Effects of muscle shortening and proteolysis on Warner–Bratzler shear force in beef longissimus and semitendinosus

Evaluation of the water state and protein characteristics of Tibetan pork under the storage conditions of modified atmosphere packaging: Effect of oxygen concentration

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P 3 in the two-dimensional relaxation spectra, shorter T 1 and T 2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork.

Optimal conditions for beef tenderization through radiofrequency heating with cold air

High-temperature (15-37°C) aging can shorten the tenderizing time of beef; however, the use of constant temperature heating can lead to microbial spoilage. This study tested radiofrequency (RF) tenderization (RF-T) to find the appropriate conditions for the aging-like effect of beef without microbial spoilage. After subjecting beef to 22 h RF-T with four different cooling temperatures (15, 5, -10, and -20°C), the proliferated aerobic bacteria on the surface showed a concentration of 6-6.2 log CFU/g at -10 and -20°C, lower than 7-7.5 log CFU/g at 15 and 5°C. When beef was treated with 25 W/kg RF heating power for 48 h RF-T, the estimated reduction rate of the sliced shear force (SSF) and the increase rate of glutamic acid based on the weight before RF-T were 22.6% and 1.51-fold, which were greater than 19.6% and 1.37-fold with 20 W/kg, and 11.0% and 1.11-fold with 15 W/kg. The optimal specific RF heating power was calculated as 30 W/kg from the results' extrapolation. When processed for 48 h under optimal conditions (30 W/kg specific RF heating power, -20°C cooling air), the tenderization rate and the increased rates of free amino acids based on the weight before RF-T of beef reached over 20% and 1.5-fold with 5.22 log CFU/g aerobic bacteria, which was lesser than the Korean regulation value of 6.7 log CFU/g (5 × 106  CFU/g). Therefore, RF-T could be proposed as a promising high-temperature tenderization method with lowered risk of microbial spoilage. PRACTICAL APPLICATION: We showed that lowering the chamber temperature during RF-T was effective in surface drying and inhibiting aerobic bacteria. RF-T for 24-48 h with 30 W/kg specific RF heating power had an aging-like effect given tenderization and increase in FAAs. Moreover, by providing the matching circuit and impedance during RF-T, this method could be industrially reproducible.

Relationship between pre-rigor temperature of pork longissimus muscle, myofibril-bound calpain activity and protein degradation

The effect of pre-rigor temperature incubation on the activity and distribution in sarcoplasmic and myofibrillar fractions of calpains, and meat quality attributes was investigated. Porcine longissimus thoracis muscles were incubated pre-rigor at 14, 22, 30 and 38 °C to 6 h postmortem, followed by another 2 h incubation at 14 °C. Thereafter, muscles were stored at 2 °C for 1 or 4 days. With higher pre-rigor temperature, sarcoplasmic Ca²⁺ concentration, purge loss and myofibril-bound calpain-1 content increased, while shear force declined. Water-holding capacity of isolated myofibrils was lower after pre-rigor incubation at 38 °C. Desmin and troponin T degradation, and myofibril fragmentation was greater upon incubation of isolated myofibrils with added Ca²⁺ in the order 800 μM Ca²⁺ > 40 μM Ca²⁺ > no Ca²⁺, suggesting that calpain-1 and calpain-2 were associated to myofibrils and proteolytically active with sufficient Ca²⁺. Activity of myofibril-bound calpain-1 in muscle incubated pre-rigor at 22 and 30 °C were higher than when incubated at 14 and 38 °C. These results indicate that calpains translocate from the sarcoplasm onto myofibrils with higher pre-rigor temperature to 30 °C and the proteolytic potential of myofibril-associated calpains is thereby increased.

Effects of alternating electric field during freezing and thawing on beef quality

Alternating electric field (AEF) technology was used during freezing-thawing-aging (FA) of beef aged for 0, 1, 3, 5 and 7 days. Color, lipid oxidation, purge loss, cooking loss, tenderness, and T₂ relaxation time were determined for frozen-thawed-aged beef with AEF (AEF + FA) or without AEF (FA) and compared to aged only (OA) controls. FA increased purge loss, cooking loss, shear force values and lipid oxidation (P < 0.05) but decreased a* values compared with AEF + FA treatment. It also exacerbated the spaces between muscle fibers and contributed to the transformation of immobile water to free water. AEF served to maintain meat quality by reducing purge loss, cooking loss and increasing meat tenderness and maintaining color and lipid oxidation only in steak that was frozen before aging. This most likely occurred due to AEF increasing the speed of freezing and thawing and by reducing the space between muscle fibers compared to FA alone.

