What is a CL?
Establish Critical Limits Principle # 3 B.K.Kolita Kamal Jinadasa, Research Officer, Post Harvest Technology Division, NARA- Colombo-15, Sri Lanka.
A maximum and/or minimum value to which a biological, chemical or physical parameter must be controlled at a CCP to prevent, eliminate or reduce to an acceptable level the occurrence of a food safety hazard (NACMCF -1998)
A Critical Limit is a criterion which separates acceptability from unacceptability (Codex)
9A critical limit (CL) must be specified for each control measure at a CCP. 9Represent the boundary between safe and unsafe product.
A critical limit (CL) must be specified for each control measure at each CCP
CL exceeded CCP out of control
CL
not met may indicate one of the following: Existence
of a direct health hazard e.g. detection of Salmonella in a RTE product.
A
direct health hazard could develop e.g. under processing of a canned food.
Health hazard Unsafe product
A
product not under conditions assuring safety e.g. metal detectors at a CCP adjusted incorrectly.
Common criteria used:
Criteria for Critical Limits: 9Should be: 9Scientifically based (scientific publications, regulatory guidelines, experimental studies). 9A measurable parameters that can be, 9Routinely monitored. 9Easily and quickly measured (real-time monitoring)
(OH5 P72-FDA)
General Source
Industry/regulatory guidelines Experts
Experimental studies
Examples Journal articles, food science texts, etc. Local and foreign countries’, guidelines, tolerances and action levels Consultants, food scientists, scheduled process authorities, research institutes, equipment manufacturers, etc. In-house experiments, product analysis, contract labs, etc.
Temperature
¾
Time
¾
Moisture level
¾
pH
¾
Water activity
¾
Concentration level
¾
sensory parameters : e.g. texture, appearance
Sources of Information on Critical Limits: Scientific publications
¾
Examples of Critical Limits: Hazard Bacterial pathogen (biological)
CCP Drying
CL Water activity on dried shrimps <0.85
Metal fragments Metal detection (physical)
No metal detected
Sulphites (chemical)
Receipt of raw/frozen shrimps
<100 ppm
Bacterial pathogens (biological)
Cooking
Cook shrimps at 1000C for 3 mins.
Critical Limits for Biological Hazards: Microbiological criteria do not make practical CLs : 4 Microbiological testing is too time consuming 4 Large number of samples required 4 Costly
Instead, physical and chemical criteria used as an indirect measure of microbial growth/survival. e.g. to control pathogens in dried shrimps – dry shrimps in oven at minimum 940C, 120 mins with air flow rate of at least 0.06m3/min to achieve aw of less than 0.85.
Role of Microbiological Testing in HACCP: Initial monitoring of process safety to develop a history for comparison. Provides useful trend information over a period of time. As a tool in HACCP Verification - to verify that the HACCP Plan is working effectively and the identified limits are valid. Monitoring the sanitation/hygiene program.
Critical Limits for Chemical and Physical Hazards:
oChemical Hazards • naturally occurring - maximum limits • added - zero tolerance or permitted levels
oPhysical Hazards • zero tolerance
Monitoring raw material when no supplier quality assurance program exists.
OPERATING LIMITS: Control criteria that are more stringent than CLs, and that can be used to take action and reduce the risk of a deviation (loss of control at a CCP i.e. before CLs are exceeded)
PURPOSE OF OPERATING LIMITS:
9To account for normal variability of processing and monitoring equipment so that CLS are not violated
9e.g. a fryer with a 5OC variability should be set at least 5OC above the CL to avoid violating it.
9As opposed to safety for CLs. 9E.g. a higher cooking temp. for flavor development, inactivation of enzymes, or to control spoilage organisms- the temp. may exceed that necessary to destroy the pathogens of concern.
PURPOSE OF OPERATING LIMITS:
9To avoid exceeding a CL and the need to take costly corrective action 9OLs are more stringent than CLsestablished at a level that would be reached before the CL is exceeded. 9An additional layer of control to enable the operator to carry out process adjustment should monitoring indicate a trend towards loss of control at a CCP i.e. CL about to be exceeded.
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