Peracetic acid (PAA): Broad-spectrum and low-residue biocide

Cleaning, sanitising and disinfecting are three essential processes in the food industry. Three actions whose objective is ensuring food safety, thus preventing food poisoning, in addition extending the products’ commercial life. Out of these three sanitation phases in the food industry, based on its importance, we will focus our attention on the disinfection of surfaces and environments. All equipment and tools in the work areas must be disinfected to ensure that sufficient hygienic conditions are achieved to achieve the highest hygiene and safety level.

But what does “disinfecting” mean? The Royal Spanish Language Academy defines disinfect as « removing the infection from something or the property that causes it, destroying harmful germs or preventing their development. » Therefore, unlike the sanitising product, disinfectants are aimed at attacking the microorganism vital elements, destruct it and cause the cell lysis. In the food industry, the elimination of pathogenic microorganisms and the reduction of the altering microorganisms to acceptable levels is a necessity.

Nowadays, there is a wide range of active biocide substances to disinfect and attack microorganisms in the food industry, such as chlorinated agents, aldehydes, salts of quaternary ammoniums, alcohols, hydrogen peroxide, tertiary amines, polymeric biguanides or peracetic acid, among others. We are going to talk about the latter in this post.

 

What is peracetic acid (PAA)?

It is an organic compound with the formula CH3CO3H, also known as peroxyacetic acid. More specifically, we could say that it is a product of equilibrium reaction that occurs by the reaction of acetic acid with hydrogen peroxide.

The PAA has many industrial applications, but we are only going to focus on its use as a disinfectant in the food and beverage industry, although other typical applications include industrial laundry, the paper industry or the treatment of water and wastewater.

Its use is very widespread for disinfecting surfaces and circuits in the food industries due to the fact that its by-products are harmless (acetic acid, oxygen and water), thus minimising the risk to the environment and human health.

The United States Environmental Protection Agency (EPA) describes peracetic acid as an ideal antimicrobial, due to its high oxidant potential on the outer membrane of bacteria, endospores, fungi, viruses and yeasts. Its oxidation mechanism consists in the transfer of electrons from the oxidised form of the acid to the microorganisms, thus causing their inactivation or even their death.

These good efficacy characteristics, essentially without toxic residues, easy application (in aqueous solution) and relatively low cost, have cause peracetic acid to become an increasingly popular antimicrobial in many food and beverages related industries.

Regulations from the Environmental Protection Agency (EPA) and the United States Department of Agriculture (FDA) establish that peracetic acid can be applied as a disinfectant on surfaces in contact with food and for direct contact of food with fruits, vegetables, meat, poultry and seafood.

The use of peracetic acid solutions as an antimicrobial agent in carcasses and poultry meat is accepted in the United States by the FDA with limits of 220 ppm for peracetic acid and 110 ppm for hydrogen peroxide. A report was sent in 2013 regarding this use to the EFSA, the European Food Safety Authority for its assessment. The EFSA analysed the data and a few months ago published a favourable scientific opinion regarding the safety and effectiveness regarding the use of peracetic acid to control pathogens in poultry meat.

The report issued by the EFSA concludes that peracetic acid can be effective to disinfect bird carcasses without affecting its skin or meat. In particular, the acid is applied to the carcass, once plucked and eviscerated, by immersion or spraying thereof with an aqueous solution of peracetic acid. The results of this evaluation support the direct application of peracetic acid on chicken meat as a complement to other strategies to control the presence of pathogens, but at the moment, there is no European Regulation that allows using PAA on meat.

It is therefore a high-level surface disinfectant, it has biocidal efficacy against bacteria, fungi, yeasts, endospores and viruses at concentrations below 100 ppm in 5 minutes or even less. It can be used on a wide temperature range (up to 60 °C), it is not affected by water hardness or protein residues.

What can be disinfected with peracetic acid?

Due to its characteristics and benefits, this disinfectant helps in a large variety of industries such as food, food and beverage processors, including from meat processing operations to canning and dairy.

PAA is considered the disinfectant par excellence for closed systems. It is used to disinfect CIPs, pasteurisers, tanks, surfaces or fillers, due to its excellent low level of foam and easy rinsing. It can also be used in environments with carbon dioxide, such as fermentation tanks, aging containers or carbonators, in the brewing, wine and bottling industries, among others.

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