The Effect of Kosher Determinants of Beef on Its Color, Texture Profile and Sensory Evaluation

Traditional ritual slaughter is an underlying practice in religious Jewish communities and it translates into eating in accordance with core beliefs. This paper aims to comprehensively analyze factors determining the kosher status of beef (sex, slaughter method, and muscle type) and assess their impact on selected quality properties, such as color or texture profile. Sensory evaluation was also performed. The muscles were obtained from 80 carcasses (50% of heifers and 50% of young bulls). The experimental results indicate that each studied kosherness determinant influenced beef quality properties. The process of koshering caused the darkening of beef and lowered the share of color parameters red (a*) and yellow (b*). The influence of the type of slaughter on the values of adhesiveness, gumminess, and chewiness of beef was confirmed; higher values were mostly obtained in the muscles of cattle from kosher slaughter. As to sensory evaluation, the study showed that in the case of muscle type, the sex and slaughter method positively influenced only some of the properties.

The Influence of Vacuum Packaging of Hot-Boned Lamb at Early Postmortem Time on Meat Quality during Postmortem Chilled Storage

To evaluate the effects of early postmortem vacuum packaging (VP) on meat quality during postmortem chilled storage, hot-boned lamb was vacuum-packaged at 1, 6, 12, 24, and 48 h postmortem and stored around 2°C until 168 h postmortem, with lamb packaged in plastic wrap as the control (aerobic packaging). Intramuscular pH decline was delayed when lamb was vacuum packaged at 1, 6, and 12 h postmortem (p<0.05). The lamb vacuum-packaged at 1 h postmortem (VP-1h group) had significantly lower shear force values and purge losses accompanied by lower free thiol group values than other treatments during postmortem storage and was also higher in extractable calpain-1 activity by 6 h postmortem (p<0.05). Free thiol group concentrations were significantly higher after VP at 6 and 12 h postmortem (p<0.05). Packaging lamb under vacuum very early postmortem produced the lowest shear force and purge loss, likely by slowing heat loss and muscle temperature decline, implying that lamb quality is improved by VP when applied very early postmortem. This was at the expense of protein oxidation, which was unrelated to other meat quality measurements, most likely because potential contracture during hot boning confounded its impact. Further research is required to understand the implications of the interaction between protein oxidation, VP, and hot boning on the acceptability of lamb.

Comparative Study on Pale, Soft and Exudative (PSE) and Red, Firm and Non-Exudative (RFN) Pork: Protein Changes during Aging and the Differential Protein Expression of the Myofibrillar Fraction at 1 h Postmortem

In this paper, the protein changes during aging and the differences in the myofibrillar protein fraction at 1 h postmortem of pale, soft and exudative (PSE), and red, firm and non-exudative (RFN) pork longissimus thoracis (LT) were comparatively studied. The PSE and RFN groups were screened out based on the differences in their pH and lightness (L*) at 1 h, and their purge loss at 24 h postmortem. Based on the measured MFI, desmin degradation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, PSE meat presented more significant changes in the myofibrillar protein fraction compared to RFN meat during postmortem aging. Through liquid chromatograph-mass spectrometer/mass spectrometer (LC-MS/MS) analysis, a total of 172 differential proteins were identified, among which 151 were up-regulated and 21 were down-regulated in the PSE group. The differential proteins were muscle contraction, motor proteins, microfilaments, microtubules, glycolysis, glycogen metabolism, energy metabolism, molecular chaperones, transport, and enzyme proteins. The AMP activated protein kinase (AMPK) signaling pathway, HIF-1 signaling pathway, calcium signaling pathway, and PI3K-Akt signaling pathway were identified as the significant pathways related to meat quality. This study suggested that the different changes of the myofibrillar protein fraction were involved in the biochemical metabolism in postmortem muscle, which may contribute to the molecular understanding of PSE meat formation.

