If you’re shopping around for kitchen torches, you’ll probably notice that they use one of two fuel sources: butane or propane. You want the best product you can find for your money, so it’s natural to question which fuel source is better.
What actually really matters here is how hot the fuel burns, more so than what type of fuel it is. Neither propane nor butane will have an adverse effect on the flavor of the meat, but both of these common gas fuels can burn considerably hotter than methane, the key component in the natural gas that powers gas stoves.
What you do want to do, however, is to adjust the flame on your kitchen torch until it turns dark blue. The blue color means that it’s an oxidizing flame, not a reducing flame. This is a chemistry difference that matters for your food. If the flame is yellow, it’s a reducing flame, and there will be hydrocarbons from the fuel — whether it’s propane or butane — that aren’t fully combusted. These can end up in your food, creating an “off” taste in whatever you’ve seared with the torch.