Sanitizing cheesecloth just before use
Dairy fermentation usually consists of four basic steps: heating, culturing, incubating, and chilling. Other steps might include adding flavors, thickeners, and draining. Once you get the hang of the fermentation process, you can customize your ferment to the tartness, thickness, and flavor you crave. There really is something here for everyone in the family — even those who are lactose intolerant!
At last we get to the nuts and bolts of crafting homemade dairy ferments! The steps outlined in this chapter are relatively simple and easy to master, and they cover the basic techniques for all of the dairy ferment recipes in this book. See visual step-by-step.
It’s a good idea to wash all fermentation equipment both just before and after use. In most cases, it isn’t necessary that you sanitize your equipment and tools as long as you have scrubbed and rinsed them with hot water. (If you are a commercial fermenter, though, you should always sanitize your equipment in order to adhere to the “best practices” outlined in food safety plans.) Woven and mesh draining items are the exception. Because they are absorbent and harder to properly clean, it’s a good idea to sanitize them. To sanitize, slowly pour boiling water over the equipment and tools to expose the surfaces to the hot water for 30 seconds or use a properly diluted “no-rinse” concentration of chlorine or another food-safe sanitizer (read the label for instructions and use the appropriate test strips to verify sanitizer activity).
Cheesecloths in particular can harbor unwanted bacteria as well as dust and hairs. Hand-wash them immediately after each use and then hang them to dry. If they are bunched up and wet, microbes will start to grow, and the cloths will become smelly, too! If they are dry, microbes cannot grow on them.
When you clean up after fermentation, allow everything to air-dry, rather than using a towel to dry, as this will reduce the possibility of spreading microbes from the towel onto the equipment. A dishwasher works well for washing and drying smaller tools. Reinspect all your equipment and tools before use, and rewash or reclean if needed.
Sanitizing cheesecloth just before use
All the ferments in this book require that the milk be at a certain temperature (called the incubation temperature) for optimal fermentation. Depending on the recipe, you may first need to heat the milk above the ideal fermentation temperature and then cool it back down. This is done to destroy some or almost all of the bacteria in the milk, as well as to denature (change the structure of) some of the milk proteins in order to improve the final texture of your product.
Whether you are working with raw milk or even pasteurized milk, it will contain some bacteria. Raw milk will likely have a lot of microbes, and even though many of them will be harmless or even helpful, they create competition for yogurt and kefir cultures. If you are trying to create a superprobiotic product, then it’s often a good idea to give the culturing microbes a blank canvas on which to work. How hot you heat the milk and how long you hold it there will determine how many microbes are killed. Simply put, the hotter or longer the milk is kept hot, the more microbes are destroyed. Note that heating milk on the stovetop will never destroy all microbes. Some types of bacteria, called spore formers, can form protective shells that allow them to survive all but pressure-cooking heat levels. Most of these types of microbes lead to food spoilage over time. This is why an unopened carton of pasteurized milk still “goes bad.”
Heating milk to denature its proteins will thicken the final ferment and give it a smoother texture. If you are making kefir or a drinkable dairy ferment, you may not want to denature the proteins because you want a thinner, drinkable consistency. When you make yogurt, however, you generally want to create a thick product. Whey proteins are very heat sensitive. When heated to certain temperatures, they can basically stick to the caseins. This is a bad thing if you are making cheese (as it prevents a good rennet coagulation), but in the case of yogurt, it’s terrific! Because they have adhered to the caseins, the whey proteins are retained in the yogurt curd rather than lost in the whey liquid, which increases the yogurt’s thickness as well as the total protein content. The degree to which you can thicken the final product depends on the volume of whey protein in the milk (remember, it varies from 20 to 30 percent of the total protein) and on how hot and for how long it’s heated. I start by heating the milk to 180°F (82°C) and then experiment with holding it at this temperature for various lengths of time beginning with 10 minutes, or heating it higher, but feel free to play around with temperature and time.
|
Treatment |
Parameters |
Purpose |
|
Thermization |
145°F–149°F (63°C–65°C) for 15 seconds |
Reduces bacteria count |
|
Low temperature, long time |
145°F (63°C) for 30 minutes |
Pasteurization |
|
High temperature, short time |
161°F (72°C) for 15 seconds |
Pasteurization |
|
Scalding to boiling |
180°F–220°F (82°C–104°C) for 10–30 minutes |
Whey protein denaturing and microbe reduction |
|
Ultrahigh temperature |
275°F (135°C) for 1–2 seconds |
Pasteurization, whey protein denaturing |
The milk must be at the proper incubation temperature, which varies depending on the recipe. If the milk is coming straight from the fridge, you’ll have to heat it to the proper temperature. You can use one of several methods: gently heat the milk in a pan directly on the stove or in a double boiler, set the milk container in a bowl of warm water and stir, or pour the cool milk into the incubation jar and warm that in a bowl or pan of warm water.
