Esters are formed by the reaction of an alcohol and a carboxylic acid, usually in the presence of sulfuric acid to catalyse the process, or by the reaction of an acyl chloride … with a carboxylic acid (this requires no catalyst and is irreversible without additional reactants) are the most common ways used.o, esters are neutral and they are organic compounds that result from the interaction of acids and alcohol. The presence of esters can cause the fruity-ish flavors and arom … as, such as banana, blueberry, rasberry and pear, that intentionally or unintentionally occur in some beers.