Isoflavones in Coffee: Influence of Species, Roast Degree, and Brewing Method

This paper reports the isoflavone contents of roasted coffee beans and brews, as influenced by coffee species, roast degree, and brewing procedure. Total isoflavone level is 6-fold higher in robusta coffees than in arabica ones, mainly due to formononetin. During roasting, the content of isoflavones decreases, whereas their extractability increases (especially for formononetin). Total isoflavones in espresso coffee (30 mL) varied from similar to 40 mu g (100% arabica) to similar to 285 mu g (100% robusta), with long espressos (70 mL) attaining more than double isoflavones of short ones (20 mL). Espressos (30 mL) prepared from commercial blends contained average amounts of 6, 17, and 78 mu g of genistein, daidzein, and formononetin, respectively. Comparison of different brewing methods revealed that espresso contained more isoflavones (similar to 170 mu g/30 mL) than a cup of press-pot coffee (similar to 130 mu g/60 mL), less than a mocha coffee (similar to 360 mu g/60 mL), and amounts similar to those of a filtered coffee cup (similar to 180 mu g/120 mL).