The chemistry of chocolate
The word "cacao," which refers to a plant, is where chocolate gets its name. This plant has a high concentration of antioxidants and minerals. The cacao bean is where the compounds in chocolate that are said to have health benefits originate, so darker chocolate has more of these ingredients. More than 300 to 500 known chemicals are present in chocolate, some of which interact with the human brain to affect mood.
Chocolate's sensory and physiological character comes from a small group of naturally occurring compounds carried through from the cacao bean. Theobromine is the dominant one: a bitter chemical that dilates blood vessels, stimulates the heart and has mild diuretic properties. Caffeine is present in cacao in very small amounts, has a structure similar to theobromine, and contributes stimulant and mild anti-inflammatory properties. Both contribute bitterness, which is why formulation and processing decisions in a chocolate plant are inseparable from the underlying chemistry of the bean.
Phenylethylamine (PEA), often referred to as the 'love drug', is another bitter chemical in chocolate. It encourages the body to produce mood-altering compounds and is frequently held responsible for the uplifting effects of chocolate. Theobromine is also described as an amino acid essential in producing serotonin, the happy hormone.
On the nutritional side, cocoa contains more phenolic antioxidants than most foods. That antioxidant activity is primarily mediated by flavonoids, particularly catechin, epicatechin and procyanidins. These flavonoids are the basis of much of the health positioning around dark chocolate and cocoa-based products, and preserving them is a consideration for anyone specifying cocoa processing and confectionery lines.
The same alkaloid chemistry explains why chocolate is toxic to dogs. Theobromine is an alkaloid, from a class of organic nitrogen compounds, and nearly all alkaloids are poisonous in large quantities. For humans the lethal dose is 1000 mg/kg, whereas for canines it is 300 mg/kg, so dogs can reach the lethal dose easily due to their small size.