Answers found for colour and tenderness

Scientists for the first time say they have separated environmental and genetic components of meat quality in sheep.

Their work, based on the Sheep CRC’s Information Nucleus flock and conducted by Robin Jacobs, of DAFWA, Janelle Edwards, of SARDI, and Robyn Warner, of DPI, Victoria, has assessed data from more than 2000 lambs in the project’s first year.

“We all know that consumers expect premium quality and value from their lamb meat purchases, and both of these are influenced by environmental and genetic factors, ” Dr Warner said.

“This work will deliver ways of improving meat yield, quality and nutritional value, and will be applicable to different breeds, regions and lamb management systems across Australia.”

Dr Warner said the study came to some key conclusions.

“For tenderness, the level of intra-muscular fat (IMF) and processing conditions are most important, as indicated by the chemically measured fat in the meat, and the ultimate pH and the rate of pH fall. Most lamb loin meat was acceptably tender after five days of ageing.

“The most important determinant of fresh colour appears to be ultimate pH. Most of the lamb loin meat was acceptable in terms of fresh meat colour.

“We also found that IMF and mineral content affect the browning of meat during retail display, hence playing a role in shelf-life management. Overall, the breeding and management practices that increase muscle IMF levels and the processing practices that optimise muscle pH post-slaughter do most to improve the tenderness of lamb.

“The confounding factor is that extension of retail colour stability may be antagonistic to traits associated with tenderness, particularly IMF level and the rate of pH decrease, though more work will help us to unravel this area.”

The results also indicated that older lambs have more pigment, a darker colour and a higher level of myoglobin pigment than younger lambs.

Carcases from lambs finished using high-energy pelleted diets have less redness compared with those from lambs fed low-energy diets and pasture.

The results also suggested that colour stability during retail display had moderate heritability and that it was likely to be responsive to genetic selection.

Tenderness results found females produced meat that had a lower shear force on days one and five post-slaughter and had a lower shear force difference than wethers, although, while the difference was significant, it would most likely not be detected by the consumer.

The results also showed that in general, Merinos took more time to reach slaughter weight than other breeds at given nutritional regime and thus would generally be older than other breeds at slaughter and so had darker meat.