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How to Maintain a Yogurt Culture
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.
Thick and creamy custard-style yogurt
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.
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.
High-Low method yogurt has a smooth texture.
Tip #3: If waiting longer than one week before making yogurt again, feed your seed culture.
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 an 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.
To feed the seed culture, just add milk and stir.
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.
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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!
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.
“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
I thought you are suppose to not heat milk any higher then 110 to not kill beneficial microbs?
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!
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?
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.
Can you freeze a culture?
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!
What powdered cultures, can I use. that will have the proper amount of probiotics?
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
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?
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.
Lovely article – thanks. Would this work if nut milk is used? What I mean, can we preserve seed colture from nut yoghurt?
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.
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.
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!
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.
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.
My question : before making a new batch of yogurts, how soon can I expect the seed culture woud be ready after being fed with milk and kept in the fridge ? 1, 2 or 3 days would be ok ? Less ? Comparativly, it takes three or four hours for sourbread. Thank you for the perspective you bring. Michel. France.
The seed yogurt culture reserved separately from a yogurt recipe is an entirely different process than Sourdough cultures. No feeding is necessary for the reserved seed yogurt culture to be used for making another recipe of yogurt. No time is required for the culture to “grow” but the culture should be stored with proper refrigeration and used within about 7-10 days. Enjoy making your own yogurt, reserving a separate seed culture from each recipe for the next batch. All the best to you!
Thank you for your answer. But I suppose my question was poorly formulated, maybe because english is not my mother tongue… Actually I refered to your own article just above. You write : “””Tip #3: If waiting longer than one week before making yogurt again, feed your seed culture. 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. “”” My question was relating only to this paragraph : how soon can I expect this newly regrown seed culture to be ready after being fed with milk ? Your indication in tip #3 is about two weeks betwen sessions. 1, 2 or 3 days would be enough ? I dared a comparison with sourdough, which probably was a bad idea. Thanks ! Michel.
Hi Michel, I would agree that comparing feeding a yogurt culture to maintaining a sourdough culture is a not a good way to think about it. I would imagine that it would take less than a day for the freshly fed culture to be ready to use. A great resource for questions about yogurt cultures and maintaining them is https://www.culturesforhealth.com/learn/category/yogurt/
I’ve seen a couple of places saying that you can only make 3-4 batches before having to buy another starter from the store (this being the method I used). Is this true or can I keep using my last batch of yogurt for as long as I like? I’m still very new to this so I’m a bit lost. Thanks for the helpful article!
Ebin, Great question! You can definitely keep using the last batch of yogurt for as long as you like. Each time you make yogurt, just put enough for the seed culture in its own jar. This way, the starter keeps getting fed and stays healthy–and just needs attention if it isn’t used in over a week.
Is the temperature range adjustable manually or is it set temperatures? My yogurt recipie needs to be 100 degrees for 36 hours. Over 100 degrees will kill the beneficial microbes. Thank you.
Sheryl, Yes – the folding proofer and slow cooker allows you to set the temperature degree by degree, so you can definitely set it to 100F!
Very helpful information! Is always something new to learn! A long time ago, I read an article that mentioned yogurt over time would get sweeter if you made a new batch each day with culture from yesterday’s batch. I have applied that concept by freezing my starter from each batch the day after it is made (and cooled), essentially stopping the aging of the starter at one day old. In that way, I am using one-day old starter no matter when I make the next batch. I must say, my family feels no commercially available yogurt comes close to the naturally sweet “clean” flavor of my home-made yogurt. I control the tartness of each batch by how long I culture it; tarter yogurt is still deliciously sweet! Some caveats: I usually make the next batch within 8 weeks (most often sooner); I keep the starter in a tall thin little glass jar that freezes very quickly; the culture does indeed separate into proteins and whey during freezing, but I prevent the little “skin” pieces from affecting the texture of the new batch by straining the “thinned” starter (I.e., after adding some of the new warmed milk and before adding that all back into the new batch). In addition to the flavor advantage, I never have the pressure of feeding my starter, monitoring how long it has been in the fridge, etc. I do label the starter jar with the date as I freeze it – is a “best practice” for anything in the freezer, I think, as time does manage to get away from us periodically.
Hi! I like making my own yogurt and today I’m making a new batch. This time I will be setting aside a cup of the yogurt to use as a perpetual starter (I am using Bulgarian starter). By taking one cup for reuse I will have ten cups left to eat. Will my starter be okay for ten days or should I feed it at seven days. You say to top off the starter but approximately how much milk should I use to top it off.
Linda – It should be okay for 10 days without feeding. If you have more questions, please reach out to our customer service at contact@brodandtaylor.com and we are happy to help further.