On the other hand, if you just heated your milk above the ideal incubation temperature in order to destroy bacteria and denature proteins, then you will have to let it cool down before you can add the culture. You can cool your milk very quickly by placing the pot of hot milk in a sink full of cold tap water and stirring the milk to help it cool quickly and prevent a skin from forming on the top. Add more cool water to the sink as needed.
Marvelous fermentation microbes inhabited the porous utensils and vessels our early dairy producers used, but in modern times, we usually have to add these microbes to our milk to ensure proper and delicious dairy fermentation.
Freeze-dried culture powders come with instructions, and amounts are usually given with quite a range of measurements. Start with the smallest amount recommended and see how the batch proceeds. If it doesn’t reach the desired thickness and flavor in the right amount of time, add more culture to the next batch. If it does, you can try adding less the next time. Using accurately measured, small amounts will allow you to conserve your culture and save money over the long run. In general, you should sprinkle the powder on top of the milk, allow it to sit for 1 minute or more, and then stir it in. This allows the fine particles to absorb some moisture so that you can stir them in evenly without having them clump.
If your starter consists of a bit of fresh yogurt or kefir, heirloom seed, or kefir grains, the amount you need will depend upon how fresh the donor batch is — the older it is, the more you are likely to need. It never hurts to add more than you think is required, but it might make the batch ferment more quickly than expected. If you don’t mind some inconsistency, then don’t worry about it! Generally, you will have good results if you use about 2 tablespoons per quart of milk.
When using fresh yogurt or kefir as the culture, place the amount you need in a small bowl, add a bit of the warmed milk, and whisk together until evenly smooth. Then add the thinned yogurt or kefir to the rest of the milk. Otherwise, the yogurt or kefir is unlikely to stir in evenly and can result in a thick gel only at the bottom of the vessel.
If you’re using heirloom seed, you will usually simply mix the seed into the milk directly in the incubation container. The only exception to this is viili, for which you spread the seed over the bottom and sides of the container; see the recipe.
If you’re using kefir grains, simply place them at the bottom of the container and add the milk, or vice versa.
No matter what type of starter you are using, it’s imperative that the milk be at a temperature that will not destroy the fermentation microbes! It’s fine if the milk is a couple of degrees above the incubation temperature, as the milk will continue to cool while you are adding the culture.
After you add the culture, it’s time to let the milk sit so the fermentation microbes can do their thing. This is called the incubation, ripening, or culturing stage. During this time, even slight temperature variations will affect the texture, acid level, probiotics, and flavor of the finished ferment. Feel free to play around with the temperature range during this stage and see how you like the results. Of course, you can only do this successfully if you are aware of those temperature differences, so plan on having an accurate way to monitor and adjust the temperature. You can also take a more casual approach and simply accept the variations!
Most dairy ferments shouldn’t be stirred during the incubation, unless it is early in the process and you aren’t confident that the culture has been evenly incorporated or the temperature is even. If you are making a thick product like yogurt, stirring or agitating it in any way toward the gelling stage of incubation might disrupt the formation of the curd. If you are making a drinkable product, don’t worry about movement; in fact, gently stirring or rocking kefir or drinkable dairy ferments once or more during their incubation can help create an even texture.
Once the product has finished its incubation phase, it’s important that you cool it as quickly as possible to stop the fermentation. If fermentation continues, the product will become more sour and begin to separate as more whey is expelled from the curd. For the most rapid chilling, cool the product in a cold water bath, set it in the freezer for an hour or two, and then transfer it to the refrigerator. These times are approximate; the smaller the container, the faster your ferment will chill.
There is some wiggle room, especially with warm-temperature ferments like yogurt. You can start the cooling process a bit early by bringing the ferment down to a more moderate temperature; it will continue to develop some acid, but at a slower rate. For example, if a product should ferment for 4 hours and then be rapidly chilled, you could ferment it for 3 hours and then cool in the refrigerator or even for a short period of time on the countertop if that fits your schedule better. Again, as with incubation, you can take a more casual approach as long as you don’t mind the variation in the results. Hopefully you are getting the idea that there is a lot of resilience in the entire process!
If you are using powdered culture, sprinkle it on top of the warm milk, let sit for 1 minute, and then whisk it in.
