How Can You Tell If Yogurt Has Spoiled?

Mold, an unexpected unpleasant smell or a swollen package is a warning not to use yogurt. Normal smell and appearance do not guarantee safety. A thin liquid layer may be separated whey; this alone proves neither spoilage nor safety.

What Signs Should You Watch For?
If mold appears, discard all the yogurt rather than scraping off the surface. Do not judge safety by the color of the mold or taste a suspect product. Do not use it if there is unexpected gas formation, leakage or a distinctly unpleasant smell. Storage time and temperature matter as much as sensory observations.

Common Yogurt Storage Mistakes
Avoid putting dirty spoons into the container, leaving it uncovered or neglecting the cold chain. Transfer the amount needed for serving to a separate dish with a clean spoon, and return the remaining yogurt to the refrigerator. Do not eat a product past its use-by date because it smells normal.

How Long Does It Keep After Opening?
Keep yogurt covered at or below 4 °C / 40 °F. Follow the package instructions for use after opening; there is no one-week or two-week safety period that applies to every product. Consider the date and storage instructions together.

Does Homemade Yogurt Spoil Differently?
The keeping time of homemade yogurt depends on the milk, fermentation process, cleanliness of the containers and refrigeration conditions. Store-bought yogurt cannot be assumed to contain additives or to be sterile. For homemade yogurt, follow a reliable, tested preparation and storage method; no validated shelf life is provided here. Clean containers and spoons help, but cannot compensate for improper fermentation or storage.