Unprocessed Milk Poses Health Risk

Ever since the Kenya Dairy Board launched a campaign for safe milk consumption, debate has raged over the correct processing methods. This article sets the record straight on a number of safety, quality and processing issues. To start with, it is important not to misunderstand pasteurisation. It does no harm to the nutrients in milk. It is a process that subjects milk to a specific temperature and time treatment to destroy all pathogenic (disease-causing) organisms without interfering with its nutritional value.

The milk is then cooled immediately to below 10 degrees centigrade to ensure multiplication of residual micro-organisms is stopped or retarded. There are two types of temperature/time pasteurisation processes - the long-holding low-temperature time process and the short-holding high-temperature time process. Pasteurisation is not to be equated to boiling, because, though a relatively high temperature is achieved by boiling, the temperature may not be adequate to effectively destroy pathogenic micro-organisms, especially the heat-resistant ones. Also, the exposure time has not been put into consideration and the immediate cooling required is not achieved. Furthermore, prolonged boiling will destroy the nutritional value, usually seen at the bottom of the heating vessel as a brown layer.

Other very important steps involved in milk processing are:

• Organoleptic, chemical and microbial tests done by qualified and healthy persons on raw milk received at the processing plant, ensuring that only milk of good quality is processed;
  
• Proper cleaning of all processing lines, tanks and machines, using detergents at the right concentrations, temperature and exposure time, followed by sterilisation to eliminate contamination in processing;
  
• Homogenisation, which breaks fat globules into smaller particles, hence ensuring product uniformity; and
  
• Packaging done in clean and sterilised material to avoid post-pasteurisation contamination.

If handled under clean and hygienic conditions, unprocessed milk will have a low microbial load. However, in an informal set-up, popularly known as hawking - where milk is sold raw - quality and safety can be compromised in a number of ways:

• The milk is handled by a number of people with no proper handling techniques and whose health status is unknown;
  
• The hawker lacks the facilities and the technology to check the quality of the raw milk delivered before transfer to the consumer, milk which could be from unhealthy cows or contain veterinary drug residues;
  
• Being an ideal medium for microbial growth, holding raw milk for a long time at room temperature encourages spore-forming and thermoduric micro-organisms, which resist heat treatment when the milk is boiled at home.

It is important for scientific research to be done on milk-borne health risks.

In Kenya, in 1999/2000 a small-scale dairy project involving the Kenya Agricultural Research Institute, the Ministry of Agriculture and Rural Development, the International Livestock Research Centre and University of Nairobi scientists confirmed that samples from the informal milk sector did not achieve the Kenya Bureau of Standards' requirements. To arrest the microbial growth, itinerant milk traders use harmful chemical preservatives. The Kenya Dairy Board, therefore, recommends that milk be processed by appropriate technology to ensure it is safe and maintain the nutritive value and natural physical composition.

To legalise hawking and advocate boiling for consumption is to put the public's health in jeopardy. Nowhere in the world is milk allowed to be sold in an unhygienic environment and the industry can never be developed through hawking. The board is, therefore, encouraging hawkers and producers to form groups and register with the board to enable them to benefit from the board's training for small-scale milk traders on proper methods of handling and processing.