Question 1

How do Lactobacillus bacteria turn milk into curd?

Accepted Answer

Lactobacillus ferments lactose in milk and produces lactic acid. The falling pH causes milk proteins, especially casein, to coagulate into a thick gel, which gives curd its texture.

Question 2

Why does dough rise during fermentation?

Accepted Answer

Yeast, commonly Saccharomyces cerevisiae, ferments sugars in the dough and releases carbon dioxide. This gas is trapped by the gluten network, so the dough expands and becomes leavened.

Question 3

Is rennet a microorganism?

Accepted Answer

No. Rennet is a coagulating enzyme used to set milk proteins during cheese making. Cheese also involves a large number of bacteria and fungi, but rennet belongs to the enzyme component rather than the microbial culture.

Question 4

How is toddy produced from palm sap?

Accepted Answer

Yeast ferments the sugars naturally present in palm sap. The fermentation produces ethanol and carbon dioxide, creating an alcoholic beverage with a frothy surface; distillation is not required for toddy itself.

Question 5

What is common across these household fermentations?

Accepted Answer

Each process uses a suitable microorganism to transform a food substrate. The products differ because the organisms and pathways differ: lactic acid coagulation in curd, carbon dioxide inflation in dough, mixed microbial activity with rennet in cheese, and alcoholic fermentation in toddy.

Microbes in Your Kitchen: Curd, Dough, Cheese & Toddy

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