A comparison of technical replicate (cuts) effect on lamb Warner–Bratzler shear force measurement precision

Revealing the Mechanism of Protein Degradation in Postmortem Meat: The Role of Phosphorylation and Ubiquitination

The aim of this study was to investigate the possible effects of phosphorylation and ubiquitination on the degradation of myofibrillar proteins in mutton with different tenderness. The longissimus thoracis lumborum muscles were chosen and divided into tender and tough groups (n = 9), and then stored at 4 °C for 1 h, 12 h, 1 d, 3 d, and 5 d postmortem. Shear force, pH, myofibril fragmentation index, AMPK activity, E3 ubiquitin ligase abundance, protein phosphorylation, and the ubiquitination levels of muscle samples were measured. The results demonstrated that the meat of samples in the tender group had a higher degradation of desmin and a lower phosphorylation level of desmin at 1 d compared with the tough group. The ubiquitination level of desmin, AMPK activity, and E3 ubiquitin ligase abundance in the tender group were noticeably higher than those in the tough group at 12 h. There was a negative correlation between the shear force and desmin degradation. The desmin degradation was negatively correlated with desmin phosphorylation and ubiquitination levels. The phosphorylation level of desmin was positively correlated with its ubiquitination. In summary, this study suggests that AMPK and E3 ubiquitin ligase concurrently play significant roles in regulating meat tenderness by regulating phosphorylation and ubiquitination in meat postmortem.

Electrical stimulation and wet ageing effects on the carcass and meat quality of Australian rangeland goats

Medium voltage electrical stimulation and wet ageing periods effects on the carcasses and meat quality of Australian rangeland goats were investigated. 64 rangeland goats were slaughtered as 2 equal consignments, wherein half were exposed to post-dressing electrical stimulation (300 V, 500 ms pulse width, 45 s) and half were not (control). Carcass and pH decline parameters and glycogen concentration were recorded. At 24 h post-mortem, fresh colour was measured and longissimus lumborum muscles (LL) removed. Within carcass, paired LL were halved and allocated to each of 4 ageing periods (1, 2, 4, or 21 d). There were no significant effects from electric stimulation on LL pH at 18 °C, LL temperature at pH 6, LL pH at 24 h post-mortem, semitendinosus pH at 24 h post-mortem, and LL glycogen concentration. There were no significant interactions between stimulation and ageing period on cooking loss, particle size, purge loss, sarcomere length, shear force, and ultimate pH. Independent to stimulation, shear force, particle size, and cooking values declined as ageing period increased. Purge loss was highest after 21 d of ageing. Colour stability was unaffected by ageing, although all CIE colour coordinates varied across the 74 h total retail display period. There were negative linear relationships found between LL glycogen concentrations and LL temperature at pH 6, ultimate pH, and sarcomere length. These findings suggest there to be little benefit to post-dressing electrical stimulation of rangeland goat carcasses, when applied independent to or in combination with ageing.

The carcass characteristics and quality of meat from lambs grazing perennial wheat with different companion legumes (clover, serradella, lucerne) or a mineral supplement

This study compared carcasses as well as the quality and mineral concentration of meat from lambs extensively grazing perennial wheat with clover (PW + C), serradella (PW + S), lucerne (PW + L), or a mineral salt supplement (PW + Min). A split-plot design was used, wherein 3 crossbred ewe lambs (n = 72 in total) (sub-plots) grazed each of 4 forage types (plots), that were replicated across 6 locations (blocks). The feeding study concluded after 96 d, when all the lambs were slaughtered. The left longissimus lumborum muscles (LL) were collected and wet aged for either 5 or 56 d post-mortem. Lambs grazing PW + Min were found to produce carcasses with lower dressing percentage values to those grazing the other forage types (P = 0.037). The LL of lambs grazing PW + L had the lowest crude protein values (P = 0.015). Forage type by ageing period interactions did not affect meat quality. The 56 d ageing period resulted in higher purge loss (P < 0.001) and TVB-N values (P < 0.001) and a decline in shear force (P < 0.001) compared to the 5 d ageing period. The other carcass and meat quality parameters were not affected by forage type; including hot carcass weight, pH decline parameters, eye muscle area, cooking loss, intramuscular fat, sarcomere length, colour stability, and concentrations of calcium, iron, magnesium, sodium, and zinc in the LL. These findings confirm that perennial cereal production systems, that include legume forages with contrasting protein, energy, and micronutrient profiles, can deliver comparable lamb carcasses and meat quality.

