The firm analysed food safety risks based on recalls in Europe and the US to understand the root causes of contamination.
They found the problem could sometimes be traced back to accumulation of food within the machinery, particularly hollows, crevices and other areas with poor accessibility for cleaning.
Scrutiny of hygienic processing practices
Stephen Jacobs, Bühler UK product manager for fruit and vegetable sorting, said there have been some high profile cases of product contamination in the past couple of years.
“There was a major Listeria outbreak in the US that was traced back to a frozen fruit and vegetable processing plant. A Food and Drug Administration report said inspectors found chipped and cracked plastic on parts of the plant equipment, which also did not allow for proper cleaning and maintenance,” he said.
“Thorough and regular cleaning of food processing facilities and equipment is the cornerstone of good manufacturing practice and one of the key pre-requisites for maintaining hygiene standards.”
Bühler’s food hygiene team worked with EHEDG, an organisation of which it is a member of, and Campden BRI to test the SORTEX F for robustness and its design for cleaning and maintenance.
The optical sorter was designed to prevent the build-up of pathogenic bacteria such as Salmonella, E. coli, Listeria and Norovirus.
It features panels that lift away (such as the rotating chute) giving access to critical product flow areas.
Jacobs said in industries that handle dry foods, such as grains or nuts, the risk of microbial growth is lower than with fruit and vegetables, which, due to high moisture content supports growth of bacteria, fungal mould and yeast.
“Crevices, hollow spaces or places in the machine which are not accessible for cleaning can harbour food soil which, in contact with water, leads to microbial growth and poses a risk for food contamination,” he said.
“Given the high moisture of the product, wet cleaning is the preferred cleaning method. High attention to hygiene is necessary for all products which are ready-to-eat, like fruits or vegetables for salads.
“Process lines are generally cleaned down after each product run or, for example, if the freezer is defrosted. This would involve a full wash down, using a high pressure hose and soap (often in the form of foams), cleaning the entire area. Cleaning usually includes disinfection to reduce the microbial risk.”
Cleaning: the objective
Jacobs said the objective is removal of visible food soil and to achieve a certain target regarding microbiological cleanliness.
“Cleaning may also have the objective of removing strong odour or allergens like, soy or celery. Wet cleaning and disinfection is preferred for the significant reduction of bacteria and allergens,” he said.
“Thorough cleaning means that the cleaning targets can be achieved efficiently minimizing time and the use of water and chemicals. The cleaning intervals are dictated by the production plan, the type of product, product changeover and the build-up of food residues in the machine.”
Cleaning methods have essentially remained the same in recent years, added Jacobs.
“However, awareness of the importance of proper cleaning is far higher today, mainly because of the high profile product recalls, associated with bacterial contamination,” he said.
“For sustainability reasons, the industry is looking for effective cleaning that saves water, energy, labour and cleaning chemicals - which is where hygienic design can make a difference.”
Well-designed hygienic equipment brings benefits for manufacturers and processors, said Bühler.
It reduces the risk of contamination, minimises the possibility of costly product recalls and increases productivity, as less water, chemicals, time and people are needed for cleaning.
Product changeover is also shorter due to faster cleaning and so is inspection and maintenance, due to accessibility and dismantling.
Jacobs said it was important to work with customers before, during and after machine installation.
“We recommend how the machine should be fed and how the product should be taken away after sorting. We also ensure that the machine is set up properly during commissioning and we supply a guide for cleaning the sorter.”