In the production of food quick methods are important to check the quality of cleaning.
During the cleaning of utensils and machines it is important to remove from the surfaces as much organic material as possible
- to insure a later disinfection and to avoid protein failure and
- to withdraw organic material for further growth of bacteria.
The ATP-luminescence measures the ATP (Adenosine tri phosphate) from animal and from vegetable cells as well as living or dead bacteria. It shows in this manner how much impurities have been left after cleaning.
Principle of the ATP-bioluminescence-method
The ATP taken up with a swab from approximately 100 cm² of the surface to be tested is put together with a luciferin/luciferase system of commercially available kits. There is light emitted which is proportional to the amount of ATP being present. This light is measured with a luminometer as “Relative Light Units RLU” .
The light being emitted during this method is proportional to the amount of ATP being present on the surface to be examined.
In order to achieve a better supervision of the hygiene it is advisable to use both system: The ATP luminescence method showing how much residues are left after cleaning, and the normal method of contact cultures telling what kind of bacteria are present,
As the ATP-method gives the total amount of organic material left, it is necessary to determine for every place how much residues are still being considered as “good”, and “bad”.
To determine the maximum RLU being accepted for these two points proceed as following:
Measure for about 1 week the RLU of all relevant places of the production line and list the results for each place and note as:
- Good cleaning: Sum total of RLU measured during one week divided by the number measures for each place.
- Bad cleaning: 2 times the “Good Cleaning” point.
In order to determine the standard of hygiene which can be obtained during normal production proceed as follow:
Determine the RLU after “normal” cleaning.
Continue the cleaning by hand using different detergents and determine the RLU after “rigorous cleaning”. This is considered as being the best achievable cleaning.
The best reference data are those values of “normal cleaning”which are as close as possible to the values of “rigorous cleaning”.
After one to two month repeat the determination of the reference points “good” and “bad”. It is very likely that these points will be reduced because cleaning is growing better as a result of the continuous supervision.
The checks may be “horizontal” being made on the same specific critical places of all machines.
It is good to change from time to time to “vertical” checks from isolated machines checking all their parts.
Understanding cleaning of food process plants
Liu and colleagues assessed the removal of food fouling deposits during the cleaning of process plants. According to the authors deposits form by adhesion to the surface and cohesion between elements of the deposit. Cleaning can result from either or both adhesive and cohesive failure.
The authors measured the adhesive/cohesive strength of deposits in terms of the work required to remove them from the surface, using a range of coated surfaces They found that tomato concentrate, bread dough and egg albumin deposits have a lower adhesive than cohesive strength, whilst others (whey protein) have a lower cohesive than adhesive strength.
The researchers present a simple model to analyse the results in terms of the work required to remove the deposit per unit surface area and volume.
Manual dishwashing for restaurants
FDA recommendation for manual dishwashing in restaurants
The FDA recommends restaurants to follow a three-step process when washing dishes, scrub in soapy hot water at an uncomfortable 110 degrees Fahrenheit (44°), rinse with clean water, and then soak in sanitizer.
Low temperatures found to be sufficient for dishwashing in restaurants
Melvin Pascall and colleagues 2007 assessed the sanitization efficiency of the manual cleaning dishwashing procedure. Pascall and colleagues found that using a combination of low washing temperatures of 75°F (24°) and and minimal sanitizer concentration (150 ppm) of quaternary ammonium compounds the FDA recommended bacteria reduction greater than 5-log bacterial reductions were achieved. The stress, however, that different material of the utensils and different food residues, like milk may have different survival opportunities for various bacteria. The authors recommend to wash dishes right away before food dries. It saves washing time and gets rid of problematic places, like gaps between prongs of forks,where bacteria might be able to survive washing and drying. This is valid for restaurants as well as for home kitchen.
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