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Hygiena

1st April 2013


Good Hygienic Practices are an essential to ensure food safety. They are required by law under national and international Food Hygiene Regulations and are frequently considered as pre-requisites to food safety systems based on Hazard Analysis such as HACCP.

 

The effective removal of product residue is of prime importance since it not only removes gross contamination (organic matter and 90% of the micro organisms) but removes any product residue the could support the subsequent survival and growth of microbes. Accordingly the effective removal of product residue is more important than residual micro organisms.

 

Until the 1980’s the only method available to measure the hygienic status of food contact surfaces was the conventional cultural method based on agar plate counts. These methods provide information about the number and types of microbes present on the surface however they tell us nothing about product residue left on the surface that can support the survival and growth of microbes.

Microbiological tests need to be conducted in a laboratory by a skilled technician, and the results are generally available in 24 – 72 hours, which is too slow to provide useful feedback information to the sanitation and manufacturing processes.

The primary objective of cleaning is to remove product debris, so the ideal test to measure the efficacy of cleaning and hygienic status is a test for product residue itself. This should give rapid results to facilitate immediate corrective action, and be simple enough to be performed on the production floor by the sanitation crew or supervisor without the need for a laboratory.

 

There are several alternative methods for measuring the hygienic status of product contact surfaces that approach the ideals above. There are instrumental methods and simple visible colour tests.

 

ATP bioluminescence assay is a biochemical test uses an enzyme luciferase that emits light in the presence of ATP. The light is measured quantitatively in an instrument called a luminometer and results are available in 15 seconds. Since almost all organic matter contains ATP (the universal energy carrier), it is present in almost all organic matter in huge amounts. ATP is also present in viable microbes (albeit in much smaller and variable amounts).

 

ATP bioluminescence is the most widely used rapid hygiene test because it delivers a direct, objective test with simple, easy-to-use equipment at low cost. The technology and application has been established for over 30 years and is widely recognised as a test of cleaning efficiency (Griffiths 1997). It can be applied to equipment and processes for raw material collection, storage, and haulage and all subsequent production equipment where cleaned manually of by clean-in-place systems. The benefits include;

·       Direct detection of product residue.

·       Improved cleaning efficiency and optimisation of cleaning chemicals giving potential savings of 25 – 50%.

·       Result in 15 seconds permitting immediate corrective such as re-cleaning.

·       Rapid results enable fast trace-back and trouble-shooting to quickly identify and prevent problems from escalating out of control.

·       Reduced risk of cross contamination that facilitates the production of high quality products with best shelf life.

·       Generation of data that provides evidence of due diligence for auditors and  trend analysis for continuous improvement

 

The rapid ATP hygiene test measures ATP from all sources which is mostly derived from food residue. This application is not a replacement bacteria test however there is a good relationship between the two methods primarily because both product residues and microbes are simultaneously removed by the cleaning processes. Microbes present on clean product contact surfaces (typically <500cfu/100cm2) are too low to be detected by their ATP content (Kyriakides et al 1991).

 

Advances in solid-state technology have enabled new instruments to be developed that deliver performance, convenience and robustness at lower cost. One such instrument is SystemSURE Plus (Hygiena International; http://www.hygiena.net/all_products-hyg_mon.html ) which also has the following unique features;

  • Low background that enables reliable detections at low ATP levels therefore reducing false positives.
  • The RLU output scale is quantitative and 1 RLU = 1 fmol ATP because high RLU numbers do not mean higher sensitivity.
  • Self-calibration that significantly reduces service and maintenance costs
  • Secure data download to PC by either of 2 software options including advanced, simplified trend analysis (Sure Trend) with pre-defined and customised report generation at the click of a button.
  • Other features include sampling plans, Re-test tag and trace function, on-screen statistical review of results without the need to download to PC.

The unique feature of the systemSURE is the low background from its novel photodiode detection system and liquids stable reagent formulation. This means  fewer false positive results and clearer trend analysis and differentiation between test results particularly at low ATP levels.

 

Sampling devices are available for solid surfaces (Ultrasnap) and for liquid samples (Aquasnap) such as CIP rinses and other water samples. All sampling devices have a simple snap and squeeze activation step ( see virtual demo http://www.hygiena.net/demos-01/ss2/SS2_demo/SOURCE_FILES/intro-02a.html ). Sample device are slim, light-weight and do not leak thus combining easy-of-use, low maintenance with reduced environmental impact.

 

SystemSURE is used by many International food processors companies whose evaluations have demonstrated with other equivalent performance to other more expensive systems using photomultiplier tube detectors.  A leading UK dairy processors compared SystemSURE Plus with the Biotrace UniLite system in a working dairy situation and found >98% agreement in terms of sensitivity, specificity and accuracy ( see Table 1) .

 

A novel liquid-stable luciferase has been developed that gives the repeatable and consistent results and long shelf life of 12 months and is very robust being tolerant to temperature abuse at 21oC for 4 – 6 weeks. This negates the need to freeze dry reagents and hence reduces manufacturing complexity and cost.  A universal ATP swab device (snapshot) fits most luminometers (http://www.hygiena.net/snapshot/info ) offering significant cost savings.

 

Several different technologies can be harnessed to provide a simple colour test that is visible to the naked eye, do not require an instrument and give results in 1 - 10 minutes. Accordingly these tests are appropriate for small and large food processors but also catering outlets and food service applications.

The two most common commercially available colour hygiene tests are those detecting protein or simple sugars ( http://www.hygiena.net/all_products-surf_sani.html ). Protein tests generally detect protein and amino acids only and are applicable to foodstuffs that are high in protein such as meat and fish, whereas sugar tests detect a much broader range for foodstuff such as dairy, fruit and vegetables. However the ATP test detects a broader range of samples, and is 10 – 100 times more sensitive than any colour hygiene test ( see Table 2).

 

There is an acceptance that hygiene monitoring methods that detect food residues on product contact surfaces provides a direct and relevant measurement of cleaning efficiency and hygiene. These methods do not necessarily replace the traditional cultural methods but provide additional information in a timely manor to supplement food safety programs by facilitating immediate corrective action, providing evidence of due diligence, optimising manufacturing processes and reducing costs whilst providing a product quality dividend.

 

References

 

Griffith, C  et al, (1997) Food Science and Technology Today (1997) 11 (1) pg 15 –24.

 

Kyriakides et al (1991) In: Bioluminescence and Chemiluminescence: current status; 519 – 522. John Wiley and Sons, Chichester


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