How to Make Yogurt

• 946 mL of fresh milk (any type will work, but if you use "sterilized," "UHP," or "UHT" milk, you can skip the first step as these types are already heated to the required temperature before packaging)
• 1/4 to 1/2 cup of non-fat milk (optional)
• 1 tablespoon of white sugar to feed the bacteria
• A pinch of salt (optional)
• 2 tablespoons of pre-fermented yogurt (or as an alternative, you can use frozen bacteria cultures)

Heat the milk to 185ºF (85ºC). Use two large pots, placing one inside the other to create a double boiler. This prevents the milk from scorching, and you only need to stir occasionally. If you can't use this method and must heat the milk directly, ensure you monitor it closely and stir continuously. Without a thermometer, 185ºF (85ºC) is the temperature at which the milk begins to bubble. It's best to purchase a thermometer that ranges from 37 - 100ºC, especially if you plan to make yogurt regularly.

• You can use any type of milk, including whole milk, 2%, 1%, skim milk, sterilized milk, homogenized milk, organic milk, raw milk, condensed milk, powdered milk, cow's milk, goat's milk, soy milk, etc. UHP or sterilized milk, processed at higher temperatures, breaks down some proteins that bacteria need to turn milk into yogurt. Some people report difficulties making yogurt from UHP milk.

Cool the milk to 110ºF (43ºC). The best way to cool the milk is by placing it in a cold water bath. This helps reduce the milk's temperature quickly and evenly, with minimal stirring. If cooling at room temperature or in the refrigerator, you'll need to stir the milk more frequently. Remember not to stir until the milk is below 120ºF (49ºC), and don't let the temperature drop below 90ºF (32ºC); the ideal temperature is 110ºF (43ºC).

Prepare the starter culture. The starter culture is the bacteria you add to the milk, which helps create more bacteria—essential for the yogurt-making process. Let the yogurt culture sit at room temperature while you wait for the milk to cool. This prevents the milk from becoming too cold when you add the culture.

• All yogurt requires "beneficial bacteria." The easiest way to add bacteria is by using pre-made yogurt. For your first batch, use plain, unsweetened yogurt from the store. Ensure it contains "live cultures" by checking the label. The bacteria in yogurt die over time, so look for the freshest yogurt with a tangy taste and no added flavors. Taste different plain yogurts before starting. You'll notice variations in flavor. Choose the one you like best for your starter. Different flavors result from additional bacteria strains beyond the two main types needed for yogurt.
• Alternatively, instead of using pre-made yogurt, you can use frozen bacteria cultures (available online or in specialty stores), which are more reliable.
• You can use a small amount of flavored yogurt, but the taste of your homemade yogurt may differ from using plain yogurt.

Optionally, add skim milk, low-fat milk, or powdered milk. At this stage, adding about 1/4 to 1/2 cup of powdered milk can enhance the nutritional content of the yogurt. Additionally, the yogurt will thicken more easily. If you're using skim milk, this method is even more effective.

Add the starter culture to the milk. Mix in 2 tablespoons of pre-made yogurt or frozen bacteria cultures. Use a whisk or blender to evenly distribute the bacteria throughout the milk. Uneven stirring can cause the milk to heat too quickly or too slowly. In such cases, use a double boiler or stir frequently while monitoring the temperature with a thermometer. If you live at a high altitude, this issue may occur more frequently.

Transfer the mixture to containers. Pour the milk into clean containers such as jars, bowls, or large bottles. Seal each container tightly with lids or cover them with plastic wrap.

• You can also use smaller jars if preferred, though this is not necessary.

Allow the yogurt bacteria to incubate. Keep the yogurt warm to encourage bacterial growth, aiming to maintain a temperature close to 100ºF (38ºC). The longer the mixture incubates, the thicker and tangier the yogurt will become.

• Leave the yogurt undisturbed during incubation. Gentle shaking won't ruin it but may extend the incubation time.
• After seven hours, the yogurt will have a custard-like texture, a cheesy aroma, and may have a few drops of slightly bluish liquid on top. This is exactly what you want. The longer the mixture incubates (beyond seven hours), the thicker and more flavorful the yogurt will become.

Choose a suitable incubation method. There are many ways to incubate yogurt. Use a thermometer to ensure the temperature remains consistent. Select the method that is most convenient and suitable for you. The most common method is using a yogurt maker. Detailed instructions for using a yogurt maker are as follows.

• You can use the oven light in a preheated oven, turning it off and on periodically to maintain the desired temperature. This method can be tricky; ensure the oven doesn't get too hot. Alternatively, try an oven with a bread-proofing setting.
• Other methods include using a food dehydrator, the warm setting on a rice cooker, a low-temperature heating pad, or a slow cooker on its lowest setting.
• If you don't have these tools, you can place the yogurt near a sunny window or in a car parked outside. However, remember that exposure to light may reduce the milk's nutritional value. Ideally, maintain a temperature below 120ºF (49ºC) but not lower than 90ºF (32ºC); 110ºF (43ºC) is optimal. Alternatively, place the yogurt containers in a large bowl, basin, or small cooler filled with warm water.

Choose a yogurt maker. If you plan to use a yogurt maker, there are many types available on the market (this is recommended). Yogurt makers ensure the fermentation process is safe and timed accurately.

