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Yogurt Production

Yogurt Production

Yogurt Production


Well simply put, yogurt is fermented milk, but it’s not that simple. The fermentation causes the lactic acid (which is formed from lactose) to act on the milk and give it its yogurt-y texture and taste. Only recently though has yogurt become a phenomenon because of low-fat healthy nature and the introduction of fruits and flavours among other things. It is thought to be invented around the 5000BC era by the Mesopotamia’s.


Milk Modification

In this process the milk is standardized, meaning its milk composition is altered by reducing the fat content and increasing the total solid content. A centrifugation process is used to separate the milk and the fat. We need around 16% of solid content, in which 1.5% is for fat and the remaining 11-14% is left for solid not fat.

This process is important for increasing the nutritional value of yogurt and for better storage composition.

Pasteurization And Homogenization

Pasteurisation: In this process, the milk is heated to less than a 100°c and stirred to help improve shelf life and remove pathogens.

Why do we need to pasteurize in yogurt production?

  • As mentioned above this destroys the pathogens and micro-organisms which will disrupt the fermentation process
  • It helps give a better texture to the yogurt by denaturing the whey protein in milk
  • Alters the flavour of yogurt massively
  • Helps in the growth of starter cultures

This process (pasteurization) can be done as either a batch process or a continuous process.

You can pasteurize milk at 85°C for 30 minutes or at a higher temperature of 95°C for 10 minutes. This helps prevent water separation at storage

Homogenisation: This is the process of breaking down fat molecules into smaller more consistent dispersed particles staying integrated, this helps in giving it a smoother and creamier end product. Nothing external is added in this process unlike the pasteurisation in which stabilizers are added to the milk.

This is done by forcing milk through small openings at high pressure and due to the shear force exerted by this the fat molecules are broken.


The milk is now cooled (between 43-46°C) and fermentation culture is added at 2%. It is held at this temperature for 3-4 hours while incubation takes place. During this bacteria breaks down certain components to form yogurt flavouring.

Different yogurt types are fermented differently, some are stirred in a large container and then poured into a settling container and left to ferment while others are just left to settle and ferment in the container without much interference.

Lactic acid is used to determine the ready-ness of the yogurt whereby a sample is taken and tested against Sodium Hydroxide (NaOH) to see its PH level and acidity percentage. The minimum standards of these process are a PH of 4.4 and 0.9% acidity.

Once the preferred standard of the company is achieved the yogurt is cooled and package

  • Flavouring

This is an additional step taken if you want to add flavour or fruits to your yogurt. Depending on the yogurt, different techniques are used. For example, set yogurt the fruit is placed at the bottom and inoculated yogurt is poured on top and fermented in the cup. A different process is used for Swiss yogurt whereby the flavouring is added to the fermented and cooled yogurt and then mixed and packaged.

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