Nutritionists long viewed chocolate with great suspicion, considering it something to be avoided in a healthy diet because it is high in calories and fat. Chocolate, the nutritionists thought, should be spurned entirely by those attempting to lose weight and stay healthy, or consumed only as a special treat.
The pendulum has now swung the other way. While nutritionists are not yet advising people to eat chocolate with abandon, they say that it has some health benefits - it's believed that it stimulates blood circulation, is good for the heart and can alleviate depression.
I tend to view most nutritional studies with scepticism - after all, they keep changing their minds, and who knows what they'll be saying about chocolate 10 years from now. As with most foods, chocolate should be enjoyed in moderation but without guilt.
Of course, 'in moderation' is the part that many people find difficult: a complete 250 gram bar is a pretty hefty snack. If you gain weight from that, it's not the chocolate's fault.
Chocolate is sometimes chocolate in name only. Different countries have different regulations stipulating the minimum percentage of cacao (chocolate liquor and cocoa butter) there must be in their chocolate; and some countries allow the inclusion of fat other than cocoa butter. A higher cacao percentage almost always translates into a higher price, although there's a limit on how much it can contain before the chocolate becomes unpalatable. I find that chocolate with more than 85 per cent cacao content is too bitter except when mixed with other ingredients.
The broad categories for chocolate destined to be eaten on its own are bitter (without sugar, or very little of it), bittersweet, semi-sweet, milk chocolate and white chocolate (which doesn't contain any chocolate liquor). For chocolate bars, truffles and filled chocolates, there are two basic types: coating chocolate and couverture. Coating chocolate - also called compound chocolate - is used for inexpensive confectionery because it's cheap, doesn't require tempering (the long process of melting, cooling and heating chocolate to precise temperatures in order to give it gloss and 'snap') and stays solid at room temperature. It doesn't have much chocolate taste and, because it contains vegetable fat rather than cocoa butter, it has a waxy, fatty mouthfeel. At the opposite end of the scale is couverture - expensive, high-quality chocolate with more cocoa butter than other types. When melted, it is very fluid so gives thinner, more delicate 'shells' for dipped chocolates and greater shine when it cools.
Although connoisseurs look with disdain on anything other than bittersweet chocolate, there is some very good quality semi-sweet, milk and white chocolate on the market. Some of it gets its flavour from innovative combinations with fruit, nuts and spices, but others - usually made by smaller, artisanal manufacturers - are delicious because such great care has been taken in selecting the cacao beans and processing them.