Benefits of Yogurt
Normally there are more than 40 trillion bacteria in the digestive tract that promote healthy digestion, boost the immune system and produce Vitamin K2 (which plays a role in blood clotting). Yogurt provides several strains of friendly bacteria (probiotics) that are naturally present in the digestive system. Dairy based yogurt also a good source of protein, calcium, vitamin B-2, vitamin B-12, potassium, and magnesium.
Equipment and Supplies
- 2 litres of milk (your choice)
- 4 ounces (125ml) of yogurt starter (save the container)
- Glass bowl or saucepan to heat the milk
- Glass bowl to strain the cultured milk
- Large strainer
- Coffee filters (basket, unbleached)
- Plastic wrap or lids
- Wire whisk
- Thermometer (optional)
Types of Milk
- Cow’s milk is the most popular choice.
- Goat’s milk makes a thinner yogurt than cow’s milk.
- Sheep’s milk is sweeter than cow’s milk and contains more protein, producing a thicker, creamier yogurt. It is used more for making cheese than for making yogurt.
- Non-dairy milks (almond, coconut, cashew, hemp, soy etc.) often contain additives that can interfere with the culturing process. The cultures generally don’t survive for long so you have to use a new starter each time. The best way to ensure you have additive-free and preservative free non-dairy milk is to make your own.
- Lactose-free is not suitable for culturing as the bacteria feed on the lactose.
- Reduced-fat milk will be thinner than yogurt made with whole milk.
- Homogenized or non-homogenized milk can be used. Most cow’s milk sold in stores is homogenized. Goat and sheep milk are naturally homogenized. With non-homogenized milk the cream will rise to the top of the yogurt just like it does with the milk, so the top layer of the yogurt will be thicker and more yellow in color.
- Raw milk can be used, but should be heated to reduce competing or harmful bacteria.
- Pasteurized milk has been heated to remove harmful bacteria.
- Organic or non-organic milk can be used.
Yogurt Starters
A yogurt starter is a unique blend of bacteria that consume lactose (milk sugar). Common varieties of bacteria found in yogurt include Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus casei. The bacteria convert the lactose in milk to lactic acid giving it a tart taste and lowering the pH which allows it to be stored longer. The bacteria also changes the protein structure, giving yogurt its texture.
Store-bought varieties of yogurt starters often have a fewer types of bacterial strains. They are like a ‘hybrid’, which means they don’t do well in successive generations. The commercial companies do this so their product produces the same results every time you use it. Heirloom yogurt cultures have more strains of beneficial bacteria naturally. Every heirloom culture has its own unique bacterial strains.
Making Yogurt
Heat 2 liters of milk to 180 degrees F (80 degrees C) by pouring the milk into a glass bowl and microwave, on full power, for about 16 minutes. Or heat the milk on the stove in a medium pan, stirring frequently to prevent scalding. Don’t let the milk come to a full boil, just let it begin to bubble or simmer. The milk is heated to kill off any harmful bacteria or mould spores that might have contaminated it.
Remove the bowl from the microwave (or the pot from the stove) and allow it to cool to 110 degrees F (40 degrees C). Stir the milk occasionally to help prevent a skin from forming. It takes about 60 or 70 minutes to cool the milk until it’s warm to the touch, like milk for a baby bottle. Stir in the yogurt starter with a wire whisk and cover with a lid or plastic wrap.
Heat the oven to its lowest setting (usually 170 degrees F or 76 degrees C) then turn it off. Place the covered container in the oven and leave it for several hours or overnight. Put a sticky note on the oven to remind others not to turn it on without removing the yogurt first. If you want to use the oven during the incubation time, just remove the yogurt and place it back in the oven when the oven cools to slightly warm.
Yogurt-making bacteria like to be maintained in a certain temperature range. Too hot and they die, too cold and they don’t work fast enough to protect the milk from spoilage organisms. They are happiest at around 110 degrees F (40 degrees C).
After several hours of incubation, the yogurt is ready to strain. Straining removes some of the liquid (whey) and makes a thick, Greek style yogurt. Place the strainer with a coffee filter over a medium bowl and pour half of the yogurt in the filter. Save 4 ounces (125 ml) of yogurt as a starter for your next batch. Put the yogurt, the straining yogurt and the starter in the fridge.The next morning, remove the yogurt from the strainer – it is now thick and ready to eat!
Save or discard the whey, wash the bowl and the strainer and replace the coffee filter. Strain the remaining yogurt. Start your next batch now, to ensure a continuous supply. If you are not ready to start a new batch, the starter can be stored in the fridge for two to three weeks.
The strained whey can be used in place of milk or water in most recipes. It can also be used as a base for fermenting fruits and veggies or starting a sourdough culture as it contains the same beneficial bacteria as the yogurt.