Dietary enzyme addition on the growth performance and carcass characteristics of pigs fed diets containing avocado oil cake silage

Avocado oil cake (AOC) was mixed with dried grape pomace and sugarcane molasses and ensiled for 90 days. A total mixed ration containing 5% AOC silage was formulated and top dressed with Axtra® XB enzyme at 0, 2.5 and 5%. The experimental diets were fed to 24 (8 pigs/diet) Large White × Landrace (LW × LR) cross pigs (± 22-kg live weight). Growth performance data was recorded for 60 days, after which the pigs were adapted to chromic oxide mixed diet for 3 days, whereby faeces were collected for 5 days after to determine nutrient digestion. Following nutrient digestion, pigs were fasted for 12 h, weighed and slaughtered. Carcass samples were collected and analysed for meat quality. Dietary addition of enzyme increased (P < 0.05) dry matter intake and nutrient digestibility, but did not affected (P > 0.05) feed conversion ratio and average daily gain. Carcass characteristics were not affected (P > 0.05); however, small and large intestine weight and length were increased (P < 0.05) with enzyme inclusion in feed. Dietary treatments did not affect (P > 0.05) the colour and cooking quality of the meat. Enzyme addition was worth in the growth performance and nutrient digestion but did not affect the carcass characteristics and meat quality of pigs.

Inhibition of mitochondrial calcium uniporter enhances postmortem proteolysis and tenderness in beef cattle

The purpose of this study was to examine the role of mitochondria in postmortem calcium homeostasis and its effect on proteolysis and tenderness. We hypothesized that mitochondria buffer cytosolic calcium levels and delay the activation of calpain-1 and subsequently the development of meat tenderness. To test this hypothesis, pre-rigor bovine longissimus thoracis et lumborum muscle samples were injected with DS16570511 to inhibit mitochondrial calcium uptake. Free calcium, tenderness, texture profile analysis (TPA), calpain-1 activity, and proteolysis were evaluated over a 336 h aging period. Inhibition of mitochondrial calcium uptake increased (P < .0001) cytosolic calcium concentration and calpain-1 autolysis and activity at 24 h compared to control steaks. Further, tenderness and TPA at 168 and 336 h, calpastatin degradation at 24 h, and proteolysis at 168 h were all enhanced (P < .05) in the treated steaks. Collectively, these data indicate that inhibition of mitochondrial calcium uptake can enhance postmortem proteolysis and tenderization through an early activation of calpain-1.

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.

Effects of Traditional Sauce Type and Storage Time on Quality Characteristics, Shelf-life and Flavor Compounds of Marinated Pork Cooked by Sous Vide Method

The present study aimed at evaluating effects of traditional sauce type and storage time on shelf-life and flavor compounds of marinated pork cooked by Sous-Vide method. Five different traditional sauces (Meju soy sauce, Brewed soy sauce, Fish-soy sauce, Ishiru fish sauce and Anchovy fish sauce) purchased from Asian countries were used. After marination with the sauces, polyvinylchloride film bags containing the marinated pork samples were cooked using Sous-Vide method for 55°C for 5 h and 60°C for 30 min, and were then stored for 8 wk at 10°C. Results showed that the pork samples marinated with the sauces retarded the growth of total plate counts (TPC) during storage. At 8^th wk storage, TPC counts were significantly lower in all samples marinated with the sauces compared to control (p<0.05). Lipid oxidation level was significantly lower in the T2 (Meju soy sauce) and T6 (Anchovy fish sauce) compared to those of T3 (Brewed soy sauce) and T5 (Ishiru fish sauce) or control after 8 wk storage (p>0.05). Forty volatile flavor compounds were detected from the control and marinated samples at 4^th wk of storage. The pork marinated with Anchovy fish sauce presented significantly higher amounts of importantly pleasant flavor compounds such as; pyrazines and sulfur-containing compounds than those marinated with other remaining sauces and control. It is concluded that the marination with Anchovy fish sauce partly improved the shelf-life and increased amounts of pleasant flavor compounds of Sous-Vide cooked pork products during storage in comparison to the other remaining sauces.

Effects of electrical stimulation and pre-rigor conditioning temperature on aging potential of hot-boned beef M. longissimus lumborum

The objective of this study was to create various pH/temp decline rates in hot-boned bull beef M. longissimus lumborum (LL) through a combination of electrical stimulation (ES) and pre-rigor holding temperature. The relationship between the pre-rigor interventions, the activities of µ-calpain and small heat shock proteins (sHSP), and the impacts on meat product quality were determined. Paired LL loins from 13 bulls were hot-boned within 40 min of slaughter, immediately ES and subjected to various holding temperatures (5, 15, 25, and 35°C) for 3 hr. The rate of muscle pH decline, sarcomere length, shear force, and proteolysis of muscle proteins were measured. ES-25°C had a longer sarcomere length compared to non-electrical stimulation samples. ES-25°C and ES-35°C samples had lower shear force values, higher µ-calpain activity and higher desmin, troponin-T, and sHSP degradation. The above findings suggest that pH/temp decline rates created in hot-boned muscle impacted muscle protein proteolysis by increasing the activity of proteases and degradation of sHSP.

