Consumer Perceptions of Meat Redness Were Strongly Influenced by Storage and Display Times.

Lamb (n = 79) meat colour was scored by 879 untrained consumers using a scale of 0 (brown) to 100 (red). This consumer colour score (CCS) was obtained on m. longissimus lumborum (loin) and m. semimembranosus (topside), stored for short (5-7 days), medium (33-35 days), and long periods (110-112 days) and a retail display time of up to 4 days. Consumers perceived topside to be less red initially and changed from red to brown more rapidly when stored for the long-storage period (p < 0.01). Whereas, the initial CCS of loin samples were similar across the storage periods (p > 0.05). CCS and the instrument measure oxy/met (reflectance of light at wavelengths 630 nm and 580 nm) had a low correlation coefficient of 0.33 (p < 0.01). The propensity for lamb growth and leanness indicated by sire breeding values for lamb weight, eye muscle depth, eye muscle fat depth, and loin intramuscular fat had varied and inconsistent effects on CCS. Therefore, even the selection on CCS.

Alternative cutting methods and dry aging reduce the shear force of hot boned beef striploin in Bos indicus cattle.

Hot boning (HB) is an economical processing technique often resulting in poorer meat quality and tenderness. This study tested a method of partial HB, where the short loin section was removed from the hot carcass and chilled, with the striploin remained in the skeletal system. Thirty six yearling Bos indicus steers carcasses were subjected to either low, high or no electrical stimulation and each side allocated to a cutting treatment of HB, partial HB and conventional (Achillies hung). Striploins were divided into 3 and aged for 5, 14 and 28 days. Warner Bratzler Shear force (WBSF) and sarcomere length were tested. Partial HB resulted in greater tenderization without aging compared to HB. However, optimized electrical stimulation was a requirement. Treatment did not influence sarcomere length. The study also tested the impact of Dry aging of HB striploins, which resulted in further increases in tenderness at 28 days of aging compared to wet aged product, reducing WBSF by 9 N.

Genetic correlations between meat quality traits and growth and carcass traits in Merino sheep1.

Genetic correlations between 16 meat quality and nutritional value traits and live weight at various ages, live ultrasound fat and muscle depth, carcass measures, and carcass dissection traits were estimated for Merino sheep in the Information Nucleus (IN). Genetic correlations between live weight at various ages and the carcass traits are also reported. The IN comprised 8 genetically linked flocks managed across a range of Australian sheep environments. Meat quality traits included between 1,200 and 1,300 records for progeny from over 170 sires for intramuscular fat (IMF), lean meat yield (LMY), shear force (SF5), pH, meat color, and meat nutritional value traits including iron and zinc levels and long-chain omega-3 and omega-6 polyunsaturated fatty acid levels. The genetic correlations indicated that selection of Merino sheep to either reduce fat or increase muscle using ultrasound assessments will result in little change in IMF and SF5. Myoglobin levels would tend to be reduced following selection for reduced ultrasound fat depth (0.35 ± 0.21, 0.43 ± 0.14), whereas increases in myoglobin levels would occur due to selection for increased ultrasound muscle depth (0.25 ± 0.24, 0.38 ± 0.15). Selection for increased live weight will result in favorable correlated responses in hot carcass weight (0.76 to 0.97), dressing percentage (0.13 to 0.47), and carcass muscle (0.37 to 0.95), but unfavorable responses of increases in carcass fatness (0.13 to 0.65) and possible small reductions in muscle oxidative activity (-0.13 ± 0.14 to -0.73 ± 0.33) and iron content (-0.14 ± 0.15 to -0.38 ± 0.16), and a possible deterioration of shear force from selection at later ages (0.15 ± 0.26, 0.27 ± 0.24). Negligible changes are generally expected for LMY and meat color traits following selection for increased live weight (most genetic correlations less than 0.20 in size). Selection for increased LMY would tend to result in unfavorable changes in several aspects of meat quality, including reduced IMF (-0.27 ± 0.18), meat tenderness (0.53 ± 0.26), and meat redness (-0.69 ± 0.40), as well as reduced iron levels (-0.25 ± 0.22). These genetic correlations are a first step in assisting the development of breeding values for new traits to be incorporated into genetic evaluation programs to improve meat production from Merino sheep and other dual-purpose sheep breeds.

A supply chain approach to improving the shelf life of lamb meat; vitamin E concentration, electrical stimulation, ageing period and packaging system.

This study investigated the effects of vitamin E, electrical stimulation, aging and packaging system on the colour stability of lamb meat. Eighty crossbred wether lambs, 6-8months old were fed on either vitamin E or control pelleted diet for 31days prior to slaughter. Half of the carcases from each group were electrically stimulated before being split longitudinally into 2. Each side was randomly allocated 1 of the 4 aging periods (5days fresh, 10, 20 and 30days CO2). Muscle samples were set for retail display, after the respective aging period, colour was measured over 96h. Supplementing vitamin E nutritionally is likely to lengthen the shelf life of lamb products aged longer than 10days. Muscle vitamin E concentrations >3.0mg/kg are required to increase the shelf life of lamb cuts aged for up to 30days to 60h. Medium voltage electrical stimulation did not have a detrimental effect on the display life of aged lamb meat.

