Carboxyl groups have an electronegative oxygen atom double bonded to a carbon atom. This carbon-oxygen bond is very polar and the fact that its a double bond increases the polarity of the bond.
PEA agar, also referred to as Phenylethyl Alcohol Agar is a medium  used by microbiologists to grow microorganisms. The ingredient that  supplies nitrogen is casein. Making the world better, one answer at a time.
Whatâs so startling about this discovery is that labs have spent years trying to recreate the complexity of eggs, scoop by powdery scoop. Start with pea protein or wheat gluten, add a dash of tapioca starch or potato flour, a pinch of gums and celluloses, and you end with something, uh, vaguely goopy and egg-like.