When you buy a vacuum-packed joint of meat, there is often a red solution in the packaging which might be assumed to be blood. In fact, it is a result of leakage from the joint by a process known as drip loss and the liquid consists of a solution of soluble proteins in water from the breakdown of the meat.
Fresh meat from slaughtered animals contains about 70% water which is essential to its quality but it begins to leak away soon after death. Boning and cutting can result in losses of 1-2% and further long-term storage can lead to much greater losses of up to 12%. Drip loss on this scale represents a large reduction in the yield of meat leading to financial losses as well as affecting the appearance, nutritional value and palatability of the meat to the consumer.
Some animals retain water after death better than others and this water holding capacity (WHC) appears to be the key to drip loss, although the factors governing WHC are unclear. A number of factors are thought to be influential, including genetic predisposition and the meat handling protocols.
A team of scientists based in Ireland has explored possible molecular factors in a proteomics study of pork. Pig farming is important economically in Ireland, providing employment for a large number of people and a large export business, so understanding yield reduction due to drip loss will have major consequences.
Anne Maria Mullen, Alessio Di Luca, and Ruth Hamill from the Teagasc Food Research Centre, Ashtown, and Giuliano Elia from UCD Conway Institute of Biomolecular and Biomedical Research, Belfield, wanted to identify proteins and peptides associated with drip loss in order to try and gain a better understanding of the process.