12 Questions About Yogurt Starters for Homemade Yogurt

Sneak Preview: Many of your questions about yogurt starters for homemade yogurt will be answered here. This is not exhaustive but rather a beginner’s guide to the ins and outs of common yogurt starters.

1. What’s a yogurt starter?

A yogurt starter contains live yogurt microbes like Lactobacillus bulgaricus, Streptococcus thermophilus, L. acidophilus, among others. If you set it up right, adding a yogurt starter to warm milk and incubating for several hours will result in yogurt. No starter? No yogurt.

There are other methods for making yogurt without the usual starter, but I will not address them here as they are for advanced fermenters.

2. Can I use a jar of my favorite yogurt from the store?

Yes, if it’s unflavored, fresh, and contains live cultures
Avoid yogurt with additives such as gelatin or other thickeners as they can cause a grainy texture

3. What’s the difference between using yogurt from the store and freeze-dried yogurt starters?

Store-bought unflavored yogurt:
- Readily available in almost every grocery store
- Relatively inexpensive
- Usually suitable for 3-4 generations, sometimes more.
- Unpredictable the more generations the farther you get from the original store-bought yogurt

package of commercially sold traditional freeze-dried starter

Freeze-dried yogurt starters (paid link)or traditional starters (aka heirloom starters) come in foil packets in the form of granules and cost more. They’re available online, in health food stores, or in specialty supermarkets.
- Hardier than commercial yogurt: Resists wild yeast better.
- Beginner challenges: First batch may be thin; follow starter directions
- Improvement over time: Subsequent batches will be thicker as cultures mature
- Can be used for infinite generations if cared for properly (when used every week to 10 days)
Single-use starters (paid link): Sometimes referred to as sachets, they are for making one batch of yogurt. You can try for a second generation but it may be weaker.

4. What is the difference between a thermophilic yogurt starter and a mesophilic starter?

Thermophilic yogurt starters culture at 104-112˚F. They produce a thicker texture and a tangier flavor. They are the focus of this post and what I use in my published homemade yogurt recipe.

Mesophilic cultures ferment at lower temperatures (70-77˚F). They produce a thinner texture (sometimes referred to as drinkable yogurt) with a milder flavor. Fermentation usually takes longer, about 12-24 hours.

5. Can I use yogurt from a previous batch of homemade yogurt?

Yes, if it is no more than a week to 10 days old. Yogurt bodies die off quickly as yogurt ages. Yogurt is still safe to eat if it smells good and you don’t see mold, but it may not be potent enough to make more yogurt.
If you use commercial yogurt as a starter, buy commercially prepared yogurt from the store every 3-4 batches or generations. Otherwise, you risk contamination by wild yeast, which can result in slimy yogurt.
If properly cared for, traditional or freeze-dried yogurt starters can be used repeatedly for years and countless generations. To keep them strong, make a fresh batch of yogurt every 7-10 days for the best results.

6. Do I have to warm the starter before adding it to my cooled-down milk?

No. Little yogurt bodies don’t mind jumping straight off the diving board into warm milk. So I’ve made hundreds of batches of yogurt using a refrigerator-cold starter.

However, it is a good idea to mix the starter with cooled-down milk and whisk it until well mixed. This helps to avoid “hot spots” and results in smoother yogurt.

7. If I want to make Greek yogurt, do I have to use Greek yogurt as my starter, or will regular unflavored yogurt work?

It doesn’t matter. Greek yogurt starts life as regular yogurt. The only difference is that Greek yogurt (same with Skyr) has been strained to remove some of the whey and make it thicker.

Use any thermophilic yogurt starter. Freshness is more important.

8. Does it matter if there are flavorings such as vanilla or fruit in the starter?

The best situation is unadulterated, unflavored yogurt. A little vanilla doesn’t seem to hurt. However, I don’t recommend using yogurt with any fruit, sugar, or other flavorings as a starter. If you are in the habit of adding flavorings to an entire batch of yogurt after incubation, save back a ¼-½ cup of plain yogurt before you do it.

9. How much yogurt starter should I use?

Use a scant tablespoon of yogurt starter per quart of milk. More starter is not necessarily better. Yogurt bacteria are big eaters and don’t like to be crowded.

10. Can I freeze the starter when I’m away from home for a long period?

When you are unable to use your starter within 7-10 days, I recommend freezing a small amount to thaw and use later. You will probably need to use more starter than you usually do because the yogurt becomes less potent with time—even in the freezer.

11. Can I use whey drained from yogurt as a starter?

Yes. Read more about using whey strained from yogurt as a starter.

12. Will these starters work for non-dairy yogurt?

No. You will need to buy a starter specifically designed for non-dairy yogurt (paid link).

When choosing a yogurt starter, think of it like choosing a hydrangea plant.

Using store-bought yogurt as a starter is like buying blooming hydrangeas from the grocery store that were raised in a hot house. They look beautiful when you buy them, but they quickly decline. Planting these delicate plants in your garden often fails, as they weren’t raised to withstand natural forces

In contrast, a traditional or heirloom starter is like the hardy hydrangea transplants from your neighbor’s yard. These plants are proven to endure heat, irregular watering, and disease. If they survive the transplant, they thrive and improve over time. Similarly, a traditional freeze-dried yogurt starter, once established, becomes more robust and yields better results batch after batch.

Parting Thoughts: If you still aren’t sure what starter is right for you, ask yourself how often you make yogurt and whether it’s regular or sporadic. If it’s regular and frequent, a traditional starter would be my first pick. If it’s sporadic and often longer than a week or two between batches, choose store-bought yogurt or direct-set yogurt.

If you have more questions related to the yogurt-making process, chances are they will be answered in my list of 29 questions and answers about homemade yogurt. If you don’t find what you’re looking for, don’t hesitate to send me an email.

If you have questions or suggestions, email me privately for a quick answer: Paula at saladinajar.com. Hope to see you again soon!