Abstract
Flavour perception is an important aspect for consumer acceptability of cheese products. There is rich knowledge of the constituents that contribute to the flavour of cheeses including both volatile and non-volatile compounds responsible for aroma and taste perception, respectively. When these compounds are combined together they can perceptually influence the intensities of each other through sensory interactions, both within and across the senses (modalities). How these compounds combine together to give a cheese flavour perception and the way interactions influence the flavour intensity and character, however, is poorly understood. Investigations of sensory interactions are required for a better understanding of the perception of cheese flavours. The current thesis determined the cross-modal sensory interactions between taste and aroma towards the perception of cheese flavour intensity and character.
Tastants that represented five basic tastes, singly and also in mixtures, were combined with cheese aroma comprising 10 volatile compounds. Single taste and cheese aroma combinations using sucrose, NaCl, and some combinations using monosodium glutamate (MSG) enhanced cheese flavour intensity while lactic acid caused suppression. The magnitude of intensity enhancement was greater when all five basic tastes (combined together at equi-intense levels) were mixed with cheese aroma. Meanwhile aroma enhanced umami and bitterness intensities.
As the mixture of tastants was shown to be more important for cheese flavour intensity than single tastants, a mixture of five tastants resembling the taste of a Cheddar cheese was determined in three steps. First the taste profiles of commercial cheeses were determined, second the taste-taste interactions were studied to aid reconstruction, and third the reconstructed taste solution was validated. This reconstructed taste solution was cross-modally interacted with aroma, including variations of aroma compound mixtures. Key tastants and a single aroma mixture were varied using the simultaneous gustometer olfactometer. Within the mixture, NaCl, lactic acid, and aroma were the largest contributors to cheese flavour intensity. Tastants collectively contributed to cheese flavour intensity more than cheese aroma. Variations in aroma mixtures with increased esters, methyl ketones, or diacetyl contributed to the flavour intensities of fruity cheese, blue cheese, and buttery cheese, respectively. Increase in esters or diacetyl suppressed the flavour intensities of overall cheese and blue cheese. Regardless of cheese aroma mixture, tastants collectively contributed largely to flavour attribute intensities.
Differences in cheese flavour character as a function of NaCl, lactic acid, and aroma were determined. Increases in lactic acid and aroma changed the flavour character while increases in NaCl maintained it. The changes in flavour character were determined through a sorting task followed by evaluation of a subset of samples using free choice profiling. A range of cheese flavour characters were determined on the general procrustes analysis map. Cheese flavour character was therefore dependent on the balance between taste and aroma components. Taste played a pivotal role in providing the generic flavour character of cheese and determined the flavour balance while aroma changed flavour character by cheese type. The series of studies in the thesis demonstrated the cross-modal sensory interactions of complex taste-aroma mixtures and potential changes in flavour character.