1. In vivo aroma release during eating of a model cheese: relationships with oral parameters.

This study aims to follow the kinetics of aroma compound release during model cheese consumption in order to clarify the relationships between flavor release and some oral parameters. Eight subjects participated in the study. Breathing, salivation, chewing, and swallowing were monitored during the eating process. Temporal nosespace analyses were performed using on-line atmospheric pressure ionization-mass spectrometry (API-MS) and off-line solid-phase Micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS). Flavor release profiles were obtained only for ethyl hexanoate, heptan-2-one, and heptan-2-ol. Among them, only the concentrations of ethyl hexanoate and heptan-2-one could be determined by API-MS. Absence of competition between the aroma compounds was checked for both techniques. In-nose maximum concentration (C(max)) varied with aroma compounds. However, C(max) was reached at the same time (T(max)) for the three compounds. Interindividual differences were observed for most of the parameters studied and for all of the aroma compounds. They were related to the interindividual differences among the oral parameters. The aroma release parameters C(max) and AUC (area under the curve) could be related to respiratory and masticatory parameters. In most cases, the same relationships were observed whatever the nature of the aroma compound.

2. In vivo nonvolatile release during eating of a model cheese: relationships with oral parameters.

This study deals with the release kinetics of nonvolatile compounds (NVC) (leucine, phenylalanine, glutamic acid, citric acid, lactic acid, propanoic acid, sodium, potassium, calcium, magnesium, chloride, and phosphates) during the eating of a model cheese and the relationships to some oral (salivary and masticatory) parameters. The aroma release has previously been characterized in similar conditions [Pionnier, E.; Chabanet, C.; Mioche, L.; Le Quéré, J.-L.; Salles, C. J. Agric. Food Chem. 2004, 52, xxx-xxx (1)]. Saliva samples were collected from the tongues of eight assessors at different times during and after the chewing sequence. Atmospheric pressure ionization-mass spectrometry and/or high-performance liquid chromatography analyses have been performed on these samples in order to quantify the 12 NVC released in saliva. The maximum concentration (C(max)) in saliva varied significantly according to the compound. However, there was no significant effect of the compound on the time to reach maximum concentration (T(max)). Interindividual differences were observed for most of the parameters and for all of the NVC studied. The parameters extracted from the release profiles of the NVC were closely correlated. High T(max) and AUC (area under the curve) values could be related to high chewing time and low saliva flow rates, low chewing rates, low masticatory performances, and low swallowing rates.