How to Maintain a Yogurt Culture

homemade yogurt with fruit and granola

Thick and creamy custard-style yogurt

Reports from the blogosphere that yogurt cultures are difficult to maintain or become more acidic over time are highly exaggerated. The truth is that homemade yogurt is simpler and easier to make than homemade bread, and a home yogurt culture is easier to start and maintain than a sourdough culture. A few simple tips will keep your culture healthy week after week, month after month, even year after year.

Note: When using the Folding Proofer to make yogurt, be certain there is no water in the water tray. The water tray is not needed for making yogurt.  You can remove it from the Proofer, if you like, or leave it empty. But do not add water because it will affect temperature settings.

Tip #1:  Store your seed culture in a separate jar. 

If the yogurt you will use to start your next batch (i.e., the seed culture) is stored in a separate jar from the rest of the yogurt, it will be easier to care for. If it is in a different shape or size of jar, that can also help it avoid being eaten by hungry family members or housemates.

Tip #2:  Remove your seed culture as soon as it sets.

thick creamy homemade yogurt

High-Low method yogurt has a smooth texture.

When making yogurt, the seed culture jar should be removed from the Proofer as soon as it sets. If you are allowing other jars to culture longer for more flavor or to reduce lactose content, be sure to remove the seed jar early. This is so the seed culture will still have enough food (lactose) to eat while waiting for the next yogurt-making session. Putting yogurt into the refrigerator slows the activity of the lactic-acid bacteria, but does not stop it completely. It will still consume lactose and continue to acidify over time.

For our custard-style yogurt making method, one week is about the ideal interval between sessions- if the seed culture jar is removed from the Proofer as soon as it sets, each batch of yogurt will be consistent with the last, acidifying at a predictable rate.

Tip #3:  If waiting longer than one week before making yogurt again, feed your seed culture.

homemade yogurt

To feed the seed culture, just add milk and stir.

To go two weeks between sessions, feed your seed culture after the first week. It’s simple and convenient to fill the seed culture jar only half full, then when it comes time to feed it, just top off the jar with milk and stir until smooth. Be sure the milk is long away from its use by date and to keep the culture pure, scald the milk and cool it before feeding the culture. Then put the fed jar of seed culture back into the fridge.

Tip #4:  If you do use an older seed culture, check the yogurt early.

From time to time you may end up using a seed culture that has been in the fridge longer than one week without a feed or that remained in the Proofer for a while after it set. Provided it hasn’t spoiled, you can still use it to make your next batch of yogurt, but check to see if it sets earlier than usual as it may acidify more quickly.

Tip #5:  Keep the lid on. 

Keep yogurt jars covered during culturing to avoid introducing yeasts or foreign bacteria that could weaken the culture over time. The lactic acid-producing culture in yogurt does not need oxygen to thrive.

two gallons homemade yogurt in Folding ProoferTip #6:  Stir cream-top yogurt. 

If you are lucky enough to find a source of non-homogenized milk, it will make delicious cream-top yogurt. For the seed culture jar, it’s a good idea to stir the cream back into the yogurt to redistribute the beneficial bacteria that have risen to the top with the cream. This will allow them to be near the lactose that they need to sustain themselves from batch to batch and preserve the full potency of your culture.

 

2017-03-11T02:28:52+00:00 Yogurt & Dairy|21 Comments

21 Comments

  1. Andrea March 18, 2014 at 1:46 am - Reply

    These are some great yogurt making tips! I’ve been making my yogurt for years now, and you’ve given me some new things to incorporate into my methods. Thanks!

    • Amy March 25, 2014 at 2:23 pm - Reply

      Hi Andrea,
      So glad you picked up some new tips! It’s good to know that if you’re not ready to make yogurt yet (or don’t have time) and your starter culture is starting to languish, that you can feed it to keep its cultures thriving until you’re ready.

      As far as our technique, maybe you are already doing something like this with your own recipe. Our High-Low method is practically foolproof for producing thick and creamy yogurt.

      • Sophie-Lee April 1, 2016 at 7:18 am - Reply

        “It’s good to know that if you’re not ready to make yogurt yet (or don’t have time) and your starter culture is starting to languish, that you can feed it to keep its cultures thriving until you’re ready.”

        And it’s good to know why I occasionally get a batch of yoghurt that won’t set – because I put that starter in the fridge a month ago! Don’t know why it didn’t occur to me that it’s similar to a sourdough starter in that I need to regularly feed it to keep it healthy/happy

  2. Anare March 27, 2015 at 10:23 pm - Reply

    I thought you are suppose to not heat milk any higher then 110 to not kill beneficial microbs?

    • Julie April 8, 2015 at 3:33 pm - Reply

      Hi Anare, thanks for your interest! If you are referring to scalding and cooling the milk before feeding the culture (between yogurt-making sessions), the idea is to kill off microbes in the milk so that the yogurt culture remains pure.

