Search

The use of total volatile basic nitrogen (TVB‐N) as a quality parameter for fish is rapidly growing to include other types of meat. Investigations of meat quality have recently focused on TVB‐N as an index of freshness, but little is known on the biochemical pathways involved in its generation. Furthermore, TVB‐N and methylated amines have been reported to exert deterimental health effects, but the relationship between these compounds and human health has not been critically reviewed. Here, literature on the formative pathways of TVB‐N has been reviewed in depth. The association of methylated amines and human health has been critically evaluated. Interventions to mitigate the effects of TVB‐N on human health are discussed. TVB‐N levels in meat can be influenced by the diet of an animal, which calls for careful consideration when using TVB‐N thresholds for regulatory purposes. Bacterial contamination and temperature abuse contribute to significant levels of post‐mortem TVB‐N increases. Therefore, controlling spoilage factors through a good level of hygiene during processing and preservation techniques may contribute to a substantial reduction of TVB‐N. Trimethylamine (TMA) constitutes a significant part of TVB‐N. TMA and trimethylamine oxide (TMA‐N‐O) have been related to the pathogenesis of noncommunicable diseases, including atherosclerosis, cancers, and diabetes. Proposed methods for mitigation of TMA and TMA‐N‐O accumulation are discussed, which include a reduction in their daily dietary intake, control of internal production pathways by targeting gut microbiota, and inhibition of flavin monooxygenase 3 enzymes. The levels of TMA and TMA‐N‐O have significant health effects, and this should, therefore, be considered when evaluating meat quality and acceptability. Agreed international values for TVB‐N and TMA in meat products are required. The role of feed, gut microbiota, and translocation of methylated amines to muscles in farmed animals requires further investigation. [ABSTRACT FROM AUTHOR]

Objective: This study was aimed to investigate the muscle-specific beef color stability at normal and high ultimate pHs. Methods: The impact of muscle (Longissimus lumborum [LL] vs psoas major [PM]) and pH (normal ultimate pH [Np] vs high pH dark cutting beef [Hp]) on color stability, indicated by basic color traits, metmyoglobin reducing activity (MRA) and oxygen consumption (OC), as well as the lipid oxidation, were determined over 7 days of display at 4°C. Results: Hp-LL had the highest pH (6.92), followed by Hp-PM (6.01), Np-PM (5.76), and Np-LL (5.52). Hp-LL had increased (p<0.05) a*, chroma and % oxymyoglobin during display. Hp-LL also had the highest metmyoglobin (MMb) reducing activity and OC among all the samples, thus, the greatest color stability, although very dark throughout storage, with lowest values for lightness (L*) and yellowness (b*). Np-LL also exhibited relatively high color stability, as a result of its lower % MMb and OC and higher MRA than psoas muscle samples. The 0.2 unit difference of the pH between Hp and Np psoas muscle, resulted in the difference of the color intensity, not the color stability. Interestingly, high pH psoas muscle (Hp-PM) did not have better color stability than Np-PM, and in fact had lower color stability than even Np-LL. The similar level of OC and lipid oxidation cannot explain the difference in color stability between Hp-PM and Np-LL. Conclusion: The Hp does not always show better color stability compared with Np beef, which depends on the muscle type. The balance of MRA and OC is important to keep the color in great intensity and stability in the meantime. [ABSTRACT FROM AUTHOR]

Carcase pH and temperature decline rates influence lamb tenderness; therefore pH decline parameters are beneficial when modelling tenderness. These include pH at temperature 18 °C (pH@Temp18), temperature when pH is 6 (Temp@pH6), and pH at 24 h post-mortem (pH24). This study aimed to establish a relationship between shear force (SF) as a proxy for tenderness and carcase pH decline parameters estimated using both linear and spline estimation models for the m. longissimus lumborum (LL). The study also compared abattoirs regarding their achievement of ideal pH decline, indicative of optimal tenderness. Based on SF measurements of LL and m. semimembranosus collected as part of the Information Nucleus slaughter programme (CRC for Sheep Industry Innovation) this study found significant relationships between tenderness and pH24LL, consistent across the meat cuts and ageing periods examined. Achievement of ideal pH decline was shown not to have significantly differed across abattoirs, although rates of pH decline varied significantly across years within abattoirs. [ABSTRACT FROM AUTHOR]

