March 31/Oporto, Portugal/Agriculture Business Week -- According to a study from Oporto, Portugal, "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 six-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 (30mL) varied from similar to 40mu g (100% arabica) to similar to 285mu g (100% robusta), with long espressos (70mL) attaining more than double isoflavones of short ones (20mL). Espressos (30mL) prepared from commercial blends contained average amounts of 6, 17 and 78mu g of genistein, daidzein, and formononetin, respectively," wrote R.C. Alves and colleagues, University of Porto.
The researchers concluded, "Comparison of different brewing methods revealed that espresso contained more isoflavones (similar to 170mu g/30 mL) than a cup of press-pot coffee (similar to 130mu g/60 mL), less than a mocha coffee (similar to 360mu g/60 mL), and amounts similar to those of a filtered coffee cup (similar to 180mu g/120 mL)."
Alves and colleagues published their study in the Journal of Agricultural and Food Chemistry ("Isoflavones in Coffee: Influence of Species, Roast Degree and Brewing Method." Journal of Agricultural and Food Chemistry, 2010;58(5):3002-3007).
For more information, contact R.C. Alves, University of Porto, Fac Farm, Serv Bromatol, REQUIMTE, Rua Anibal Cunha 164, P-4099030 Oporto, Portugal.
From the April 12, 2010, Prepared Foods E-dition