Yoghurt, the Turkish word for fermented milk, (it comes from a root word meaning “thick”) is made using safe bacteria to convert most of the lactose into lactic acid to produce the thick creamy dairy product we are all now familiar with. Lactose-intolerant people should have no problem with yoghurt — or most cheeses for that matter — as there is very little lactose left in either after the bacteria have done their work. Making yoghurt is a way of preserving milk and its tart “green apple” flavour is addictive.
It’s all about the milk
Yoghurt is made from all sorts of milk. Goat, sheep, cow and buffalo milk are all used. In its traditional incarnation the flavour, like all regional products (wine, olive oil, tea, cheese), varies according to where it comes from, what the animal whose milk is used ate and possibly who made it.
Yoghurt has been made for thousands of years in India, North Africa, Eastern Europe, the Middle East and Central Asia. It was probably originally the result of someone leaving milk sitting around, which spontaneously fermented with natural bacteria. It didn’t become popular in Western Europe and here until the 1960s, when it was marketed as diet food and it had a slightly counterculture reputation.
Not all yoghurt is created equal
The bacteria used in most industrially made yoghurt are of two necessary types, according to Harold Magee’s book On Food and Cooking: Lactobacillus delbrueckii, subspecies bulgaricus and Streptococcus salivarius, subspecies thermophilus. These work together to encourage fermentation and thickening of the milk but neither can survive in the human gut.
However there are many brands using bacteria such as Lactobacillus acidophilus and bifidus as well as the other two, or state they are “probiotic” and these are bacteria which can survive in the human body. Yoghurt tastes good, so why would you care about which bacteria is used? Magee again: “strains of these bacteria variously adhere to and shield the intestinal wall, secrete antibacterial compounds, boost the body’s immune response to particular disease microbes, dismantle cholesterol and cholesterol-consuming bile acids, and reduce the production of potential carcinogens. These activities may not amount to prolonging our youth, but they’re certainly desirable!”
Read the label
If you want to eat only a diet of real food that doesn’t contain additives, then a look at labels on yoghurt is interesting. Many brands are traditionally made. They are made of milk and bacterial cultures and nothing else and they are thick and creamy. Many other brands contain stabiliser (a starch in some form) and thickeners such as pectin, gums and gelatine (watch out vegans and vegetarians). It would seem these additives are “fillers” added to artificially thicken the yoghurt, make it feel creamy and stop it separating into curd and whey.
Traditional yoghurt will separate slightly into curd (the delicious creamy white substance) and whey (the pale yellow watery liquid). Naturally made yoghurt can separate if bounced around during transportation, so stabilisers are added. Being a cynic I also suspect that it is quicker and cheaper to make commercial yoghurt that is artificially thickened.
It is completely unnecessary to add these things to yoghurt. The natural brands I eat do sometimes have a little whey on top (which I simply pour off) but I would far rather eat a natural product than anything with additives. The thick creamy additive-free organic Cyclops brand from Christchurch that has been around for 30 years is my go-to yoghurt. I also like the Gopala and the Clearwater Dairy brands.
It is surprising which premium brands use artificial thickeners — check it out next time you buy. The other reason that some think stabiliser has to be added is that yoghurt will separate and curdle if added in cooking. This is simply avoided by adding the yoghurt when the dish is taken off the heat at the end of cooking, or by not letting it come to the boil.
How to make yoghurt
Yoghurt is easily made at home and costs less than half as much as the bought stuff. Bring 1 litre of milk to the boil. Cool it to 45C or cool enough so you can hold the end of your very clean finger in it while you count to 10. Whisk in 3 tablespoons of natural, unsweetened, unstabilised yoghurt and pour it into a sterilised uninsulated container or wide-mouthed Thermos. If using an uninsulated container, wrap it in a thick cloth and place it in a small chillybin and leave it overnight and in the morning the miracle of fermentation will have occurred and you will have yoghurt. The thermos will do it without the wrapping and the chillybin.
Easier still is the never fail EasiYo method with its insulated vessel and sachets of yoghurt mix from the supermarket — but they do contain an emulsifier, lecithin.