The aim of the current study was to identify whether changes in pH or temperature during the development of rigor mortis influence spectral quality and thus the prediction of intramuscular fat (IMF) in hot lamb carcases. Semimembranosus muscles (SM) of 75 lamb carcases were measured pre-rigor 3 times (Runs 1–3) using a near infrared (NIR) spectrometer with muscle pH and temperature also recorded. Calibration models for the prediction of IMF showed that spectra measurements taken at Run 2 (R 2 = 0.42, RMSE = 0.75) and Run 3 (R 2 = 0.38, RMSE = 0.78) provided more accurate and precise models compared to Run 1 (R 2 = 0.27, RMSE = 0.84). An association between spectral variance, internal and surface temperature of the SM was observed across runs. These results suggest that, as muscle temperature declined during the early post-mortem period there was an improved ability of NIR spectra to predict IMF. [ABSTRACT FROM AUTHOR]

Simple Summary: The increased incidence of heat stress in lambs has been reported in many countries, especially warmer parts of the world, compromising lamb welfare, having flow on effects for meat quality traits. While heat stress impacts can be variable depending on the severity and duration, the exposure of lambs to one week of elevated temperature increased the muscle omega-6 fatty acid concentration compared with the thermoneutral group. The one week heat stress is believed to enhance pro-inflammatory actions through induced free radical formation and oxidative stress. Somewhat independently, supplementation of the diet with vitamin E improved the growth rate and reduced oxidative stress. This suggests that under more extreme heat stress conditions, lambs fed in feedlots would benefit from enhanced levels of antioxidants such as vitamin E. The impact of antioxidant supplementation and short-term heat stress on lamb body weight gain, meat nutritional profile and functionality (storage stability of lipids and colour) of lamb meat was investigated. A total of 48 crossbred ((Merino × Border Leicester) × Dorset) lambs (42 ± 2 kg body weight, 7 mo age) were randomly allocated to three dietary treatments (n = 16) by liveweight (LW) that differed in dosage of vitamin E and selenium (Se) in the diet. Vitamin E and Se levels in the control (CON), moderate (MOD) and supranutritional (SUP) dietary treatments were 28, 130 and 228 mg/kg DM as α-tocopherol acetate and 0.16, 0.66 and 1.16 mg Se as SelPlex™/kg DM, respectively. After four weeks of feeding in individual pens, including one week of adaptation, lambs were exposed to two heat treatments. Animals were moved to metabolism cages for one week and subjected to heat treatments: thermoneutral (TN; 18–21 °C and 40–50% relative humidity) and heat stress (HS; 28–40 °C and 30–40% relative humidity) conditions, respectively. Final LW and hot carcass weight were influenced by dietary treatments with higher final live weight (FLW) (p = 0.05; 46.8 vs. 44.4 and 43.8 kg, respectively) and hot carcass weight (HCW) (p = 0.01; 22.5 vs. 21.3 and 21.0 kg, respectively) recorded in lambs fed the SUP as opposed to the CON and MOD diets. Vitamin E concentration in the longissimus lumborum (LL) muscle tended to be higher in lambs fed MOD or SUP diets than the CON group. Lipid oxidation of aged meat at 72 h of simulated retail display was reduced by antioxidant supplementation. Short-term (one week) heat stress treatment significantly increased muscle linoleic acid and total omega-6 concentrations compared with the CON group. The results demonstrate that four-week antioxidant supplementation at the SUP level improved animal productivity by increasing LW and carcass weight and the functionality of meat exhibited by reduced lipid oxidation. An increase in muscle omega-6 fatty acid concentration from short-term heat stress may induce oxidative stress via proinflammatory action. [ABSTRACT FROM AUTHOR]

