In the West, curd, yoghurt and buttermilk are 3 distinct products, all dairy but very very different and emanating from different parts or processing of the raw milk. In addition, in Australia at least, even “natural” yoghurt is sweetened beyond what is necessary, and the sharp tangy yoghurts of Europe are difficult to find.
In India the use of curd/yoghurt stretches back to the beginning of existence, with even the Rg Veda (spiritual texts from the beginning of time) mentions curd rice. Compare this with The West, where yoghurt is a recent introduction, often looked on as a bit of an exotic treat in some parts.
In India, the healing power of foods has long been regarded as important and Indian cuisine incorporates many medicinal elements. I doubt if our ancient Indian ancestors understood what bacteria are, but I imagine they had worked out that yoghurt helped with digestion. We know now that this is because the bacteria that turn milk into yoghurt also help fight infections in the intestine. In a hot country like India where stomach bugs were easy to pick up, yoghurt acted as an ancient antibiotic. That was why it is rarely heated (heat kills bacteria) and is eaten it as close to room temperature as possible in most cases. (This is paraphrased from an excellent article on Indian curd vs Western Yoghurt.)
When working with Indian recipes you may find that curd and buttermilk are variations of yoghurt.
Let me explain.
Also let me ask if anyone can add more information, comments are very very welcome. The following are my rules of thumb.
When asked, I recommend to people that they find a good, unsweetened yoghurt variety to use in slightly different ways in Indian recipes. They can be hard to find in supermarkets here, but either a good health shop or Indian grocery shops will have thick, unsweetened yoghurts. You can, of course, make your own yoghurt, and then you have total control over the sweetness level as well as other undesirable additives.
When all else fails, a good brand of natural Greek yoghurt will suffice.
When an Indian recipe calls for yoghurt, use it as it is, or drain a little of the whey before using.
Curd is such an important part of Indian meals, and traditions vary. If plain curd is served with a meal, in some parts it is eaten first, some with the meal and some eat it at the end of a meal. I really like it at the end, but if the meal is REALLY hot-spicy, it is wonderful to have the yoghurt to balance the heat.
Curd can also be used as an ingredient in dessert and savoury dishes. It may form the basis of a dish in its raw form, or it can be a component of a cooked dish.
To make curd for Indian recipes, I place about 1.25 – 1.5 cups of yoghurt for each cup of curd that is required, into a strainer lined with a piece of muslin, and allow the whey to drain away for 10 – 30 mins, depending on the time available. This thickens the yoghurt slightly and it is excellent to use where curd is required.
Buttermilk is yoghurt to which some water has been added and it has been churned, or mixed with a beater for a minute or so. It sounds simple, right? But interestingly the act of thinning and churning the yoghurt changes its properties, making it more digestible and more cooling on the body (hence its use in many summer dishes and drinks).
Giri and Jain say in their book Sukham Ayu: “After-meal drinks are known as ANUPANA in Ayurvedic texts. Buttermilk or takra, which is diluted and churned yogurt, is considered an ideal anupana after lunch. There is often a misconception that yogurt and buttermilk have similar properties. According to Ayurveda, yogurt which is hot and sour in essence, when churned into buttermilk undergoes manthan samskara and becomes sweet after digestion, and exerts a cooling effect. The sutras proclaim: Just as nectar is for Gods, buttermilk is for humans. One who consumes buttermilk daily does not suffer from disease and diseases cured by it do not recur.”
Because buttermilk is most often used for drinks, you will find the term buttermilk used to indicate a cooling drink with spices such as chilli, ginger and cumin.
When Buttermilk is called for in an Indian recipe, use yoghurt thinned 1:1 with water, or if you have thicker yoghurt, use twice as much water as yoghurt. Then beat or churn it as above. You can also use the Western buttermilk if you can get it; I have found that it also gives excellent results. I tend to use it when “sour buttermilk” is called for, as it has a tangier, sharper taste than you can get from yoghurt.
- If you are planning to cook with yoghurt, curd or buttermilk, read On Cooking with Yoghurt
- An excellent post on making curd at home