Why does curd smell like yeast after a day?

Question

Noticed a yeasty or bread-like smell from your curd? Learn what causes this to happen during the fermentation process.

Answer 1

Curd smells like yeast after a day due to the fermentation process where lactose (milk sugar) is converted into lactic acid and other byproducts by microorganisms, including yeasts, which can produce yeasty odors. This is more pronounced when the curd is not stored properly or when the starter culture contains a higher proportion of yeast.

Detailed Explanation:

The characteristic sour taste and smell of curd (yogurt) are primarily due to the production of lactic acid by bacteria during fermentation. However, other microorganisms, including yeasts, can also be present in the milk or starter culture used to make the curd. These yeasts can ferment lactose and other sugars, producing ethanol, carbon dioxide, and various aromatic compounds. Some of these compounds can have a yeasty or slightly alcoholic smell.

Several factors can contribute to a more pronounced yeasty smell:

1. Contamination: Unhygienic conditions during curd preparation can introduce unwanted yeasts and other microorganisms.
2. Starter Culture: Some starter cultures may naturally contain a higher proportion of yeast.
3. Temperature: Higher temperatures can favor the growth of yeasts over lactic acid bacteria.
4. Storage: Improper storage, especially at room temperature, allows yeasts to proliferate.

The lactic acid bacteria typically dominate the fermentation process, suppressing the growth of yeasts. However, if conditions favor yeast growth, they can contribute significantly to the aroma of the curd.

Pro Tip:

To minimize the yeasty smell, ensure you use a fresh and reliable starter culture, maintain strict hygiene during preparation, and refrigerate the curd promptly after it sets. This will slow down the growth of unwanted yeasts and preserve the desired flavor profile.