The quality and nutritional value of beef from Angus steers fed different levels of humate (K Humate S100R)

This study compared the effect of four levels of K Humate S100R (potassium humate) supplementation on the quality, shelf-life, and nutritional properties of beef. Angus steers (n = 40) were individually housed and fed either 0, 35, 70, or 140 g K Humate S100R/animal/day for 100 days, following a 30 day adjustment period. The steers were slaughtered at the completion of the feeding study. The left m. longissimus lumborum (LL) was collected at 24 h post-mortem and aged for either 2 or 6 weeks before analysis. K Humate S100R supplementation did not affect beef drip loss, cooking loss, shear force, sarcomere length, ultimate pH, intramuscular fat content, or total volatile basic nitrogen concentrations (P > 0.05). Steers supplemented with 70 g/day K Humate S100R produced beef with higher a* values on Days 1 and 3 of retail display (P < 0.05). Beef mineral composition was unchanged by K Humate S100R supplementation (P > 0.05), but there were minor changes to the fatty acid profile. Specifically, the ratio of omega-6 to omega-3 (P < 0.05) and C20:2n-6 concentrations (P < 0.05) increased with supplementation level. Together, these results demonstrate no detrimental effects on beef quality and shelf-life as a result of K Humate S100R supplementation.

Canola meal as a supplement for grass-fed beef cattle: Effects on growth rates, carcase and meat quality, and consumer sensory evaluations

The current study examined the growth rates, carcase characteristics, meat quality, and consumer sensory evaluation of the longissimus lumborum muscle (striploin) from steers that were supplemented with either canola meal or grain-based pellets. Forty Angus and Hereford × Angus steers received one of these two supplements with ad libitum lucerne hay for 60 d prior to slaughter. Average daily weight gain was not affected by dietary treatment; however, hot standard carcase weight was significantly lower for steers offered canola meal compared with steers on the grain-based pellets. Dietary treatment did not affect the carcase characteristics, meat quality traits, and consumer sensory evaluation, irrespective of ageing periods. Therefore, canola meal can be used as an approved Pasturefed Cattle Assurance System (PCAS) supplement on moderate dry quality forages without negatively affecting carcase and meat quality traits.

Role of Intramuscular Connective Tissue in Water Holding Capacity of Porcine Muscles

BACKGROUND

This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT), semimembranosus (SM) and semitendinosus (ST) muscles were cut and boiled for 30 min in boiling water, followed by detection of water holding capacity (WHC), tenderness, fiber volume shrinkage and protein denaturation.

RESULTS

Compared with LT and SM, ST had the best WHC and lowest WBSF and area shrinkage ratio. The mobility of immobilized water (T22) was key to holding the water of meat. ST contained the highest content of total and heat-soluble collagen. On the contrary, ST showed the lowest content of cross-links and decorin, which indicate the IMCT strength of ST is weaker than the other two. The heat-soluble collagen is positively correlated to T22.

CONCLUSIONS

The shrinkage of heat-insoluble IMCT on WHC and WBSF may partly depend on the structural strength changes of IMCT components rather than solely caused by quantitative changes of IMCT.

Comparison of Effects from Ultrasound Thawing, Vacuum Thawing and Microwave Thawing on the Quality Properties and Oxidation of Porcine Longissimus Lumborum

The effects of vacuum thawing (VT), ultrasound thawing (UT) and microwave thawing (MT) on the quality, protein and lipid oxidation, internal temperature distribution and microstructure of porcine longissimus lumborum were compared. The results showed that a significant decrease (p < 0.05) in quality compared with those of fresh meat (FM) occurred for all of the thawing samples, especially for the MT samples. Changes in quality of the VT and UT samples were less significant than those of the MT samples. The increases in carbonyl content and TBARS value indicated that proteins and lipids in the thawing samples were oxidized. The decreases in uniform degrees of internal temperature distributions of muscles from the thawing samples were analysed by infrared thermography. Scanning electron microscopy images showed that the myofibril arrangements of thawing samples were looser than those of the FM samples with compact and ordered structure, which was proven by the obvious increase in the myofibril gap value of the thawing samples.

Proteomics analysis to investigate the impact of diversified thermal processing on meat tenderness in Hengshan goat meat

During the thermal processing, proteins of Hengshan goat meat undergo structural modifications such as degradation, oxidation and denaturation, ultimately affect the palatability and acceptability. The results of several objective metrics demonstrated that thermal processing exhibited significant impacts on the tenderness of goat meat. The 551, 84, 72, and 121 proteins were identified in the control and thermal processed groups (boiled, steamed, and roasted), respectively. Compared with the control group, the 101, 98, and 109 differentially-expressed proteins were explored in the treatment groups. Furthermore, the functions of metabolic and skeletal muscle proteome were investigated and discussed. Sensory evaluation and proteomics analysis showed that steaming and boiling treatment had no significant effect on the tenderness of goat meat, while roasting significantly reduced the tenderness, indicating that the available thermal processing methods to ensure the tenderness of goat meat were steaming and boiling treatments. Thus, the established proteomics database of goat meat provided the valuable reference for rational selection of thermal processing methods.

Acetylation of Sarcoplasmic and Myofibrillar Proteins were Associated with Ovine Meat Quality Attributes at Early Postmortem

The objective of this study was to examine the relationship between meat quality attributes and the changes of sarcoplasmic protein acetylation and myofibrillar protein acetylation in lamb longissimus thoracis et lumborum muscles at different postmortem phases. Protein acetylation, color, pH, shear force, myofibril fragmentation index and cooking loss were measured. The total level of acetylated sarcoplasmic proteins showed a negative relation with pH, a positive relation with a*, b* and cooking loss at the pre-rigor phase. Sarcoplasmic proteins acetylation affected postmortem pH by regulating glycolysis, which in turn affects color and cooking loss. The total level of acetylated myofibrillar proteins showed a positive relation with shear force at the pre-rigor phase. Myofibrillar proteins acetylation affected meat tenderness by regulating muscle contraction. This study indicated that acetylation played a regulatory role of meat color, water-holding capacity, and tenderization process at early postmortem.

The quality and mineral composition of the longissimus lumborum and semimembranosus muscles from lambs fed perennial or annual wheat forage with or without lucerne

This study compared the effect of a novel perennial wheat forage and a conventional annual wheat forage, fed to lambs with or without lucerne, on the quality and mineral profile of the longissimus lumborum and semimembranosus muscles. This involved 48 Poll Dorset × Merino ewe lambs, 12 per treatment, managed for 28 days within individual pens. Consumer sensory panel scores showed 'good eating quality' for all samples irrespective of diet, a conclusion supported by the shear force, cooking loss, particle size, and intramuscular fat results. Drip loss was affected by a significant interaction between diet and muscle. The ultimate pH of meat from lambs fed annual wheat was highest. Comparable colour stability and purge results suggested that diet did not impact on lamb retail-potential. Sodium, sulphur and zinc concentrations were higher in the meat from lambs fed annual wheat, compared to perennial wheat. Overall, these outcomes support the use of perennial wheat as a forage for lamb production.

The association between total volatile basic nitrogen (TVB-N) concentration and other biomarkers of quality and spoilage for vacuum packaged beef

Beef longissimus lumborum muscles (24) were each portioned into 6 steaks, and these were held at ~0.5 °C for up to 14 weeks. Total volatile basic nitrogen (TVB-N) data was compared against other measures of quality and freshness: total viable microbial count (TVC), ultimate pH, drip loss, purge, moisture content, cook loss, shear force, particle size, vitamin E, intramuscular fat content (IMF) and colour parameters. There was an association between TVB-N and colour parameters; and between TVB-N and several parameters for microbial load, tenderness and moisture. IMF and vitamin E were not correlated to TVB-N. TVB-N of 5.1 mg/100 g (95% confidence intervals: 4.6-5.5 mg/100 g) was estimated as equivalent to a TVC of log 7 cfu/g. When beef samples were categorised as either spoilt or fresh using this TVC recommendation, TVB-N was correct in 77.9% of its assignments. Additional investigation is necessary to confirm this result against a larger sample population with a broader range of TVB-N values.

Testing different devices to assess the meat tenderness: preliminary results

Meat tenderness is one of the principal attribute associated with consumer preferences. This study describes tenderness measurements at three final endpoint cooking temperatures (51, 61 and 71 °C) using a mechanical Warner-Bratzler (WBSF) as the standard instrument versus digital texturometer (CT3) and penetrometer (FHT) devices. Thirty-six cross-breed heifers (Bos indicus) with initial body weight 330 ± 40 kg, 20-24 months of age, were slaughtered after 100 days on feed. Subsequently, 48 h post-slaughter, Longissimus thoracis (LT) samples were collected between the 10th and 13th ribs. Six LT samples from each animal were used to evaluate tenderness and cooking losses through analysis of variance and regression analyses. No interaction between device × temperature was observed (p = 0.57). Shear force values were greater (p < 0.05) as endpoint cooking increased and the results from CT3 were close to the ones using the WBSF (R² = 0.76; p < 0.0001). In conclusion, the digital CT3 can replace the mechanical WBSF because these devices were strongly correlated (r = 0.85; p < 0.00). However, the results from FHT were underestimated (R² = 0.19; p < 0.006), indicating that FHT device should not be used for the evaluation of meat tenderness.

