amino acids were grouped as monosodium
glutamate-like (MSG-like) (aspartic acid + glutamic acid), sweet (alanine + glycine + serine + threonine), bitter
(arginine + histydine + ileleusine + leusine + methionine + phenylalanine + triptophane + trypsine + valine) and
tasteless (cystidine + lysine + proline)