The new study, published in the International Dairy Journal, suggests that aroma compounds from foods are released during the chewing process, and not just as sections of the food are swallowed. As these aromas reach the nose, an increase in sensory perception may strengthen flavour intensity.
“The results of the present study provide information about the range of variations in the main oral parameters when cheese samples are eaten and the course of cheese breakdown in human mouth,” said the researchers, led by Dr Amparo. Tarrega, from University of Burgundy, France.
“These results will also enable a better fit of the chewing simulator for in vitro study of cheese aroma release before analysing the interaction between oral parameters, cheese composition and sensory perception by consumers,” they said.
Food texture
Depending on the texture of a food, it can either be broken down into separate particles or softened by chewing action, leading to changes in the rheological properties of the bolus (a ball of food that has been chewed ready to be swallowed).
Salivary flow rate varies according to the intensity of stimuli, which according to Tarrega and colleagues is stimulated during food consumption by food composition (especially sour tastants) and chewing activity.
They noted that most of a foods sensory properties are perceived during chewing and swallowing.
“In recent years, more attention has been paid to studying the mastication process and its relationship with the sensory perception mechanisms. This process is determinant for i) texture and mouthfeel perception, and ii) flavour release and perception by consumers,” wrote the authors.
The perception of aroma compounds may be influenced by different events occurring in the mouth; as such the availability of volatile (aroma) compounds depends on their release from food and their transfer to the olfactory receptors in the nose cavity.
“The present study describes the changes in mechanical properties and saliva incorporation for cheese samples with different composition and texture, and their influence on the rate of aroma release,” said the authors.
Study details
Subjects were asked to chew seven gram cubes of cheese without swallowing. The researchers measured chewing work per mastication cycle, salivary flow rate and chewing rate varied highly among subjects. Chewing activity, swallowing events and aroma release profiles during cheese consumption were also simultaneously recorded.
They reported that despite differences in cheese hardness, at the end of mastication, bolus texture was the same for cheeses with the same lipid content. They noted that low fat cheeses gave harder bolus than high fat ones, despite being chewed longer, with higher work per cycle and more moisture.
Salivary flow rate did not vary among cheese samples, but at the end of mastication the amount of saliva in boluses differed depending on the hardness and fat content of cheeses, said the authors.
“As soon as the subject started to chew the cheese sample, the amount of aroma compound increased,” said Tarrega and co workers.
They also observed distinct differences in aroma release pattern between subjects, which they suggested may be explained by individual differences in both chewing process and salivary flow rates.
“Even if subjects were not allowed to swallow during the first 20 chewing cycles, an increase in aroma released in the nose was observed for this period, confirming that, during mastication of solid foods there are pulses of aroma from the mouth to the nose which are not necessarily associated with swallowing events,” said the researchers.
They concluded that the study highlighted “a strong interaction between oral physiology parameters on aroma release during cheese consumption.”
Source: International Dairy Journal
Published online ahead of print, doi: 10.1016/j.idairyj.2010.12.010
“In-mouth aroma compound release during cheese consumption: Relationship with food bolus formation”
Authors: A. Tarrega, C. Yven, E. Sémon, C. Salles