This study describes the impact of sous vide cooking at different temperatures and time intervals on the eating quality, specifically tenderness of two muscles, bicep femoris (BF) and semitendinosus (ST) from spent buffalo (Bubalus bubalis). Spent buffalo refers to water buffalo that are no longer considered productive following a sixth lactation cycle. Steaks from each muscle were obtained and cooked at three combinations of time and temperature, namely 55 °C-8H, 65 °C-5H, and 95 °C-45 M, respectively. Warner-Bratzler Shear Force (WBSF), cooking loss, cooking yield, color, water activity (a w), total water content (TWC), total collagen content (TCC), heat soluble collagen (HSC), myofibrillar fragmentation index (MFI), and sensory evaluation were measured. The collagen solubilization results showed that temperature and time interacted (P ≤ 0.05), reducing the toughness of the muscles. The tenderization achieved through sous vide cooking was mainly attributed to the thermal denaturation of proteins at the typically lower temperatures and extended time used, weakening of connective tissue through collagen solubilization, and water retention. More cooking loss (P ≤ 0.05) was observed at high temperature treatment of 95 °C-45 M. Meat color, TWC, MFI, and overall acceptability exhibited differences among treatments (P ≤ 0.05). An extended heat interval at lower temperatures caused initial denaturation of myofibrillar proteins, then solubilization of connective tissue proteins. Cooking treatment 55 °C-8H (P ≤ 0.05) reduced the WBSF in both muscles; however, the ST appeared more tender than BF. [ABSTRACT FROM AUTHOR]

The physicochemical parameters of hot-boned bovine semimembranosus muscles after s ous vide cooking were investigated. Hot-boned or wet-aged steaks were collected, and cooked by different cooking methods, including sous vide (57 °C, 11 h, SV), grilling (at 200 °C to the central temperature of 72 °C, GR) or boiling (100 °C, 2 h, BO). The meat color, tenderness, water-holding capacity, degree of oxidation, myoglobin denaturation and sensory quality traits were determined, as well as the changes in the microstructure. Compared to other cooking methods, SV reduced the degree of oxidation and muscle shortening, and significantly improved the water holding capacity (WHC), tenderness, connective tissue content and overall acceptability for both hot-boned and wet-aged steaks. The oxidation and muscle shortening were reduced in hot-boned SV steaks (P < 0.05), and the water-holding capacity and sensory scores for juiciness, connective tissue content and overall acceptability were increased (P < 0.05) compared to the wet-aged steaks. The combination of hot-boning and SV cooking resulted in an acceptable tenderness, better overall sensory acceptability and higher WHC than other combinations of muscle states and cooking methods. Therefore, it is a good choice to cook hot-boned semimembranosus muscles using SV to improve the eating quality, which can eliminate the need for aging, benefiting the beef industry. [ABSTRACT FROM AUTHOR]

The effect of muscle fibre orientation and measurement interval on lamb meat drip losses was tested using the EZ-DripLoss (EZ) method. Sample cores were removed from 100 semimembranosus (SM) and longissimus lumborum (LL) muscles, sourced from different Merino lamb carcasses. Two cores with either horizontal or vertical fibre orientation, relative to the core diameter, were removed from each SM. One core with vertical fibre orientation was removed from each LL. The drip loss (%) of these cores was then monitored across four 24 h measurement intervals. It was found that fibre orientation did not impact on SM drip losses. Both SM and LL drip losses increased, linear to measurement interval. SM drip loss increased more than LL over the four measurement intervals and consequently, SM drip losses were higher than LL. Longer measurement intervals which are defined in the methods section are recommended when testing lamb meat drip losses using the EZ method. [ABSTRACT FROM AUTHOR]