The effect of encapsulated active principles (eugenol, thymol and vanillin) and clove and rosemary essential oils on the structure, collagen content, chemical composition and fatty acid profile of Nellore heifers muscle

The objective of the present experiment was to evaluate the effects of encapsuled active principles (eugenol, thymol and vanillin blend), and clove and rosemary essential oils inclusion into the finishing diets of Nellore heifers on chemical composition, collagen content, fatty acid profile and structural traits (fibers types, type I and III collagen and sarcomere length) of longissimus muscle. Treatments had no effect (P > .05) on type of fiber, the meat chemical composition or in the muscle fatty acid profile. However, the diet with clove and rosemary essential oil and the active principle blend led to an increase in sarcomere length, higher soluble collagen content and a lower amount of type III collagen (P < .05). The mixture of both active principles and essential oils clove and cinnamon essential oil, have a potential use in animal feed, favoring a greater sarcomere length, that is directly related to the increase of the meat tenderness, without altering the meat chemical composition or fatty acid profile.

Performance, carcass and meat quality traits of grazing cattle with different exit velocity

To evaluate the effect of grazing cattle temperament on performance, as well as carcass and meat quality traits, exit velocity (EV) was assessed throughout two production cycles (PC1, n = 38 and PC2, n = 52). Individual EV determinations were assessed throughout each PC and then 100-days period averages were calculated for each animal. Animals were ranked based on their EV (EV-RANK) in the first 100-days period as SLOW, FAST and MEDIUM. The EV decreased from weaning to slaughter in FAST and MEDIUM (P &lt; 0.05); but did not change in SLOW (P &gt; 0.10). Initial liveweight was lowest in FAST and highest in MEDIUM (P = 0.03). DM intake (P = 0.08) and average daily gain (P = 0.94) were not affected by EV-RANK, but carcass subcutaneous fat thickness was lowest in FAST and highest in MEDIUM (P = 0.02). Longissimus muscle colour and shear-force were not affected by EV-RANK (P &gt; 0.05), but muscle glycogen content at slaughter was higher in MEDIUM than in SLOW or FAST (P = 0.047). No EV-RANK effects were observed in the present study on meat colour and shear-force. However, its effects on subcutaneous fat thickness and muscle glycogen could result in low meat quality of temperamental cattle under more stressful handling situations.

Mechanical texture profile of Hanwoo muscles as a function of heating temperatures

Background

Cooking temperature and consequently doneness of beef muscles are most important for the palatability and consumer acceptability. Current study assessed the response of mechanical texture of Hanwoo muscles as a function of cooking temperature at different ageing days. Six muscles (Psoas major (PM), Longissimus thoracics (LT), Gluteus medius (GM), Semimembranosus (SM), Biceps femoris (BF) and Triceps brachii (TB)) were collected from each 10 Hanwoo steers. Warner-Bratzler WB-shear force (WBSF) and texture profile analysis (TPA) texture profiles were determined after 3 or 21 days of chiller, and randomly assigned to four groups; non-cooked, cooked at 55, 70 or 85 °C.

Results

Toughness of WBSF and TPA hardness of Hanwoo muscles were presence in the order of LT = PM = GM = SM < BF = TB (p < 0.001) for non-cooked raw muscle, and PM < LT = GM = SM < TB=BF (p < 0.001) for cooked meat aged for 3 days. WBSF linearly increased in 3 days aged meats after cooked at a higher temperature (P < 0.05). On the other hand, toughening of the muscles were significantly (P < 0.05) differed at various temperature when muscles were aged for 21 days. WBSF of PM and LT muscles were significantly increased at a higher cooking temperature, while other muscles (i.e., GM, SM, BF, TB) showed the lowest values at 70 °C. In the case of TPA hardness, the effect of cooking temperature was very less in the toughness of the muscle (P > 0.05).

Conclusion

Taken together, these findings clearly showed that the toughness of the muscle highly depends and varies upon the temperature and ageing of the muscle. Moreover, the effect of cooking temperature was very limited on aged muscles. The results mirror the importance of cooking temperature for objective measurements which ultimately estimate sensory tenderness and other quality traits.

