Coffee: It’s the way you make my mouth feel

Ever had a disappointingly watery coffee? We probably all have from time to time. It’s not really the fault of the person or machine that made it apparently, it’s all about what scientists call ‘Mouthfeel’.

All of us coffee lovers instinctively know when we are enjoying a smooth, rich cup of coffee and that is because in addition to cream or sugar we may add the coffee itself contributes to the sensation. Until recently, the specific compounds in the coffee which contributed to this effect were not well known, but that’s all about to change. Now, researchers report several coffee compounds that contribute to the feeling of the beverage coating the inside of the mouth, as well as astringency and chalkiness sensations. The results could be used to tune processing and roasting conditions for specialty coffees.

Essentially, it all boils down to small molecules within our mouths and the scientists set out a series of tests to see which was most involved in the sensation of ‘mouthfeel’. They started with four different coffees that evaluators licensed by the Specialty Coffee Association had given varying ratings in terms of body. A separate panel of eight experienced tasters, skilled in tactile awareness, then agreed on a set of references that illustrated the sensations differentiating each cup.

Then each coffee was assessed with chalkiness, mouthcoating, astringency and thickness in mind. The researchers found that a cluster of small molecules contribute to coffee’s mouthfeel. Peterson says they isolated melanoidin compounds, formed by the Maillard reaction during roasting, and for the first time associated them with astringency. Two compounds, 3- and 4-caffeoylquinic acid, correspond with mouthcoating. Unexpectedly, the sensation subsided with increased concentrations. Peterson says that although biological responses are multifaceted, it is uncommon for an attribute to be perceived at low levels, but not at high levels. Finally, they isolated a novel compound related to chalkiness that contains an amino acid.