Homemade yogurt
Pasteurized milk, a little yogurt and a few hours of steady heat. What makes it set, how to strain it, and how to culture cream and butter too.
8 min read First steps Reviewed October 26, 2026 56 facts, each with its source
What yogurt is
Yogurt is milk fermented by two bacteria, Streptococcus thermophilus and Lactobacillus bulgaricus1. They work warm, at about 43 °C (110 °F): they turn the sugar in milk into lactic acid, and that acid thickens it2.
Two barriers protect it at once: the heat at the start and the acidity at the end3. Acidity alone isn't enough, because there have been outbreaks of E. coli O157:H7, a bacterium that tolerates acid4. That's why homemade yogurt depends more on the thermometer than on the recipe.
Crème fraîche, sour cream and cultured butter are made with other bacteria, which work at room temperature. They come at the end of this guide.
The milk, always pasteurized
Use pasteurized milk, or pasteurize it yourself before you start5. Whole, 2% or skim all work, pasteurized or ultra-pasteurized6.
The heating step in the recipe does not replace pasteurization7. If you have raw milk, first heat it to 74 °C (165 °F) while stirring, then cool it right away in ice water8. This is not a detail: in the United States, a homemade raw-milk yogurt caused two cases of listeriosis, one of them fatal9.
For a firmer yogurt, stir nonfat dry milk into the cold milk: the more milk solids, the firmer it sets10.
What you need
- A kitchen thermometer. It's essential: accurate temperatures are the key11.
- A pot, ideally a double boiler, so the milk doesn't scorch.
- Something that holds 43 °C (110 °F) for hours: a yogurt maker, or a cooler warmed with hot water and filled halfway up the jars with 43 °C (110 °F) water12.
- Glass jars with lids, washed in hot soapy water, rinsed and air-dried13.
- For straining, a strainer, cheesecloth and a bowl.
The four temperatures
Heat changes the milk proteins so they set together instead of separating into curds and whey14. Then the milk is cooled, inoculated and kept warm, without moving it.
| Step | Temperature | Time |
|---|---|---|
| Heat | 85–93 °C (185–200 °F), without boiling | 10 min, or 20 for a thicker yogurt15 |
| Cool | To 44–46 °C (112–115 °F)16 | Under 1 h, and never more than 217 |
| Inoculate | The mix ends up at 43–44 °C (110–112 °F)18 | Right away |
| Incubate | 43 °C (110 °F), between 41 and 46 °C (105 and 115 °F) | 4–7 h19 |
Both limits matter. Above 46 °C (115 °F), the heat can kill the culture20. Below 37 °C (98 °F), the bacteria grow poorly21 and the milk sits warm without souring. Check the temperature every hour and don't move the jars. The University of Illinois gives a longer window, 6 to 10 hours at 42–46 °C (108–115 °F)22.
The starter
For 1 liter of milk, 60 g of plain yogurt. That's the ratio of the NCHFP, the National Center for Home Food Preservation: ¼ cup per quart23. It should have no sugar or flavorings, and the label should say it contains live cultures24. Blend it with a cup of the warm milk and stir it back into the pot.
You can use your own yogurt as starter, as long as it's no more than 5 to 7 days old25. The NCHFP prefers a store-bought yogurt each time26. If a batch comes out weak or tastes odd, start again with a store-bought one.
When it's done
It's done when it has set firm, which happens when it reaches pH 4.627. In the NCHFP's test it got to 4.6 at about 5 hours28. The longer it sits after setting, the tangier it gets29. A little whey on top is normal. A lot of whey comes from incubating too long or jostling the jars while it sets30.
If it doesn't set, throw it out: it may be a bad culture or microbes that shouldn't be there31. Fervida calls it lost if it hasn't set after 10 hours. That's a house rule: 10 hours is the longest any guide gives, the Illinois one. As soon as it sets, into the fridge.
Straining it: Greek, labneh and skyr style
Straining means draining off whey through cheesecloth in a strainer. It's always done in the fridge32, with the bowl covered, and the time decides what you get33:
| Strained in the fridge | What you get |
|---|---|
| 2–4 h | Greek or Greek-style yogurt |
| 8–24 h | Labneh, or yogurt cheese |
Use a yogurt without gelatin, because gelatin stops the whey from draining34. Icelandic skyr is another story. BCCDC, the British Columbia Centre for Disease Control, counts it among the types of yogurt35, but traditional skyr is also set with rennet, and no official guide explains how to make it at home. Fervida's is skim-milk yogurt with dry milk, strained for 8 to 12 hours: skyr-style, not skyr.