Plain yogurt and kefir are great, but, well, plain. Sometimes you just want to play with your food, adding some spice, some sweetness, or some savory notes. Playing with the flavor is also a great way to make the product more versatile so that you can more easily introduce a healthy food to family members who might not yet be adoring fans of dairy ferments. There are no hard-and-fast rules about adding flavors; I’ll introduce you to some of my own favorite ideas here, but if you have other ideas, go for it!
Sweetened flavored yogurts have been popular commercially since Dannon debuted them in 1947 in the United States. Savory flavors have appeared on — and disappeared from — the grocery shelves more recently. Two examples are Fage Crossovers (marketed as “chef-level snacking”) in combos such as tomato basil with roasted almonds and carrot ginger with pistachios, and New York’s famous restaurant empire Blue Hill Farm’s carrot, beet, and tomato yogurts. Both sweet- and savory-flavored dairy ferments have long-standing traditions in many cultures. You can even find a cannabis-enhanced version in India! I feel that there will be a continued trend toward and a growing appreciation of these less-sweet flavors.
You can add liquid sweeteners like honey, maple syrup, agave, or simple syrup at any time before or after incubation. Granulated sugars need to be stirred in when the milk or ferment is warm, so that they can dissolve. The amount of sweetener is up to you, but keep in mind that if added before incubation, these sugars will add extra fuel for the bacteria, which can increase the acid level and decrease the final sweetness if they are allowed to continue to ferment. Keep your sweetened finished dairy ferments cold to limit or prevent this.
If you want to make your dairy ferments sweeter but don’t want to add any sugar, you can make them with lactose-free milk, which is simply milk to which the enzyme lactase has been added to break down all of the lactose. (In a regular fermentation, there is always some residual lactose remaining at the end of the process.) Once the lactose molecule is split into two simple sugars, glucose and galactose, you can instantly taste the sweetness; your taste buds experience simple sugars as sweeter than more complex sugars. Lactose-free ferments are easy to make. You can use store-bought lactose-free milk with any recipe, or you can create your own lactose-free milk by adding lactase to the ferment at the same time you add the culture (see the box).
Liquid extracts (natural products) and flavorings (usually not natural) are an easy way to add distinctive taste to your dairy ferment, from the popular vanilla, almond, and lemon to coconut, maple, root beer, and yes, even pumpkin pie spice. Having an assortment and letting your family members flavor their own yogurt or kefir not only is fun for everyone but can encourage consumption. Often adding a bit of extract will give an illusion of sweetness, but without the added sugar.
In most cases, you will add liquid extracts and flavorings to the milk just before you add the culture and incubate it. If you are making a stirred yogurt or drinkable milk ferment, you can add them after incubation. Use 1⁄2 to 1 teaspoon of extract or flavoring per quart (4 cups) of milk.
The sky’s the limit when it comes to seasoning your dairy ferments. You can add most herbs and spices either before or after incubation. If you add them before incubation, they will yield stronger flavor, but if you add them after incubation, you have more flexibility — a single batch might be divided and flavored in different ways to suit your family members’ tastes. Take care with herbs and spices known to have an antimicrobial effect, like sage; they could impede fermentation and should be stirred in after incubation.
When using dried herbs and spices, you’ll get the best flavor when you add them early in the process, just before heat treatment or incubation. Fresh herbs are best added after incubation and chilling to maintain their fresh-picked flavor. Here are some herbs and spices that I really enjoy:
Citrus zest. Grated citrus zest adds amazing flavor and a bit of pleasing texture. Add zest just before or after fermentation. If adding after fermentation, the flavor will improve if allowed to sit for a bit of time (overnight in the fridge is usually adequate). Add about 1 tablespoon of grated lemon, lime, orange, or other citrus zest per quart of milk or finished ferment. I don’t usually add sweeteners when I use citrus peel, since the peel adds a fruitiness that seems sweet, but you certainly can to make an almost dessertlike treat.
Turmeric. Turmeric has anti-inflammatory as well as other health benefits, and it gives dairy ferments a beautiful buttery color and nuanced flavor. Add about 2 teaspoons of dried ground turmeric per quart of milk. Incubate as indicated in the recipe. It can go in either a savory or a sweet direction. Try it with a bit of honey, black pepper (the piperine in pepper enhances the health benefits of turmeric), a chai spice infusion, or on its own. I have a premixed blend of turmeric, black pepper (about 1 teaspoon turmeric to 1⁄4 teaspoon black pepper), and a bit of cinnamon, and I mix 1 teaspoon with my fresh glass of kefir. Yummy and healthy!
