Per Acetic Acid

peracetic acid

CH3CO.OOH

                       

 

Guidance note for the food industry

N.E.M Business Solutions © 2001

General Information

 

PAA was first introduced as an antibacterial agent in 1955, it has a broad spectrum of activity including bacteria, yeast's, algae and viruses. It finds wide use in the food industry mainly due to the fact that its breakdown products...(oxygen and minor traces of Acetic acid)........ need not be rinsed from the process plant

In general peroxides can be considered as high-energy-state compounds and as such they will be thermodynamically unstable.

PAA is considerably less stable than Hydrogen peroxide, PAA under normal storage conditions will loose 1% to 2% of its active ingredients per month compared to the 1% per year for Hydrogen peroxide.

NOTE dilute PAA solutions are even more unstable, a 1% solution of PAA can lose 50% of its strength due to hydrolysis in just 6 days.

In order to try and stabilise the PAA solution a "stabiliser" either Sodium pyrophosphate or 8-hydroxyquinoline are often added, these remove trace metals that accelerate the decomposition of peroxides. Lower pH solutions of PAA are also more stable, at pH 7 a 1% solution of PAA lost 84% of its strength in one day, where at pH 2.5 only 13.4% will be lost.

Anionic surfactants have been shown to improve both the stability and micro biological potency of PAA solutions.

Commercially available PAA solutions

% by weight

Interox Chemicals (Proxitane)®

Henkel Chemicals

Oxinia active® P3â

Diversey Lever

S.T. 201H®

Peracatic acid

15

5

14

Hydrogen peroxide

14

25

22

Acetic acid

28

6

28

Water

42

63

35

Sulphuric acid

0

0

0

Stabiliser

<1.0

1.0

1.0

 

Corrosion risks

PAA should be stored in a cool place in its original container. It is unaffected by glass and most plastics but may extract the plasticizer from some vinyl formulations used as gaskets. Pure Aluminium, stainless steel and tin are all resistant to PAA but plain steel, galvanised steel, Copper, Brass and Bronze will all suffer corrosion.

 

Health and Safety

 

PAA in concentrated solutions is an irritant affecting skin, mucous membranes and especially eyes. Respiritory tracts may also be irritated by PAA fumes. Contamination of the skin or eyes should be washed off immediately with large quantities of water, if swallowed, give milk or warm water and contact a doctor immediately.

 

Anti bacterial potency

In tests carried out by M.G.C Baldry and J.A.L Fraser (both of Interox Chemicals) exposure to a 250 ppm solution of "Proxitaneâ " for ten minutes produced the deaths of 106 /ml gram-positive and gram-negative bacteria, yeast's and obligate anaerobes were also killed.

Use of PAA as a sanitising agent within the food industry.

A large number of field trials were carried out by manufacturers of PAA prior to marketing PAA as a sterilant. In tests in Breweries and Dairies PAA was found to have a better sterilising effect than Chlorine at similar usage rates (typically 200 - 250 ppm as PAA). In trials were organic contaminants were found in the plant being sterilised, PAA showed far superior bactericidal properties than Chlorine, being almost unaffected by organic material or hard water scale.

 

Proxitane is a registered trade mark of Interox Chemicals Ltd

Oxinia active P3 is a registered trade mark of Henkel Chemicals Ltd

S.T. 201H is a registered trade mark of Diversey Lever

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