Labneh is served with oil on the plate, never stored in oil. In Canada, a labneh in oil was recalled because it could allow the botulism bacterium to grow36.
Cultured cream and butter
These don't use yogurt but a commercial mesophilic culture, and they ferment covered at room temperature, away from drafts37. There are no home guides with figures. Fervida's recipes follow British Columbia's food safety sheets for professional kitchens and the University of Guelph's dairy science book.
- Crème fraîche: whipping cream with more than 33% fat. With UHT cream or added stabilizers, it won't thicken38.
- Sour cream: cream with 14 to 20% fat39.
- Cultured butter: the fermented cream is chilled and churned at 7–10 °C (45–50 °F) in summer and 10–13 °C (50–55 °F) in winter40. If you want it salted, 1 to 3%41.
The rules are the same for all three. Only pasteurized cream42, and always a commercial culture: a previous batch is not a starter43. It ferments for 16 to 20 hours at 20–25 °C (68–77 °F)44. If it hasn't reached pH 4.6 two hours past the expected time, it's discarded45; without a meter, Fervida discards it if it hasn't thickened after 22 hours, and that's a house rule. Then it's cooled to 20 °C (68 °F) within 2 hours and to 4 °C (40 °F) within 4 more46, and used within 3 days47.
Storing it
What can go wrong
| What you see | Why | What to do |
|---|---|---|
| It doesn't set | You added the starter too hot, or the incubation drifted out of range51 | Throw it out and start again with a thermometer and store-bought yogurt |
| Clumps or strings while heating | Some of the proteins have set | Lift them out with a slotted spoon or strain the milk before inoculating52 |
| It tastes or smells bad | Contaminated starter, or boiled milk53 | Throw it out, and new starter for the next batch54 |
| Mold, or a smell that isn't yogurt | Microbes that shouldn't be there | Throw it out55, whole: in yogurt, mold reaches below the surface56 |
The recipes
- Homemade yogurt: the starting point, with 1 liter of milk.
- Greek yogurt, labneh and skyr-style strained yogurt: the same yogurt, strained for more or fewer hours.
- Crème fraîche and sour cream: cream with a mesophilic culture, at room temperature.
- Cultured butter: the fermented cream, churned, which also gives you buttermilk.
Where every number comes from
Every number in the text leads to its figure: the exact sentence from the official guide it comes from, in its own language.
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1
Two bacteria make it, Streptococcus thermophilus and Lactobacillus bulgaricus
“Yogurt is made by adding Streptococcus thermophilus and Lactobacillus bulgaricus into heated milk.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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2
Lactic acid is what thickens the milk
“The milk is coagulated (thickened) by an increase in acidity from lactic acid produced by the bacteria.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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3
Yogurt has two barriers: heat and acidity
“Yogurt provides two significant barriers to pathogen growth: (a) heat and (b) acidity (low pH).”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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4
Acidity alone isn't enough: E. coli O157:H7 tolerates acid
“Acidity alone has been questioned by recent outbreaks of food poisoning by E. coli O157:H7 that is acid-tolerant.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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5
Always pasteurized milk
“Therefore, always pasteurize milk or use commercially pasteurized milk to make yogurt.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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6
Pasteurized or ultra-pasteurized milk both work
“must be pasteurized or ultra-pasteurized before the addition of the characterizing bacterial culture”
U.S. Food and Drug Administration, Code of Federal Regulations (eCFR) · 21 CFR 131.200 Yogurt · read on October 25, 2026
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7
Heating the milk does not replace pasteurization
“Do not substitute this heating step for pasteurization.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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8
Raw milk, heated to 165 °F while stirring
“Cover the milk and heat to 165°F while stirring constantly for uniform heating. Cool immediately by setting the top section of the double boiler in ice water or cold running water.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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9
A homemade raw-milk yogurt: listeriosis, with one death
“Listeria monocytogenes 2 and 1 death Homemade Raw milk-based yogurt”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.6: Yogurt (April 2024, updated December 2024) · read on October 25, 2026
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10
More milk solids, firmer yogurt
“The higher the milk solids the firmer the yogurt will be.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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11
Accurate temperatures are the key
“Accurate temperatures are critical for successful processing.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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12
A cooler warmed first and filled with 110 °F water
“To use an insulated cooler, prewarm the cooler with almost-boiling water. Empty, then fill with 110°F water that comes halfway up the sides of jars filled with 110°F cultured milk.”
