Critical limit

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Critical limit
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Critical Limit a criterion of minimum or maximum value that have to be met or can not be exceeded for each preventive measure associated with the critical control point (Donald A. Corlett 1998). Each parameter is separated by acceptability or unacceptability in order to prevent from the loss of safety of the finished product. Limits must not be exceeded to eliminate completely or reduce to minimum an acceptable level of a food safety hazard.

This applies usually to psychical, biological or chemical parameters which have to be controlled based on the principles of HACCP (Hazard Analysis Critical Control Point). Critical limits are identified after hazard analysis have been implemented and critical control points have been specified.

Definition prepared by Microbiological Criteria for foods describes the critical limit as: “a maximum and/or minimum value, to which a biological, chemical or physical parameter must be controlled at a CCP (critical control point) to prevent, eliminate or reduce to an acceptable level the occurences of a food safety hazard” (Regulation (EC) No 852/2004, 2004).

HACCP System Identification of critical limits (CLs) is one of seven HACCP principles, which were established in 29th April 2004 by European Parliament and European Council as a regulation 852/2004 on the hygiene of foodstuffs . HACCP is a preventative food safety management system and it is based on 7 general principles.

Stages in establishing critical limits

Establishing a critical limits is an integral part of preparing a PCP (preventive control plan).

  1. For each Critical Control Point write a critical limit for ensuring safety of food
  2. If CCPs are not identified by critical limits, it is needed to establish them in order to prevent food safety hazard. Each establishment is responsible for that kind of food safety control. It is possible to obtain assistance from HACCP experts who will help to identify critical limits
  3. For future references it is advisable to keep documentations and any scientific reports from outside experts of critical limits that have been identified. This all documentation can be necessary to validate that limits are properly established

In the course of setting a critical limit it is necessary to include all government regulations, safety food models, literature searches and many industry standards. After establishing critical limits for a CCP, this processing limits can be changed to more strictly controlled process or just to keep them with normal limitations. In case of exceeding a critical limits, it is ordered to initiate a corrective actions. Operational limits are different from critical limits. They show regular processing conditions and regulations are tighter than in critical limits (J. G. Surak, S. WIlson 2007).

Example of setting a critical limit

Critical limits are specific parameters or numbers which result from visual observation, for example:

  • Temperature
  • Time
  • pH
  • Water activity
  • Chlorine Level
  • Humidity (Donald A. Corlett 1998)

A good example of setting a critical limit can be process of milk pasteurization. Requirements for this process are that the temperature must be higher than 161 F and it should last for minimum 15 minutes to eliminate all pathogens from milk.

Another example occures in process of cooling a cooked meat product. The temperature that is maximum for product that is cooked can not remain between 40 F and 80 F for more that 4 hours neither between 80 F and 130 F for time more than 1,5 hours. It assures recontamination and that bacteria do not exist (J. G. Surak, S. WIlson 2007).


Author: Agata Drabik