Dry Cleaning Best Practices

When does water make cleaning harder? Considerations for when dry cleaning is the better option.

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Wait…I’m allowed to clean without soap and water?!

No doubt about it, cleaning and sanitizing food contact surfaces are core components of on-farm produce safety. However, for crops like onions and garlic, moisture may increase the risk of microbial growth and premature decay, and make overall cleaning harder than it needs to be.

The FSMA Produce Safety Rule requires growers to monitor and keep all food contact surfaces clean. The rule does not specify how to keep those surfaces clean. In other words, you need to keep things clean, but you don’t necessarily have to use water. Let’s dive into how to achieve a clean surface without using water. 

When dry cleaning is appropriate:

We already mentioned some crops in the Allium family as good candidates for dry cleaning. For alliums, dry cleaning typically happens after curing, when onions and garlic have developed a protective outer skin. Crops like tomatoes and soft fruits are also commonly handled and packed on dry lines. Keeping these crops, and the surfaces they come into contact with, dry is important for maintaining their already-fragile shelf lives. Even crops like apples, which are often washed and waxed, benefit from a dry environment after waxing. 

Dry cleaning may be appropriate in all of these examples since introducing water could increase the risk of bacterial growth. Cross-contamination risks can be high in these environments because dormant bacteria, such as Listeria and Salmonella, can be revived with the introduction of water. Cleaning and sanitizing appropriately is just as important on dry lines as it is on wet lines. 

How does dry cleaning actually work?

The process for dry cleaning equipment, tools, and surfaces is very similar to the standard wet cleaning procedure. The difference is that, when water is used in wet cleaning, an alternative dry option is swapped in, eliminating the need for a rinse step.

1. Start by removing visible soil and debris. Use a clean, dedicated, dry brush. Or, for heavily soiled surfaces, use a vacuum or compressed air to remove visible debris.

2. Once all visible dirt is removed, use a waterless cleaner to clean the surface. Alcohol-based cleaners are a popular choice, since they are waterless and very fast-drying. 

3. Finish by using an air-dry sanitizer. Make sure the sanitizer is labeled for food-contact surfaces, and wait until the surface is completely dry before using it again. 

   1. Alternatively, you could use sanitizer technologies, such as dry steam or UV radiation, instead of a liquid sanitizer.

      
      

Can I just dry clean everything? ...and other final thoughts:

While surfaces on dry lines can be dry cleaned during peak use, it is recommended to still incorporate wet cleaning at routine intervals, such as before and after peak season. Studies have shown that bacteria such as Listeria and Salmonella persist in biofilms in dry packinghouse environments, even with the use of dry cleaners and sanitizers. Scrubbing all food-contact surfaces with water and detergent periodically can help remove biofilms and built-up residue and lower the risk of pathogen contamination.  

In summary, dry cleaning and sanitizing food-contact surfaces is a good way to preserve quality and prevent post-harvest losses in moisture-sensitive crops like onions and garlic. Regular, thorough waterless cleaning helps ensure crops reach consumers in good and safe condition. Additional periodic cleaning with water, such as before and after harvest season, can improve cleanliness without increasing the risk of moisture contacting the crop.

Want to learn more? 

Michigan Produce Safety Technicians are ready to help you meet your on-farm produce safety goals. We will work with you to identify, manage, and minimize risks to food safety on your farm, and help you create a comprehensive food safety plan to prepare you for an MI Produce Safety Risk Assessment Certificate. Working with produce safety technicians is always free and confidential, and there is no cost to apply for the certificate. Click here to get started.

Sources: 

1. Callahan, C. (2022). “Dry cleaning” on produce farms: Alternatives to using water & detergents. University of Vermont Extension Ag Engineering. https://blog.uvm.edu/cwcallah/2022/06/22/dry-cleaning-on-produce-farms-alternatives-to-using-water-detergents/. 

2. Dawson, P. & Cooksey, K. (2021). Survival of Listeria monocytogenes and Salmonella on surfaces found in the dry packinghouse environment and effectiveness of dry-cleaning processes on pathogen reduction. Center for Produce Safety. https://www.centerforproducesafety.org/research-database/survival-of-listeria-monocytogenes-and-salmonella-on-surfaces-found-in-the-dry-packinghouse-environment-and-effectiveness-of-dry-cleaning-processes-on-pathogen-reduction. 

3. Dry sanitation in fresh produce food safety. International Fresh Produce Association. (2023, July 18). https://www.freshproduce.com/resources/food-safety/dry-sanitation/

4. Lupo, L. (2013). Dry cleaning: Reducing moisture to increase food safety. Quality Assurance & Food Safety. https://www.qualityassurancemag.com/article/qa1213-dry-cleaning-reducing-moisture/

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Article by Landen Tetil, Produce Safety Technician