How to use formula's to pull information out of long text?

Hey guys, I’d Like to use formula’s to create custom tags (multiple field type) from data entered in long text field. For example from this long text bellow, I’d like to be able to create tags “beef” & “lamb” in the products offered column (multiple field type). I wouldn’t want “eggs” tag be created, because the text doesn’t contain “eggs” for example

Grassland farm raises natural grass-fed beef and lamb because it is good for the land and good for you. We realize everything comes from the sun. We harvest grass, the sun’s bounty, in the form of beef and lamb. Low fat, grass-fed meat tastes better, too. You can almost taste the sunshine.

I’m thinking the formula would look something like this:
IF (product description) Contains: “beef”
THEN Create (Product) = “beef”