This study investigated the effectiveness of visible-near-infrared (VISNIR) spectroscopy at classifying Australian lamb for: a) ultimate pH (pH 24), b) meat tenderness (i.e. shear force at day 5 of ageing, SF5) and c) intramuscular fat (IMF) content at 24 h post-slaughter using a custom-made handheld probe coupled with the ASD Labspec Pro instrument. VISNIR predictive regression models were developed. In the loin muscle (M. longissimus thoracis et lumborum), the models classified the predicted pH 24, SF5 and IMF content at above or below a threshold value with 94%, 98% and 88% accuracy, respectively. The observed difference between the actual and predicted value (i.e. the standard error of cross validation, SECV) for ultimate pH and IMF content are approaching accuracies required to attain highly reliable Meat Standards Australia grading standards. However, further development is required to improve the SECV for SF5. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the effects of frozen storage time on the quality and muscle structure in normal and pale, soft and exudative (PSE)-like pork. The meat quality of M. longissimus et lumborum (LL) was studied at 0, 3, 6, 9, 12, 15 and 18 weeks of storage at −18 °C, and M. Biceps femoris (BF) was studied at 0, 3 and 18 weeks of storage at −18 °C. Storage time affected all the measured parameters (pH, thaw loss, TVB-N, shear force and muscle structure). There were no differences between normal and PSE-like meat for thaw loss (%) or TVB-N (mg/100 g) values at all storage times. An initial tenderizing effect in PSE-like samples was observed at weeks 3 and 6 in LL samples, but thereafter samples became tougher during frozen storage and after 3 weeks in the BF. Storage for 6 weeks for PSE-like and 9 weeks for normal pork at −18 °C does not reduce quality. Highlights • The effects of freezing storage time on the quality of normal and PSE pork was studied over 18 weeks. • Freezing time affected the thawing loss, pH value, TVB-N, and shear force of LL and BF muscles. • An initial tenderizing effect in PSE samples as a result of freezing was observed at weeks 3 and 6 in LL samples. • No differences in thawing loss (%) and TVB-N (mg/ 100 g) values between normal and PSE pork at all storage times. • The results suggest a storage time of 6 weeks for PSE and 9 weeks for normal pork at -18°C before major changes in the quality occur. [ABSTRACT FROM AUTHOR]

Abstract The longissimus thoracis et lumborum (LL), and adductor femoris (AF) muscles from 39 castrated, 23 (±1) month old huacaya alpacas were used to determine vitamin E content and the impact on lipid oxidation levels. At 24 h post death the LL and AF muscles were removed and sampled for meat quality analysis and subjected to simulated retail display. Vitamin E content of either muscle had no significant impact on colour stability or oxidation traits during retail display. This is thought to be due to the high levels of vitamin E (>5.4 mg/kg) in both muscles. Lipid oxidation levels were 0.2 mg MDA/kg higher in both muscles post retail display. However, overall differences in TBARS levels detected pre and post display were very low (<1.19 mg MDA/kg) and well below sheep threshold values of >3 mg MDA/kg. The mechanism behind why alpaca meat has such high vitamin E levels compared to other species requires further investigation. [ABSTRACT FROM AUTHOR]

Abstract 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. Highlights • Different temperature-time combinations on eating quality and safety were tested. • Higher temperatures and longer ageing time influenced microbial safety. • Temperature-time combinations did not influence colour or quality. • Temperature-time combinations did not influence consumer satisfaction. [ABSTRACT FROM AUTHOR]

