Following our “Dry Cleaning: Is Water Friend or Foe in Food Safety and Sanitation?” webinar on Aug. 25, 2022, Deb Smith from Vikan and Karl Thorson from General Mills received over 130 questions. Below are the top 9 most frequently asked questions, together with responses from Deb and Karl, which we thought might be useful to share with you. Some questions have been edited for brevity and clarity.
1. How can you achieve an allergen-free level of clean using only dry cleaning?
IF you can get ALL food contact surfaces visibly clean using the dry-cleaning methods employed, Karl advocates that 100% visibly clean = allergen clean.
Physical access to surfaces is also critical - if you can’t see and touch the surface at the same time it will be difficult to ensure that it is visibly clean. All cleaning methods (except CIP) require full accessibility to all surfaces for cleaning and inspection. So, you need the surfaces and equipment that will, or are likely to, pose a risk of controlled allergen cross-contact to be of hygienic design (as mentioned during the webinar).
Cleaning validation, verification, and monitoring for controlled allergens should not be based only on analytical sampling of the surface/piece of equipment. Sampling of a relatively small area of a surface/piece of equipment for a controlled allergen alone doesn’t guarantee that ALL of that surface/piece of equipment is allergen free since sampling can easily miss allergens in an area that has been missed during cleaning or lurking in hidden area.
Here is a very good external article link on what to look at when validating, verifying, and monitoring a cleaning operation: Validation, Verification, and Monitoring of Cleaning in Food Processing Factories | Food Safety (food-safety.com).
The principles of cleaning validation have also been described in a European Hygienic Design Group (EHEDG). Guideline on Cleaning Validation that you can purchase on-line at https://www.ehedg.org/guidelines-working-groups/guidelines/guidelines. Unfortunately, there are some soils where dry cleaning is simply not sufficient to remove the hazard to an acceptable level and where either dry chemistry or wet cleaning methods are required to do so. The decision on which to use should be based on risk.
2. Why is the use of compressed air a high-risk activity for a dry-cleaning operation?
Compressed air just moves or spreads the material that you want to remove over a great distance. So, debris, which may include food, food allergens, and microbes, can be spread to another area/line. If there is no food safety risk related to the spread of these things, and you are aware of the spread, compressed air can be very useful for detail cleaning.
3. Does Vikan manufacture (coloured) vacuum attachments, and where can we find the ATEX-certified vacuum cleaners that were mentioned in the webinar?
Vikan do not produce vacuum-attachments, but we know some vacuum manufacturers that sell coloured ones to support hazard segregation, i.e., Delphin, and Nilfisk. Both companies also offer ATEX rated and U.S. compliant vacuum systems for use in explosive environments. An internet search would help you find a local supplier.
4. Can you suggest a dry-cleaning method for an oily and sticky product?
We have a range of scrapers, squeegees and brushes that could possibly be used to support you with your dry-cleaning challenge. Please have a look at our Guidance Tool tailored towards helping select cleaning tools for dry cleaning. As mentioned in the webinar, damp microfibre cloths are also good at removing oily and sticky soils.
Unfortunately, there are some soils where dry cleaning is simply not sufficient to remove the hazard to an acceptable level and where either dry chemistry or wet cleaning methods are required to do so. The decision on which to use should be based on risk.
5. Can I apply dry cleaning to drains?
We are interested to know:
- Why would you want to dry clean a drain? Because if the drain is wet (through its use to remove fluids), then dry cleaning it doesn’t offer any benefits.
- If the drain is dry, why is it there? If it’s not in use, it should be closed or sealed, in which case it won’t need cleaning.
Most drains are normally wet-cleaned and disinfected. However, dry cleaning techniques, i.e., physical removal of large debris and bulk solid using a scoop, a brush, or a squeegee, can be a preliminary step in wet drain cleaning.
6. Are there innovative dry-cleaning technologies currently in use?
Although the most common dry-cleaning tools and methods are manual and/or mechanical (i.e., vacuuming, wiping, scraping, scrubbing, sweeping, pigging, and granular purging) as mentioned in the webinar, there have been some innovations in dry cleaning technologies. The key innovations are as follows:
(i) Use of Dry Ice – uses carbon dioxide to form dry ice crystals which are fired at high velocity on to the surface to be cleaned. A good information reference link: Province of Manitoba | agriculture - Dry Ice Blast Cleaning for the Food Processing Industry (gov.mb.ca)
(ii) Use of Dry Steam – uses super-heated saturated steam with almost no moisture (<0.5%). Here is a good reference link from the internet: Dry Steam Cleaning Growing as a Strong Sanitation Solution in 2020 | Goodway
(iii) Use of Ultrasound – use of sound waves with higher frequencies to remove dirt, grease, and grime from surfaces. Please see this link for more information: Ultrasonic cleaning food industry (ultratecno.eu)
(iv) Use of Hot Oil Flushes – used to melt fats/fatty foods in pipework, but care is taken not to increase temperatures excessively above melting point thresholds, as fats may burn, polymerise, and stick to the surface, etc.
Please note that the use of these techniques is still limited, and manual cleaning remains the most used for dry cleaning due to its flexibility in dealing with the diversity of the cleaning challenges encountered. You should also note that the use of dry ice and granular blasting can result in the uncontrolled spread of contamination (similar to that created through the use of compressed air), so these techniques should be considered carefully before being used.
7. We have a nut grinding machine that we would prefer to dry clean, and we are being asked to disinfect/sanitize after dry cleaning. How can disinfection/sanitization be accomplished using dry methods?
Some examples of dry disinfection/sanitization include:
- Alcohol-based wipes and sprays
- Heat
- UV light
- Vaporised hydrogen peroxide or gaseous ozone as a fumigant
- Karl uses DrySan Duo Cleaner and Sanitizer from Ecolab
These methods should be used in accordance with the manufacturers’ instructions. Also ensure that they are approved for use on food-contact surfaces according to local regulatory requirements, e.g., the EPA in the U.S.
8. Is it possible to dry clean a tool with an approved disinfectant/sanitizer only?
Tools should always be cleaned (gross soil removal) first, even if that only involves gently knocking or shaking the brush or rinsing or wiping the tool surface. The reason for this is that organic matter reduces the efficacy of disinfectant/sanitizer. Additionally, disinfectants/sanitizers are aimed at microbial reduction so they are unlikely to be as effective for the removal of other contaminants, e.g., food soils, including allergens, foreign bodies, and chemical residues.
More information about the cleaning and maintenance of tools is available in our white paper on the subject.
9. Could you share some of your favorite dry cleaning-related publications?
We would highly recommend the following:
Further resources (white paper, articles, and posters) are available at vikan.com under Services and Knowledge.
Disclaimer: The responses given to the questions selected are the professional opinions of hygiene experts and are not necessarily endorsements of any of the products and services mentioned. Companies should conduct their own site-specific risk assessment and develop their own hazard controls as part of their food safety plan. For further information and support on dry cleaning and water management, please feel free to contact:
