Yogurt is made by adding a number of types of harmless bacteria to milk, causing it to ferment. This thickens it and gives it its characteristically tangy flavour. Cow's milk is the most common type used, but goat's, ewe's, sheep or buffalo's milk are also suitable.
Most yogurt sold in the UK is 'live', which means that it still contains live bacteria. Such organisms are thought to stimuate the gut's friendly bacteria and suppress harmful bacteria.
Choose the best
There are a number of different types to choose from - some yogurts will fall into more than one category - for example whole milk bio yogurt.
Live yogurt has been fermented with live culture bacteria. It has a smooth, creamy texture and a fresh, slightly tangy flavour. Bio yogurt has had additional 'friendly' bacteria added to it. It has the mildest flavour and a particularly creamy texture.
Greek/strained yogurt can be made from cow or ewe milk. It has had quite a high proportion of its whey strained off, which creates a thick, mild and very creamy result. Although it has a higher fat content than other yogurts (around 10.2%), it's still lower in fat than cream.
Set yogurt is allowed to set in the pot in which it was sold, so has a firmer texture than other yogurts, but is still creamy and smooth.
Whole milk yogurt is made with whole milk, while low-fat yogurt is made with skimmed milk, and has a fat level of less than 2%. Long-life yogurt has been pasturised after fermentation in order to increase its shelf life, a process that kills off all its friendly bacteria.
Most yogurts are available either plain ('natural') or with additional flavourings. These can range from fresh fruit to sugar, artificial flavourings or additives such as starch, which acts as a thickener. Some yogurts are thickened with gelatine, which makes them inappropriate for vegetarians - always read the label.
Yogurts of all kinds are ready to use straight from the container. If you plan to cook with yogurt, bring it to room temperature before you add it to the dish, so that the temperature shock is not too great (otherwise it might curdle and separate), and add it to the dish spoon by spoon. Higher-fat yogurts are the best to cook with, as they're more stable.
If you want to cook with a low-fat yogurt you can increase its stability by making a paste of ½ tsp cornflour and 1 tsp water; stir it into the yogurt before you add the yogurt to the dish.
Keep all live yogurts in an airtight container (preferably the one in which you bought it) in the fridge, for up to 4 days, or in line with the 'best before' date on the tub. After this date has expired, the yogurt will start to taste increasingly acidic. Long-life yogurt can be kept for longer than live yogurt - again, check the 'best before' date.
Use in sweet and savoury dishes, dressings and marinades, baking or with fruit. Serve Greek or strained yogurt with honey and flaked, toasted almonds.
Try fromage frais.