Effect of High-pressure Processing on the Quality Characteristics and Shelf-life Stability of Hanwoo Beef Marinated with Various Sauces

The effects of high-pressure processing (HPP) treatment on the quality characteristics of low graded Hanwoo beef marinated with five different sauces (soy, fish, fish-soy, soy-fish and fish-soy-meat sauces) obtained from Asian countries were studied. The Hanwoo beef striploins were marinated with the aforementioned sauces (at ratio: 3:1 w/w) for 3 days at 4℃ before they were treated with HPP at 550 MPa for 5 min at 10℃. All the sauces used were equalized to a same salt level of 12.5%, and the samples marinated with a 12.5% brine solution were served as a control. After treating with the HPP, all the samples were stored for further 7 days at 4℃ for analyses. Results revealed that HPP treatments showed some effects on technological quality traits (pH, cooking loss and color) but had no effect on the collagen contents of the marinated beef. Noticeably, the HPP treatment led to the increases in amounts of free amino acids associated with monosodium glutamate–like taste and sweet taste in the samples marinated with fish sauce or soy-fish sauce, fish-soy sauce and fish-soy-meat sauce whereas, it only reduced these amino acids in the samples marinated with soy sauce or control. Furthermore, the total bacteria count in all the marinated beef samples treated with HPP were significantly (p<0.05) lower than those of the non-HPP-treated samples throughout the storage periods. It is concluded that HPP could be applied for enhancing the taste-active compounds production such as free amino acids, and improving the shelf-life stability of the marinated beef.

Modelling postmortem evolution of pH in beef M. biceps femoris under two different cooling regimes

A model based on enzyme kinetics was developed to predict differences in postmortem pH change in beef muscles as affected by cooling rate. For the calibration and validation of the model, pH and temperature measurements were conducted at different positions in M. biceps femoris following conventional carcass cooling or faster cooling of the muscle after hot boning. The glycogen conversion, and, hence, the pH fall, was observed to significantly vary with position and cooling regime but only during the initial hours of cooling. Comparison of the cooling regimes indicated that fast cooling following hot boning avoids heat shortening induced by the combined effect of high temperature and low pH.

Phosphorylation inhibits the activity of μ-calpain at different incubation temperatures and Ca2+ concentrations in vitro

This study aimed to investigate the effects of phosphorylation on the activity of μ-calpain and its sensitivity to temperature and Ca²⁺. For temperature sensitivity analysis, sarcoplasmic protein was treated with alkaline phosphatase (AP) and phosphatase inhibitor (PI) at 4, 25 and 37°C. The results showed that the degradation degree of μ-calpain in the AP group was significantly higher after incubation for 12h. For calcium sensitivity analysis, samples treated with AP and PI were incubated at 0.01, 0.05, 0.1 and 1mM Ca²⁺. The results showed that the degradation rate of μ-calpain was maximum in the AP group and minimum in the PI group at 0.01, 0.05 and 0.1mM Ca²⁺. The differences between the three groups reduced as concentration increased. These data demonstrate that phosphorylation plays a negative role in regulating μ-calpain activity. This study clarifies the regulatory mechanism of μ-calpain activation in vitro and/or in postmortem muscle.

Effect of marbling and chilled ageing on meat-quality traits, volatile compounds and sensory characteristics of beef longissimus dorsi muscle

Effects of marbling and chilled ageing on technological quality traits, volatile compounds and sensory characteristics of Hanwoo beef were investigated. Three marbling groups of longissimus dorsi muscles (n = 10 each), namely, high marbling (HM), moderate marbling (MM) and slight marbling (SM), classified according to the Korean carcass-grading system, were used. Each longissimus dorsi muscle from each marbling group was divided into two equal portions, vaccum-packaged and then assigned to 1- and 7-day ageing groups. The ageing was conducted in a chilling room at 4°C. Marbling level was significantly correlated with intramuscular fat content, shear force, cooking loss, tenderness and flavour. Particularly, the HM group had a lower shear force value, and higher fat content, lightness, tenderness, flavour and overall-liking scores than did MM and SM groups. Ageing significantly reduced the shear force value and increased tenderness, flavour and overall-liking scores for the HM group. Twenty-four volatile compounds were significantly influenced by marbling and/or ageing. The SM group had the highest concentration of benzaldehyde, while HM group had the highest concentrations of octanal, nonanal and dimethyl sulfide. In conclusion, our results demonstrated that a high marbling positively affected some technological quality traits and eating quality of beef, and ageing for 7 days reduced the shear force and improved eating quality of samples in the HM group, suggesting that the highly marbled beef responds to the ageing at a faster rate.