Cinnamon, nutmeg, or allspice. These spices lend warm, comforting aromas and flavors to yogurt and other dairy ferments. Add them in a ratio of about 1⁄4 teaspoon of ground spice per quart of milk either before or after incubation.
Curry powder. Curry powder is a mixture of spices that vary depending on the brand. Commonly you’ll find it contains ingredients such as turmeric, ginger, cumin, coriander, and pepper. It’s great mixed into finished yogurt and even kefir, but use it sparingly; start with 1⁄4 teaspoon per quart of milk. If you are adding it to a drained dairy ferment, you can use a bit more.
An infusion is basically a tea, and in dairy ferments, we make a “milk tea” with various herbs and spices to add flavor to our creations. It’s most efficient to infuse a portion of the total milk used with the flavoring and then add the infused milk to the rest of the milk. Add the infused milk just before incubation, at about the same time as you add the culture. You can strain the infusion and just add the flavored milk, but if the ingredient you steeped is small and has a pleasant texture (like softened rosemary or lavender), you can add it as well. Here are some infusions I really like; the proportions assume that you will be using the infusion in a ferment of about 1 quart (4 cups) of milk.
Coffee or tea. Heat 1 cup of milk until it just simmers. Turn off the heat and add 1 to 2 tablespoons of ground coffee or tea leaves (any type of tea you enjoy). Stir, cover, and let infuse for 10 minutes. Strain through a fine-mesh strainer or cheesecloth. Coffee and tea infusions are great with chocolate- and amaretto-flavored dairy ferments. If you are a tea lover, you can do what my husband does and simply pour a bit of kefir into your steeped tea!
Cardamom pods, cinnamon stick, nutmeg, or allspice. Use these spices in combination or individually to flavor yogurt. Heat 1 cup of milk until it just simmers. Turn off the heat and add 2 teaspoons of slightly crushed whole spices (to crush the spices, use a mortar and pestle or a cocktail muddler, or put them in a ziplock bag and crush them with a rolling pin). Stir, cover, and let infuse for 10 minutes. Strain through a fine-mesh strainer or cheesecloth.
Chai spice blend. Heat 1 cup of milk until it just simmers. Turn off the heat and add half of a cinnamon stick, four cloves, and two crushed cardamom pods (you can vary the amounts according to what you like). Stir, cover, and let steep for 10 minutes. Strain and add to the rest of the milk for your ferment. If you like, try adding black tea leaves to the spice mix.
Lemongrass. Found in many Thai dishes, lemongrass is a subtle herb that lends itself to both sweet and savory dishes. You can find it in segments or whole, fresh or frozen, in most Asian grocery stores and sometimes even in higher-end natural foods stores. You can also find it dried, but as with many herbs, the dried version is a pale representation of the herb’s flavor. To infuse milk with lemongrass, first slice or chop four 1- to 2-inch segments. Bring 1 to 2 cups of milk to a boil, then add the sliced or chopped lemongrass. Turn off the heat, cover, and let stand for 1 hour. Strain and add to the rest of the milk for your ferment.
Fruit and veggie purées make wonderful additions to yogurt, adding fiber, flavor, nutrients, and color. As with most flavorings, you are limited only by your imagination — and possibly the produce section at your local grocery store. Purées should be smooth, close to baby food in texture, with minimal chunks so that they don’t separate in the yogurt.
Following are some of my favorite fruit and vegetable mixtures. They will flavor 1 to 2 quarts of yogurt or kefir. Put all of the ingredients in a blender or food processor and purée until smooth. Mix with the milk just before adding the culture or after incubation and/or draining. If adding a purée makes your drinkable yogurt too thick, just add milk to thin the mixture.
Mango, Banana, and Lime
This recipe comes courtesy of New England Cheesemaking Supply Company.
Carrot, Ginger, Cinnamon, and Orange
Mixed Berries and Roasted Beets
Indian Shrikhand
This is a classic Indian flavoring mixture usually combined with drained yogurt (chakka).
Chunks of fresh fruit, jam, or marmalade can be stirred into any dairy ferment before or after incubation. When added earlier in the process, the fruit chunks tend to settle to the bottom, but this can be a beautiful fruit-at-the-bottom or sundae-style presentation in a glass and fun to eat as well. Use 1⁄2 to 1 cup of unsweetened fruit or about 1⁄4 cup of sweet preserves per quart of milk, or to taste.
Sheep, water buffalo, and other high-fat and high-protein milks usually set into a thick yogurt without any help, but most goat and cow milks will not. If you’re looking for a little extra body, mouthfeel, and spoonability, you can either drain your yogurt or add a thickener.
Draining is an age-old technique for creating a thicker, creamier yogurt with less lactose and a longer shelf life. Draining removes most of the residual lactose, which helps prevent further fermentation, keeping the yogurt from growing more tart in the refrigerator. The removal of the lactose also makes the yogurt easier to digest for people who have difficulty digesting milk sugar. Despite the fact that many cultures have been draining their dairy ferments for centuries, drained yogurt is commonly now called Greek yogurt.
To drain yogurt, you’ll need to choose one of the draining options, such as cheesecloth and colander or draining basket, mentioned here. Once the yogurt has been incubated, you can drain it immediately or chill it and then drain it later. Simply place the yogurt in the draining basket or cloth-lined colander and cover it to protect it from pets or dust. It should be at a cool room temperature (between 65°F and 72°F/18°C and 22°C). It helps to stir it every 30 minutes or so during draining. Depending on the thickness desired, the draining time will vary (see the chart). Once done, stir it well and place in a container, cover tightly, and refrigerate.
There’s no hard-and-fast rule as to how long you should drain your yogurt or kefir. It depends on how thick your yogurt is to begin with and how thick you want your finished yogurt to be. Milk that has undergone a high-heat treatment to denature whey proteins will produce a thicker yogurt than one made from unheated milk.
Our natural inclination is to suspect “additives” in our food. In fact, health food marketers have so capitalized on this mistrust that additives are now almost an anathema. In truth, a recipe is formed by adding ingredients; in some respects many are additives. Though thickening agents are often categorized as additives, none of the thickeners listed here have any negative health consequences, unless you have an allergy to a particular substance or to its source (for example, if the pectin comes from lemons and you have an allergy to citrus). See the chart for how to use each of the following thickeners.
Adding powdered milk is another tried-and-true way to thicken yogurt, and it is used by many manufacturers. (You might see “skim or low-fat milk” listed as an ingredient if manufacturers start with low-fat milk and dehydrate it themselves as a part of their recipe for making the yogurt.) Using milk powder has the added advantage of boosting the protein and calcium content of the product while lowering the fat content. Milk solids create the creamiest texture of all the thickeners I’ve tried, but they also change the flavor the most. When using milk powder, choose a high-quality brand for the best flavor.
|
Draining Yogurt |
|||
|
Time Draining (at room temperature of about 70°F/21°C) |
Volume Reduction |
Texture |
Common Description |
|
1–2 hours |
25% |
Slightly thick |
Lightly drained |
|
3–4 hours |
50% |
Medium thick |
Moderately drained, Greek, labneh |
|
12–18 hours |
75% |
Very thick |
Fully drained, or yogurt/kefir cheese |
Natural gelatin is made from animal collagen (the technical name for connective tissue such as cartilage and tendons). Commercial gelatin is most often a by-product from pork and beef processing. In large enough servings, it provides protein and a few other nutrients, but when used to thicken products, the nutritional value is negligible. Gelatin isn’t an option for vegetarian, vegan, or kosher (with the exception of pareve gelatin) dairy products.
Gelatin needs to be heated to activate its gelling properties, so if you are making room-temperature ferments, you’ll want to heat the milk and gelatin and then cool the mixture back down to room temperature before culturing. Gelatin won’t gel until it’s cooled, so don’t be surprised if your ferment is still runny when you take it out of the incubator. Gelatin won’t impact the flavor, but the texture it yields is a bit uneven.
Some common brands of gelatin include Knox (from pork), Great Lakes (from beef), Zint (from grass-fed beef), and NuNaturals (from grass-fed beef). There is even a fish-based gelatin available for kosher and pescatarian diets. I recommend choosing a grass-fed variety, as that helps ensure a healthier product and also a hopefully more natural existence for the animals. I’d love to see a certified humane gelatin one day!
Also called fruit pectin, this soluble fiber is usually derived from apples and citrus. It’s most commonly used to gel jams and jellies, making it a readily available ingredient in grocery stores. I find that it imparts a smoother texture than gelatin does, unless you use too much. Pectin can be purchased in granular form or as a liquid. Only one brand that I’m aware of has no additional ingredients, and that’s Pomona’s Pectin.
Most pectin is labeled and marketed with jelly and jam makers in mind, therefore two types of pectin are sold: those designed for low-sugar recipes and those designed for high-sugar ones. In low-sugar preserve recipes, pectin requires a boost from calcium (instead of relying only upon sugars) to perform its gelling magic. Pectins destined for low-sugar recipes contain added calcium, or else a separate packet of powdered calcium is included in the package, which you mix to make to make “calcium water” that is added to the recipe. You don’t need extra calcium for gelling dairy ferments, so buy the high-sugar pectin instead. If you are using the pectin to gel plant-based ferments, you will need to add some calcium, so buy the low-sugar pectin.
Pectin thickens without changing the flavor but creates a bit of an uneven texture. Common brands include Sure-Jell/Certo, Ball, and (my choice) Pomona’s Pectin.
Sometimes marketed as vegan gelatin, agar (or agar-agar) is sourced from a type of seaweed known for its natural gelling properties. The product has some nutritional value, but as with other thickeners, it is usually used in such small amounts that it doesn’t contribute much nutrition to milk ferments. Agar sets more firmly than pectin (reminiscent of Jell-O Jigglers), so I recommend it more for use in yogurt and kefir desserts than in the dairy ferments themselves. As with natural gelatin, agar is heat activated. It must be heated to boiling for 5 minutes or to 190°F (88°C) for 10 minutes. It can be heated in water and then added to the ferment if you don’t want to heat-treat the milk. Agar thickens without impacting the flavor, but the texture is a bit uneven.
There aren’t many brands, but agar powder is usually available at even the smallest natural foods store and can be ordered online.
Guar gum is made from the seeds of the guar plant from Africa and Asia. It’s used as a thickener in many commercial brands of yogurt and lends a smooth, naturally thick consistency. Add a small amount for drinkable products and more for spoonables. It’s one of the only thickeners that isn’t heat activated, so you can add it when you add the culture or even after the product is done. It’s a helpful product for stirred, or Swiss-style, yogurts.
As with agar powder, there aren’t many brands, but guar gum is usually available at natural foods stores and online.
Tapioca starch is made from the dried root of the cassava plant (also known as yucca and manioc) native to South and Central America. Tapioca starch is an excellent thickener and is used in many plant-based ferments along with pectin. Occasionally you will see it labeled tapioca flour, but technically tapioca flour is a different product and will not produce the same results. I know — confusing! The starch version is very fine, pure white, and silky to the touch. I really like the smooth and creamy texture of products created by tapioca starch, and it has no detectable taste. It is heat activated but only needs to reach 140°F (60°C) to work.
|
Type of Thickener |
How Much to Use |
How to Add |
|
Agar |
1⁄2 teaspoon per quart of milk |
Stir into the cold milk, heat to 190°F (88°C) for 10 minutes, and then cool to the incubation temperature. Alternatively, dissolve in 1⁄4 cup cold water and simmer for 5 minutes (the volume will reduce by half), then add to the warm milk just before adding the cultures. |
|
Gelatin |
1–3 teaspoons per quart of milk |
Stir into the cold milk, heat to at least 120°F (49°C), and then cool to the incubation temperature. |
|
Guar gum |
1 teaspoon or less per quart of milk |
Stir into the cold milk before heating, or stir into the yogurt after making it. |
|
Milk powder |
1⁄2–1 cup per quart of milk |
Stir into the cold milk before heating. |
|
Pectin |
1–2 teaspoons per quart of milk (try the lesser amount first); add an equal amount calcium water when making plant milk ferments |
Stir into the cold milk. (For powders, dissolve first in a few tablespoons of cold water and then mix into the cold milk.) Heat, stirring constantly, to 140°F (60°C), then cool to the incubation temperature. |
|
Rennet |
Dilute 1 drop of double-strength rennet or 2 drops of single-strength rennet in 4 tablespoons cool, nonchlorinated water; use 11⁄2 teaspoons of this solution per quart of milk |
Stir into the cultured milk before incubation. Adjust the amount for future batches according to the desired thickness. |
|
Tapioca starch |
2 tablespoons per quart of milk |
Stir into the cold milk, heat to 140°F (60°C), and then cool to the incubation temperature. If the milk needs a higher heat treatment, mix the starch with a few tablespoons of cold milk and add at 145°F (63°C), when the milk is cooling down to the incubation temperature. |
If you’ve never worked with sheep’s milk, it’s hard to appreciate how wonderful it is for making all kinds of dairy ferments, from cheese to yogurt. In fact, two of the world’s best-known cheeses, French Roquefort and Spanish Romano, are both sheep’s milk cheeses. One of the first commercial producers to use ovine milk for yogurt is California’s Bellwether Farms, nestled in the rolling green coastal hills of Sonoma County, to the north of San Francisco.
Bellwether (named for the moniker given to the lead sheep, often a castrated male, or wether, who wears a bell to help guide the flock as it grazes) has been making sheep’s milk cheeses since 1990. It was founded by Cindy Callahan and is now guided by her son Liam. Cindy and her husband originally purchased the sheep as a way to organically manage the overgrown fields surrounding their 34-acre property. A casual acquaintance of Cindy’s planted the idea of milking sheep in her head, and it wasn’t long before the dairy was up and running. The cheeses were a hit, and at the time they had no thoughts of expanding into yogurt because low-fat yogurt was all the rage — and if there’s one thing sheep don’t do well, it’s low fat.
By the early 2000s, whole-food products were becoming more appealing and customers were asking the Callahans for a sheep’s milk yogurt. In 2005, the company became the second in the nation to sell sheep’s milk yogurt (the first being New York’s Old Chatham Sheepherding Company). Now, about 75 percent of the milk they process (they also make cow’s milk products) goes to making yogurt. All of their sheep’s milk comes from East Friesian and Lacaune sheep. In 2018, the company added a line of cow’s milk yogurt that Liam says “we always meant to launch, but somehow it took us until then to bring it to the market.” Fortunately, their decade-plus of working with their sheep’s milk yogurt meant that the transition to cow’s milk production was seamless.
Bellwether makes several flavors, including delicious, warming spiced apple. I asked Liam what his favorite flavor is and he replied, “That’s a tough question, because I really do love them all. However, I almost always eat the plain — I like to add so much stuff to my yogurt, it’s just easier to start out with the plain.” His mom’s favorite is the strawberry sheep’s milk yogurt. “She eats quite a bit of that one,” he said fondly. Liam said his kids aren’t quite yet keen on either the yogurt or the sheep, but time has a way of winning over even the youngest finicky eaters.
Bellwether has seen many changes over its many years of production. Even though dairy sheep are still quite uncommon in the United States, there are several other producers of sheep’s milk yogurt, many of them small crafters selling only locally. Misconceptions about the flavor and properties of sheep’s milk are also being set straight. Liam said that in the beginning they were “bombarded with people’s fears of ‘goatiness’ in the yogurt.” (Yes, some people think goats and sheep are the same thing.) Now, most people understand and appreciate the unique nature of sheep’s milk and seek out its natural richness, digestibility, and deliciousness. If you’d like to sample Bellwether Farms’ yogurts, you’re in luck — you can find them in many stores across the United States. Visit their website (see Resources) to learn more about their products and find stores near you that sell them.
The Icelandic yogurt called skyr is made with rennet, the coagulant used in cheesemaking. In skyr, rennet knits together the milk proteins into a custardlike gel. This is a very effective way to thicken yogurt. I’m actually surprised it isn’t used more often! I use vegetarian microbial rennet, but any type will do. (See my recipe for skyr.)
Rennet comes in two forms — tablet and liquid — and in two strengths — single and double. Liquid rennet must be kept in the refrigerator and protected from light, whereas tablets are shelf stable. Liquid rennet, however, is much easier to measure in small doses. It’s important to buy real cheesemaking rennet rather than “junket” rennet, the type often found in grocery stores. Junket rennet will gel but creates bitterness due to its high level of the enzyme pepsin.
Store your ferments in sealed containers in the refrigerator. The cold temperature in the fridge will slow but not fully stop the fermentation, so that the ferments will continue to slowly become more acidic as the bacteria process any remaining sugars. This continues until either the bacteria run out of sugar to consume or the product becomes too acidic for even dairy fermentation microbes to survive. The bacteria die off at different rates depending on their acid tolerance and competitiveness; in general, an older ferment will have a lower probiotic count, though it may still taste delicious and be safe to eat. I can’t give you an accurate idea of how long the probiotics will remain active, as it completely depends upon the numbers present at the end of fermentation. Obviously, the more you start with, the higher the count will be as time goes by. I try to size batches to last a week, just to be sure.
Remember that spoilage microbes such as mold are present in the air. Every time a container is opened, the surface of the ferment is exposed to these usually unwanted intruders. For this reason, it is better to divide a large batch among several smaller containers and go through them one at a time. If you are too slow to finish a yogurt, kefir, or other milk ferment, you are likely to get some mold growth in the container, particularly along the sides where it’s drier. Although most of these molds are unlikely to be harmful, they do ruin the flavor and are a sign that the product is getting old — also your indicator that the probiotics are dying off (an exception is Finnish viili that is traditionally capped with a wrinkly white mold top). You can wipe the edges clean and finish off the product quickly or reseal it in a fresh container. Once opened, yogurt and kefir made from culture should keep their flavor for several weeks. Kefir made from grains will keep its flavor for only a few days, then it gets progressively more sour.
