Quick Dips

Low Fat and Tender Meat

A revolutionary new fat detector has AgResearch and the rest of the meat industry excited. The new instrument, called NICL-D (Non-Invasive Chemical Lean Detector), will allow meat processors to determine the amount of fat in each meat box with exceptional precision, as the boxes pass through the scanner.

Previously, meat companies have relied on chemical testing to estimate the fat content of boxed meat. Such testing is invasive, time-consuming, expensive and uses potentially dangerous chemicals. The results can be variable, due to testing only small samples from a small number of boxes. Often the sampled boxes must be repacked or the contents downgraded.

"The enormously improved accuracy will enable processors to reduce the amount of 'free meat' they give away over and above their customers' specification, while at the same time minimising the possibility of claims by customers that shipments contain more fat than specified," says AgResearch project leader Philip Petch.

Another significant advantage is that the same instrument can simultaneously detect metal or other contaminants. Science leader Dr Robert Burling-Claridge says that small pieces of metal or bone that have accidentally been left in a box of meat are clearly visible to the scanning system.

They can be automatically detected and the contaminated boxes dealt with before the contamination is spread. This provides a new level of assurance for meat suppliers and their customers, and helps minimise the risk of damage to plant equipment or worker injury.

Meat may be more tender thanks to work undertaken by Lincoln University's Meat Research Group.

During the first hours after slaughter, meat cools and becomes acidic as a result of lactic acid accumulation. The rate of acidification and cooling can be controlled by the processing conditions. It has been known for more than 30 years that very rapid chilling may toughen meat because it induces extreme muscle contraction.

"What we found in our recent work is that if chilling is too slow, the meat is tough as well," says researcher Dr Geert Geesink.

The study involved taking samples from lamb in the first hour after slaughter and storing them overnight at temperatures between 5 and 35^oC. After overnight storage at the different temperatures, the amount of calpain, a muscle enzyme, was measured. This enzyme helps to make meat tender during chilled storage. Further chilled storage of the vacuum packed samples was at 2^oC.

After 24 hours, and again after 14 days of chilled storage, meat samples were cooked and the tenderness was measured. Measurements of the water loss from the meat and the changes in colour were also taken. This is because customers choose to buy meat based on its appearance.

"It was very satisfying to find that the meat with the least water loss and change of colour was that stored overnight at 15^oC. This was also the best temperature for meat tenderness" says Geesink.

"When we measured the amount of the tenderising enzyme present in the meat we found that at higher temperatures, this enzyme is destroyed when the muscle acidifies. Without the action of this enzyme the meat didn't tenderise during chilled storage."

"Meat processors need to make sure that the acidification and the temperature drop of the meat are neither too fast nor too slow to ensure the production of tender meat."