The Differences in Chemical Composition, Physical Quality Traits and Nutritional Values of Horse Meat as Affected by Various Retail Cut Types

The effects of retail cut type on chemical, quality and nutritional characteristics of horse meat were studied. Jeju female breed horses (n = 9) at 32-mo-old were slaughtered and the carcasses at 24 h post-mortem were fabricated into 10 retail cuts including: tender-loin, loin, strip-loin, shoulder-chuck-roll, shoulder-clod, top-round, outside-round, brisket, short-plate-brisket, and shank. The results revealed that all of parameters (chemical, meat quality and nutritional composition) examined significantly (p<0.05) differed between the cuts. The chemical composition range (minimum to maximum) of cuts was found as such: moisture 65.06% to 71.69%; protein 19.07% to 21.28%; collagen 1.40% to 2.45%; fat 2.56% to 12.14% and cholesterol 55.76 to 79.50 mg/100 g. Shoulder-chuck-roll had the highest pH and water-holding capacity, while top-round had the highest cooking loss. Shear force ranged between the cuts from 2.80 kg/cm(2) to 4.98 kg/cm(2). The Cu, Fe, and Zn contents ranged between the cuts from 1.52 mg/kg to 2.75 mg/kg, 21.25 mg/kg to 30.85 mg/kg, and 16.51 mg/kg to 40.42 mg/kg, respectively. Additionally, most of the cuts studied showed favorable polyunsaturated fatty acid/saturated fatty acid, n-3/n-6 and essential amino acid/non-essential amino acid ratios.

Effect of cut type and post-mortem ageing on the technological quality, textural profile and sensory characteristics of horse meat

The present study was conducted to investigate the effects of cut type and ageing period on the technological quality, colour, texture and sensory characteristics of horse meat. Nine different cuts: loin, shoulder chuck roll, shank, outside round, tenderloin, shoulder clod, brisket, top round and striploin from 28-month-old female horses were used in the present investigation. The cuts were randomly assigned into 2, 10, 20 and 30 days’ ageing groups and ageing was carried out in a chilling room (2 ± 2°C). The results showed that there were significant (P < 0.05) differences among the cuts for the drip loss, pH and cooking loss at all ageing days; particularly, striploin had the lowest pH and highest drip loss whereas shoulder chuck roll had the highest pH value. Ageing significantly (P < 0.05) increased in pH and drip loss in most cuts with the highest drip loss ~5.17% in striploin and the highest cooking loss ~9.27% in shoulder chuck roll after 30 days of ageing. At Day 2 of ageing, no differences in Warner–Bratzler shear force values occurred between the cuts (P > 0.05). Ageing only decreased Warner–Bratzler shear force in the loin and outside round (P < 0.05). Colour parameters also revealed differences between cuts and ageing periods, particularly the L* (lightness) values ranged between the cuts from 34.38 to 37.14, 34.0 to 37.24, 33.24 to 37.07, and 34.7 to 38.92 at Days 2, 10, 20 and 30 of ageing, respectively; similarly the a* (redness) values ranged between the cuts from 16.76 to 17.81, 16.61 to 17.85, 17.46 to 19.46, and 17.72 to 20.47 at Days 2, 10, 20 and 30 of ageing, respectively. For the compression, the lowest hardness values (4.41–5.73 kg) were found in tenderloin at all ageing days. Furthermore, the scores for tenderness, flavour, juiciness and acceptability were different (P < 0.05) among the cuts at all ageing days. Ageing improved flavour of loin, shank and striploin, and juiciness of tenderloin and striploin whereas it decreased the juiciness and acceptability scores of some cuts (e.g. shoulder chuck roll). Thus, the present data provide not only useful information for horse meat producers but also important databases for further investigations.

Effect of Rapid Chilling on Beef Quality and Cytoskeletal Protein Degradation in M. longissimus of Chinese Yellow Crossbred Bulls

The objective of this study was to investigate the effect of rapid chilling (RC) on beef quality and the degradation of cytoskeletal proteins. Twenty Chinese Yellow crossbred bulls were selected and randomly divided into two groups. RC and conventional chilling (CC) were applied to left and right sides of the carcasses respectively after slaughtering. To determine whether electrical stimulation (ES) treatment can alleviate the potential hazard of RC on meat quality, ES was applied to one group. The effects of RC and ES were determined by meat color, shear force and cytoskeletal protein degradation postmortem (PM). The results showed that RC decreased beef tenderness at 1 d and 3 d postmortem, but had no detrimental effect on meat color. Western blotting showed that RC decreased the degradation rate of desmin and troponin-T, but the effects weakened gradually as postmortem aging extended. Degradation rates of both desmin and troponin-T were accelerated by ES. The combination of RC and ES could improve beef color, accelerate degradation rate of cytoskeletal protein and improve beef tenderness.

