There are a lot of things that different industries have learned from one another over time. One example is the food and beverage industry and what it has learned from pharmaceuticals, particularly how they conduct research and run production operations.
A Pharmaceutical Approach
Markus Keller, Gabriela Baum, and Udo Gommel of the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, Germany developed a white paper titled Research on Hygienic Coating Systems: Particle Emission, Outgassing, Chemical Resistance, Biological Resistance and Cleanability.
The paper is based on extensive research done by Fraunhofer IPA. The research reflects a pharmaceutical approach to measure various properties and environmental effects of floor and wall coating materials inside a food plant. The result is the creation of additional tools which owners and specifiers can use to make informed choices regarding the best materials suited for their specific operational needs.
As the paper’s title implies, it’s far-ranging in scope. It also sets the pharmaceutical industry as a benchmark for the food industry. There is a strong correlation between the two - one reason being that they have to combat the same enemies: particles and microorganisms.
In this article, you will learn more about:
1. Particle emission
2. Biological resistance
3. VOC outgassing
5. Chemical resistance
The white paper begins with an overview of the importance of a hygienic manufacturing environment. “In order to minimize contamination risks during manufacturing processes, production environments need to be carefully planned to ensure that no sources of contamination will be present in the final product,” say the authors. “Due to the large exposed surface area in production settings, coating materials that are used to make walls and floors need especially to be taken into consideration.” This relates largely to the particles they emit, but also includes chemicals, outgassing and other factors as well.
One of these factors is air quality, as described in the EU-GMP Guideline Annex 1 for the manufacture of sterile pharmaceutical products. In a typical production environment, for instance, particles between 10 and 20 μm in size make up the majority of airborne microorganisms. Reducing them by 5 μm or more automatically reduces the count.
Wear and tear are other factors — stresses caused by transport trolleys, forklifts, and other equipment and the potential they have in releasing particles from floor abrasion into the air. Further, if a material corrodes or becomes brittle and cracks as the result of an aggressive cleaning agent, it not only loses its material properties, but may also become a dangerous source of particulate emissions. Fraunhofer IPA developed a prototype “Cleanroom-suitable tribiological test bench IPA” to measure particulate emissions from material surfaces.
Biological resistance has to do with whether materials are inert to molds and bacteria, or if microorganisms are able to interact with them. For example, if process water accumulates in the joint of a poorly sealed flooring system, mold spores if present could flourish because of the good local growing conditions (humidity, temperature, nutrients) and become a major source of infection.
How resistant are various materials to harboring mold and bacteria growth? Right now, the only measurement method used is simple visual observation made after a material is allowed to incubate at a certain temperature for a certain time with results plotted on a chart for comparison against other materials. Currently, there is a push to replace subjective visual assessment with more reliable, objective mechanical assessment instead.
In case of reactive systems (e.g., organic resin floors versus tiles or ceramics), care must be taken to ensure that the outgassing of organic contaminants (VOCs) is kept to a minimum in order to protect employees and if sensitive processes are concerned the products as well. The quantity of organic compounds released into the air depends on surface area, outgassing time, age and temperature of the materials in question.
The process Fraunhofer IPA used to determine outgassing of various floor and wall coatings in this research involved a number of sophisticated measuring instruments and a micro chamber heating device that hold the test material pieces at 22° +/- 1° C for one hour before gasses were siphoned off for analysis.
A clean floor makes for a healthy working environment and safe, healthy food. Different floor and wall systems have different cleanability characteristics. Which one is best suited for your operation? A well-known and widely used method of finding out is called the Riboflavin Test.
It consists of preparing a contamination solution made of 0.2 g riboflavin, 1000 ml ultrapure water and 5 g hydroxyethyl cellulose and spraying it onto the test piece. Once it’s dry, it simulates a worst-case contamination scenario including the most stubborn soils possible. To clean it off, a cleanroom cloth is moistened with ultrapure water and wiped over the surface using a linear wiping simulator with standardized surface pressure and wiping speed. There are machines set up to do this in a controlled and consistent manner. After wiping, residual fluorescence from the solution is measured, photographed and plotted for comparison against other test samples.
Results of a cleanability test for three different surface finishes
Different materials react differently to the same chemicals. There are several internationally-recognized methods for assessing their resistance to them. Flooring materials, particularly in food and beverage plants, should have the highest level of resistance.
As a rule of thumb, the under-surface of a flooring system should be permanently sealed and liquid-proof. If it isn’t, liquid residues from a previous cleaning or disinfection process can linger for long periods. If the flooring has poor chemical resistance, it will likely start corroding as a result.
The procedure for assessing chemical resistance is called the ‘Immersion Test’. The flooring samples to be measured are placed in a receptacle filled with the chemical in question. The receptacle is then hermetically sealed. After being exposed for periods of one, three, six and 24 hours, the materials are examined under a microscope for blistering, discoloring, swelling, softening, reduced scratch resistance, and other effects, with results recorded in comparison. The chemicals used in the test present a representative spectrum of chemicals used in cleaning and disinfection agents.
A comprehensive understanding of the many aspects of cleanliness in hygienic manufacturing is the key to selecting suitable flooring systems for hygienic production in every industry including food and beverage. Reliable and consistent procedures for measuring particle emissions, biological resistance, VOC outgassing, chemical resistance, and cleanability make it possible to compare materials objectively. Many of the test procedures in this research are either already part of an ISO standard or in the process of becoming one.
As for the pharmaceutical industry, it has always been cleanroom-friendly and recognized for having pioneered a scientific approach to measuring the cleanliness of a plant, its processes, and the materials in a consistent and objective manner. It is encouraging to see the food industry catching up. This research program led by Fraunhofer IPA and supported by Sika is an important step in this direction.