Effect of Kisspeptin-54 immunization on performance, carcass characteristics, meat quality and safety of Yiling goats

This study aimed to evaluate the effects of kisspeptin-54 immunocastration vaccine on performance, carcass characteristics, meat quality, and safety of Yiling goats. Thirty buck goats were randomly assigned into three groups: PVAX-B2L-Kisspeptin-54-asd immunized (PBK-asd), control, and surgically castrated. PBK-asd immunization significantly stimulated serum anti-kisspeptin antibody production and reduced testosterone hormone compared with the control group (p < .05). Interestingly, PBK-asd plasmid did not integrate into the host genome and had no significant effect on growth hormone, body weight, and average daily gain (ADG). Conversely, surgical castration significantly reduced ADG and carcass weight compared to the control group. Furthermore, PBK-asd immunization did not affect carcass characteristics (dressing percentage, loin area, and fat thickness) and meat quality traits (pH, color, cooking loss, drip loss, and shearing force). These results indicate that the Kisspeptin-54 DNA vaccine is safe and has potential to be used as an alternative to surgical castration for goats without negatively affecting carcass and meat quality.

Evaluating the performance of a miniaturized NIR spectrophotometer for predicting intramuscular fat in lamb: A comparison with benchtop and hand-held Vis-NIR spectrophotometers

This study compares a miniaturized spectrophotometer to benchtop and hand-held Vis-NIR instruments in the spectral range of 900-1700 nm for prediction of intramuscular fat (IMF) content of freeze-dried ground lamb meat; and their ability to differentiate fresh lamb meat based on animal age (4 vs 12 months). The performance of the miniaturized spectrophotometer was not affected by sample temperature equilibration time. Partial Least Square regression models for IMF showed R_cv² = 0.86-0.89 and RMSECV = 0.36-0.40 values for all instruments. Day-to-day instrumental variation adversely affected performance of the miniaturized spectrophotometer (R²_p = 0.27, RMSEP = 1.28). This negative effect was overcome by representing day-to-day variation in the model. The benchtop spectrophotometer and miniaturized spectrophotometer differentiated lamb meat by animal age. The miniaturized spectrophotometer has potential to be a fast, ultra-compact and cost-effective device for predicting IMF in freeze-dried ground lamb meat and for age classification of fresh lamb meat.

Point of purchase fatty acid profile, oxidative status and quality of vacuum-packaged grass fed Australian beef held chilled for up to 12 weeks

We investigated the fatty acid (FA) composition, oxidative biomarkers and quality traits of chilled beef. Specifically, striploin portions were held in vacuo and chilled (~ 1.5 °C) for up to 12 weeks, and analysed dependent on their assigned chilled storage period (0, 2, 5, 8, 10 and 12 weeks). There were no practical effects observed on beef FA composition as a result of chilled storage - including several polyunsaturated FA (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Intramuscular fat content was found to have a covariate effect, but only for saturated FA and monounsaturated FA. Vitamin E and thiobarbituric acid reactive substances were unchanged. Furthermore, improvements to shear force and particle size were evident at 2 weeks and thereafter, no further variation was evident. These findings suggest that beef produced to be healthier based on the EPA, DHA and PUFA content will remain so, for up to 12 weeks. Likewise, beef quality will be preserved across this same period.

The effect of different temperature-time combinations when ageing beef: Sensory quality traits and microbial loads

The ageing of beef is essential to provide a tender product which is deemed acceptable by consumers, with beef processors routinely ageing beef for ~ 14 d at 0-2 °C. The rate of tenderisation is directly affected by temperature, and as such the possibility of decreasing the required ageing time by increasing storage temperature could provide an opportunity to decrease associated costs. To test this, 320 beef M. longissimus lumborum portions were subjected to one of 72temperature-time combinations (TTC) incorporating temperatures of 3, 5 or 7 °C and ageing times of 6, 8, 10 or 12 d, with some temperature changes occurring during ageing. Controls (n = 32) were held at ~ 1 °C for 14 d. The application of TTCs did not affect beef quality, however longer storage at higher temperatures resulted in higher microbial loadings. Therefore, it can be concluded that shorter, cooler TTCs could be implemented to decrease ageing time requirements and maintain beef safety.

