N-acetyl-L-cysteine or N-acetylcysteine is the acetylated precursor of both the amino acid L-cysteine and reduced glutathione (GSH).
Acetylcysteine is a derivative of cysteine with an acetyl group attached to the nitrogen atom.
Heat denatures amino acids which alters their molecular structure and leaves them unusable or less usable by the body and also less insoluble. Most proteins denature between 57°C and 75°C.