Natural
A natural dairy product
 

Plain yoghurt is a natural dairy product made from milk and two associated bacteria cultures: Lactobacillus bulgaricus and Streptococcus thermophilus.
 
Natural fermentation

Yoghurt is produced by lactic fermentation. The process is very similar to the one used for making beer, wine and cheese - in each case, beneficial organisms transform a basic ingredient via a process known as fermentation.

Fermentation is a process that naturally extends the shelf life, notably thanks to the presence of lactic acid produced during the fermentation process. It is the lactic acid that gives the recognisable sour taste in yoghurts, and acts as a natural preservative.

Fermentation also has other advantages such as the addition of organoleptic properties (taste, flavour, texture and consistency), improving the nutritional quality, and enhancing the digestibility of the milk and the better assimilation of minerals naturally present.

 


Yoghurt production

Preparation of the milk
  • The milk composition - which can be a mix of either whole, low fat or non-fat milk - is adjusted to achieve the desired fat and solids content. Often dry milk is added to increase the amount of protein and so provide a more desirable texture.
  • The milk is then pasteurized.
  • This high heat treatment allows the proteins to form a gel and also removes any harmful bacteria in the milk and provide a better environment for the starter cultures to grow.
  • Milk is pasteurized before the starter cultures are added.
  • The milk is then cooled to 42°C. This is the ideal temperature for the growth of the starter culture bacteria.
 

Adding the microorganisms

  • The starter cultures, Lactobacillus bulgaricus and Streptococcus thermophilus are mixed into the cooled milk.
  • The milk is kept at 42°C to maximise the fermentation process.
  • As the bacteria grow and multiply, they transform the milk sugar, lactose, into lactic acid, which in turn acts on the milk proteins, which then solidify and coagulate.
  • Streptococcus thermophilus hydrolyses the milk proteins and contributes to the unique aroma, texture and flavour of yoghurt.
  • This process of fermentation thickens the milk into yoghurt, giving it its characteristic custard-like texture and its tangy taste.
  • After several hours, the yoghurt is cooled to stop the fermentation process.
 
Fruits and flavouring

Fruits, flavours and other ingredients can be added to the yoghurt at various points in the manufacturing process depending on the type of yoghurt.

  • For set yoghurt, the fruit - for example - is added to the bottom of the jar and the yoghurt is fermented directly in the cup.
  • For stirred yoghurt, the fruit is blended with the fermented, cooled yoghurt prior to the packaging.
 

Other varieties

This manufacturing process is identical for all types of yoghurt, only the source of milk changes. The manufacture of other fermented milks also follows the same type of process, again only the starter cultures and fermentation parameters are different (temperature, time ...).
 
 
YLFA INTERNATIONAL
Ave d'Auderghem 22-28
B- 1040 Brussels
Belgium

ylfa@ylfa.org

T +32 2 549 50 81