The risk of food contamination increases when foods produced on an industrial scale come in contact with contaminants trapped in the enormous stainless steel processing machines. These machines can be difficult to clean and over time with repeated use the machines develop scratches and grooves where harmful bacteria attach and hide. Although on the surface these scratches are tiny and only a few micrometres in size, they are the perfect place for microscopic bacteria to grow and for biofilm (surface-trapped food) to adhere to. As a result, when this biofilm and pathogens come in contact with food being processed, it leads to an increased risk of food contamination.
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So how can food industries find an effective way to prevent bacteria from thriving on these machines? To answer this, researchers from the University of Toronto researched a cheaper, safer and more effective way of preventing pathogen adherence and biofilm formation.
They found that a layer of everyday cooking oil on the metal surface fills in the microscopic scrapes, cracks and fissures, forms a hydrophobic layer and creates a barrier to bacterial attachment. The researchers found that this resulted in a 1000x reduction in bacterial levels inside the industrial machines that were tested.
Alkylphosphonic acid (used as a cleaning agent) was introduced on stainless steel surfaces of the machines coated with food safe oil-based slippery coatings (FOSCs) to preferentially wet the layer of food-grade oil. The researchers found that FOSCs reduced the effective surface roughness and thus the adhesion of organic food residue and bacteria. FOSCs significantly reduced biofilm formation and also enhanced surface cleanability, which was measured by bacterial counts after conventional detergent cleaning. Importantly, antibiofilm activity remained even after the erosion of the oil layer by surface wear with glass beads, which suggests that there is a residual volume of oil that remains to block surface cavity defects.
The results show the potential of a low-cost and effective method of using cooking oils to clean stainless steel food processing machines. They are difficult to clean thoroughly with harsh cleaning agents due to their large size. Plus, the bacteria trapped in these machines build a resistance to these cleaning agents resulting in food contamination.
Everyday cooking oils like olive, corn or canola provide safer and cheaper option for cleaning food processing machines as it is more effective in reducing biofilm growth and keeping dangerous bacteria at bay.
Source: ACS Applied Materials & Interfaces