Abstract The effect of superchilled storage (SC, −4 °C) on shelf life and quality characteristics of M. longissimus lumborum from Chinese Yellow cattle compared with traditional chilling (TC, 2 °C) and frozen storage (−18 °C) was studied. The shelf life of beef steaks held at −4 °C extended to 12 weeks based on the total volatile basic nitrogen (TVB-N) value, which was 2.4 times longer than steaks stored at 2 °C. As the storage time increased, SC samples showed a lower increase of the total aerobic count (TAC), pH and thiobarbituric acid reactive substances (TBARS) values compared to TC samples. Further, L ⁎ and a⁎ values of SC samples changed more slowly than that of TC samples. Beef steaks held frozen had a longer shelf life than SC steaks, however, the shear force of frozen steaks remained above 55 N throughout the storage time indicative of toughness. Consequently, SC offers an effective approach for maintaining better shelf life and quality of beef steaks. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of homogenisation speed and centrifugation on particle size (PS) evaluation, and examine its relationship with shear force. Beef Longissimus lumborum (LL) muscle portions were randomly assigned to different ageing periods (0, 3 or 5 weeks), and tested for PS and shear force. The PS analysis was conducted at different homogenisation speeds (11,000, 16,000 and 19,000 rpm) with and without a centrifugation step prior to measurement. Samples homogenised at 11,000 rpm and not centrifuged gave PS results significantly different at each ageing time as did samples homogenised at 19,000 rpm and centrifuged. Overall samples homogenised at 11,000 rpm produced the lowest coefficient of variation for PS results. There was a significant correlation between PS and shear force across the different homogeniser speeds and centrifugation statuses. It is concluded that best practice when measuring PS in beef includes a homogeniser speed of 11,000 rpm with no centrifugation prior to measurement. [ABSTRACT FROM AUTHOR]

This study compared the fatty acid and mineral concentrations of lamb meat that was prepared to different levels of cooking doneness. Ten m. longissimus lumborum were each sectioned into 4 slices that were randomly assigned to be uncooked or grilled to an internal end-point temperature of 60 °C (rare), 71 °C (medium), or 77 °C (well done). It was found that cooking loss increased as the level of cooking doneness increased. The proportion of most major fatty acids were not altered by cooking. However, when adjusted for cooking loss (i.e., mg/135 g serve of lamb as-is equivalent prepared to each level of cooking doneness), the concentration of most major fatty acids, including C16:0, C18:0, C18:1n-9, and many conjugated linoleic acids, were lowered after grilling to any level of cooking doneness and compared to the uncooked samples. The omega-6 to omega-3 ratio was lowest for the uncooked samples and highest for those prepared to a well done level of cooking doneness. Conversely, the concentration of health claimable omega-3 fatty acids in the uncooked meat was retained upon cooking and across all the different internal endpoint temperatures. Calcium, magnesium, phosphorous, potassium, and sodium were reduced with preparation of lamb meat to any level of cooking doneness, compared with uncooked meat. Zinc, iron, and selenium were retained within the cooked samples. These findings show that consumer preference for a level of cooking doneness will have only minor effects on the concentration of minerals and fatty acids in lamb meat. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of chilled followed by frozen storage on lamb quality and safety parameters. Experimental ( n = 360) M. longissimus lumborum (LL) were randomly sampled from the boning room of a commercial Australian abattoir, at 24 h post-mortem, and assigned to five chilled storage periods (0, 2, 4, 6 and 8 weeks) and six subsequent frozen storage periods (0, 4, 8, 12, 24 and 52 weeks). Upon completion of each storage treatment combination, corresponding LL were sub-sectioned and analysed for colour stability (0, 1, 2 and 3 days), shear force, fluid losses (purge, thaw and cooking losses), intramuscular fat content, sarcomere length, water activity and microbial load (lactic acid bacteria, Enterobacteriaceae sp. , Brochothrix thermosphacta , Clostridium perfringens and Escherichia coli ). LL stored chilled for 2–4 weeks prior to freezing presented superior results for shear force, display colour and low levels of spoilage microbes, correlating with good eating quality and safety following more than one year of frozen storage. [ABSTRACT FROM AUTHOR]

