What is burnt meat syndrome or yake in Japanese?
Faced with stressful circumstances, the organisms of bluefin tuna (and other animals) respond by secreting lactic acid in their muscles, which imparts a metallic taste in the meat when eaten raw and accelerates the degradation process due to a drop in pH.
This phenomenon is known as yake in Japanese, which means “burnt meat syndrome.” Its main feature is that it has a pronounced metallic flavour when raw, and has a brown colour. The market punishes this feature severely, especially in Japan.
The Ike Jime technique is a particularly manual, hand-crafted method of sacrifice that requires a lot of precision and is applied individually by a team of experts. Divers enter the fish husbandry facility and select the tuna according to its size, as per the customer’s requirements. Sacrifice is performed with a gunshot, avoiding nervous stimuli. Once sacrificed, two incisions are made in the main blood vessels, promoting the development of inosinic acid (taste enhancer). This process also prevents certain stress hormones from reaching the muscles and causing them to overheat.
After 12 seconds, the fish is on deck. A flexible wire is then inserted into the spinal canal, eviscerated it accurately and immediately – which prevents any parasites, if there are any, from passing into the muscle tissue – and immersed in ice water to lower its body temperature.