Pre-rigor carcass stretching counteracts the negative effects of high rigor temperature on tenderness and water-holding capacity – using lamb muscles as a model

High pre-rigor muscle temperature has negative consequences on quality and has been predominantly studied in the excised longissimus muscle of beef and lamb carcasses. There is little data on other muscles, the application in whole carcasses or potential amelioration techniques such as stretching. This study evaluated the effects of electrical stimulation, high pre-rigor temperature and stretching of lamb sides on quality traits and protein denaturation in four leg muscles [gluteus medius (GM), rectus femoris (RF), semimembranosus (SM) and semitendinosus (ST)]. Twenty lamb carcasses were used with two electrical stimulation treatments (stimulated or non-stimulated, +/−) and two pre-rigor temperature treatments (chilled at 2°C directly after slaughter, or held in 37°C water for 4.5 h before transfer to a 2°C chiller) applied. One side of each carcass was suspended from the Achilles tendon, whereas the other side was stretched by allowing the leg to drop and tying it to the ribs. Electrical stimulation did not influence the different traits except for pH fall post slaughter and myosin denaturation. Stretching resulted in greater muscle and sarcomere lengths for the GM, SM and ST, but a decrease in sarcomere length for the RF. For the non-stretched GM and SM, the 37°C treatment resulted in tougher meat at 1 and 8 days post mortem compared with the 2°C treatment. In contrast, the stretched 37°C treatment resulted in more tender meat for the GM, SM and ST at 1 day post mortem compared with the 2°C treatment. For all muscles, the 37°C treatment resulted in a decrease in the water-holding capacity (increased purge, surface exudate and cooking losses). The magnitude of this effect was generally diminished by stretching for the GM, SM and ST, but for the RF, (which was not stretched by the treatment) this effect was reversed. The 37°C treatment resulted in paler meat (increased L*-values) for the GM, SM and ST relative to the 2°C treatment. The observed effects of the 37°C treatment on water-holding capacity and colour could be explained by the effects of this treatment on indicators of protein denaturation (sarcoplasmic protein solubility and myofibrillar ATPase activity), which were decreased for the GM, SM and ST. The response to both temperature and stretching varied between the muscles, due to different anatomical location and also due to postulated differences in the fibre types. In conclusion, pre-rigor stretching of lamb sides can counteract the negative effects of high early post-mortem temperature on tenderness and water-holding capacity for those muscles that are stretched as a result of this hanging method.

Impacts of hanging method and high pre-rigor temperature and duration on quality attributes of ovine muscles

This study evaluated effects of high pre-rigor temperature and duration and suspension of lamb sides on quality traits and protein denaturation in two muscles [semimembranosus (SM) and longissimus thoracis et lumborum (LTL)]. Twenty-four lamb carcasses, within each of 3 slaughter days, were used to assign eight carcasses to one of four pre-rigor temperature treatments: chilled at 2°C directly after slaughter, or held at 37°C in water for 1.5, 3.0 or 4.5 h before transfer to a 2°C chiller. At ~15 min post slaughter, one side of each carcass was suspended from the Achilles tendon, whereas the other side was suspended by the aitch bone and the leg tied down to the ribs. The sides subjected to aitch bone hanging had an increased sarcomere length in the SM, but decreased sarcomere length in the LTL. For the LTL, the time of exposure to high pre-rigor temperature had a significant effect on measures of protein denaturation and related meat quality traits such as purge and colour, although tenderness (shear force) after 2 days of aging was not affected. For the SM, the high temperature treatment also resulted in increase in measures of protein denaturation and thus negatively influenced meat quality traits such as purge, colour and shear force after aging. However, these effects on purge and shear force in the SM were significantly mitigated by the aitchbone hanging treatment. The results of the present experiment indicate that pre-rigor aitchbone hanging of muscles can counteract the negative effects of high pre-rigor temperature on both water loss and meat tenderness.

Influence of high pre-rigor temperature and fast pH fall on muscle proteins and meat quality: a review

The impacts of accelerated pH decline combined with high muscle temperature on post-mortem muscle metabolism and subsequent meat quality attributes have been extensively studied. Traditionally, this phenomenon has been observed in pork muscles, primarily due to the relatively fast post-mortem glycolysis rate and its relationships to stress susceptibility of pigs before slaughter. However, the protein-denaturing condition of high temperature/rapid pH fall and subsequent PSE (pale, soft and exudative)-like abnormal meat quality characteristics have been observed in muscles from other species such as beef, lamb, venison and even poultry. Various pre-rigor conditions including the application of electrical stimulation, hot-boning, and/or pre-rigor carcass chilling temperatures in various muscles, in conjunction with carcass stretching/hanging methods, can also contribute to muscle-protein denaturation pre-rigor. This review considers the influence of a faster than normal pH fall at a higher than normal pre-rigor temperature on glycolysis, post-mortem muscle proteins and subsequently meat quality attributes. Gaps in current knowledge are identified and recommendations made for additional research.

