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Dairy Products Safe and True

Part B     Standards

MRD Standard 3

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Standard for Pasteurisation Heat Treatments (Superceded)

1. Purpose
2. Scope
3. References
4. Heat treatments for pasteurised milk
5. Alternative heat treatments
6. Phosphatase test

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1.     Purpose

This standard defines heat treatment conditions for the pasteurisation of dairy products.

2.     Scope

The standard applies to any dairy product and to the range of heat treatments including "low temperature, long time", "high temperature, short time" (HTST), and "higher temperature, shorter time" (HHST). It does not include ultra pasteurisation or ultra heat treatment.

3.     References

This standard is based on manuals MQD 1B and MQD 12, the Food Regulations 1984, the Codex Alimentarius Code of Hygienic Practice for Dried Milk (CAC/RCP 31 - 1983) and the US Public Health Service Grade "A" Pasteurised Milk Ordinance.

4.     Heat treatments for pasteurised milk

Pasteurised milk is milk that:

• has been heat treated by one of the following minimum temperature and time combinations:
• the batch holding method (63 ^oC for 30 minutes), or
• the HTST method (72 ^oC for 15 seconds), or
• the HHST method (89 ^oC and above for 1 second and less), or
• an equivalent heat treatment allowed in Section 5 below; and

• has been
• cooled immediately to 5 ^oC or less in the case of drinking milk or milk for storage, or
• cooled to the processing temperature if the milk goes to the next stage of processing within a time specified in the company's approved product safety programme,

using heat treatment equipment designed, installed, operated and checked in a manner that ensures that no untreated or partially treated milk passes forward.

5.     Alternative heat treatments

Alternative heat treatments must have a bactericidal effect equivalent to the treatments in Section 4.

Equivalent heat treatments for pasteurisation of milk up to 10% fat are one of the combinations below or an interpolation between them:

Minimum Holding Time (s)	Minimum Temperature (oC)
0.01 0.05 0.1 0.5 1.0 8 9 10 11 12 13 14 15 16 17 18 19 20 22 24 26 28 30 35 40 45 50 55 60	100 96 94 90 89 73.4 73.1 72.8 72.7 72.5 72.3 72.1 72.0 71.9 71.8 71.7 71.6 71.5 71.3 71.1 70.9 70.8 70.7 70.4 70.1 69.9 69.7 69.5 69.3

Equivalent minimum heat treatments for HTST pasteurisation of some specific dairy products are:

Dairy products (including cream) with a fat content of 10% or more	Increase the minimum temperature at any specified holding time by 3 oC, followed by immediate cooling to 7 oC or less, or to the processing temperature if the product is to be used immediately for further processing
Dairy products containing added sweeteners
Condensed or concentrated milk, whey or milk or whey products
Concentrated milk transported between plants	80 oC for 25 s, followed by immediate cooling to the processing or packaging temperature

Equivalent heat treatments for other dairy products depend on such factors as the nature of the product, solids content, viscosity, etc. The holding time shall be calculated from maximum flow rate data.

Some manufacturing processes (e.g. for AMF, butter and milk powder) may include adequate heat treatment to ensure product safety. A separate pasteurisation step is not required provided:

• the heat treatment is equivalent to those in the table above, allowing for the nature of the product;

• all other standards for pasteurisation apply, including product diversion for inadequate heat treatment, instrumentation for temperature control and recording, checking, and independent evaluation.

In some countries, alternative heat treatments are not permitted. Products manufactured for export to these countries must be derived from milk that has been heat treated according to the minimum standards (commonly 72 ^oC for 15 seconds) specified by the health authorities, and a separate pasteurisation step may be required in manufacturing processes.

6.     Phosphatase test

The phosphatase test (colorimetric method) does not detect small amounts of raw milk in pasteurised milk. It is therefore useful to detect contamination by raw milk, but cannot replace pasteuriser validation.

Cows' milk is not considered to be pasteurised if, when tested by the phosphatase test (MQD 4, Method 1.10.1), it shows a reading > 10 Lovibond units, i.e. phosphatase positive. However, a phosphatase negative result alone cannot be taken to mean that the milk has been pasteurised. This phosphatase limit does not apply to goats' or sheep's milk, because phosphatase levels in raw milk are much lower. When cream is tested for phosphatase, the colour of the "blank" comparator tube must compensate for the natural colour of the cream.

Revision status

Rev	Date	Status	By	Approved
2.0	8 September 1993	Issued for use	MAF Reg (Dairy)