The Benefits and Perils of a Long Culturing Time for Yogurt


Most people agree that yogurt is a great food to have in your diet. From mainstream doctors to everyday consumers, yogurt has caught the eye of just about everyone in the western world.

But not all yogurts are made alike. Cultured foods are living foods and as such are rarely the same from one batch to the next. Time, temperature, and microorganisms all play a part in determining what this particular batch of yogurt will be like.

What Makes Long-cultured Yogurt Different

You may notice that the directions given for making yogurt often include a culturing time frame like “6 to 24 hours.” That’s a big window and you will end up with a slightly different product if you culture 6 hours versus 24 hours.

As soon as you combine the warmed milk with your yogurt starter an organic process begins. The culture begins to feast on the lactose in the milk and produces organic acids, namely lactic acid, and the culture proliferates and spreads throughout the milk.

The longer the culturing process goes on, the longer the culture has time to multiply, thereby increasing the amount of bacteria and acids in the yogurt while decreasing the lactose content of the milk.

Why 24 Hours?

Some people promote a 24-hour culturing period for yogurt. Specifically, those following the GAPS or SCD diets are told that they should allow their yogurt to culture the full 24 hours.

This may be due to the lower lactose content of the yogurt after a longer culturing time. Lactose is the milk sugar that many people have trouble digesting in milk. This longer culturing time helps to eliminate most of the lactose in the milk, which some people feel makes it easier to digest.

Another benefit to the longer culturing time is the increased quantity of bacteria and beneficial acids. These two elements of yogurt are often why yogurt is touted as a beneficial part of the diet.


While some find the longer culturing period of yogurt helpful, there may be a concern for the health of the yogurt culture itself.

Because the yogurt culture feeds off the lactose in the milk, and because the lactose dwindles to almost nothing at the end of 24 hours, your culture may be on the verge of starving toward the end of the long culturing period. This can stress the culture or even kill it if you aren’t careful.

Of course this isn’t an issue if you are using a direct-set culture, which is used only once. But if you are using a self-perpetuating culture, that is, you use your new batch of yogurt to make your next batch of yogurt, your culture might grow weak or unhealthy over time and would have to be replaced.


Because of the risks involved to the culture, we recommend that if you are doing an extra-long ferment, you use a direct-set yogurt variety. If you do choose to use a reculturing variety of yogurt, remove and refrigerate enough to start your next batch at the end of the regular culturing period, then let the rest continue for the longer time.


Homemade Yogurt with Blueberries

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