To most, milk may be what you put on your cornflakes in the morning or the stuff you use to make coffee. But there's a whole load more to it than you think. Behind every carton of Milk is a fascinating story.

Typically cows spend about 8 hours eating, 8 hours sleeping and 8 hours eating grass. Cows are usually provided with a fresh paddock of grass in the morning after milking and another fresh paddock of grass in the evening after milking. They may also be fed some grain in the dairy while being milked and Hay or Silage if there is not enough grass available.

Cows are normally milked 2 times per day, however some high producing herds are milked 3 times per day. Milking time is traditionally 6 am in the morning then around 5 pm in the evening.

The actual process of “Milking” the cow, which used to be done by hand, is now done much faster, more efficiently and thoroughly by automatic milking machines. On average this can take about 5 minutes for each cow but much depends on the type of machine and the amount of milk the cow is producing.

Most dairies have enough machines to milk 20 to 40 cows at one time, which reduces the amount of time the cows have to wait to be milked, in turn reducing any discomfort they may be feeling, if they have full udders – which you can think of as the milk storage part of the cow! Milking machines mimic the action of a young calf suckling its mother, by creating a pulsating vacuum around the teat, causing the milk to be released from the udder.

Milk storage vats or silos are refrigerated and come in various shapes and sizes. Milk is stored on the farm at 4 degrees Celsius and left for no longer than 48 hours. Vats and silos are agitated – ie shaken briskly to make sure that the entire volume remains cold and milk fat does not separate from the milk. After milk has been collected, storage vats and stainless steel pipes are thoroughly cleaned before the next milking session. 

Milk is collected from the farm every 24 or 48 hours. The tankers that are used have a special heavily insulated stainless steel body to keep the milk cold during transportation to the processing factory. Milk tanker drivers are accredited milk graders, which allows them to evaluate the milk prior to collection. Tanker drivers grade and if necessary reject milk based on temperature, sight and smell. A representative sample is collected from each farm pickup prior to being pumped into the tanker. After collection, milk is transported to factory sites and stored in refrigerated silos before being processed.

Samples of milk arealso taken from the bulk milk tanker on arrival at the factory. These are tested for antibiotic levels and temperature before the milk enters the factory processing area. Farm milk samples are tested for milk fat/protein/bulk milk cell count and bacteria count. If milk is unsuitable for Kerr’s quality products it will be rejected. Most farmers are paid on quality and composition of their milk and it is extremely important that these samples are collected and stored correctly.

Whole milk, once approved for use, is pumped into storage silos where it undergoes pasteurization, homogenization and further processing.

Pasteurization:

This process involves heating every particle of milk to a specific temperature for an exact period of time and cooling it again without allowing recontamination. Pasteurization is performed for two reasons:

To ensure all milk products are safe for human consumption by destroying all bacteria (pathogens) that may be harmful to health .

To improve the storage quality of milk by killing or rendering inactivate any undesirable enzymes and/or bacteria.

Homogenisation:

This Involves pushing the raw milk through an atomizer, causing it to form tiny particles so that the fat is dispersed evenly throughout the milk, stopping the fat from floating to the top of the container. That’s why you don’t get the cream on the top of the milk as was the case in days gone by – even if it still comes in bottles to your door!

Further processing:

This can include; reducing the fat content by micro-filtration, increasing the storage life by ultra high temperature (UHT) treatment and mixing or culturing milk for flavoured and yoghurt products.

Then milk is sent off to wholesalers and shops large and small for sale to the general public.

Copyright © 2009 John Kerr & Son Dairymen Ltd. All rights reserved.
John Kerr & Son Ltd Unit M, 207 Strathmartine Road, Dundee DD3 8PH. Telephone: 01382 825018

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