Our yogurt method is based on the principles in Harold McGee’s On Food and Cooking, and on the research by professors W.J. Lee and J. A. Lucey from University of Wisconsin-Madison on commercial yogurt making methods. These sources pointed out two important concepts for creating thick, creamy yogurt: holding milk at 195 ºF / 90 ºC for ten minutes before culturing, and allowing the yogurt to set at a lower temperature.
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.
For a Thick, Custard-Style Yogurt, Choose a Higher Initial Milk Temperature. Standard methods for making yogurt call for the milk to be heated and cooled before culturing, and different temperatures create different styles of yogurt. Yogurt made from milk kept below 170 ºF / 77 ºC is thinner and tastes fresh, a little fruity and more tart, while yogurt made from milk held at 195 ºF / 90 ºC for 10 minutes is noticeably thicker and tastes less tart and somewhat creamy/nutty/eggy.
Protein is Key to Thickening. The more protein in milk, the thicker the yogurt. The casein (protein) clusters in milk thicken yogurt by unraveling and forming a three-dimensional mesh when exposed to the lactic acid created by culturing. Heating milk before culturing denatures one of the main whey proteins, lactoglobulin, which allows it to join in the mesh (instead of remaining inactive) and effectively increases the amount of protein in the milk that will be available to thicken the yogurt. The milk needs to be held at 195 ºF / 90 ºC for ten minutes to denature most of the lactoglobulin. A little evaporation during this heating also aids the thickening benefits of this procedure. When available, higher-protein, richer milks like Jersey or Guernsey make wonderful yogurt.
Lower Temperatures Give a Better Set. In addition to the quantity of protein available to form a mesh, the stability of that mesh is also important. That stability is determined by the temperature at which the protein mesh forms, i.e., the temperature of the yogurt when it sets. The yogurt will be smoother and more stable (less likely to leak whey) when it sets at a temperature below 104 ºF / 40 ºC. Being able to turn down the temperature during culturing is a key benefit of using the Proofer, a benefit which allows the smoothest, best texture to form (see texture comparison in photo of spoons, below).
Low Temperature Cultures can be Slow. Harold McGee points out that commercial yogurt is sometimes cultured at 86 ºF / 30 ºC, and that a lower culturing temperature ensures a smooth yogurt with less risk of whey separation. Higher temperatures and longer culturing times can cause a lumpy texture and excessive whey separation (similar to the spoon on right on the photo). We tested an 86 ºF / 30 ºC culture and found that it makes perfect, smooth yogurt. However, a temperature that low takes a very long time (12-18 hours) and made us a little uneasy about food safety.
High-Low yogurt method makes smoother yogurt (left spoon) than hot culturing (right spoon).
Our “High-Low” culturing method produces smooth, thick yogurt that is less likely to leak whey, yet is much more quick and safe than a low-temperature culture. We start the culture at 120 ºF / 49 ºC, a temperature that speeds the yogurt through the earlier stages of culturing. Then as culturing progresses and the rising acidity begins to inhibit any potentially problematic microbes, we turn down the Proofer to 86 ºF / 30 ºC. The method works well, and culturing takes just 2-4 hours, not 12.
Lowering the proofer temperature to 86 ºF allows the milk to cool to 100 ºF after about 3 hours. Either the Folding Proofer or the Sahara Dehydrator can be used to make yogurt using this method.
Which Culture? Our testing showed that store-bought yogurts are not all created equal- some made better starter cultures than others. While all the brands of “live culture” supermarket yogurt worked, some produced thinner textures while others made thicker textures. Yogurt cultures that included L. Casei tended to have more viscosity and set up faster than those that didn’t. Some of our tasters loved the more viscous texture but some didn’t. A culture containing only the two classic yogurt microbes L. Bulgaricus and S. Thermophilus had very little viscosity. We also had the best luck with smaller (8 oz / 250 ml) containers. Even within the same brand, starter yogurt from 8 oz containers tended to produce smoother yogurts than larger economy tubs, possibly due to faster turnover and fresher cultures. It’s worthwhile to test a few different brands of yogurt until you find a favorite.
Sweeten after Chilling. If sweeteners are needed, we like to add them after the yogurt is set and chilled. We prefer not to add sugar before culturing to avoid feeding any undesirable bacteria. The beneficial lactic-acid producing flora are naturally well-equipped to feed on lactose, while other less desirable bacteria are not. Adding non-lactose sugars to the milk could feed any undesirable bacteria that accidentally end up in the milk through equipment or inadequate heating. As the culture progresses these will be inhibited by lactic acid, but we prefer to avoid growing undesirable bacteria on non-lactose sugars during the early stages of culturing. Honey, due to its anti-bacterial qualities, can slow down culturing and so is best added just before eating.
