Freezing Technology

8.1.11 Establish critical limits for each CCP (Principle 3)

Critical limits:

Critical limits are defined as criteria that separate acceptability form unacceptability. A critical limit represents the boundaries that are used to judge whether an operation is producing safe products. Critical limits may be set for factors such as temperature, time, physical product dimensions, water activity, moisture level, etc. These parameters, if maintained within boundaries, will confirm the safety of the product.

Sources of information on critical limits include

• Scientific publications/Research data
• Regulatory requirements and guidelines
• Experts (eg. Thermal process authorities, consultants, food scientists, microbiologists, equipment manufactures, sanitarians, academicians)
• Experimental studies (eg. In house experiments, contract laboratory studies)

Table Examples of critical limits

Hazard	CCP	Critical limit
Bacterial pathogens (Non-sporulating)	Pasteurization	72oC for at least 15 sec.
Metal fragments	Metal detector	Metal fragments larger than 0.5mm
Bacterial pathogens	Drying over	Aw < 0.85 for controlling growth in dried food products
Excessive nitrite	Curing room/brining	Max. 200 ppm sodium nitrite in finished product
Bacterial pathogens	Acidification step	Max. pH of 4.6 to control C. botulinum in acidified food
Food allergens	Labelling	Label that is legible and contains a listing of correct ingredients
Histamine	Receiving	Max. of 25 ppm histamine levels in evaluation of tuna for histamine

Table Critical limits Vs Operating limits

Process	Critical limit	Operating limit
Acidification Drying Hot fill Slicing	pH 4.6 0.84 Aw 80oc 2.0cm	pH 4.3 0.80 Aw 85oc 2.5cm