Custard-Style Yogurt

 

The Brød & Taylor Folding Proofer will work beautifully with any reliable yogurt culturing method.  We developed this recipe to make a thick, mild, “custard-style” yogurt, a very popular type for eating or making into desserts.  After the recipe, there are straining instructions for Greek-style yogurt, and in the last section we explain the concepts and testing behind our method. 

Printable Recipe
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Many yogurt recipes call for powdered milk or gelatin in order to create a thick texture.  We wanted to avoid additives and the undesirable flavors they create in our fresh yogurt, so we developed this “custard-style” method.  It uses heat to alter dairy proteins and make the yogurt thicker.  We also found that culturing with our “High-Low” temperature method was faster and more food-safe than the classic method, finishing the culture in 2-4 hours rather than the 4-6 hours needed for other yogurt makers.  This “custard” style of yogurt is delicious for eating and also makes a great yogurt base for freezing into desserts.
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Milk	4 cups (1 quart / 968g )	8 cups (1/2 gallon/ 1.94kg)	16 cups (1 gallon/ 3.87 kg)	32 cups (2 gallons/ 7.74 kg)
Live culture yogurt*	2 Tbs	4 Tbs or 1/4 cup	8 Tbs or 1/2 cup	16 Tbs or 1 cup

*Store-bought or reserved from a previous batch of homemade yogurt. 

Equipment: Brød & Taylor Proofer, thermometer, heat-proof culturing containers, such as glass mason jars.  Everything that will touch the milk should be scrupulously clean and dry.
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Step One: Heat Milk to 195F and Hold for 10 Minutes.  Using either the stove top or microwave, scald the milk by heating to about 200F, stirring continually if using the stove top to prevent scorching.  Set a kitchen timer for ten minutes and hold the milk between 195 and 200F by using moderate heat (stove top) or 30-60 second bursts (microwave).  This ten-minute holding period will denature the whey proteins in the milk, allowing it to form a thicker yogurt when cultured.
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Tip: Whisking the milk to cover the surface with bubbles will prevent the milk from forming a skin during heating and cooling.
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Step Two:  Cool Milk to 115F.  Remove the milk from the heat and allow to cool to at least 115F.  For faster cooling and greater food safety (especially important for larger batches), place the container of milk in a large pan or bowl of cold tap water.
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Set up the Proofer.  When the milk is nearing 115F, set the aluminum tray (without water in it) on the center of the proofer’s warming plate and place the rack on top of it.  Set the thermostat to 120F, put the lid on and allow the proofer to come up to temperature.
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Step Three: Inoculate with a Live Culture.  To inoculate the milk, add yogurt with live cultures to a small bowl.  When the milk drops below 115F, add a small amount to the inoculate and stir so that it is dispersed evenly and has no lumps.  Then add the liquefied culture back into the large container of milk and stir gently to distribute.  Fill culturing jars with the milk, cover and set in the proofer to culture.
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Tip:  Arrange the jars so that they are not directly over the centered aluminum tray, to allow proper heat circulation and ensure the most accurate culturing temperature.
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When the yogurt passes the tilt test, put it into the refrigerator and allow to chill thoroughly.  Once the yogurt is chilled, reserve enough to start your next batch and store it in the refrigerator for up to a week.

 

Making Strained Greek Yogurt

Line a colander or strainer with several layers of cheesecloth or one layer of paper coffee filters.  Set the colander/strainer over a bowl and spoon in the chilled yogurt.  Cover and refrigerate.  Allow to strain for 2-3 hours for thick Greek-style yogurt, or overnight for the thickest possible texture, which is what we’ve used in our frozen yogurt recipe.

 

Factors for Making the Best Yogurt

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. Lucy on commercial yogurt making methods.  These sources pointed out two important concepts for creating thick yogurt without the need to add powdered milk:  holding milk at 195F for ten minutes before culturing, and allowing the yogurt to thicken at a lower temperature.
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For a 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 170F is thinner and tastes fresh, a little fruity and more tart, while yogurt made from milk held at 195F for 10 minutes is noticeably thicker and tastes less tart and somewhat creamy/nutty/eggy.  Milk heated to 180F, which is a common recommendation in home yogurt-making, comes in half way between these two in terms of taste and thickness.
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Protein is Key to Thickening.  The casein (protein) clusters in milk thicken yogurt by unravelling and forming a three-dimensional mesh when exposed to the lactic acid created by culturing.  Heating milk above 172F 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 195F 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 milks like Jersey or Guernsey make wonderful yogurt.
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Does Boiling before Culturing Ruin the Yogurt?  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 is a thick, smooth 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.
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Culturing Temperature also Affects the Yogurt Texture.  In addition to the quantity of protein available to form a mesh, the stability of that mesh is also important, determined by the temperature at which the mesh forms.  The yogurt will be more likely to leak whey when the mesh is formed at temperatures above 104F, and more stable (less likely to leak whey) when formed at lower temperatures.  At lower temperatures there is also a longer window of opportunity to stop the culturing before the yogurt turns lumpy.
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Harold McGee points out that commercial yogurt is sometimes cultured at 86F, and that a lower culturing temperature ensures a smooth yogurt (spoon on left in the photo) with less risk of whey separation. Higher temperatures and longer culturing times can cause a lumpy texture and excessive whey separation (spoon on right).  We tested an 86F culture and found that it makes perfect, smooth yogurt.  However, a temperature that low takes a long time (12-18 hours) and made us a little uneasy about the potential to grow undesirable microbes in case our conditions were less than perfectly sterile.
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Our “High-Low” culturing method produces smooth, thick yogurt that is less likely to leak whey, yet is much more quick and safe than culturing at 86F.  We start the culture at 120F, a temperature that speeds the yogurt through the earlier stages of culturing and is more hospitable to the beneficial lactic acid-producing bacteria and less favorable to undesirable microbes.  Then as culturing progresses and the rising acidity begins to inhibit any potentially problematic microbes, we turn down the proofer to 86F.  The method works well, and culturing takes just 2-4 hours, not 12.
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Which Culture?  Our testing showed that store-bought yogurts are not all created equal- some made dramatically better starter cultures than others.  While all the brands of “live culture” supermarket yogurt worked, some produced thinner textures while others made thicker textures, and a few produced yogurts that cultured much more quickly than others and were more susceptible to the lumpy texture that comes from culturing too long or too hot. Generally, the cultures that produced the thickest, smoothest yogurt ended up being from small (8oz) containers.  Even within the same brand, 8 oz containers tended to produce smoother yogurts than larger economy tubs, which often produced more lumpy textures.  It’s worthwhile to test several different brands of yogurt until you find a favorite culture.

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 Add Honey after Chilling.  If sweeteners are needed, add them after the yogurt is chilled.  We prefer not to add honey or other sweeteners before culturing to avoid feeding any undesirable bacteria.  The beneficial lactic-acid producing bacteria are 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.  Eventually these will be inhibited by lactic acid, but we prefer to avoid growing undesirable bacteria with non-lactose sugars during the early stages of culturing.