This study investigated whether beef m. longissimus lumborum (LL) can be merchandised under retail conditions, following long-term superchilled storage (−1 °C). At 24 h post-mortem , the LL from left side of beef carcasses (n = 5) were fabricated into vacuum packaged beef thick-cuts, and then stored for 0, 2, 4, 8, 12, 16, or 20 weeks under superchilled conditions (−1 °C). Following storage, beef cuts were fabricated into steaks and aerobically displayed (0– 4 °C) for 5 days. Instrumental color, percentage of myoglobin redox forms, metmyoglobin reducing activity, oxygen consumption, and lipid oxidation were evaluated. After 4 weeks, the steaks had the highest a *, b * and chroma values between 1 and 3 days of display. Longer superchilled storage resulted in a rapid increase in discoloration and lipid oxidation which were observed in samples during display. Specifically, the a * values of steaks superchilled for 16 and 20 weeks approached the unacceptability threshold (a * ≥ 14.5) after 3 days of display. • Color stability was evaluated for the superchilled storage beef during 20 weeks. • At 4 weeks, steaks had the highest color parameters at 1–3 days of display. • Longer superchilled storage reduced color and lipid stability. • The steaks from beef superchilled for 16 and 20 weeks only can be displayed for 3 days. [ABSTRACT FROM AUTHOR]

This study investigated the effect of superchilling (−30 °C until the core temperature achieved −3 °C, then stored at −1 °C until 24 h, SC) on the tenderness of hot boned beef M. longissimus lumborum (LL), with very fast chilling (−30 °C until the core temperature achieved 0 °C, then stored at −1 °C until 24 h, VFC) and conventional chilling (0– 4 °C for 24 h, CC) as the controls. The lowest initial shear force values were obtained in SC samples compared to those from the VFC and CC treatments (P < 0.05). Clear freezing damage of muscle fibers and more myofibril fragmentation were found in SC samples compared with the other samples early post-mortem. Moreover, SC samples showed the highest level of inosine 5-monophosphate at 3 h post-mortem (P < 0.05). A reduced glycolysis rate (as evidenced by lactate content) was also found in SC treated samples suggesting little contribution of glycolysis on the tenderization of SC. • Superchilling (SC) can improve beef tenderness. • SC caused greater desmin and troponin-T degradation at 7 and 14 days of ageing. • SC caused obvious freezing damage of muscle fibers and more myofibril fragmentation. • The higher level of IMP in SC treatment may weaken the actin-myosin bridge. • SC did not affect the levels of glycolysis enzymes but reduced the glycolysis rate. [ABSTRACT FROM AUTHOR]

The effects of repeated (1 ×, 2 ×, 3 ×) pulsed electric field (PEF) treatment (10 kV, 90 Hz, 20 μs) on the quality of beef loins and topsides were evaluated, including the tenderness, purge loss, cooking loss, myofibrillar protein profile and post-mortem proteolysis. Both muscle types were obtained from each of 12 steers and were processed within 6 h. After PEF treatment samples of both muscle types were subjected to 3, 7, 14 and 21 days ageing. The 1 × and 2 × PEF treatments had no effect on the tenderisation of hot-boned beef Musculus longissimus lumborum muscle for all ageing treatment times, while the 3 × treatment reduced the tenderness. The opposite effect was observed in hot-boned beef Musculus semimembranosus muscles where the 3 × treatment produced meat with lowest shear force at 3 days post-treatment time, but this beneficial effect disappeared with longer ageing times. An increase in proteolysis of troponin T was seen to the largest extent with 1 × PEF treatment and decreased with every extra application of treatment. [ABSTRACT FROM AUTHOR]

A hand held Raman spectroscopic device was used to predict intramuscular fat (IMF) levels and the major fatty acid (FA) groups of fresh intact ovine M. longissimus lumborum (LL). IMF levels were determined using the Soxhlet method, while FA analysis was conducted using a rapid (KOH in water, methanol and sulphuric acid in water) extraction procedure. IMF levels and FA values were regressed against Raman spectra using partial least squares regression and against each other using linear regression. The results indicate that there is potential to predict PUFA ( R 2 = 0.93) and MUFA ( R 2 = 0.54) as well as SFA values that had been adjusted for IMF content ( R 2 = 0.54). However, this potential was significantly reduced when correlations between predicted and observed values were determined by cross validation ( R 2 cv = 0.21–0.00). Overall, the prediction of major FA groups using Raman spectra was more precise (relative reductions in error of 0.3–40.8%) compared to the null models. [ABSTRACT FROM AUTHOR]