University of Alaska Fairbanks Cooperative Extension Service · Making Yogurt at Home (FNH-00062, reviewed October 2024) · read on October 25, 2026
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13
Equipment washed in hot soapy water and air-dried
“Clean equipment and containers in hot detergent water, then rinse well. Allow to air dry.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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14
Heat makes the proteins set instead of separating
“Heating the milk is a necessary step to change the milk proteins so that they set together rather than to form curds and whey.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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15
185 to 200 °F for 10 or 20 minutes
“Hold temperature at 185° to 200°F for 10 minutes for thinner yogurt or up to 20 minutes for thicker yogurt. Do not boil.”
University of Alaska Fairbanks Cooperative Extension Service · Making Yogurt at Home (FNH-00062, reviewed October 2024) · read on October 25, 2026
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16
Cooled quickly to 112–115 °F
“cool milk rapidly to 112-115°F”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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17
Cooled within 1 hour, and never more than 2
“Cooling milk to the inoculation temperature within 1 hour (best practice for commercial and smallscale), and up to a maximum of 2 hours (this is a CCP).”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.6: Yogurt (April 2024, updated December 2024) · read on October 25, 2026
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18
The yogurt goes into a cup of milk; the mix ends up at 110–112 °F
“Remove one cup of the warm milk and blend it with the yogurt starter culture. Add this to the rest of the warm milk. The temperature of the mixture should now be 110-112°F.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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19
4 to 7 hours at 110 °F, give or take 5 °F
“incubate about 4 - 7 hours at 110°F ± 5°F”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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20
Above 115 °F the culture can die
“Adding culture to very hot milk (+115°F) can kill bacteria”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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21
It grows poorly below 98 °F
“They like warm temperatures, but they can be killed at temperatures above 130°F and will not grow well below 98°F.”
University of Alaska Fairbanks Cooperative Extension Service · Making Yogurt at Home (FNH-00062, reviewed October 2024) · read on October 25, 2026
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22
Illinois: 6 to 10 hours at 108–115 °F, undisturbed
“Incubate yogurt between 108-115 F for 6 to 10 hours, undisturbed.”
University of Illinois Extension · Making Yogurt at Home, Best Practice Guide (modified May 2024) · read on October 25, 2026
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23
¼ cup of cultured yogurt per quart
“Commercial, unflavored, cultured yogurt — Use ¼-cup.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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24
The label should say it has live cultures
“Be sure the product label indicates that it contains a live culture.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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25
Your own yogurt as starter, within 5 to 7 days
“If using a previous batch of homemade yogurt, use it as a starter within 5 to 7 days from when the yogurt was made.”
University of Illinois Extension · Making Yogurt at Home, Best Practice Guide (modified May 2024) · read on October 25, 2026
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26
A store-bought starter each time
“Use a fresh, recently purchased culture from the grocery store each time you make yogurt.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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27
It sets firm when it reaches pH 4.6
“Yogurt should set firm when the proper acid level is achieved (pH 4.6).”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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28
In the NCHFP's test, pH 4.6 at about 5 hours
“Our yogurt reached pH 4.7 in approx. four hours, pH 4.6 in approx. five hours and pH 4.5 in approx. six hours.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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29
More hours after setting, more tang
“Incubating yogurt for several hours past the time after the yogurt has set will produce more acidity.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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30
Lots of whey: incubated too long or jostled
“Excessive separation of whey, however, can be caused by incubating yogurt too long or by agitating the yogurt while it is setting.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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31
If it doesn't set, throw it out
“Discard batches that fail to set properly since this may be an indication of a bad culture or unwanted microorganisms.”
University of Alaska Fairbanks Cooperative Extension Service · Making Yogurt at Home (FNH-00062, reviewed October 2024) · read on October 25, 2026
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32
Always strain in the fridge
“Straining step must be performed under refrigeration.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Yogurt, production of dairy products in food service establishments · read on October 25, 2026
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33
Labneh, 8 to 24 hours; Greek, 2 to 4
“Cover the container and refrigerate. For yogurt cheese, drain for 8 to 24 hours. For Greek-style yogurt, drain for 2 to 4 hours.”
University of Illinois Extension · Making Yogurt at Home, Best Practice Guide (modified May 2024) · read on October 25, 2026
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34
Gelatin stops the whey from draining
“Do not use yogurt made with the addition of gelatin. Gelatin will inhibit whey separation.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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35
BCCDC counts skyr among yogurt types
“Common yogurt types include skyr, Greek, French, Australian, drinkable and traditional varieties”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.6: Yogurt (April 2024, updated December 2024) · read on October 25, 2026
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36
A labneh in oil was recalled over botulism risk
“The affected product is being recalled from the marketplace because it may permit the growth of Clostridium botulinum.”
