What’s with putting milk in chocolate?

Reader Jacki wants to know:

If solid chocolate can be made with cocoa butter rather than milk solids, why would anyone use the milk? What is the advantage of adding dairy when the chocolate and the cocoa butter come from the same source?

Another question that I’d love to answer. Thanks Jacki! First I should point out that cocoa butter and milk solids are almost always employed together in a chocolate blend. One isn’t a substitute for the other, they’re complimentary ingredients.

But to answer the question, it was a Swiss fellow by the name of Daniel Peter who first thought to add milk solids to confectionery chocolate, back in 1875. Prior to that time people did consume chocolate in bars (bar chocolate was introduced by J.S. Fry & Sons of Bristol, England in 1847) but it was a rather harsh experience, both for the teeth and the taste buds. Not only was the product extremely brittle and crunchy, the natural alkalinity of the chocolate was too astringent, i.e. too bitter, dry and pucker-inducing to gain mass appeal. These days many true chocoholics appreciate those qualities. But then as now, the number of people in the market for such a sensation was relatively small.

Mr. Peter, an up-and-coming confectioner, was keen to try something new. His countryman Heinrich (Henri) Nestlé was doing big business selling a new dried milk powder. So he added it — and discovered not only that milk and chocolate flavors were naturally complimentary, but that milk had a way of taking the edge off the chocolate liquor.

Food scientists have since found the reason for that. Tannins, which make up about 6% of chocolate liquor, are what are responsible for chocolate’s astringency. They are highly reactive molecules that love to bind with proteins. Milk powder contains quite a bit of protein. Put the two together and…end of astringency problem.

To say that the confectionery chocolate market went explosive-thermo-nuclear-supernova after that is putting it mildly.