Multimodal interactions in a carbonated beverage system

Predicting flavour perception is complicated by interactions occurring both within and across sensory modalities, but understanding these interactions and the resulting multimodal integration is crucial to the formulation of successful products. Despite the commercial appeal of carbonated soft drinks, few studies have examined the effects of tastant: aroma: carbonation interactions on sensory perception. To facilitate these investigations, a citrus flavoured model beverage was created containing ingredients common in commercial beverages; water, aroma volatiles, sugar (glucose or fructose; equi-sweet levels), and acid (citric and lactic acid; equi-sour levels). The complexity of the beverage was gradually increased (influence of carbonation and caffeine) until the model beverage contained elements capable of stimulating gustatory, olfactory and trigeminal systems. Samples, selected according to D-optimal designs, were evaluated instrumentally (APCI-MS measuring volatile release, rheological measures of viscosity), and sensorially (using a trained panel of assessors). Predictive polynomial models were generated from mean panel data to explain variations in the attributes as a function of the design factors. The model beverages provided evidence that multi-modal interactions occurred within this model beverage system. Increasing both sugars and acids resulted in an increase in perceived citrus flavour which was not related to any alteration in volatile release measured instrumentally. Intriguingly, glucose and fructose showed different flavour perception enhancement profiles despite being used at perceptually equi-sweet levels. This difference between the monosaccharides was also evident in the predictive models generated for mouthfeel attributes. 'Overall fizziness' was dependant only on carbonation level and unaffected by levels of tastants. However, varying levels of glucose impacted on 'tingling', a relationship not mimicked by fructose. Addition of carbonation increased perceived sourness, in agreement with previous literature, but results also demonstrated a suppressive effect on perceived sweetness. Interestingly, evaluation of non-caffeinated beverages revealed the perception of a bitter aftertaste, which was primarily driven by CO2 level, enhanced by citric acid, and suppressed by increasing sugar concentration. In caffeinated beverages, however, caffeine concentration was the main influence on 'bitterness' and 'bitter aftertaste' attributes. Despite beverage manufacturers including caffeine as 'flavouring' there was little evidence to suggest caffeine concentration modified perception of citrus flavour in this system. This project provides a comprehensive assessment of the sensory profile of a model carbonated beverage. Combining instrumental and sensorial analysis provided novel evidence of the influence of multi-modal interactions on sensory perception, and highlights the differential effects of two monosaccharides on several key sensory attributes