With the aim to define an objective threshold for consumer satisfaction, this study investigated the relationship between lamb particle size data and consumer scores for tenderness, juiciness, flavour and overall liking (sensorial properties). Data were sourced from the longissimus lumborum muscles of 273 Australian Merino lambs, these being aged for 5-d and then analysed for particle size and sensorial properties – the latter using untrained consumer sensory panels. Pearson's correlation and principal component analyses identified no significant relationship between particle size and consumer sensory scores. Linear regression models found the sensorial properties of lamb could not be predicted using particle size, indicating no univariate relationship. Further, a backwards stepwise regression analysis found there to be no multivariate or univariate relationship between the sensorial properties of lamb and its particle size. These findings demonstrate that there is little value in defining a particle size threshold for consumer satisfaction based on the sensorial properties of lamb. [ABSTRACT FROM AUTHOR]

Meat tenderness is known to be affected by sarcomere length (SL), proteolysis and collagen content (CC). Sixty lambs were slaughtered and the Longissimus muscle was sampled. Samples for shear force (SF), SL, proteolysis indicators (desmin degradation, particle size: PS) and CC were taken after the allotted ageing periods (1, 7, and 14 days). PS explained a large part of the variation in shear force (approximately 34%) when modelled across ageing periods. Other factors (CC, SL) combined with proteolysis indicators (PS, desmin degradation) explained just under 40% of the variation in shear force. Within ageing periods SL explained a small, but significant, part of the variation in shear force after 14 days of ageing (8%) and at day 1 of ageing desmin degradation explained 17% of the variation in shear force. Methods to improve the tenderness of lamb longissimus muscle should focus on increasing the extent of post-mortem proteolysis, when processing conditions are sufficient to prevent muscle fibre shortening. [ABSTRACT FROM AUTHOR]

The effects of pulsed electric field (PEF) and ageing (3, 7, 14 and 21 days) on the shear force, protein profile, and post-mortem proteolysis of beef loins ( M. Longissimus lumborum , LL) and topsides ( M. Semimembranosus , SM) w ere investigated using a range of pulsed electric field treatments [voltages (5 and 10 kV) and frequencies (20, 50, and 90 Hz)]. PEF treatment decreased the shear force of beef LL and SM muscles by up to 19%. The reduction in the shear force in the LL was not affected by the treatment intensity whereas the reduction in the SM was dependent on PEF frequency. PEF treated beef loins showed increased proteolysis, both early post-mortem and during subsequent post-mortem storage reflected by increased degradation of troponin-T and desmin. The most prominent troponin-T degradation was found in samples treated with 5 kV–90 Hz, 10 kV–20 Hz at day 3 and day 7 post-treatment in addition to 10 kV–50 Hz in subsequent post-treatment times. The degradation of desmin in PEF treated beef loins increased with ageing time. [ABSTRACT FROM AUTHOR]

The effect of aperture size on the assessment of lamb meat colour values (L*, a*, b* and R630/580) was investigated. Two experiments using 2 HunterLab MiniScan colorimeters (large [25 mm] and small [5 mm] apertures) were conducted: 1) coloured tiles were measured and 2) unaged lamb ( n = 65) m. longissimus lumborum (LL) and m. semimembranosus (SM) muscles were measured over 2.5 d under simulated retail display. For Experiment three, 2 different colorimeters were used on lamb ( n = 36) LL aged for 6 weeks before measurement over 4 d on simulated retail display. Coloured tile a* and b* values were unaffected by aperture size, but L* values and the R630/580 ratio were influenced by aperture size. The effect of aperture size on lamb meat colour measurements varied with display time and muscle type. The large aperture size generally provided the highest colorimetric values, and is recommended for measuring lamb meat colour. [ABSTRACT FROM AUTHOR]

