictive model was a segmented quadratic model with a plateau which gave significant results for FOP, drip loss, water- and salt-soluble proteins. The effect of temperature decreased curvilinearly when pH increased until a constant value above which no noticeable difference was recorded (drip loss, water- and salt-soluble proteins) or a constant difference was reached (FOP). The pH values corresponding to the convergence points differed from one trait to another. They ranged from 5·72 to 6·22. These results illustrate the importance of muscle glycogen content at slaughter and subsequent pH u with regard to the development of temperature-induced PSE meat.

A non-invasive method for postmortem temperature measurements using a microwave probe

The use of the Microwave Thermography System in Forensic Medicine for the estimation of the post-mortem interval is explained. The Microwave Thermography System, a new device which is applied to this field for the first time, is described and its mode of operation is discussed. The main advantage of using this device for estimating the time after death is its ability to measure internal body temperatures by a non-invasive method. Using this device, it is possible now to measure temperatures of internal organs of the body by placing the sensory elements on the skin. Reliability of the system and factors affecting the accuracy of post-mortem temperature measurements have been assessed and discussed.

The influence of high post-mortem temperature and differing ultimate pH on the course of rigor and ageing in pig Longissimus dorsi muscle

This study was performed in order to assess the effect of temperature and differing ultimate pH (pH u, 24 h post mortem) on the development of rigor mortis in pig Longissimus dorsi muscle. The rigor development (isometric tension and shortening) was measured continuously during the first 24 h post mortem, using an apparatus wherein muscle strips were held at constant temperatures of 12 or 35°C. pH u was manipulated by adrenaline injections preslaughter. The rates of pH fall, adenosine triphosphate (ATP) and creatine phosphate (CP) breakdown were markedly increased at 35°C compared to 12°C. For both temperatures, no delay phase was observed with regard to the development of shortening. Rigor resulted in higher maximum isometric tension and shortening and in shorter time needed to reach maximum values at 35°C than at 12°C. The results are discussed in connection with pH, ATP and CP data. The extent of ageing from 2 to 4 days post mortem, estimated through myofibrillar length determinations, was higher for 12°C than for 35°C. pH u affected significantly most of the traits under study, but its effect depended in some cases upon the rigor temperature. At 12°C, the traits related to the kinetics of rigor development were significantly affected by pH u, but this was not the case at 35°C. Maximum isometric tension was significantly related to pH u at 35°C ( r = 0·86, P < 0·001), but such a relationship was not found at 12°C. Myofibrillar lengths were significantly affected by pH u, but in an opposite manner from one temperature to another. A positive relationship was found at 12°C and a negative one at 35°C. These results illustrate the importance of the interaction between the extent of pH fall and temperature with regard to post-mortem changes in pig muscle.

POSTMORTEM SHORTENING OF LAMB LONGISSIMUS OXIDATIVE AND GLYCOLYTIC FIBERS

ABSTRACT Percentages of lamb M. longissimus thoracis et lumborum fiber types were approximately 66 oxidative and 34 nonoxidative, without significant differences among muscle regions. The effects of skeletal restraint and muscle region on sarcomere shortening during rigor development were found to be highly significant; sarcomeres of caudal‐ventral location were stretched by skeletal restraint while the rest were all shortened. In excised muscles, both fiber type and postmortem temperature exerted a highly significant effect on sarcomere shortening. Oxidative fibers showed a more intense shortening, already evident at temperatures well above those causing cold shortening. While shortening of glycolytic fibers was gradually more intense as treatment temperature decreased from 20 to 0°C, a maximum contraction of about 40% was reached at 15°C in oxidative fibers and lower temperatures did not cause any further shortening. Average fiber shortening was found to be highly correlated to meat toughening.

