New guidelines to overcome cold shortening in lamb carcase

Eblex has produced a new set of guidelines which aims to help abattoirs overcome the problem of hot and cold muscle shortening in lamb carcases post-slaughter, and thereby maintain the tenderness of the meat.

A recent study has revealed that cold muscle shortening (which results when the carcase is chilled too rapidly after slaughter, resulting in contracted, higher-density muscle fibres that do not tenderise readily during maturation) is still presenting a significant challenge to the industry.

Some abattoirs chill carcases rapidly in order to improve efficiency, but if the temperature drops too quickly, it results in tougher meat.  

The new guidelines suggest that the best way to monitor muscle shortening is to measure pH levels in conjunction with the carcase temperature. The study, which looked at a cross-section of five abattoirs, found that the optimum method was to not let the lamb carcase temperature drop below about 8˚C before the pH had reached pH6.

It also found that found that hot shortening can occur if high voltage stimulation, used to improve tenderness, is too rigorous - although this poses a less severe problem.

The Eblex guidelines suggest that abattoirs should monitor the pH before and after both chilling and electrical stimulation, and should periodically monitor lambs through the process to see at what temperature the pH drops to pH6.

Kim Matthews, head of research and development at Eblex, said: “Historically, cold shortening was a major problem for the industry. We carried out a similar exercise with beef processing because there had been a lot of changes in the industry with electrical stimulation and were surprised to find cold shortening was still presenting a challenge.
“This prompted us to evaluate the pH/temperature relationship at lamb processing abattoirs. Studies at five lamb abattoirs in England revealed it is evident that both hot and cold shortening problems still exist in the industry. As such, processors should keep chilling rates in balance with the other treatments on slaughter lines to maintain meat tenderness. Our new guidelines are aimed at helping achieve this.”