Canadian Food Inspection Agency (Government of Canada, Recalls and safety alerts) · Mounet Group brand Labneh, Soft Unripened Cheese in Vegetable Oil, recalled due to potential presence of dangerous bacteria (RA-72205, 2022) · read on October 25, 2026
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37
Covered, at room temperature, away from drafts
“Crème fraîche may be incubated by leaving it covered at room temperature in an area away from drafts.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Crème fraîche, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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38
Over 33% fat; it won't work with UHT or stabilizers
“Crème fraîche is made from high fat whipping cream (>33% BF). This recipe will not work with ultra-pasteurized (UHT) cream or cream that has added stabilizers.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Crème fraîche, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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39
Sour cream has 14 to 20% fat
“Sour cream is a cultured cream product that contains between 14 and 20% butterfat.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Sour cream, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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40
Churn at 45–50 °F in summer and 50–55 °F in winter
“7-10°C in summer and 10-13°C in winter”
University of Guelph, Department of Food Science (Goff, Hill & Ferrer) · Dairy Science and Technology eBook: Butter Manufacture · read on October 25, 2026
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41
Salted butter: 1 to 3%
“If the butter is to be salted, salt (1-3%) is spread over its surface, in the case of batch production.”
University of Guelph, Department of Food Science (Goff, Hill & Ferrer) · Dairy Science and Technology eBook: Butter Manufacture · read on October 25, 2026
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42
Only pasteurized dairy
“Purchase and use only pasteurized dairy ingredients from approved sources.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Buttermilk, production of dairy products in food service establishments · read on October 25, 2026
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43
A previous batch is not a starter
“Previous batches of crème fraîche are not approved for use as a bacterial culture.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Crème fraîche, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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44
16 to 20 hours at 68–77 °F
“cooled to 20-25°C before the addition of the starter culture. Starter is added at 1-2% and the fermentation is allowed to proceed for 16-20 hours”
University of Guelph, Department of Food Science (Goff, Hill & Ferrer) · Dairy Science and Technology eBook: Cultured Dairy Products and Cheese · read on October 25, 2026
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45
Not at pH 4.6 two hours past the expected time: discard it
“If the end point pH (pH 4.6 or lower) has not been reached after 2 hours past the expected incubation time, there is a problem with the batch and it must be discarded.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Crème fraîche, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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46
To 68 °F within 2 hours and to 40 °F within 4 more
“Cool down to 20°C within 2 hours, and 20°C to 4°C within 4 hours.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Sour cream, production of dairy products in food service establishments (September 2022) · read on October 25, 2026
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47
Use-by date: 3 days
“Date product with 3-day use by date.”
Province of British Columbia (Ministry of Health, BCCDC Environmental Health Services, Fraser Health), Guidelines for the Production of Dairy Products in Food Establishments · Sample documentation: Buttermilk, production of dairy products in food service establishments · read on October 25, 2026
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48
In the fridge at 40 °F or below, 10 to 21 days
“Yogurt will keep for about 10-21 days if held in the refrigerator at 40°F or lower.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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49
Yogurt cheese, 7 to 14 days in the fridge
“The yogurt cheese has a shelf life of approximately 7-14 days when wrapped and placed in the refrigerator and kept at less than 40°F.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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50
With fresh fruit, the same day and 3 days at most
“For example, use yogurt same day, up to a maximum of 3 days, then discard.”
BC Centre for Disease Control, Environmental Health Services · Safety of Fermented Foods, Section 3.6: Yogurt (April 2024, updated December 2024) · read on October 25, 2026
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51
Too hot or too cold slows the culture
“Too hot or too cold of an incubation temperature can slow down culture growth”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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52
Clumps while heating: lift them out with a slotted spoon
“Some milk proteins may have jelled. Take the solids out with a slotted spoon”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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53
Boiling the milk gives an off-flavor
“Overheating or boiling of the milk causes an off-flavor”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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54
If it tastes off, new starter for the next batch
“Starter culture is contaminated--Obtain new culture for the next batch.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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55
Throw it out if it has mold or smells of anything but yogurt
“Discard any yogurt samples with visible signs of microbial growth or any odors other than the acidity of fresh yogurt.”
National Center for Home Food Preservation (Nummer, 2002); copy hosted by UC Davis Food Safety · Fermenting Yogurt at Home (October 2002) · read on October 25, 2026
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56
Moldy yogurt goes out whole
“Yogurt and sour cream Discard Foods with high moisture content can be contaminated below the surface.”
USDA Food Safety and Inspection Service · Molds on Food: Are They Dangerous? · read on October 20, 2026