bitterness problem in espresso

polyphenols are potent antioxidant molecules. but the polyphenols give the coffee bean bitterness and astrigency. in this aticle is a guide to the barista in that it shows that this unwanted effect of polyphenols can be broken.

polyphenols are naturally occurring compounds found largely in the fruits, vegetables, cereals and beverages. these molecules are secondary metabolites of plants and are generally involved in defense against ultraviolet radiation or aggression by pathogens and may also contribute to the bitterness, astringency of the food. researchers have explored that these molecules are very good antioxidants and may neutralize the destructive reactivity of undesired reactive oxygen/nitrogen species produced as byproduct during metabolic processes in the body. epidemiological studies have revealed that polyphenols provide a significant protection against development of several chronic diseases such as cardiovascular diseases ( cvds ), cancer, diabetes, infections, aging, asthma etc.

there is increasing interest in the development and use of polyphenolic-rich antioxidantextracts as functional ingredients. however, their bitterness, astringency and characteristic flavour could limit their incorporation in foods and beverages.

caffeine activates the bitter taste system causing a potential problem for manufacturers wanting to develop products containing caffeine. in the present study both oral peripheral and central cognitive strategies were used in an attempt to suppress the bitterness of caffeine. subjects (n = 33) assessed the influence of sodium gluconate ( 100 milimolar ), zinc lactate ( 5 milimolar ), sucrose ( 125 milimolar and 250 milimolar ), milk (0,2 % and 4% milk fat ), and aromas ( coffee, chocolate, mocha ) on the bitterness of caffeine ( 1.5, 3 and 4.5 milimolar ). the oral peripheral strategies proved most effective at suppressing the bitterness of caffeine: zinc lactate (−71%, p < 0.05), non-fat milk (−49%, p < 0.05), and sodium gluconate (−31%). central cognitive strategies were partially effective: 250 mm sucrose (−47%, p < 0.05) and mocha aroma (−10%) decreased bitterness, while chocolate (+32%) and coffee (+17%) aromas increased perceived bitterness. overall, zinc lactate was the most effective bitterness inhibitor, however the utility of zinc in foods is negated by its ability to inhibit sweetness.

the fact that milk espresso derivatives are preferred over espresso alone can be understood from the above data. i recall an ancient italian proverb: ""life is bitter enough. at least put sugar in your coffee" if bitterity is a problem, take some cookie with your espresso or put sugar into it.

**plant polyphenols as dietary antioxidants in human health and disease : kanti bhooshan pandey and syed ibrahim rizvi

***modification of the bitterness of caffeine : russell keast.