What makes Wagyu beef taste so exceptional is the intramuscular fat—the marbling that makes higher-grade steaks, such as Japanese A5, look almost completely white. A frequently asked question is whether it is advisable to cook Wagyu sous vide, as some claim this renders out the fat, defeating the purpose of paying a premium for Wagyu beef.

The answer depends on the temperature. At 57°C / 135°F, the fat melts but does not render out. I proved this by cooking Wagyu short ribs for 48 hours. Since any fat that renders out has nowhere to go but the vacuum-sealed bag, the absence of fat in the bag proves that none was lost from the meat. In the same experiment, I also cooked Wagyu short ribs for 48 hours at 68°C / 155°F, which resulted in a significant amount of fat in the bag. Consequently, you should avoid cooking Wagyu at high temperatures. You can read more about my experiment in this article.

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