ATTRA Question of the Week

D.S.
Missouri

Answer: I am pleased to provide you with information regarding organic post harvest handling procedures for your vegetables.

Peroxyacetic acid (PAA, also called peracetic acid), in combination with hydrogen peroxide, is a popular alternative to chlorine that is allowed in organic production. Like chlorine, PAA performs well in water dump tanks and water flumes. However the treatments result in safer byproducts than chlorine treatments. The disinfection performance of PAA is comparable to chlorine and ozone. To maximize effectiveness, PAA should be maintained at a level of 80 ppm in the wash water. A post-treatment wash with clean water is required for organic standards after a disinfection treatment with PAA.

There is a good publication on this topic available on E-Organic, the Extension online portal for organic information. The title of the publication is:
“Approved chemicals for use in organic postharvest systems: In Wholesale Success: a farmer's guide to selling, postharvest handling, and packing produce (Midwest edition).” Silva, E. 2008.

An excerpt from this publication lists organically approved cleaners and sanitizers. I have pasted this list below.
Other Allowed Cleaners and Sanitizers (Suslow, 2000).
• Acetic acid. Allowed as a cleanser or sanitizer. Vinegar used as an ingredient must be from an organic source.
• Alcohol, Ethyl. Allowed as a disinfectant. To be used as an ingredient, the alcohol must be from an organic source.
• Alcohol, Isopropyl. May be used as a disinfectant under restricted conditions.
• Bleach. Calcium hypochlorite, sodium hypochlorite and chlorine dioxide are allowed as a sanitizer for water and food contact surfaces. Product (fresh produce) wash water treated with chlorine compounds as a disinfectant cannot exceed 4ppm residual chlorine measured downstream of product contact.
• Detergents. Allowed as equipment cleaners. Also includes surfactants and wetting agents. All products must be evaluated on a case-by-case basis.
• Hydrogen peroxide. Allowed as a water and surface disinfectant.
• Ozone. Considered GRAS (Generally Regarded As Safe) for produce and equipment disinfection. This is typically cost prohibitive for most producers, however. Exposure limits for worker safety apply.
• Peroxyacetic acid. Water and fruit and vegetable surface disinfectant. (1)

Also refer to the publication “Postharvest handling for organic crops.” It oultlines some the above requirements in more detail.

We encourage all of our clients to check with their certifier to insure a specific sanitation product is allowable by the national organic standards.

References:
Silva, E. 2008. Approved chemicals for use in organic postharvest systems: In Wholesale success: a farmer's guide to selling, postharvest handling, and packing produce (Midwest edition).” E-Extension. http://www.extension.org/article/18355

Resources:
Suslow, T.V. 2000. Postharvest handling for organic crops. Organic Vegetable Production in California Series. Pub. 7254. University of California Davis.
Editor's note: this was written in 2000 and some of the information is no longer accurate. Check with your certifier before using any product.

ATTRA Publication
Postharvest Handling of Fruits and Vegetables