Altered post-mortem metabolism identified in very fast chilled lamb M. longissimus thoracis et lumborum using metabolomic analysis.

The aim of this experiment was to use metabolomic techniques to investigate the energy metabolism in lamb M. longissimus thoracis et lumborum subjected to very fast chilling (VFC) post-mortem. The tissue was prepared by 2 different operators and subjected to very fast chilling (less than 0°C within 1.5h of slaughter) or typical chilling regimes (Control; 0°C within 22h of slaughter). Non-targeted metabolomic analysis ((1)H NMR) and targeted analysis ((31)P NMR, HPLC-PDA and HPLC-MS/MS) were used to examine the change in muscle metabolites post-mortem. One VFC treatment, which resulted in a colder core temperature and more tender meat, had higher levels of glycolytic intermediate metabolites pre-rigor as well as more of the end-products of adenosine and nicotine nucleotide metabolism pre-rigor, relative to conventionally chilled treatments. In conclusion, VFC to less than 0°C within 1.5h of slaughter causes considerable changes in metabolism and rigor onset, which are associated with tender meat.

Phenotypic characterisation of colour stability of lamb meat.

A study was undertaken, using 2701 overwrapped loin samples aged for 5 days and subjected to a simulated retail display (SRD) for 3 days; sourced from lambs in the Cooperative Research Centre for Sheep Industry Innovation information nucleus flock, born 2007-2009. The ratio of reflectance of light in the wavelengths of 630 nm and 580 nm (oxy/met) was measured daily during the SRD, using a Hunterlab spectrophotometer. A series of linear mixed models was fitted to the oxy/met and time data to compare 4 breed types and identify relevant covariates, of 19, using a forward selection process. Breed type, pH at 24 h post slaughter and Linoleic acid concentration (LA) were the most important factors and covariates, in that order. Merino breed type, high pH and high LA reduced colour stability. Fitting a spline model to predict the time for oxy/met to reach a set value, represents an alternative to comparing oxy/met at a set time, for describing colour stability.

Health beneficial long chain omega-3 fatty acid levels in Australian lamb managed under extensive finishing systems.

The variation in levels of the health claimable long chain omega-3 fatty acids, eicosapentaenoic acid (EPA, 20:5n-3) plus docosahexaenoic acid (DHA, 22:6n-3) across production regions of Australia was studied in 5726 lambs over 3 years completed in 87 slaughter groups. The median level of EPA plus DHA differed dramatically between locations and sometimes between slaughters from the same location. The ratio of EPA plus DHA from lambs with high values (97.5% quantile) to lambs with low values (2.5% quantile) also differed dramatically between locations, and between slaughters from the same location. Consistency between years, at a location, was less for the high to low value ratio of EPA plus DHA than for the median value of EPA plus DHA. To consistently obtain high levels of omega-3 fatty acids in Australian lamb, there must be a focus on lamb finishing diets which are likely to need a supply of α-linolenic acid (18:3n-3), the precursor for EPA and DHA.

Selenium supplementation and increased muscle glutathione concentration do not improve the color stability of lamb meat.

In the eyes of the consumer, a red surface color of lamb meat is desirable. This red color is caused by oxymyoglobin; however, under conditions of retail display this pigment slowly oxidizes and turns brown, deterring consumers. The antioxidant activity of both glutathione (GSH) and selenium has been suggested to slow myoglobin oxidation, thus improving color stability. The following experiment was designed to test the hypothesis that high muscle GSH will improve the color stability of lamb meat, and this effect of GSH will be further improved by supplementing animals with selenium. Forty-eight 12-month-old Merino wether lambs were selected from a flock for high (n = 24) or low (n = 24) GSH concentration in whole blood. Each GSH group was then randomly allocated into two selenium treatments (supplemented with or without 2.5 mg of selenium/kg for 8 weeks). The lambs were slaughtered, and samples were taken from m. semimembranosus (SM) and m. longissimus dorsi (LD) to measure muscle GSH, selenium, and vitamin E concentrations. Further samples were taken to measure color stability (as oxy/metmyoglobin ratio, reflectance at 630/580 nm) over 96 h of retail display. There was no effect of muscle GSH concentration or selenium supplementation on oxy/metmyoglobin ratio at 60, 48, or 30 h of retail display, with the only exception being the non-selenium-supplemented SM samples, which actually decreased in ratio as the muscle GSH concentration increased (P < 0.05). There was a poor correlation between blood and muscle GSH, with a correlation coefficient of 0.18 for the SM and 0.026 for the LD. Thus, it is apparent that neither GSH nor selenium improved the color stability of meat from merino lambs.