Milk Processing Steps from Cow to Consumer | How Milk is Processed in Dairy Industry

Ever wondered how the milk obtained from cows is processed in large milk factories before it comes into the market? You will be amazed to know that there are more than 10 steps that are performed in the industry before the milk reaches the consumers in packed form.

There are reasons for this kind of processing. Firstly, it is done to increase the keeping quality of milk (so that it can be stored longer than usual). It also decreases the bacterial and microbial count and promotes good sensory characteristics. Moreover, by processing, a variety of products can be made further.

So, let us take a look at how the processing is done, unraveling each step, one by one-

• RECEIVING MILK- Since there are numerous milk suppliers, milk is collected from far-off points at places called “Collection centers”, which are away from the industry. There, the milk is cooled and then supplied to the dairy industry in road tankers, or in numerous aluminum tanks of 40 Liters capacity. The milk in these containers is graded, weighed, sampled, and cooled. When milk is received in the dairy plant, it must be 5°C or below.

• PLATFORM TESTS- There are a number of tests conducted on-the-spot when the milk is received in the industry. These include tests like taste and smell, cleaning checks, Resazurin test, Somatic cell count test, Bacteria count, Protein/Fat content measurement, measuring the freezing point of milk to check adulteration. (To know these tests in detail, explore the website!)

• PREHEATING- Milk is heated for efficient filtration and clarification (because heating decreases the viscosity of milk, which aids in these processes). The usual temperature of preheating is 35-40°C, and the equipment may be a plate heater or tubular heater.

• FILTRATION/CLARIFICATION- This step as its name suggests, removes the foreign matter, which is unsightly, and may therefore cause consumer complaints. This removes the sediment in milk, which is undesirable during processing. Filtration is done using a simple filter cloth, whereas clarification is done using a clarifier that works on centrifugal force. (To know the step in detail, explore foodtechnoscience.org)

• COOLING/CHILLING AND STORAGE OF MILK- Since there is already a long time lapse between milk procurement and its arrival in the milk industry, it is necessary the chill the milk to check the microbial count. Chilling is done using ice, plate cooler, surface cooler, bulk milk cooler, roto freezer, shell and tube coolers, and intermittent absorption units.

After cooling is properly done, the milk must be stored in a storage tank, from where it gradually goes for further processing.

• STANDARDIZATION- Standardization means adjusting the fat, and solid-not-fat (SNF) content of the milk. Thus, we either increase or decrease the two values, so that we get a standard value set by the company for milk. It is done by either adding the cream with a high or low-fat percentage.

• PASTEURIZATION- In the milk industry, it refers to heating the milk at 63°C for 30 minutes, or at 72°C for 15 seconds, and then immediately cooling it to 5°C or below. In this step, the undesirable enzymes get inactivated, and pathogenic microorganisms in the milk are killed. Instantaneous cooling is very essential as it arrests the growth of microorganisms. The two methods for pasteurization are-

1. Batch Method-> Low-Temperature Longer Time- Done at 63°C for 30 minutes, with the help of steam/hot water or by circulating through a plate-heat exchanger and holding it for 30 minutes.

2. Continuous method-> High-Temperature Short Time- Done at 72°C for 15 seconds and is done in a compact unit containing about 6 parts. They are: Flow controlled balance tank, regeneration section, heating section, holding section, cooling section, flow diversion valve.

• HOMOGENIZATION- You must have observed a cream layer on the top of the milk after boiling, or after you keep the milk without moving for a few hours. This is because fat present in milk in the form of globules rises to the top, and forms a layer of cream. Homogenization is the process to break the fat globules into very minute particles of uniform size so that they get distributed evenly in the whole milk. The small globules do not form clusters, and thus cannot rise to the surface, thus no cream formation takes place in homogenized milk.

• PACKAGING- It is one of the most crucial steps, as it not only contains the product in consumer-friendly packages but plays a major role in the marketing of the product as well. Thus, it is a crucial link between the manufacturer and the consumer. The packages used for pasteurized milk may be cans, glass bottles, and single service polyethylene pouches.

• STORAGE- In a milk plant, it is necessary to have storage rooms to store the product as soon as it is processed. These rooms are refrigerated, where the milk can be stored till delivery in the market. The temperature must be 5°C or below to check the microbial growth in milk.

In this way, the entire process of milk processing in the industry is conducted. Thus, the milk we get in the market ensures safety, great taste, as well as aesthetic appeal to the consumer.

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