      On the other hand, if you’re referring to making yogurt and our High-Low method of culturing at 120F for an hour, then 86F for the remainder of the culturing time, we have tested that method extensively and the milk only gets up to about 113F by the end of the “High” stage. For most yogurt cultures, that is not hot enough to damage the culture. But there’s no problem with choosing to culture at 110F for the entire time, that works, well, too, especially if you will not be around to turn the Proofer down after the first hour.

      Hope that helps!

  3. Pat April 8, 2015 at 11:48 am - Reply

    I achieve the best results when I use plastic lids, rather than metal, in the proofing stage

  4. Julie April 8, 2015 at 3:06 pm - Reply

    We also like to use the white plastic lids for mason jars, thanks for the tip!

  5. Catherine November 1, 2015 at 5:32 pm - Reply

    Made my first batch and it was successful! Just took longer then expected to set. Finished product was super thick until I stirred it then it became thinner but still thick and creamy. It didn’t have a strong yogurt taste almost closer to a sour cream….
    Maybe this is because it’s custard style?! It also did not taste like the seed yogurt I used. I was expecting a similar taste. Either way it was delicious with some raw honey and vanilla.
    Is there a risk of it going bad if I cultured too long before refrigerating?

    • Diane November 2, 2015 at 4:49 pm - Reply

      Catherine,
      It sounds like you are enjoying making your own yogurt. We are wondering how much longer your yogurt took to set. As yogurt is culturing for a longer period of time, lactose (milk sugar content) is reduced resulting in a more tart yogurt. Even while yogurt is refrigerated it will continue to become less sweet and more acidic/tart, although at a much slower rate with cool refrigerator temperatures. After culturing the first hour at 120F, our Custard-Style Yogurt is generally set in 2-4 hours but sometimes it takes longer depending on multiple factors such as if the cows are grazing on grass or on their winter feed. If you left it at 120F for longer than one hour you may have gotten whey separation. With many choices on the market of yogurt starter cultures and also milk varieties to choose from, it may be best to take a look at “The Science of Great Yogurt” on our website. Yogurt cultures containing Lactobacillus Casei generally result in thicker yogurt as do milks with higher protein content. Acidic foods like yogurt are much less prone to spoilage. Pinpointing exactly what happened in your case is difficult without more information. Good luck with your next batch and don’t hesitate to telephone us if you have questions or if we can assist you in the future. It was great to hear from you and we hope this information is helpful.

  6. Denise April 9, 2016 at 10:42 pm - Reply

    Can you freeze a culture?

    • Diane April 12, 2016 at 5:31 pm - Reply

      Healthy bacterial survival in a yogurt culture depends on how long and how many times you freeze the bacteria. Growth of bacteria slows down in freezing temperatures as they carry out almost no metabolic reaction and enter a dormant state during freezing. There will definitely be a limit on how long you can store a culture in a household freezer. Sometimes the refrigerator temperature isn’t low enough and another problem can be the defrost cycle. Both of these factors can cause ice crystals to grow. The ice crystals can damage the cell walls of the healthy bacteria. With a short freeze time enough bacteria can survive to make the next culture. The longer it is frozen, the more bacteria are killed. You can optimize survival of your culture in the freezer by freezing it fast. This will promote smaller ice crystals. Pre-chill the culture in the coldest part of your refrigerator before moving it to the freezer. Choose a storage container with as much surface area as possible to promote fast freezing. You can also culture in a high fat medium, like whole milk. The fat will help promote smaller ice crystals. It would be worth a few experiments to see how long it is possible to store your culture under your particular conditions, as it will vary with each individual freezer, culture media and bacterial strain. Good luck with your cultures!

  7. Joy January 15, 2017 at 9:52 am - Reply

    What powdered cultures, can I use. that will have the proper amount of probiotics?

    • Diane January 27, 2017 at 4:27 pm - Reply

      Joy, We recommend contacting Cultures for Health to see if they can assist you with the specific culture you are looking for. They also sell our Folding Proofer and will be able to answer questions regarding the proper probiotics to use. Please don’t hesitate to contact us if you have further questions. https://www.culturesforhealth.com/catalogsearch/result/?q=yogurt+cultures

  8. Krisla March 21, 2017 at 3:43 pm - Reply

    I have made yogurt with lactose free milk. It thickens great and tastes good. It isn’t tart at all. I am guessing because there isn’t much to turn into lactic acid. Is this a good idea or should I be using regular whole milk? I can’t tolerate lactose and this yogurt has been extra gentle on my stomach. I use Fage as my starter yogurt. I haven’t tried using my homemade yogurt to start my next batch. Would I be able to use it since there is no lactose in mine to feed the starter?

