The Interactions of CO2, Ethanol, Hop Acids and Sweetener on Flavour Perception in a Model Beer

Beer is a complex beverage. Beer flavour is a multisensory experience in which, in addition to aroma volatiles, CO2, ethanol, bitterness (hop acids) and sweetness all contribute. To investigate the interactions between these fundamental components, a model beer system was developed using representative ingredients. Samples, selected according to a D-optimal design, were assessed by sensory profiling techniques by a trained panel. Predictive polynomial models generated from mean panel data described variations in the attributes as a function of design factors. Results show that CO2 significantly impacted on all discriminating attributes, including suppression of sweetness and modification of bitterness. A number of complex interactions with design factors showed the effects of CO2 to be dependent upon component concentration and level of carbonation. CO2 interacted with hop acids to increase carbonation and tingly perception, which increased linearly with hop acid addition but only at low levels of CO2. Ethanol was the main driver of warming perception and complexity. In agreement with other studies, ethanol enhanced sweet perception and also formed some complex interactions with hop acids and CO2 to modify various attributes, illustrating its ability to interact with both gustatory and trigeminal stimuli. Whether the mechanisms behind these interactions originate at the gustatory periphery or at higher centres in the brain is an area for further investigation. This study provides an in-depth assessment of important flavour components in beer and advances the limited data available on the effects of CO2 on sensory perception using a commonly carbonated beverage.