The correct options are i) Streptococcus thermophilus ii) Lactobacillus bulgaricus.
These are the microorganisms that are involved in yoghurt production. These are the bacterium that breaks down the lactose sugar present in milk to lactic acid. This lactic acid converts milk to yoghurt.
- Yoghurt is produced by bacterial fermentation of milk, and lactic acid is produced as a byproduct.
- Microorganisms such as Streptococcus thermophilus and Lactobacillus bulgaricus coagulate the milk protein and convert the lactose in the milk to lactic acid.
- The flavour in yoghurt is due to acetaldehyde.