Hiding Ingredients

To hide ingredients from JEI, you have to first create a plugin.

In the register method of your plugin, it is passed the IModRegistry.
From there, you can get the ingredient blacklist:

IIngredientBlacklist blacklist = modRegistry.getJeiHelpers().getIngredientBlacklist()

Any ingredient added with IIngredientBlacklist#addIngredientToBlacklist will not be shown to the player in the ingredient list.

Blacklisted ingredients will still show up in recipes.