Molecules are similar in plastics and fats causing plastic to absorb flavors.
You can use any lidded container but glass is best because it doesn't hold on to flavors the way plastic does.
A molecule is defined as an electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense. In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules.