Each year 4-5,000 tonnes of western rock lobster are cooked and exported to countries such as Japan and Taiwan. When existing cooking methods are used a proportion of cooked western rock lobster go black, this results in a product that is unacceptable to the customer

The blackening of the flesh is known as melanosis and is caused by an enzyme called polyphenoloxidase (PPO). Melanosis is a major problem for the western rock lobster industry and it has been estimated that it costs the industry over $1 million per year. Finding a solution to the problem of melanosis by stopping PPO activity is therefore necessary. Currently, cooking is the most common method used in food processing to stop enzyme activity. However, as the PPO enzyme is evidently still active after export lobsters have been cooked it was important to first understand what was happening to the enzyme when it was heated.

This study showed that when lobsters were heated to an internal temperature between 60 and 80°C there was a large increase in enzyme activity. It was not until after temperatures reached 90°C, or more, the enzyme activity stopped. Overall it was found that for 50% of the cooking time, temperatures only reached between 60-80°C. Therefore they did not get high enough to kill the enzyme; rather, current cooking methods actually increase the enzyme ‘s activity.