The relationship between instrumental colorimetric values (L*, a*, b*, the ratio of reflectance at 630 nm and 580 nm) and consumer perception of acceptable beef colour was evaluated using a web-based survey and standardised photographs of beef m. longissimus lumborum with known colorimetrics. Only L* and b* were found to relate to average consumer opinions of beef colour acceptability. Respondent nationality was also identified as a source of variation in beef colour acceptability score. Although this is a preliminary study with the findings necessitating additional investigation, these results suggest L* and b* as candidates for developing instrumental thresholds for consumer beef colour expectations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Meat from cull cows is traditionally sold in Australia for mincemeat, but this study examined whether there is potential to add value by identifying meat of higher quality from older cattle. Dentition and ossification score were recorded for 173 Angus cattle of known age, ranging from 26 months to 12.6 years. Longissimus and semitendinosus muscles were sampled to assess the effect of chronological age on shear force and connective tissue. Age explained variation in shear force of the semitendinosus better than in the longissimus muscle, but had little effect on shear force values per se. At 2 days postmortem, 18% of the longissimus muscles were classified as tender reaching 65% as ageing extended to 14 days. Soluble collagen was a better predictor of age than total collagen. This study shows that the current practice of routinely selling meat from culled cows as mincemeat overlooks a valuable opportunity to grade and sell a significant proportion at higher price as prime cuts. [ABSTRACT FROM AUTHOR]

This study compared longissimus lumborum (LL) and semitendinosus (ST) muscles, in 48 lamb carcasses, to determine their pH decline parameters and achievement of ideal pH criteria (hitting the window). These include the pH at temperature 18 °C (pH@18) and temperature at pH 6 (temp@pH6). No practical difference were found between muscles for pH@18 or the temp@pH6, although there were differences between the experimental carcasses evaluated. Indeed, for all but three carcasses, there were insignificant differences between the LL and ST in terms of their pH@18. This outcome suggests that the lower value and more accessible ST muscle can be measured to determine lamb carcass pH decline parameters, instead of the LL. Because of the scale of this study, additional investigation is advised prior to any adoption. [ABSTRACT FROM AUTHOR]

Beef ageing (in vacuo) for tenderisation and flavour development may be accelerated by favourable temperature-time combinations (TTCs), however the effect of such manipulations on volatile organic compounds (VOCs) that are generated during cooking, is unknown. We compared VOCs from grilled beef longissimus lumborum muscle samples which had been subjected to different TTCs. The TTCs consisted of combinations of temperatures (~ 3, 5, or 7 °C) and ageing time periods (6, 8, 10 or 12 d); as well as control samples, which were held at 0-2 °C for a total of 14 d. Sensory quality attributes of these same samples were measured by untrained consumer panellists. Generally, it was found that TTCs had negligible effects on grilled beef VOCs and were comparable to controls. Furthermore, many VOCs were significantly related to flavour intensity, flavour liking and overall liking. These findings support the use of TTCs as a viable means to accelerate the rate of beef ageing without compromising quality. [ABSTRACT FROM AUTHOR]

To evaluate different methods for the determination of postmortem myofibrillar fragmentation, three protocols were compared: fragmentation index method (FI) after drying the filtrate residue at room temperature for 10 min (FI room) or at 105 °C for 12 h (FI oven); and myofibrillar fragmentation index (MFI) by the absorbance method. Beef Longissimus thoracis steaks (n = 34) were randomized into two treatments (frozen/thawed and unfrozen) and aged for 0, 7, 14 or 21 days. An interaction (P < 0.05) between method and treatment, method and aging and treatment and aging was found. FI room was the best to detect a difference in fragmentation at all aging days. In addition, FI room and FI oven both detected the tenderization process that occurs by freezing while the MFI method did not, yet all three methods were similarly related to tenderness as measured by shear force. It is suggested that FI room is the most effective method (time, cost) to indicate myofibrillar fragmentation, under the conditions imposed herein. • Three protocols were compared to determine the myofibrillar fragmentation. • The choice of the better method implications better results. • The faster and less laborious method (FI room) was most effective than others. • The FI room detected the extent proteolysis at all aging days. • The FI room detected the myofibrillar changes induced by the freezing process. [ABSTRACT FROM AUTHOR]