Why Does Garlic Sometimes Turn Blue?

I've noticed sometimes when I cook garlic in butter that the garlic will turn blue after a while, and I had to ask myself why this happens.  After finding out that it is safe and poses no loss of taste, I sighed and continued reading.  It seems to be due to the presence of sulfates within the garlic, a component of what gives it such a pungent smell.  What happens is that the sulfates combine with the copper ions present in the butter, water, or cooking equipment to create something known as Copper (II) sulfate, or CuSO₄. This new compound is what gives off that bright blue colour.

So you may ask now if there are any precautions to be taken to avoid receiving this colour.  Luckily science has gained us much information about this process.  The main component of this phenomena is an enzyme present within the garlic that catalyzes this reaction, and can be deactivated simply by heating at high temperatures, or by letting the garlic age.