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 appeal is not only sensory — it is chemical. Cocoa carries a small group of naturally occurring compounds that shape both its bitterness and its physiological effect, and understanding them matters to anyone formulating, roasting, conching or labelling a chocolate product.
Theobromine is the defining alkaloid of cocoa: 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 brings stimulant and mild anti-inflammatory properties. Phenylethylamine (PEA), often referred to as the 'love drug', is a bitter chemical that encourages the body to produce mood-altering drugs and is frequently held responsible for the uplifting effects of chocolate.
Cocoa also stands out for its antioxidant load — it contains more phenolic antioxidants than most foods. That antioxidant activity is primarily mediated by flavonoids, particularly catechin, epicatechin and procyanidins, which is why processing decisions that affect flavonoid retention carry directly into the nutritional positioning of the finished product.
The same alkaloid chemistry explains why chocolate is toxic to dogs. Theobromine belongs to a class of organic nitrogen compounds, and nearly all alkaloids are poisonous in large quantities. For humans the lethal dose is 1000 mg/kg, but for canines it is 300 mg/kg, so dogs can reach the lethal dose easily because of their small size.