Waiter, has this chicken been frozen?

Consumers are willing to pay a premium for fresh poultry but how can they be certain that a product has not been previously frozen or partially frozen and then thawed?

Currently, laboratory tests based on release of the enzyme β-hydroxyacyl-CoA-dehydrogenase (HADH) can be used by UK enforcement authorities and traders to ensure that unscrupulous fraudsters are not passing off as fresh, turkey or chicken which had been fully frozen then thawed.

Now, a research study by LGC has confirmed that the HADH method remains valid to distinguish between fresh and previously frozen or rapidly frozen chicken and turkey. However, it cannot identify poultry products that have been superchilled (or partially frozen) using the new superchilling technologies.

European Commission (EC) Regulations require whole poultry or parts be marketed as either ‘fresh’ or ‘chilled’ if they have been stored between -2 and +4°C. While whole poultry or parts can also be marketed as ‘frozen’ or ‘quick-frozen’, they are not permitted to be marketed as ‘fresh’ if they have been previously frozen and then thawed.

A new superchilling refrigeration technology has been developed which can store poultry meat in a partially frozen state between -3 and -5°C for long periods. Because this new refrigeration technology does not comply with the EC Regulations, manufacturers in Europe may be mislabelling their poultry meat.

LGC, an international science-based company and market leader in analytical, forensic and diagnostic services and reference standards, undertook the study, which was funded by the Food Standards Agency, to assess the extent to which the accepted HADH method can distinguish between poultry that has been conventionally chilled or frozen and poultry chilled and frozen using new refrigeration technologies.

The HADH method was developed in earlier research and applied to the UK market. The method is based on measuring the activity of a muscle mitochondrial enzyme, β-hydroxyacyl-CoA-dehydrogenase, which is released when the mitochondrial membranes are damaged during freezing and thawing. Measurement of the relative HADH activity in juice expressed from a meat sample before and after a laboratory freezing process gives an indication as to whether or not the meat has been previously frozen.

Results from LGC’s study showed that the HADH assay was able to distinguish between poultry that had been frozen, either conventionally or using a new rapid-freezing technique and fresh or chilled poultry, but it was unable to distinguish between normally chilled poultry and the new superchilling process. Further detailed information on LGC’s study results can be freely viewed within the Journal of the Association of Public Analysts.

In the conclusion to its study, LGC refined a new numerical cut-off limit for chicken and improved the procedure used to extract cellular liquid from the meat, in order to reduce the variability of the method.

GC

www.lgc.co.uk/