Peracetic acid (also known as peroxyacetic acid, or PAA), is a organic compound with the formula CH3CO3H. This organic peroxide is a colorless liquid with a characteristic acrid odor reminiscent of acetic acid. It can be highly corrosive.
Peracetic acid is a much weaker acid than the parent acetic acid, with a pKa of 8.2.
Synthesis of other compounds
The main use of peracetic acid is for the industrial synthesis of epoxides. It transfers an oxygen atom to double bonds, e.g. in ethene and propene, to form epoxides and alcohols. It can also be used in producing synthetic glycerol from propene, and is used in nylon manufacturing.
Peracetic acid is an ideal antimicrobial agent due to its high oxidizing potential. It is broadly effective against microorganisms and is not deactivated by catalase and peroxidase, the enzymes that break down hydrogen peroxide. It also breaks down in food to safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications. It can be used over a wide temperature range (0-40 °C), wide pH range (3.0-7.5), in clean-in-place (CIP) processes, in hard water conditions, and is not affected by protein residues.
Mechanism of action
Peracetic acid kills microorganisms by oxidation and subsequent disruption of their cell membrane, via the hydroxyl radical (HO·). As diffusion is slower than the half-life of the radical, it will react with any oxidizable compound in its vicinity. It can damage virtually all types of macromolecules associated with a microorganism: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyr and o-Tyr). This ultimately leads to cell lysis and true microbial death.
The United States Environmental Protection Agency first registered peracetic acid as an antimicrobial in 1985 for indoor use on hard surfaces. Use sites include agricultural premises, food establishments, medical facilities, and home bathrooms. Peracetic acid is also registered for use in dairy/cheese processing plants, on food processing equipment and in pasteurizers in breweries, wineries, and beverage plants.It is also applied for the disinfection of medical supplies, to prevent bio film formation in pulp industries, and as a water purifier and disinfectant. Peracetic acid can be used as a cooling tower water disinfect where it prevents bio film formation and effectively controls Legionella bacteria.
Peracetic acid can be used as a bleaching agent especially for Kraft pulp. It is used at weakly acidic pH and relatively low temperature. It is a relative efficient and selective bleaching agent, and it is often used as an alternative to chlorine dioxide and elemental chlorine in totally chlorine free bleaching sequences (TCF). It is however relatively expensive, and is difficult to store due to its high reactivity. This has limited its use.
Peracetic acid is extremely effective for sanitizing fowl carcasses without affecting the skin or the flesh of the bird carcass by applying direct to the meat. In particular, peracetic acid is applying to a fowl that has been killed, plucked and eviscerated by contacting the fowl with an aqueous peracetic acid solution and maintaining that contact to a time sufficient to sanitize the fowl.