Tenderisation of lamb meat: Effect of rapid postmortem temperature drop on muscle conditioning and aging

Lamb Longissimus dorsi muscles were excised from carcasses of 9–12 kg and 16–20 kg weight and brought to internal temperatures of either 0°C, 4°C, 10°C, 15°C, 20°C or 36°C within 3–4h post mortem. After rigor completion they were allowed to age at 4°C for 7 days. Sensory panel scores obtained on the first day of post-rigor aging showed that meat from heavier animals was tougher than that of lighter ones at any temperature. In all cases aging for 7 days had a marked tenderising effect which was similar at all studied temperatures, and greater in heavier animals. Tenderness was also dependent on the temperature at conditioning, as shortening caused by either high or low temperature resulted in meat toughening. The sole and surprising exception to this fact was, however, the high sensory scores obtained in 0°C experiments, even though shortening occurred as expected. In fact, a more intense proteolysis was evident in this case, which was already apparent on the first day of aging. The effect of a rapid drop of muscle temperature to 0°C on the fast and intense proteolysis, capable of even overcoming toughness due to cold shortening, was explained by the higher pH and the dramatic increase of the sarcoplasmic Ca ++ level induced early post mortem by chilling and which might result in the activation of calpain.

Endurance-exercised growing sheep: II. Tenderness increase and change in meat quality

A study was conducted to examine the effect, in ram lambs, of chronic treadmill exercise, on meat quality. A secondary objective was to relate changes in tenderness to metabolic and chemical phonomena. Meat quality traits, including instrumental measurements of tenderness and thaw and drip losses, were recorded for two muscles from the hind limb ( semimembranosus SM; vastus lateralis, VL). Chemical analyses, including total and soluble collagen, total and myofibrillar protein, and myofibrillar fragmentation were also performed. Muscles from exercised sheep were significantly more tender than muscles from their control counterparts. A larger myofibrillar protein to total collagen ratio was observed in the VL muscles from exercised sheep ( P < 0·01) which probably contributed to the observed increase in tenderness. However, similar results were not observed for the SM muscle. The tendency for a slightly higher pH at similar post-mortem temperatures in meat from exercised sheep may also have contributed to the increased tenderness.

Postmortem interactions of muscle temperature, pH and extension on beef quality.

The effect of pH, temperature and structural damage of muscle early postmortem on the quality of beef, particularly tenderness, was examined in a randomized complete block design with a 2 x 2 x 2 factorial. Semitendinosus muscles were excised from the right sides of 64 Charolais crossbred steer carcasses, placed in a restraint device in a controlled environment and subjected to high (31 degrees C) or low (20 degrees C) temperature, high (control) or low (electrically stimulated) pH and restraint at excised length or restraint at 125% of excised length for 15 min early postmortem. Temperature, pH, shrink, drip loss, cooking loss, sarcomere length, fragmentation index, shear force, color reflectance and collagen and protein solubilities of the muscles were measured after 7 d of aging at 2 degree C. High-temperature aging increased fragmentation index and color reflectance and decreased protein solubility (P less than .05). Decreasing pH via electrical stimulation increased sarcomere length of the muscles aged at the high temperature only (P less than .05). Extension of muscles prior to aging lowered shear force values of the low-temperature muscles compared with the high-temperature muscles (6.12 vs 7.84 kg, SE .38). Stimulation of the muscles also decreased collagen solubility in the high-temperature, extended muscles. Although postmortem temperature and pH were the factors that influenced meat quality most, early postmortem extension should be considered as a modulating variable of meat tenderness.

Postmortem body temperatures in the minke whale, Balaenoptera acutorostrata

Postmortem temperature regimes were measured in 11 minke whales, Balaenoptera acutorostrata, at tissue depths varying from 1.5 (in the blubber) to 30 cm, at two different sites on the whales' sides, one in the flipper region (site A) and one in the dorsal fin region (site B). Body temperatures of instantaneously killed whales were assumed to represent those of living animals. Core body temperatures were 35.0 °C at site A and 35.6 °C at site B. Core body temperature and the size of the thermal core were affected by blubber thickness and the time between harpoon strike and death, but were not influenced by duration of pursuit prior to harpooning. Both intra- and inter-specific comparisons reveal that the thickness of the blubber layer is important for the maintenance of thermal gradients and, thereby, for heat conservation.

