In the roasting of coffee beans, normally some will put in
butter or margarine to give a better fragrance to the coffee. It is
different to adding the butter into your coffee drink. What is the
difference? Just think of marination. What would be the difference
if you marinate chicken and leave it overnight compared to just
adding the marinade minutes before you fry them?
Anyway such roasting methods are not common in Singapore, but alot
of coffee roasters in Malaysia do that.