Paraben is a kind of preservative, which has a preservative effect on food by destroying cell membrane of microbe, making cell protein lost its natural qualities and inhibiting enzyme of breathe and enzyme of deliver electron from working .Parabens are a group of antimicrobial preservatives widely used in cosmetics, pharmaceuticals, and in foods.. The product's optimal pH is 4-8 as a carboxyl group of paraben molecule has esterified at this pH range.
methyl paraben 
