Yogurt Starter Troubleshooting FAQ

Every day, we get thousands of questions about yogurt starter cultures and the do's and the don't's of making your own yogurt. As a beginner, having questions and concerns about making fermented foods, including yogurt, is expected. We want to support you in making the best possible yogurt, so you can reap all of the wonderful yogurt benefits that come with consuming this delicious and nutritious food.

This is the ultimate guide of frequently asked questions about yogurt starter cultures! Check it out!


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Q. My first batch of yogurt (using the freeze-dried starter) has been culturing for the maximum number of hours but is still the consistency of milk. What should I do?

A. At times, the activation batch will not set up as expected. While it isn’t the most desirable outcome, it should only happen with the first batch. Put a tight lid on the container and store in the refrigerator for at least 6 hours. Use a portion of the activation batch to culture the next batch - refer to the instructions to determine the correct ratio for your batch. Subsequent batches should set up well. Any milk remaining from the activation batch is cultured and can be used in smoothies. 

Q. My yogurt separated into solid and liquid layers (curds and whey). What happened?

A. Separation is usually an indication of overculturing or culturing at too warm of a temperature. Adjust the length of culture time and check the culturing temperature to make sure it is within the appropriate range.

Q. My yogurt seems to have set, but there's a little clear liquid (whey) floating on the top and the sides. Is this okay?

A. Some whey formation is normal when culturing. Drain the whey for a slightly thicker yogurt or stir it in, which will give you a thinner yogurt.

Q. My yogurt looks lumpy and curdled. What did I do wrong?

A. Sometimes over culturing (too long or too warm) can cause the yogurt to curdle or become lumpy before it separates fully. To make a smooth consistency, simply whisk it. (Remove some of the whey if you like, or stir it back in.) Check the culturing temperature to make sure it is within range: 105°-112°F for thermophilic cultures, 70°-77°F for mesophilic cultures.

A culture that is too old can also cause this problem. We recommend reculturing heirloom cultures within 7 days for best results. 


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Q. Why is my yogurt is grainy or gritty?

A. If the flavor is pleasant, but the texture is grainy or gritty, it often indicates that the milk was heated too quickly. Heat milk slowly to avoid this issue. 

Q. Why is my yogurt bitter?

A. Using too much starter can crowd the bacteria, creating a thin consistency and a bitter flavor.

Overcultured yogurt may also taste bitter. Check the culturing temperature to verify it is within the appropriate range. 

Q. Why is my yogurt thinner than store-bought yogurt?

A. Store-bought yogurts generally contain thickeners. Drain whey or add thickeners to homemade yogurt to achieve similar thickness. Details are in this article: How to Thicken Homemade Yogurt

Q. Why is my raw milk yogurt runny?

A. Heating denatures the milk proteins, which allows the milk to coagulate and thicken more. Raw milk has not been heated; therefore, the proteins remain intact and will not coagulate the same way and cannot create a thick yogurt. Choose options for thickening yogurt, if desired

Q. Why is my yogurt too sour or not sour enough?

A. Culturing temperatures on the higher end of the range and longer culture times will yield a more sour flavored yogurt. To achieve a less sour flavor, culture at the lower end of the range or for a shorter period of time. If choosing to culture for a long period of time, read our article, The Benefits and Perils of a Long Culture Time

Q. Why is my yogurt foamy (or stringy) and yeasty-smelling?

A. This issue is generally caused by cross contamination from yeast, which can come from a sourdough starter culturing too closely, or wild natural yeast that has come in contact with the yogurt. To avoid this problem, be sure to clean all equipment, utensils, counters and other materials used in the yogurt-making process.

Q. Why is my yogurt moldy?

A. Mold is rare in yogurt making. Make sure all equipment, utensils, counters and other materials are clean. Do not culture near garbage cans or compost bins. Use the freshest milk. Make sure to store direct-set cultures in the freezer to keep them fresh and reculture heirloom cultures at least every 7 days. If mold appears, discard everything and begin fresh with a new starter.

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