What evidence supports the strength of the effect of antioxidants in roasted coffee ?
Volatile compounds with nauseating odor for humans have been identified , including acetic acid ( pungent , unpleasant odor ) , propionic acid ( odor of sour milk , or butter ) , butanoic acid ( odor of rancid butter , present in green coffee with 2 mg / 100 g coffee seeds ) , pentanoic acid ( unpleasant fruity flavor , present in green coffee at 40 mg / 100 g in coffee seeds ) , hexanoic acid ( fatty - rancid odor ) , heptanoic acid ( fatty odor ) , octanoic acid ( repulsive oily rancid odor ) ; nonanoic acid ( mild nut - like fatty odor ) ; decanoic acid ( sour repulsive odor ) , and derivatives of such fatty acids - 3 - methyl - valeric acid ( sour , green - herbaceous , unpleasant odor ) , acetaldehyde ( pungent - nauseating odor , even when highly diluted , present in dried green coffee seeds at concentrations of about 5 mg / kg ) , propanal ( choking effect on respiratory system , penetrating - nauseating ) , butanal ( nauseating effect , present in dried green coffee seeds at 2 to 7 mg / kg ) , or pentanal ( very repulsive nauseating effect ) .