Despite everything you have probably heard about the number 70 and chocolate, there is absolutely no (none, nada, zilch) relationship between cocoa content and chocolate quality.
70 per cent is a quantitative measure not a qualitative measure. The only thing that the cocoa content of a chocolate tells you is what percentage of the chocolate, by weight, is derived from actual cocoa beans. It does not tell you, for example, the relative amounts of cocoa butter and cocoa powder, which have a profound affect on texture and taste.
Just as an 86 proof vodka is not better than an 80 proof vodka just because it has 3 per cent more alcohol, a 70 per cent cocoa content chocolate is not better than a 65 per cent cocoa content chocolate just because it has 5 per cent more cocoa.
The proof content of a spirit tells you nothing at all about the ingredients used to make it, the processes or equipment used, the skill of the person or people who make it, and absolutely nothing at all about what the spirit tastes like, what it smells like, or how smooth it is.
The same holds true for chocolate: the cocoa content is not a clue to anything except...the cocoa content. The number 70 provides absolutely no information about the quality of the cocoa beans, if those cocoa beans were processed properly, how the beans were roasted, how much and what kind of vanilla (if any) was used to make the chocolate, what the chocolate tastes like, what it smells like, or what the texture is. And it is not a reliable indicator of how "healthy" the chocolate might be.
Come again? If there's no connection, why is there this fixation on the number 70?
It's a case of marketing hype, pure and simple.
Cocoa Content Is Not a Qualitative Measure
You see, chocolate is a very complex food to describe, like wine. In the absence of generally accepted rating systems published by major magazines by respected critics, the chocolate industry needed something to use as a benchmark for quality chocolate and so the quantitative measure of cocoa content began to be promoted as a qualitative measure. And chocolate fans who did not know any different bought into it.
One of the most popular mistaken impressions that people have about cocoa percentage is the belief that the higher the percentage the more bitter the chocolate has to be. In fact, there is no legal distinction between semi-sweet and bittersweet chocolate, no magical ratio of cocoa to sugar at which point a chocolate automagically crosses the line from semi- to bitter.
Where Does Bitterness in Chocolate Come From?
Bitterness in chocolate tends to come from two sources: bitter compounds in the cocoa beans that remain after fermentation (usually insufficient fermentation), and burning the beans during roasting. Under certain circumstances it is possible to have a low cocoa content chocolate that is very bitter, even with a lot of sugar in the recipe, because of the use of poorly fermented beans and over-roasting. It is also possible to have a high cocoa content chocolate that is not bitter because of the use of well-fermented beans and time and attention paid to all of the manufacturing processes (which is expensive), not just roasting.
Most people also mistakenly believe that the "better" the chocolate the more robust the chocolate flavor is. In fact, the exact opposite is true. The highly prized and sought after criollo bean, especially the Porcelana variety, makes very delicately nuanced chocolate whose look can often be confused with milk chocolate because it is such a light brown. Because cocoa beans in the criollo family contain very low amounts of the bitter compounds that give beans from the forastero family their dark purple coloration, very little fermentation is needed and roasting must be handled carefully to ensure that the delicate flavors of the bean are not destroyed through even the slightest over-roasting.
Trust Your Taste
If 70 per cent is not a reliable guide, what is? Your own sense of taste, for one; what you like is what you like, irrespective of the cocoa content.
When people tell me, "I only eat chocolate that is 70 per cent cocoa content or higher," I know they are snobs who actually know very little about chocolate. Their insistence on treating cocoa percentage as a qualitative measure is the measure of their ignorance. These are the same people who will probably tell you that drinkers of white Zinfandel can't truly be serious about wine.
If there is a "right" way to approach eating a chocolate that is new to you, then that right way is to approach each new chocolate without preconceptions: with an open mind and a clean palate. In the end, it is all about what you like. A chocolate is not automatically good just because it has 70 per cent cocoa. I like to think of myself as an equal opportunity chocolate lover: white, milk, dark I don't really care. As long as it's good I love it. I do not get hung up at all about how much cocoa is in the chocolate I eat—and neither should you.