QUALITY CONTROL OF PASTEURISED MILK *
1. INTRODUCTION

Milk testing and quality control is an essential component of any milk processing industry whether small, medium or large scale. Milk being made up of 87% water is prone to adulteration by unscrupulous middlemen and unfaithful farm workers. Moreover, its high nutritive value makes it an ideal medium for the rapid multiplication of bacteria, particularly under unhygienic production and storage at ambient temperatures. We know that, in order for any processor to make good dairy products, good quality raw materials are essential. A milk processor or handler will only be assured of the quality of raw milk if certain basic quality tests are carried out at various stages of transportation of milk from the producer to the processor and finally to the consumer.
There are a number of standard manuals and text books on milk quality control. The methods selected are simple and basic and will suffice the requirements of most milk quality control laboratories of small scale processing units. For the larger plants with bigger laboratories more tests are to be found in the bibliography at the end of this booklet.
2. MILK TESTING AND QUALITY CONTROL
2.1 WHAT IS MILK QUALITY CONTROL?
Milk quality control is the use of approved tests to ensure the application of approved practices, standards and regulations concerning the milk and milk products. The tests are designed to ensure that milk products meet accepted standards for CHEMICAL COMPOSITION AND PURITY AS WELL AS LEVELS OF DIFFERENT MICRO-ORGANISMS.
2.2 WHY HAVE MILK QUALITY CONTROL?
Testing milk and milk products for quality and monitoring that MILK PRODUCTS, PROCESSORS and MARKETING AGENCIES adhere to accepted codes of practices costs money. There must be good reasons why we have to have a quality control system for the dairy industry in Kenya.
The reasons are:
i)To the Milk Producer.
The milk producer expects a fair price in accordance with the quality of milk she/he produces.
ii) The Milk Processor.
The milk processor who pays the producer must assure himself/herself that the milk received for processing is of normal composition and is suitable for processing into various dairy products.
iii) The Consumer.
The consumer expects to pay a fair price for milk and milk products of acceptable to excellent quality.
iv) The Public and Government Agencies.
These have to ensure that the health and nutritional status of the people is protected from consumption of contaminated and sub-standard foodstuffs and that prices paid are fair to the milk producers, the milk processor and the final consumer.
All the above-is only possible through institution of a workable quality testing and assurance system conforms to national or internationally acceptable standards.
2.3 QUALITY CONTROL IN THE MILK MARKETING CHAIN IN KENYA
i) At the farm
Quality control and assurance must begin at the farm. This is achieved through farmers using approved practices of milk production and handling; and observation of laid down regulations regarding, use of veterinary drugs on lactating animals, regulations against adulterations of milk etc.
ii) At Milk collection Centres
All milk from different farmers or bulked milk from various collecting centres must be checked for wholesomeness, bacteriological, and chemical quality.
iii) At the Dairy Factories
Milk from individual farmers or bulked milk from various collecting centres
iv) Within the Dairy Factory
Once the dairy factor has accepted the farmer milk it has the responsibility of ensuring that the milk is handled hygienically during processing. It must carry out quality assurance test to ensure that the products produced conform to specified standards as to the adequacy of effect of processes applied and the keeping quality of manufactured products. A good example is the phosphatase test used on pasteurised milk and the acidity development test done on U.H.T milk.
v) During marketing of processed products

Public Health authorities are employed by law to check the quality of food stuffs sold for public consumption and may impound substandard or contaminated foodstuffs including possible prosecution of culprits. This is done in order to protect the interest of the milk consuming public.