    • Diane March 22, 2017 at 4:17 pm - Reply

      Krisla, Thank you for your question. A percentage of people stop making the enzyme lactase as they age. Lactose-free milk has been pretreated with the lactase enzyme is made especially for people with lactose intolerance. Using this milk to make yogurt generally results in a very sweet tasting yogurt. If you decide to try using a portion of your yogurt as the starter for your next batch, it is important to remove a small container of the yogurt early so that your culture will still have enough food (lactose) to last until it is time to make your next batch with this “seed culture”. Be sure to remove the small jar just as soon as it sets and store in the refrigerator. We are not certain which type and quantity of live and active cultures are in Fage yogurt. Your results should give you an indication whether this is the method to follow. Are you using a Proofer and have you followed our Lactose-Free Yogurt recipe? Also, you can find more information regarding making yogurt on our website: https://brodandtaylor.com/yogurt-making-faq/

  9. Mary May 3, 2017 at 3:11 pm - Reply

    Lovely article – thanks Diane.
    Would this work if nut milk is used? What I mean, can we preserve seed colture from nut yoghurt?

    • Diane May 11, 2017 at 2:42 pm - Reply

      Mary, Thank you for your inquiry. There are so many factors which could affect results that it is difficult to answer this question. We recommend that you make a recipe of Yoghurt, reserving a small container to use as the starter for your next batch and then make the recipe again 3-4 days after the last batch was made. This way you know your reserved container of yoghurt with healthy bacteria culture to use as a started is fresh. Try your next batch with this starter and see if the results are to your liking. Nut milk yoghurt is not the preferred diet of bacterial yogurt cultures, so this would be more challenging than dairy yogurts. Another source for purchasing yogurt starters and helpful assistance with making yogurt is Cultures for Health. http://www.culturesforhealth.com/ They are familiar with and sell our Folding Proofer product. All the best to you and please let us know your results.

  10. Nicole November 24, 2017 at 4:09 pm - Reply

    Diane, thank you for amazing article!
    I tried to make my own yogurt, but I used starter cultures.
    Maybe you’ve heard of VIVO? I bought their stuff and made an amazing yogurt. It was really easy to make!
    It takes some time to make it, but it was worth it. Nice and tasty yogurt!
    I’m glad I’ve changed my mind about buying those cultures and now I’m avoiding yogurt in stores.

    • Diane November 28, 2017 at 6:58 pm - Reply

      Nicole, Congratulations on your success! We have not tried VIVO cultures. We are fortunate to have grass fed cows with delicious milk nearby. The farms sell yogurt which we can use as our starter culture, if we happen to need one. It is wonderful to hear about your results and we thank you for sharing the information. All the best to you!

  11. Sandy February 18, 2018 at 5:47 pm - Reply

    My question refers to heirloom vs starter from a store bought yogurt. I make about 3 gallons of yogurt a week for my family of hungry yogurt eaters. I started my yogurt several months ago with one container of Fage plain yogurt. The kids prefer vanilla yogurt so my routine has been to do a half gallon of yogurt from my frozen starters and use them over the next few weeks to make the vanilla yogurt. When I get low on starter, I just make a half gallon of plain yogurt and freeze that batch (in ice cube trays). My initial batch wasn’t heirloom, of course, but I’ve been making yogurt for months this way and haven’t purchased any other starter. I’m not sure what generation I’m on but it has to be 6 or more generations. My question is, will my starter fail or should I just keep going? I’ve been looking at heirloom starters but don’t want to get them if I’ve actually managed to create my own. Honest opinions on this please.

    • Diane February 20, 2018 at 7:22 pm - Reply

      Sandy, Yes, you should be able to use your homemade frozen yogurt starter and it is just as healthy as refrigerated yogurt. Healthy bacterial survival in a yogurt culture depends on how long and how many times you freeze the bacteria. Growth of bacteria slows down in freezing temperatures as they carry out almost no metabolic reaction and enter a dormant state during freezing. There is a limit on how long you can store a culture in a household freezer (generally no more than 3-4 weeks). Sometimes the freezer temperature isn’t low enough and another problem can be the defrost cycle. Both of these factors can cause ice crystals to grow. The ice crystals can damage the cell walls of the healthy bacteria. With a short freeze time enough bacteria can survive to make the next culture. The longer the yogurt is frozen the more bacteria are killed. You can optimize survival of your culture in the freezer by freezing it fast. This will promote smaller ice crystals.
      Follow these steps:

      Pre-chill the culture in the coldest part of your refrigerator before moving it to the freezer.
      Choose a storage container with as much surface area as possible to promote fast freezing. Culturing in a high fat medium such as whole milk is beneficial. The fat will help promote smaller ice crystals.
      It is worth a few experiments to see how long it is possible to store your culture under your particular conditions, as it will vary with each individual freezer, culture media and bacterial strain.

      Sounds like you are working in a successful direction. We hope this bit of information helps you and answers any concerns. All the best to you.

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