Why Is My Yogurt Slimy? 

 August 13, 2022

By  Diane Miles

Several things are needed to produce yogurt of the right consistency: incubation, milk, heating, and starters, most importantly. It can be disappoint to see that your yogurt has turned out slimy, but what causes this?

Many factors can contribute to slimy yogurt. These include yeast contamination, using raw or low quality milk, not heating the milk enough, or faulty temperature tracking in electric yogurt makers. Learning to correct these will reduce the chances of slimy yogurt.  

To avoid slimy yogurt, it’s helpful to learn about the various factors that can contribute to it. Below is a guide that provides useful information on these factors.

Why Yogurt Becomes Slimy

The ideal texture of yogurt is smooth, creamy, and similar to pudding.

Yogurt texture is one of the things that contributes to the delightful experience of eating it. But when making yogurt at home, it’s common for some to experience yogurt that’s slimy. It’s still safe to eat, but it’s slimy texture makes it less pleasant to do so.

These are the possible reasons why yogurt becomes slimy.

Yeast Contamination

Yeast contamination is the most common culprit for slimy yogurt.

All homes tend to have yeast floating invisibly in the air, and some remnants may also remain in kitchen utensils. Once yeast makes it into yogurt, this will affect the sensitive balance of the live bacteria which can result in slimy yogurt. However, there is a correlation between yeast and the type of yogurt starter you use.

The bacteria found in supermarket  yogurt starters are more prone to yeast contamination, while traditional or heirloom yogurt starters are more resilient in nature because they are composed of various bacteria that work efficiently together to maintain the balance among them even if exposed to some yeast.

There are a few things you can do to prevent yeast contamination:

  • Never make yogurt using a slimy starter. If the previous starter batch was already slimy, the new batch from the same starter won’t be different.
  • Sterilize all your utensils properly.
  • If you bake yeast-based bread in your kitchen too, it’s best to avoid doing this within the same day because cross-contamination can occur.
  • Don’t reuse your supermarket starter more than 3 or 4 times. The more it’s been reused, the higher the chances are for yeast contamination.
  • Use 2% or whole fat milk each time you reuse a starter. The fat content is helps thicken yogurt.

Using Raw or Low Quality Milk

Raw milk produces slimy yogurt because the proteins in this milk aren’t denatured. It’s also rich in enzymes that break down the milk, resulting in slimy, liquid yogurt.

The process of pasteurizing milk helps denature its protein content so that it results in better coagulation when the yogurt is being cultured, which is why pasteurized milk is always best for yogurt. On the other hand, all yogurt made from raw milk will be slimy or runny.

If you’ve already addressed all the other factors but still come up with slimy yogurt, it may be the milk brand you are using. This might be time to change the milk brand. Generally, pasteurized and high-fat milk from cows, goats, and sheep are recommended for producing thick, creamy yogurt.

If you prefer to use ultra-high temperature (UHT) milk, it should be heated to 275F for a second. Since it’s already cooked, using a direct-set culture is ideal.

Avoid these types of milk for making yogurt:

  • Raw milk
  • Lactose reduced milk
  • Lactose-free milk
  • Powdered milk

In addition, the milk you use for yogurt should always be fresh.

Not Heating Milk Enough

Generally speaking, milk should be heated at temperatures between 160 to 180 F for 20 up to 30 minutes. This is widely accepted and used for the best results in yogurt since it’s most efficient for breaking down milk proteins, resulting in improved coagulation.

Some also may make the mistake of skipping heating milk entirely just because pasteurized milk is being used. Foregoing milk heating will surely result in slimy yogurt. However, if the starter is already runny to begin with, even accurate heating will not help.

Faulty Temperatures in Electric Yogurt Makers

Sometimes, using an electric yogurt maker (or other heating appliance) for making yogurt is at fault. This can happen with temperature creep, or when the machine isn’t accurately using the correct temperature that it’s set to.

You can test your machine for this by putting a liter of tap water into the yogurt container. Set it to 104F then regularly check the temperature over the following 12 to 24 hours. A well-functioning electric yogurt maker should be able to maintain the water from 95-105F consistently throughout this period for proper fermentation.


Identifying what causes slimy yogurt may take some experimentation. But when you finally get it right with the help of these tips, it will be worth the effort eating rich, creamy yogurt.

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