If you need to take a break from making dairy ferments for more than a few days and don’t want to buy new cultures when you get back into the swing of it, you can freeze or dry your fresh starter culture. Both freezing and drying will kill off some microbes, but most microbes will survive if you freeze, dry, and store them correctly.
In my experience, rehydrated kefir grains do a decent job fermenting, but they seem stunted in their growth. Frozen kefir grains will take longer to reactivate and provide adequate acidification.
Fortunately, microbes of all kinds survive freezing quite well. They go into a hibernation of sorts, meaning that they don’t need any food to survive. When a wet substance is frozen, however, there is risk that it will be damaged by the growth of ice crystals. Yogurt and cultured kefir are very moist, so this risk goes up for them. The best way to control ice crystal growth is to remove as much moisture as possible and then to freeze the cultures rapidly.
Fresh seed. You can freeze freshly made milk ferments such as yogurt, viili, and even kefir from culture for future culturing. The number of times this will work will depend on the strains of microbes in the ferment. True heirloom ferments, such as viili and Bulgarian yogurt, are likely to do better than something made from powdered cultures, like kefir. It’s worth a try, though, if you don’t want to be purchasing new starter as often.
Freeze small amounts (about 1 tablespoon). Clean, dry ice cube trays work great! Measure the starter into the trays and place the trays in a supercold freezer; the bottom of a chest freezer works well. When the cubes are frozen, transfer them to ziplock bags (2 to 4 cubes per bag). Seal the bags with a vacuum sealer, or insert a straw partway into each bag, seal the bag around the straw, use your mouth to suck the air out, and then remove the straw and seal the bag fully. Write the date, type of ferment, and volume frozen on the bag and store in the freezer. It should remain viable for about 1 month. Thaw in the refrigerator or by dropping the frozen culture into the milk when it is at the incubation temperature, being sure to rewarm it if the icy starter cools it off too much. Use the same quantity of frozen yogurt culture as fresh.
Kefir grains. To freeze your grains, drain and rinse them thoroughly with nonchlorinated water. Gently shake them in a strainer for as long as it takes to get all of the moisture off them. When it looks like they are dry, shake the strainer over a dry paper towel to double-check. It’s important to remove as much moisture as possible because when the grains are frozen, any moisture will crystallize and damage the structure of the grains. Place the grains in a small bag and, if you want, add a dusting of dry milk powder to absorb any remaining moisture. Remove as much air as possible from the bag, seal, and then freeze in a supercold freezer; the bottom of a chest freezer works well. Frozen grains will remain viable for up to 1 year.
When freezing kefir grains, dust them with a bit of dry milk powder to absorb humidity.
Yogurt seed and kefir grains must be dried at a very low temperature or the microbes will die. The advantage of drying over freezing is that there’s no risk of ice crystals forming and damaging the microbes, meaning that once dried it can remain viable for longer than if frozen. Freezing has the advantage of being quicker and easier, however, making it a great choice for shorter-term storage.
Fresh seed. Because the volume is reduced by drying and you don’t have the risk of ice crystal growth, you can fit twice as much dried yogurt in a single container as you could if you froze it. Place 2-tablespoon portions of culture onto squares of parchment paper and spread to 1⁄8-inch thickness. Place in a safe spot (away from dust and pests — including your cat) and dry the yogurt slowly at about 80°F (27°C). In low-humidity environments with enough air movement, this might take only a day. Once it is dry, leave the yogurt on the parchment and place in a ziplock bag. Remove as much air as possible, or vacuum-seal it. Write the amount of seed (measured before drying), the type of ferment, and the date it was dried. Store in the refrigerator. When dried properly, it should remain viable for several months. To use dried seed as starter, assume that it has the same volume it had when it was fresh. That is, each square of dried starter will have lost significant volume, but you will treat it as though each portion is 2 tablespoons of yogurt or cultured kefir.
Kefir grains. To dry grains, rinse them in fresh, nonchlorinated water and drain in a sieve. Break up any very large grains. Lay the grains on a piece of parchment paper and allow to dry for a few days in a warm (about 80°F/27°C) location safe from pests and dust. Turn them a couple of times by putting your hand under the parchment and moving the grains without touching them. Once they are dry, place them in a ziplock bag. Cultures for Health recommends adding a bit of dry milk powder, which will absorb any humidity. Force all of the air out of the bag, seal, and refrigerate. The dried grains should remain viable for up to 6 months.