The effect of CaCl2 marination on the tenderizing pathway of goose meat during conditioning

In order to figure out the effect of CaCl₂ on the tenderizing pathway of goose meat, breast muscles of thirty-two Eastern Zhejiang White Geese were divided into three treatments: the control, 150 and 300mM CaCl₂. Shear force, myofibrillar fraction index (MFI), actin filaments and F-actin, G-actin and tropomodulins (Tmods) levels were investigated during 168h. Results showed that 300mM treatment had lower shear force at 48, 96 and 168h and higher MFI at 24, 48, 96 and 168h than the control. The rate of actin filaments disruption, the decrease of F-actin, the degradation of Tmods, the increase of G-actin in 300mM treatment was faster than 150mM treatment; the rate in the control was the slowest among treatments. CaCl₂ accelerated the transformation of F-actin into G-actin. We concluded that CaCl₂ tenderized goose meat by depolymerizing actin filaments and cleaving Tmods.

The effect of technical replicate (repeats) on Nix Pro Color Sensor™ measurement precision for meat: A case-study on aged beef colour stability

The Nix Pro Colour Sensor™ (NIX) can be potentially used to measure meat colour, but procedural guidelines that assure measurement reproducibility and repeatability (precision) must first be established. Technical replicate number (r) will minimise response variation, measureable as standard error of predicted mean (SEM), and contribute to improved precision. Consequently, we aimed to explore the effects of r on NIX precision when measuring aged beef colour (colorimetrics; L*, a*, b*, hue and chroma values). Each colorimetric SEM declined with increasing r to indicate improved precision and followed a diminishing rate of improvement that allowed us to recommend r=7 for meat colour studies using the NIX. This definition was based on practical limitations and a* variability, as additional r would be required if other colorimetrics or advanced levels of precision are necessary. Beef ageing and display period, holding temperature, loin and sampled portion were also found to contribute to colorimetric variation, but were incorporated within our definition of r.

Production and quality of beef from young bulls fed diets supplemented with peanut cake

Peanut cake is a biodiesel byproduct that has been tested as an alternative feed additive for use in cattle production. This study aimed to assess the importance of dietary peanut cake inclusion for young bull growth rate, beef production, and beef quality. In total, 32 Nellore young bulls individually housed in stalls with a mean initial body weight of 390±43.5kg were distributed in a completely randomized design for the experiment. The animals were fed Tifton 85 hay and one of four concentrate mixtures with 0, 33, 66 or 100% peanut cake instead of soybean meal. There was a linear reduction (P<0.05) in the slaughter weight and hot carcass weight and a quadratic effect (P<0.05) on the beef texture. No alterations occurred in the physicochemical characteristics of the longissimus thoracis; however, changes were observed (P<0.05) in the longissimus thoracis fatty acid profile. The replacement of soybean meal with peanut cake at levels up to 100% in the diet of feedlot-finished young bulls promotes a beneficial increase in the levels of PUFAs and the following nutraceutical compounds: conjugated linoleic acid (CLA) and Ω3 and Ω6 fatty acids.

The influence of peri-conception and first trimester dietary restriction of protein in cattle on meat quality traits of entire male progeny

Primiparous Santa Gertrudis heifers were used to evaluate the effects of gestational dietary protein content on meat quality traits of 20month old bull progeny (n=40). At -60d before AI, heifers were randomly allocated to HIGH or LOW protein diet (HPERI and LPERI). From 24dpc, half of each treatment group changed to an alternative post-conception HIGH or LOW protein diet (HPOST and LPOST). LPERI and LPOST diets resulted in higher shear force of the semitendinosus muscle than HPERI (P=0.053) and HPOST (P=0.003), respectively. Heat-soluble collagen in the semitendinosus muscle was lower (P=0.019) for LPERI than HPERI. Collagen and tenderness of the longissimus muscle were not affected by dam nutrition (P>0.05). Color, pH, sarcomere length, cooking loss, compression values, desmin and troponin-T degradation, fiber type, intramuscular fat and polyunsaturated fatty acid content were not affected by dam nutrition during the peri-conception and first trimester gestational period (P>0.05).

Optimum number of technical replicates for the measurement of compression of lamb meat

Up to six (average 4.63) replicate compression values were collected on cooked m. semimembranosus of lambs that had been raised at six sites across southern Australia (n=1817). Measurements on each sample were made with one of two Lloyd Texture analyser machines, with each machine having a 0.63 cm diameter plunger. Based on a log normal model with common variance on the log scale for within sample replicate results, estimates of the within sample variability of compression values were obtained, resulting in a quality control procedure for compression testing based on the coefficient of variation.