Techniques to reduce the temperature of beef muscle early in the post mortem period – a review

A review of the literature was conducted on the effects of high temperature and low pH (HTLP) on meat quality, with a focus on interventions that increase the rate of cooling post slaughter. HTLP can potentially change meat tenderness, water-holding capacity and colour due primarily to protein denaturation during the first 5 h post mortem. Deep muscles in large carcasses are susceptible to HTLP when cooled conventionally. Ante mortem and post mortem solutions that increase the rate of carcass cooling are discussed. Ante mortem solutions include access to feed and water, showering with water and provision of shade. Post mortem solutions included vascular flushing, hot fat trimming, opening seams, hot boning, spray chilling, blast chilling, immersion cooling, and very fast chilling. Accelerating rigor with electrical stimulation before HTLP remains controversial. Combinations of different techniques, that suit the specific requirements of a particular processing plant, is the likely best solution to HTLP, but further development of commercial solutions is suggested.

Minimal electrical stimulation is effective in low stressed and well fed cattle

Four groups of carcasses of eighty grain fed low stressed steers (~12 months old, 240 kg carcass weight) received no stimulation or had low voltage stimulation for 15, 45 and 90 s. M. longissimus was aged for 2 and 14 days at 2 °C. Shear force, sarcomere length, water holding capacity, purge, muscle fibre detachment, sarcomere breaks and colour shelf life over 7 days was measured. Both 45 s and 90 s stimulated samples completed rigor above 35 °C and 15s stimulated and non-stimulated samples below 35 °C. The greatest muscle fibre detachment occurred for 15s stimulated samples which were the most tender at all times with non-stimulated samples toughest at 2 days of ageing and all samples being tender at 14 days of ageing. The 45 and 90 s stimulated samples consistently exhibited a brighter red colour at 2 days of ageing with no differences in colour intensity for the samples aged 14 days.

Effect of ageing time on suckling lamb meat quality resulting from different carcass chilling regimes

The effect of ageing on suckling lamb carcasses subjected to three chilling treatments was studied: Conventional (2 °C for 24h), ultra-fast (-20 °C for 3.5h then 2 °C until 24h post mortem) and slow chilling (12 °C for 7h then 2 °C until 24h post mortem) treatments. Meat quality measurements were carried out in carcasses at 24h post mortem and also after 5 days of ageing. Carcass chilling losses were not affected by a chilling regime. Aged meat showed higher cooking losses than non-aged meat (p<0.05). Sarcomere length of ultra-fast t was shorter (p<0.05) than conventional and conventional was shorter than slow chilling treatment (p<0.05), at 24h and after 5 days of ageing. Conventional and ultra-fast chilling treatments resulted in higher shear force values at 24h post mortem (p<0.05) compared to slow treatment. All treatments improved sensory scores with ageing (p<0.05), but ultra-fast chilling treatment did not attain higher values as the other two treatments.

Study of the Warner-Bratzler shear force, sensory analysis and sarcomere length as indicators of the tenderness of sun-dried beef

Sun-dried beef is a frequently consumed and valued product in Brazil, however, there have been no scientific studies on its texture. To assess the tenderness of sun-dried beef, an instrumental analysis (Warner-Bratzler Shear Force; WBSF), a sensory analysis (Quantitative Descriptive Analysis; QDA) and the sarcomere length (SL) were used as indicators. Significant differences were observed among the sun-dried beef samples. Sample 3 (composed of sun-dried meat purchased at three fairs from Region 3 in the city of João Pessoa-PB) was considered the most tender by the assessors, with a score of 6.7, and its WBSF analysis revealed a maximum value of 2.70 kgf. Additionally, this sample exhibited the highest SL value (1.89 µm). Samples 1 and 2 (composed of sun-dried meat purchased at three fairs from Regions 1 and 2, respectively, in the city of João Pessoa) exhibited very similar tenderness values (WBSF and QDA) but differed in their SL values, which suggested that sample 2 was the least tender. In conclusion, these results demonstrate that the studied parameters are complementary and can be used as tenderness indicators for sun-dried beef. However, although the difference was beyond the detection limit of the assessors and the texturometer, the SL analysis appears to have been the most effective.