• Basic yogurt makers without timers, which use heating elements, are common due to their affordability. These may be less reliable as they aren't designed to control the precise temperature needed for fermenting yogurt bacteria in the milk you use. They are designed for average room temperatures, but external heat or cold can alter the fermentation time and affect the yogurt's quality. These models often come with smaller cups and require weekly use to provide daily yogurt. For larger families, they may not be practical as producing a significant quantity of yogurt takes longer.
• Yogurt makers with adjustable temperature settings are more expensive due to the electronic components needed to maintain set temperatures. These come in two styles.
• One style features machine-controlled temperature settings (optimized) to maintain consistent heat regardless of external conditions. You cannot manually adjust the temperature settings on these models.
• Some yogurt makers combine features from both styles. For example, certain models offer machine-controlled temperature settings, timers, and shut-off functions. These machines can produce high-quality yogurt in just two hours due to their superior temperature control compared to other home fermentation methods. They allow the use of larger containers, though they also come with containers of various sizes. You can use a 1-gallon (3.785 L) container or four wide-mouth 1-quart (0.95 L) containers to make larger batches. However, taller containers may require additional lids or a cloth to cover gaps between the lid and the machine's base (where heat is controlled and supplied).

Understand the benefits of a yogurt maker. Users can adjust the machine's temperature settings to maintain the precise heat required for the bacteria used in yogurt fermentation. Once set, the machine maintains this temperature regardless of your kitchen's ambient conditions.

• Yogurt makers allow users to set the duration of heat application to the containers. While customizable timing is convenient, you should still monitor the process. Stay nearby (preferably indoors) so that if any issues arise (e.g., the machine fails to turn off)—though rare—you can address them promptly.

Place the cooled milk and starter culture containers into the yogurt maker. Ensure they are evenly distributed and upright (avoid spills or leaks).

Prepare the lid to retain heat. This helps maintain the containers at the optimal temperature for the bacteria to thrive and transform the milk into yogurt.

Check if the yogurt has thickened. At the appropriate time—depending on the bacteria used, temperature, and milk's nutrient content—the milk will thicken into a consistent yogurt texture. This process can take as little as two hours or up to 12 hours or more. Shorter fermentation yields milder yogurt, while longer incubation allows the bacteria to fully develop. For those with lactose intolerance, longer fermentation creates more digestible yogurt.

Remove the containers. Once the yogurt has reached the desired incubation time and quality, take the containers out of the yogurt maker and place them in the refrigerator to cool and store until ready to eat. The containers—which may come with the machine—can be small cups, allowing you to enjoy the yogurt directly from them. Larger containers, holding 4 liters or more, can also be used in yogurt makers for those who need larger quantities of yogurt regularly.

Ensure the yogurt is ready. Gently shake one of the yogurt cups—if the yogurt doesn’t move, it’s done and can be removed from the yogurt maker and placed in the fridge. If not, you’ll need to wait longer for the yogurt to set, which may take an additional 12 hours or more.

Strain the yogurt through cheesecloth for a thicker consistency. Place the cheesecloth in a strainer, set the strainer over a large bowl to catch the whey—the thin, yellowish liquid. Add the yogurt to the strainer, cover it with a plate, and refrigerate everything. Straining for a few hours yields Greek-style yogurt. For an ultra-thick, cream-cheese-like consistency, strain overnight.

Chill the yogurt. Refrigerate the yogurt for a few hours before consuming. The fridge preserves yogurt for 1-2 weeks. If you plan to use some containers as starter cultures, use them within 5-7 days to ensure the bacteria remain active. A layer of liquid may form on top. You can either pour it off or stir it back in before enjoying the yogurt.

• Many store-bought yogurts use thickeners like pectin, starch, gum, or gelatin. Don’t be surprised if your homemade yogurt appears thinner without these additives. For a smoother texture, chill the yogurt in the freezer briefly before refrigerating. You can also stir or shake the yogurt to blend it thoroughly.

Add flavorings as desired. Experiment until you find the taste you love. Cake crumbs, jam, maple syrup, and creamy candies are excellent options. For a healthier choice, use fresh fruits, optionally sweetened with sugar or honey.

Use yogurt from this batch as a starter culture for the next batch.

• Store-bought yogurts are often very sweet. Making your own yogurt is a great way to avoid excess sugar.
• The longer the mixture incubates, the thicker and tangier your yogurt will become.
• Chilling the yogurt briefly in the freezer before refrigerating helps achieve a smoother texture. You can also stir or shake the yogurt thoroughly.
• Most yogurt makers require adding water to the base to facilitate heat transfer to the containers. Follow the machine's instructions.
• Using a double boiler makes it easier to control the temperature.
• Always use a thermometer. It helps monitor the water temperature (if using water to maintain heat during thickening) and ensures the yogurt sets properly.

• If your yogurt smells odd, tastes strange, or looks unusual, do not eat it. "When in doubt, throw it out!" Try making another batch. Remember, homemade yogurt differs from store-bought yogurt because it lacks stabilizers, thickeners, etc. As a result, it may appear thinner than commercial yogurt, and whey (a thin, clear liquid) may separate. This is completely normal. However, the yogurt should have a pleasant aroma, similar to fresh cheese or baked bread.

• Pot
• Metal spoon
• Thermometer
• Double boiler (Optional)
• Containers with lids
• Oven
• Refrigerator