A student researched the industrial process for manufacturing yoghurt and found the following production guidelines:
Name a genus of bacterium typically added in the starter culture to ferment milk into yoghurt.
Explain why the milk is heated to 90 ∘C90\text{ }^\circ\text{C}90 ∘C at the start of the process.
Explain why the milk must be cooled to 42 ∘C42\text{ }^\circ\text{C}42 ∘C before adding the starter culture bacteria.
Explain why the mixture is kept at a warm temperature of 42 ∘C42\text{ }^\circ\text{C}42 ∘C for 6 hours.
During fermentation, the accumulation of lactic acid causes a significant drop in pH. Describe and explain how this decrease in pH helps to preserve the yoghurt and affects its texture.