Frequently Asked Questions
1. Control the ingredients: commercial yogurt often contains additives that you may not want to consume. Some of these additives (such as titanium dioxide added to many Greek yogurts) are not required to be disclosed on labels. When making your own yogurt you control the type and source of the milk and any other ingredients. In addition to cow milk, you can also use goat milk or non-dairy milks such as soy, rice, oat, or coconut.
2. Use glass containers: making your own yogurt provides the flexibility to make yogurt in your own container. Most users choose glass jars (often 1-quart size) for convenience and food safety.
3. Control taste and texture: temperature control makes it possible to adjust the recipe in ways not possible with conventional pre-set home yogurt makers. By adjusting time and temperature, yogurt can be made sweet or tart, thick or thin. Making Greek yogurt is also easy this way.
4. Control the lactose content: many users want the benefits of probiotic yogurt but cannot tolerate lactose. Using temperature control features, you can make lactose free yogurt.
Either the white plastic or the metal canning jar lids. It will not affect the results of your yogurt.
It is important to understand that the Proofer is calibrated to keep its contents near the temperature set point – not the air inside. Heating in the Proofer takes place by two mechanisms: Convective and radiative heating. Convective heating occurs when the air in the Proofer is heated by the aluminum plate – then rises. It passes its heat energy into an object plated in the Proofer. Radiative heating occurs when the heat in the aluminum plate is passed directly to the objects in the Proofer without heating the intervening air – just as when you feel the intense heat of a fire when you hold out your hand – it is much hotter than the surrounding air. This is why measurements of the air inside the Proofer will give unreliable readings.
Smaller containers may cool more quickly than larger ones, and cooler temperatures mean the yogurt is slower to acidify and set. Nothing is wrong with the smaller jar, just give it a little more time in the Proofer.
There are two reasons for heating the milk before starting to culture yogurt.
1. Heating milk before adding the yogurt starter ensures that only the beneficial bacteria is cultured.
2. Heating the milk creates a firm spoonable yogurt. At 195°F / 91°C the structure of the whey proteins become denatured and open up. The result is a yogurt you can scoop rather than one which will pour.
Yogurt that lumps or leaks whey is often caused by culturing too hot or too long. To prevent lumpy yogurt hold the milk above 195°F / 91°C for ten minutes before cooling and culturing. Yogurt starter cultures containing Lactobacillus Casei generally result in thicker smooth yogurt. Milk with a higher protein content can also develop a thicker yogurt. Both of these steps will help yogurt utilize more of the whey proteins in milk for thickening and stabilizing the texture.
Brod & Taylor Custard-Style “High-Low” culturing method produces smooth, thick yogurt less likely to leak whey, and takes less time than most other methods.
Yogurt starter is a blend of bacteria which are added to milk to consume the lactose (milk sugar). Lactose in the milk is converted into lactic acid which gives yogurt a tangy taste. Increased lactic acid allows yogurt to be stored longer than dairy milks and also changes the milk’s protein structure resulting in a smooth thick yogurt texture. Thickness and flavor of yogurt are determined by the starter’s blend of bacteria which has been introduced into the milk.
Yes, sometimes there is no plain yogurt available. A flavored yogurt will work as long as it is labeled “live culture.” After the first batch of yogurt, the flavor will no longer be detectable
No, but yogurt sets faster at high altitudes. Simply check the yogurt more often to see when it has set. Refrigerate for storage when set.
Yes, there will be a difference in both texture and flavor depending on whether you are using whole or skim milk. Fat content affects both. Whole milk is generally sweeter in taste than skim milk even though both have about the same lactose (milk sugar) content. This taste difference may be due in part to the fact that skim milk has about 30% more sodium than whole milk. Fat in dairy products produces a creamier and smoother texture.
No. The casein proteins and whey proteins do not coagulate when heated unless acid is also present, and the integrity of the fat in milk is actually strengthened by boiling. To test this, we made yogurt from milk that had been simmered long enough to reduce the volume by 25%. The result was a thick and smooth creamy yogurt, although it had a prominent cooked milk taste with a custard texture.
No, but it also will not kill unhealthy microbes. Heating milk to 195°F / 90°C for 10 minutes will kill any unhealthy microbes present. Between yogurt-making sessions, high heating the milk followed by cooling and then adding starter culture keeps the yogurt culture pure and healthy.
One key point in yogurt making is that heating the milk before culturing determines part of the flavor and how thick the yogurt will be. If you just heat milk to 165°F / 74°C briefly and then cool, the yogurt will taste fresh, a little fruity, and will be thinner and more tart when it sets. If you heat the milk to 195°F / 90°C and hold it there for ten minutes, the yogurt will be milder and thicker when it sets, and will have a bit more of a cooked milk taste.