FACTORS RELATED TO LONGISSIMUS TENDERNESS AMONG ALTERNATE METHODS OF LEAN BEEF PRODUCTION

ABSTRACTA 23 factorial arrangement of treatments comparing bull versus steer, Angus versus Limousin, and zeranol implanted versus nonimplanted controls was used as a data source for this trial. Bulls had less intramuscular lipid and more total collagen than steers. Limousin had less intramuscular lipid, shorter sarcomere lengths and a higher percentage of fast‐twitch glycolytic fibers than Angus cattle. Limousin and implanted cattle had more rapid postmortem temperature declines. Chemical, physical and histological traits as well as yield and quality grade traits were used in correlation procedures to examine their relationship with sensory panel tenderness and Warner‐Bratzler shear force values of longissimus muscle steaks. The results of this trial indicate that postmortem muscle temperature decline plays a role in longissimus palatability and must be considered in the production of leaner beef.

Research Note: Effect of Postmortem Aging Temperature on Sarcomere Length and Tenderness of Broiler Pectoralis major

Forty male broilers (49 days of age) were hand processed and randomly placed into four postmortem aging temperature treatments: 41, 28, 14, and 0 ± 1 C, 10 carcasses/treatment. Sarcomere length (SL) measurements were made on left Pectoralis (P.) major muscle at 0, 1, 2, 3, and 4 h postmortem. At the end of 4 h, all carcasses (except 0 C temperature group) were chilled at 0 ± 1 C for 1 h. The right P. major muscles were removed, weighed, and frozen for cooking loss (CL) and tenderness (Kramer shear) measurements.There was a significant postmortem temperature (P<.05) and aging time (P<.001) effect for SL. Overall, sarcomere shortening was greatest at 0 C. The CL and shear values were 32.4, 29.6, 27.9, and 25.1% and 13.4, 12.9, 11.1, and 10.1 kg force/g for the 41, 28, 14, and 0 C treatments, respectively. Overall, 0 and 14 C treatments resulted in shorter SL, less CL, and lower shear values of P. major muscle than 28 and 41 C treatments.

The Effect of Three Temperature Conditioning Treatments and Subcutaneous Fat Removal on Lamb Quality

Thirty Suffolk and Suffolk crossbred ewe lambs w e r e blocked on live weight and randomly assigned to carcass conditioning treatments of 0, 16 and 23C for 8 h. Subcutaneous fat over the longissimus muscle and kidney fat were removed from the left side of each carcass during slaughter. The 23C conditioning treatment had significantly higher temperatures from 2 through 12 h compared with 0C and 16C treatments, and the 16C treatment had higher (P < .05) temperatures from 2 through 12 h compared with the 0~ treatment. There was an interaction between conditioning treatments and fat removal for postmortem temperature. The intact sides had significantly higher temperatures at 2 and 4 h for the 0C treatment, whereas trimmed sides had higher (P < .05) longissimus muscle temperatures than the intact sides at 6 h postmortem for both the 16 and 23C treatments. The conditioning treatments increased the pH decline; the 23C treatment had lower pH values at almost all time periods compared with the 0C treatment. The 16~ treatment had lower (P < .05) pH values at 6, 8 and 12 h postmortem than the 0~ treatment. The 16C treatment improved tenderness of the longissimus muscle, as indicated by lower shear force (3.45 kg) and higher sensory panel tenderness ratings (4.80) compared with the 0~ (4.74 kg and 3.82) and 23C (4.63 kg and 3.61) treatments. Fat removal had no significant effect on pH, sarcomere length, shear force or sensory panel ratings. The 16~ conditioning treatment improved lamb tenderness compared with 0 and 23C, whereas fat removal at slaughter had no significant effect on lamb quality. (