Why will single cream curdle if you boil it, but double cream won’t? What’s the difference between crème fraîche and sour cream? How is buttermilk made? I’ve been reading and surfing to answer these questions and here is what I’ve found.
Crème fraîche, sour cream, yoghurt, and buttermilk are all produced by taking milk or cream and adding bacteria that causes fermentation, a process that thickens the milk.
Crème faîche is a speciality of Normandy. It has a slightly tangy, slightly nutty taste and a consistency of thickened cream. Traditionally, crème fraîche was made from unpasteurised cream that naturally contained the right bacteria to thicken it. Nowadays it is normally made through artificial fermentation. Crème fraîche has two advantages over sour cream: because of its relatively high fat content, it can be whipped like whipping cream and it will not curdle if boiled.
If you want to make your own crème faîche – here’s how to do it.
Sour cream, or soured cream, has a creamy, tangy taste and is looser than crème faîche. It works well with both savoury and sweet dishes. Traditionally it was made by letting unpasteurised fresh cream sour naturally, but nowadays bacteria or a lactic acid culture is added to single/light cream. The bacteria grows until the desired taste and consistency is reached. The cream is then repasteurised to stop the bacteria growing further. It has less fat than crème faiche and so will curdle even at simmering temperature. But it can be stirred into a dish that is cooked and off the heat.
To make any yoghurt the starting process is the same. Milk is heated and then cooled before bacterial culture in the form of a small amount of yoghurt is added. The mixture is then kept warm to help the bacteria grow, produce lactic acid and gel the milk. To make low fat yoghurt use low fat milk, or for creamier yoghurt use milk with a higher fat content. Even a creamier yoghurt will curdle if heated as the fat content is never sufficient to prevent this.
If you want to make your own yoghurt, there is a good recipe here.
Here is a recipe using yoghurt:
Rhubarb, almonds and yoghurt
To turn yoghurt into Greek yoghurt, which is thicker and with more fat, regular yoghurt is strained to remove the liquid whey. You can do this yourself by lining a sieve placed on a bowl with a muslin or loosely woven cloth, pouring the yoghurt in then waiting several hours for the whey to drip through and separate to leave you with Greek yoghurt.
Here is a recipe using Greek yoghurt:
Summer fruits, amaretti and Greek yoghurt
Buttermilk used to be the liquid left over when cream was churned to butter. Nowadays it’s made by introducing bacteria to low fat milk, causing it to thicken and producing a tangy flavour. Buttermilk is used in recipes where bicarbonate of soda is used, for example, soda-bread, pancakes and scones. The acid from the buttermilk combines with the alkaline in the bicarbonate of soda to create pockets of air which cause the baking goods to rise. If you can’t find buttermilk, you can achieve a similar result by adding 1 tablespoon of lemon juice to 290ml/½pt of warmed milk.
Double or heavy cream has a fat content of 48%. It’s good for pouring, heating and whipping. When whipping double cream, watch it closely once it starts to thicken, as over whipped cream becomes grainy. If it reaches the stiff peak stage, a little milk can be added to soften it; but don’t whip any further or the buttermilk will start to clump together and the whey will separate out.
Whipping cream has a fat content of 36%. It can also be poured, heated or whipped. It’s not quite as stable as whipped double cream. It is the best cream for ice cream as it gives a lighter, less fatty texture and is less likely to become overworked and too buttery. Double cream can give ice cream a grainy texture if it is overworked.
Single or light cream is perfect for pouring. It can’t be boiled without curdling and cannot be whipped as it’s fat content is only 18%.
Half-and-half cream is a combination of whole milk and cream. With a fat content of around 10.5%, it’s really too light to be considered a real cream.
Clotted cream is made by heating cream to concentrate it, and then allowing it to stand. The butterfat rises to the top as a thick, creamy crust, and it is this you spread on your scone with a topping of strawberry jam. It’s also pretty good with fruit salad and as a topping on Christmas pudding. It’s at the top the league when it comes to fat content.
Here is a recipe using clotted cream:
Raspberry and pecan scones
Clotted cream – 55%
Double/heavy cream – 36% – 48%
Whipping cream – 34% – 40%
Crème faîche – 31%
Sour cream – 18%
Single/light cream – 18%
Half and half – 11%
Greek yoghurt – 10%
Buttermilk – 2%
Yoghurt – 0.5 – 4%
The Professional Chef – Ninth Edition – Wiley
Leiths Techniques Bible – Susan Spaull and Lucinda Bruce-Gardyne