Short answer: heat 2 quarts of milk to 180–190°F, cool it to 110–112°F, stir in 1 to 2 level teaspoons of Natren Yogurt Starter, and keep it warm for about 4 to 8 hours until it sets. Then chill it. Once you know the method, preparing the milk usually takes less than 30 minutes.
Natren Yogurt Starter is a culture of Lactobacillus bulgaricus LB-51 and Streptococcus thermophilus BC 122, the traditional Bulgarian-style recipe Natren's founder grew up with: her father made yogurt in California from 1956. One bottle makes up to 30 quarts of yogurt, and the starter has no gums, additives, sweeteners or preservatives.
What you need
- Natren Yogurt Starter
- 2 quarts (2 liters) of milk. Natren's directions call for organic milk; don't use powdered or reconstituted milk.
- A cooking or candy thermometer that reads from about 110°F to 200°F (40°C to 95°C)
- A 2–3 quart double boiler with a lid, in stainless steel, glass or enamel. No double boiler? A 2-quart glass jug set inside a large saucepan of water works too.
- An oven or a yogurt maker for incubation
If your pan has a tight-fitting lid you can incubate in it directly. A lidded casserole dish also works well because it holds heat longer.
Step 1: Heat the milk
Heat the milk in a double boiler or water bath so it doesn't scorch. Don't use a microwave, and don't let it boil.
- Standard method: hold the milk at 180–190°F (82–88°C) for 20 to 40 minutes. Low-fat and non-fat milk need the full 40 minutes.
- Faster method: hold the milk at 190–200°F (88–93°C) for 5 to 10 minutes, watching closely.
Step 2: Cool the milk to 110–112°F
Cool the milk to 110–112°F (43–44°C) before you add the starter. Milk that's too hot will harm the cultures, and milk that's too cool won't set properly, so don't let it drop below 110°F. To speed things up, set the pan in cool water (without splashing any into the milk) and stir. It takes about 10 minutes.
Step 3: Add the starter
Use 1 to 2 level teaspoons of Yogurt Starter for 2 quarts of milk. Put the starter in an empty cup, add about 2 tablespoons of the cooled milk and stir to a smooth paste. Keep adding milk a little at a time, blending after each addition, until the cup is nearly full. Then stir the mixture gently back into the pan and mix thoroughly.
Step 4: Incubate for 4 to 8 hours
- Yogurt maker: follow the manufacturer's instructions.
- Gas oven with a pilot light: put the pan on the top shelf, toward the back.
- Electric oven, or gas oven with electronic ignition: wrap the container in a towel before placing it in the oven. The oven stays off; it's there to give a warm, steady environment.
- No oven free? Wrap the pan in a towel and set it in a small insulated chest, or wrap it in a heating pad on a low setting no higher than 110°F (43°C).
Depending on how much starter you use, incubation takes about 4 to 8 hours. Start checking after 4 to 6 hours and take the yogurt out as soon as it has set, which keeps it sweeter. If you incubate overnight, take it out when you get up.
How to tell when it's ready
The yogurt is ready when it has thickened, looks like custard, or pulls away from the edge of the container. If it needs longer, check every 15 to 20 minutes, without opening and closing the oven door more than you have to.
Step 5: Chill
Refrigerate the yogurt and leave it undisturbed for several hours until it's thoroughly chilled. A watery layer may form on top. That's whey: pour or spoon it off rather than stirring it back in. Some people drink it or use it in smoothies or cooking.
Choosing your milk
- Whole milk gives the sweetest, thickest, creamiest yogurt.
- Low-fat and non-fat milk work too; the yogurt will be a little more tart. Remember the full 40-minute heating time.
- Goat's milk tends to make a thinner yogurt. Natren suggests adding a 6-ounce can of evaporated milk or one heaping tablespoon of non-fat powdered goat's milk (blended in to remove lumps).
- Soy milk is another option Natren's directions mention.
Troubleshooting
Why is my homemade yogurt runny?
The most common causes are milk that cooled below 110°F before the starter went in, too little starter, or not enough time incubating. Check that your thermometer reads correctly, use the full 1 to 2 teaspoons, and let it incubate longer, checking every 15 to 20 minutes. Low-fat milk needs the full 40-minute heating time, and goat's milk naturally sets thinner (see above).
Why is my yogurt lumpy?
Usually the starter wasn't mixed in thoroughly, or too much was used. Make the smooth paste first, blend it fully into the milk, and stick to 1 to 2 teaspoons. Too much starter crowds the cultures; too little and the yogurt won't thicken.
Can I use my last batch as the starter?
For consistent results, Natren recommends starting each batch with fresh Yogurt Starter. A spoonful of old yogurt gives you less control over the cultures you're adding and can make a lumpier yogurt.
Storing your yogurt and your starter
Keep homemade yogurt covered in the refrigerator. It gets more tart as the days go by; if you have some left after about a week, it's a good time to turn it into yogurt cheese. Keep the Yogurt Starter bottle refrigerated, just like Natren's probiotics. Our refrigeration guide explains why.
If you'd like to add a Natren probiotic powder such as Megadophilus or Bifido Factor, stir about ½ teaspoon into your serving just before you eat it, not into the batch you're storing.
What to make with it
Top it with fruit, nuts or honey, use it instead of sour cream, or try our favorite toppings and yogurt cheese, warm yogurt recipes for winter and green yogurt recipes.
More yogurt guides
- Instant Pot yogurt, step by step
- How to make Greek yogurt at home
- What is Bulgarian yogurt?
- Kefir vs yogurt: what's the difference?
- Lactobacillus bulgaricus, the yogurt culture
Frequently asked questions
How long does homemade yogurt take to ferment?
About 4 to 8 hours with Natren Yogurt Starter, depending on how much starter you use. Take it out as soon as it sets for a sweeter yogurt.
What temperature should the milk be when I add the starter?
110–112°F (43–44°C). Don't add the starter to hotter milk, and don't let the milk cool below 110°F.
How much yogurt does one bottle of starter make?
Up to 30 quarts, using 1 to 2 level teaspoons per 2 quarts of milk.
Do I need a yogurt maker?
No. An oven with the light or pilot on, an insulated chest or a heating pad on low all work.
Questions? Our team is happy to help at customerservice@natren.com or 1-866-462-8736. Ready to start? Shop Yogurt Starter.
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