Holding the milk at 195°F / 90°C for ten minutes is optional. It helps produce a thicker and slightly milder yogurt. The process denatures whey proteins, allowing them to contribute to the solidification of the yogurt. With the extra protein, the yogurt sets a little earlier in the culturing process so that the flavor can be mild. Yogurt can be cultured for a longer time if more tartness is desired.
One way to make yogurt is simply to run the entire culture at 85-90°F / 29-32°C. However, this is a very slow culturing process (often 12-18 hours) and is not food safe during the first hours.
Keep your seed culture in a smaller, separate jar and remove it from the Proofer as soon as it sets, even if the rest of your batch will culture longer. If you are going more than a week between yogurt-making sessions, feed the yogurt after one week by stirring in a little plain milk.
Yes, frozen yogurt 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. 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: 1. Pre-chill the culture in the coldest part of your refrigerator before moving it to the freezer. 2. 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 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.
After culturing the first hour at 120°F / 49°C, our Custard-Style Yogurt is generally set in 2-4 hours. However, time can vary depending on multiple factors including whether the milk cows were grazing on grass or on winter feed. Yogurt resting at 120°F / 49°C for longer than one hour may result in whey separation. As yogurt is culturing for a longer period of time, lactose (milk sugar content) is reduced resulting in more tart yogurt. Even while yogurt is refrigerated it will continue to become less sweet and more acidic or tart over time, although at a much slower rate with cool refrigerator temperatures.
Yogurt will keep up to a month in the refrigerator when it is stored in a tightly sealed container. Glass mason jars work well. Acidic foods like yogurt are much less prone to spoilage than some dairy products. Yogurt becomes more acidic with more tart flavor the longer it is in storage.
Although it consists mainly of water, whey also contains protein, potassium, and calcium.
—the yogurt should be below 104°F / 40°C at the point at which it sets. —the yogurt should not be cut into or jostled. —higher protein levels in the milk help prevent whey leaks. —stop culturing the yogurt once it has set. Refrigerate when set. —a little sugar dissolved in the milk may help prevent whey leaks.
When heated, milk proteins begin to coagulate. At the surface of the milk, water also evaporates causing a skin to form. This happens more readily in whole milk because fat aids in the coagulation of the proteins. If the skin is allowed to fully develop, heat will be trapped underneath the skin and cause the milk to boil over. One way to combat this is to constantly stir the milk to break up the clumps of protein and keep the skin from forming. However, vigorously whisking the milk surface to form a foam (do this once the milk is above approximately 120°F / 49°C so that the foam will not dissipate) will also protect the surface from forming a skin. The reasons for this are complicated, having to do with the behavior of milk proteins in bubbles. Bubbles force the milk proteins to form a regular structure that resists clumping, like in steaming milk to create foam for a coffee latte beverage. Since evaporation of water tends to harden the skin, covering the containers used for culturing the yogurt will also discourage the formation of a skin over the yogurt.
Yes, if there is brown residue stuck on the bottom of the pot we recommend pouring the milk into a clean and sterilized warm pot before cooling and adding the yogurt starter. This is more likely when using an electric burner stove, a thinner-bottom pot, or forgetting to stir often and stir all the way to the bottom of the pot. If the residue is not dark or burned, your yogurt should be fine. Customers with electric stoves can leave the heated burner on while covering the pot with a tight fitting lid and immediately slide the pot to an adjacent cold burner during the ten minutes at 195°F / 91°C. About 3-5 minutes after moving the covered pot, check the temperature. If it is dropping below 195°F / 91°C, set it back on the warm burner (turn it on for up to 1 minute, if necessary) and check that the temperature has risen back up to 195°F / 91°C. Again slide it over to the cool burner for the remainder of the ten minutes. This will help prevent a residue from forming on the pot bottom.
Whole-fat milk will produce a thicker, creamier Greek-Style yogurt. The yogurt will be similar to the yogurt made in Greece which is commonly used in Greek cooking in the form of sauces. Making Greek-Style yogurt is similar to making regular yogurt but it involves straining to remove some of the whey which makes the yogurt thicker. Goat’s milk can also be substituted for whole-fat cow’s milk.
Homemade yogurt is easy to strain (cheesecloth or coffee filters) for a true Greek-Style yogurt. The results are much better than store-bought which simply add nonfat dry milk or other ingredients to thicken texture. Commercially sold non-fat Greek yogurts often have additives, stabilizers or fillers to enhance the palatability of yogurt they sell. Making your own yogurt eliminates unwanted submicroscopic particles. FDA-approved titanium dioxide is used in plastics, paint and cosmetics, but is also used to whiten foods including commercially sold Greek yogurt.
