New washing treatment conserves strawberry properties
Researchers have discovered washing strawberries in a combination of oxygenated water and acetic acid, known as peracetic acid, is less dangerous than using chlorine, website Lt10digital.com.ar reported.
Argentina’s Universidad Nacional del Litoral (UNL) chemical engineering specialist María Elida Pirovani, said they decided to study alternatives to using chlorine whose reactions reduce strawberries’ nutritional benefits.
“Fruits are washed and disinfected with chlorinated compounds 90% of the time, which causes reactions with both organic and inorganic substances, generating by-product reactions which can become cancerous.
“However, we started disinfecting with peracetic acid, whose unquestionable advantage is that it doesn’t generate such reactions.”
According to an Institute of Food Technology (ITA) expert, peracetic acid isn’t a health risk because its by-products are vinegar and oxygen which are both harmless.
Pirovani said fruit conservation was aimed at finding ways to optimise treatment without compromising beneficial bioactive compounds.
“We tested peracetic acid at various dilutions to see which were effective enough to destroy harmful microorganisms and not alter the fruit’s bioactive compounds.”
The study looked at how varying conditions of temperature, peracetic acid concentration and exposure time could modify vitamin C, polyphenols and anthocyanins.
“We found that as we increased the peracetic acid concentration vitamin C decreased, but it was not a significant decrease. On the otherhand, the chemical transformation of ascorbic acid reduces itself to dehydroascorbic acid, which is a form of vitamin C.”
They analyzed washing times discovering 60-120 seconds was best but saw no significant changes with different washing temperatures.
Pirovani stressed that although the study was confined to strawberries the same process could be applied to other fruits.
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The article above is well written, but one point should be clarified. When the ITA expert said that peracetic acid (PAA) is not a health risk, he or she probably meant to say that it was not a health risk to consumers since any PAA on the produce will have broken down to acetic acid, oxygen and water. However this is not say that there are no health risks to workers using PAA.
PAA is a strong oxidant and a primary irritant and even though currently there is no OSHA permissible exposure limits for it, the EPA has issued Acute Exposure Guidelines (AEGL 1 = 0.17 ppm calculated as a time weighted average of 10 minutes to 8 hrs. http://www.epa.gov/opptintr/aegl/pubs/results80.htm; and the ACGIH has proposed a 15 minute STEL of 0.2 ppm. http://www.acgih.org/store/ProductDetail.cfm?id=2199.
Employers should ensure that there people are not exposed to excessive concentrations of PAA vapor, through the use of engineering controls, continuous PAA gas monitors, good work practices. Engineering controls include ventilation, extraction hoods, automated dilution equipment and vapor barriers etc. Continuous gas monitors are commercially available that can detect PAA to levels to below the AEGL 1 and proposed ACGIH STEL and provide an alert if the concentration exceeds alarm threshold values http://www.chemdaq.com/gases/Peracetic_Acid.html. Work practices should be designed to minimize exposure to PAA liquid and vapor and include training (at least the requirements of the OSHA Hazcom standard 29 CFR 1910.1200, available from http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=10099).