Salt and fat contents influence the microstructure of model cheeses, chewing/swallowing and in vivo aroma release
Résumé
The effects of the lipid/protein ratio (20/28, 24/24, 28/20) and salt content of model cheeses were investigated simultaneously with respect to chewing behaviour, swallowing events and in vivo aroma release. Chewing parameters were measured by electromyography. Swallowing events were recorded manually. In vivo aroma release was investigated using nose-space on-line atmospheric pressure chemical ionisation-mass spectrometry. The values for chewing activity and time before swallowing were higher with lower lipid/protein ratios and lower salt contents, due to the greater mechanical resistance of the model cheeses. The corresponding microstructure was made up of smaller and more circular fat droplets in a stronger protein network. Furthermore, the maximum intensity and in-mouth release rate of aroma decreased as the lipid/protein ratio fell. This could be explained by a retention effect of the proteins, which was stronger than the chewing effect. A rise in salt content triggered more rapid aroma release from the protein phase of the model cheese to the oral cavity, and thence to the nasal cavity. The larger fat droplet size in salt-supplemented model cheeses slowed down the transfer of aroma release and the levels of aroma release after swallowing were higher. A more rapid swallowing was observed for model cheeses containing added salt and with a higher L/P ratio. It is suggested that this was due to greater salivation and lubrication. Moreover, the number of swallows was positively correlated to the total amount of aroma release.