Greek-Style yogurt has more protein is because the proteins become more concentrated when the whey is removed. The same amount of Greek-Style yogurt has more protein than an equivalent amount of yogurt that has not been strained.
Both fresh goat milk and cow milk have comparable flavor and nutrient content, but goat milk contains only trace amounts of one major protein in cow milk to which many people are allergic (alpha S1 Casein protein). Goat milk primarily contains Alpha S2 casein. The higher proportion of beta-casein in goats’ milk means that the casein profile of goats’ milk is closer to human milk than that of cows’ milk. Nutritional values of goat milk vary for reasons including seasonality, type of herd, time of milking. Goat milk has a higher percentage of short-chain fatty acids than cow’s milk. These shorter chains are more easily digested than the longer-chain fatty acids which are in cow’s milk. Many people who have trouble with cow milk successfully switch to goat milk. Goat milk is naturally rich in nutrients such as calcium and vitamin A, and offers a high bio-availability of iron.
Yes, all mammalian milks contain the milk sugar lactose although goat milk contains less than cow milk.
Fat molecules are more evenly suspended in goat milk so they do not easily form a cream on top as cow milk does. Goat milk is naturally homogenized in the goat’s digestive system.
Yes, customizable degree-by-degree temperature control with the Folding Proofer gives you the ability to make lactose-free yogurt at home. The Proofer can be set to exact temperatures, and culturing can be customized allowing you to make lactose-free yogurt from either lactose-free or regular milk. To make lactose-free yogurt with regular milk, you simply need a longer culturing period to give beneficial bacteria enough time to consume all of the lactose in regular milk.
Tests do not show any benefit using the “High-Low” method compared to culturing at 108°F for 6 hours. The reason is that a plant-based starter culture needs time to adapt to the new food source (oat, soy or rice sugars). By the time the culture adapts and gets going, our High-Low method instructs a lower temperature.
The process for making almond milk yogurt is more complicated and carries a higher risk of food safety problems. For this reason, we do not recommend homemade almond milk yogurt.
For oat milk yogurt we use Pacific Foods brand Organic Oat Milk and use CFH Vegan Yogurt Starter for culturing. View Recipe Vegan Yogurt Starter and follow directions on the CFH starter, set the Proofer at 108°F / 42°C and culture for six hours.
No, plant-based milks usually do not thicken, so you may have to add a thickener. Agar can be used to thicken plant milk yogurts. It is a natural product derived from seaweed and has a powerful setting action. The nice thing about agar for yogurt making is that it sets at about 90-95°F / 32-35°C, so the plant milk remains liquid throughout the culturing process, but sets as soon as it starts to cool. This allows the culturing microbes to circulate and find plenty of food during culturing. Use 1/8 – 1/4 tsp of powdered agar per cup of milk, and dissolve it at 190°F / 78°C or higher. Other thickeners will also work: arrowroot, corn starch, potato starch or flour, cassava (tapioca) starch or flour, gelatin and agar. Whatever you use, it will need to be simmered in a small amount of water or the plant milk you are using and then whisked with the warm plant milk to blend. You may need to wait a few minutes for the plant milk/starch mixture to cool back to 110°F / 43°C before adding the culture.
Soy milk which has been heated using the “High-Low” method creates a somewhat thicker and more stable yogurt. We recommend our Soy Milk Recipe when culturing soy milk. To confirm that no added sugar is necessary to culture soy yogurt, we have tested one jar with unsweetened soy milk and unsweetened cow’s milk yogurt as starter, and both work.
Soy milk yogurts do have a tendency to separate and release a watery liquid more easily than dairy milk yogurt. We recommend the “High-Low” method following our Soy Milk Recipe.
There are three additional steps you can take to minimize the tendency of liquid separation.1 1. Hold the soymilk above 195°F / 90°C for at least ten minutes before culturing, as this helps produce a thicker and more stable yogurt. 2. Only culture the soy yogurt long enough to get a thick set. Remove it from heat promptly once it has thickened and don’t agitate or shake the container. 3. Consider adding cornstarch, agar or gelatin to the soymilk before heating. This will gel and bind the yogurt to make it very stable and thick.
No. The milk will not curdle when boiled unless acid is also present, and the integrity of the fat in milk is actually strengthened by boiling. To test this, we made yogurt from milk that had been simmered long enough to reduce the volume by 25%. The result is a thick, smooth and creamy yogurt with the strongest “custard” taste of any of the yogurts we tested. We didn’t choose this method for our custard-style yogurt because the cooked milk/custard taste is so prominent that it starts to seem like something other than yogurt. But it was a favorite among some of our tasters, and it’s good to know that if you accidentally heat the milk hot enough to produce a few bubbles, nothing bad will happen to your yogurt.