What It Means When Sous Vide Beef Turns Green

Sous vide steak is a wonderful thing, but there are a few things you need to look out for when doing sous vide cooking. One thing sous vide home chefs are taking notice of is the tendency for beef to turn an unpleasant green color if it's left cooking in the sous vide machine for longer than a few hours. Unfortunately, the food health science hasn't quite caught up with this phenomenon, so reputable sources concerning the issue are scarce.

That said, the general consensus on the internet is that the issue is caused by bacteria left on the surface of the beef prior to cooking, which thrive at sous vide temperatures. Some who have wound up with green sous vide beef reported that the meat didn't smell as if it had gone bad, which was confusing since visually it looked like it was rotten. For some, this was enough to throw the meat away, while others were confident that the bacteria wasn't harmful. To remove the greenish tinge, try searing the meat on both sides after it is done cooking in the sous vide machine to kill the bacteria and turn the beef a nice, textured brown again. The USDA does have guidelines on what color beef should be and indicates that a change in color alone does not indicate spoilage, but the organization does not address this sous vide problem specifically.

If you're worried about the discoloration and don't want to sear the color away after it's done cooking in the sous vide, there are some steps you can take beforehand to reduce the likelihood that it will happen to you. The first option would be to cook your beef for four hours or less. The green tinge doesn't tend to show up unless the beef is cooked for longer periods of time, usually at 131 degrees Fahrenheit. By reducing your cook time, you can limit the opportunity for bacteria to develop.

The second viable option would be to kill the bacteria before placing it in the sous vide machine. You can do this by searing the meat prior to placing it in the sous vide or you can boil the beef for a quick 30 seconds. Either way should kill the bacteria without cooking the beef all the way through. At that point, you should be free to sous vide for as long as you like.

Food safety is a serious issue, though. If your beef has turned green and it smells rotten, that probably means it has gone bad. If you're getting multiple sensory signals that you shouldn't eat the beef, you would be wise to heed that warning. That being said, it appears that beef turning green after a long time in the sous vide machine isn't dangerous to your health.