Christian Salles

In-Mouth Mechanisms Leading to Flavor Release and Perception

During eating, foods are submitted to two main oral processes—chewing, including biting and crushing with teeth, and progressive impregnation by saliva resulting in the formation of a cohesive bolus and swallowing of the bolus. Texture influences the chewing behavior, including mastication and salivation, and in turn, these parameters influence texture perception and bolus formation. During this complex mouth process, flavor compounds are progressively released from the food matrix. This phenomenon is mainly dependent on the food texture, the composition and in-mouth breakdown, and on saliva impregnation and activity, but an individuals anatomical and physiological aspects characteristics should also be taken into account. This article reviews the knowledge and progresses on in-mouth processes leading to food breakdown and flavor release and affecting perception. Relationships between food texture and composition, food breakdown, oral physiology, and flavor release are developed and discussed. This review includes not only the mechanical aspects of oral physiology but also the biological aspects such as the influence of saliva composition, activity, and regulation on flavor perception. In vitro and in silico approaches are also described.

Determination and gustatory properties of taste-active compounds in tomato juice

The water-soluble compounds of a tomato juice selected for its high taste intensity and quality, have been investigated by both physico-chemical and sensory analyses. The physico-chemical assessment of the crude juice led to the construction of a synthetic model juice. Although 97% of the material contained in the crude juice has been identified and quantified, significant sensory differences between the crude and model juice have been found concerning bitterness and sharpness, showing that the components responsible for these gustatory descriptors have not yet been identified in the juice. For the other descriptors: sweetness, saltiness, sourness, umami and astringency, no significant differences were found between these two solutions. Using the model juice, omission tests were performed to explain the three main tastes of the juice: saltiness, sweetness and sourness. Sweetness was mainly attributable to sugars while the non-dissociated and dissociated forms of the organic acids, with potassium as counterion, seemed mainly responsible for sourness and saltiness. Moreover, several masking effects were observed between taste-active components. The contribution of the taste-active compounds to the main tastes were quantified by stepwise multiple linear regressions. The model explained up to 95, 89.9 and 85.8% of sourness, saltiness and sweetness, respectively.

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.

In vivo sodium release and saltiness perception in solid lipoprotein matrices. 1. Effect of composition and texture

Reducing the sodium content in foods is complex because of their multidimensional sensory characteristics and the multifunctionality of sodium chloride. The aim of this study was to elucidate how food composition may influence in-mouth sodium release and saltiness perception. Lipoprotein matrices (LPM) were produced using milk constituents and characterized by means of rheological measurements, texture, and taste sensory profiles. Texture and taste perceptions were affected differently by variations in the salt level, dry matter, and fat contents. Composition and textural changes also modified temporal sodium release and saltiness perception recorded in five subjects, but the effects varied as a function of the salt content. The water content mainly appeared to influence the amount of sodium released, whereas saltiness perception was mainly related to fat content. Elasticity, coating, and granularity were found to be correlated with temporal sodium release and/or saltiness parameters.

Salt and Aroma Compound Release in Model Cheeses in Relation to Their Mobility

Physicochemical properties (partition and diffusion coefficients) involved in the mobility and release of salt and aroma compounds in model cheeses were determined in this study. The values of NaCl water/product partition coefficients highlighted interactions between proteins and NaCl. However, these interactions were not modified by the product composition or structure. On the contrary, model cheese composition and structure influenced NaCl diffusion and both partition and diffusion for aroma compounds. Analysis of in-nose measurements of aroma release during eating, with regard to physicochemical properties, showed that product and aroma properties partly contributed to flavor release. Depending on the model cheese composition, structure and firmness, physicochemical properties, food breakdown, and chewing behavior can lead to different aroma release profiles. Finally, a discussion of all the results with regard to salt and flavor perception of the model cheese showed that both physicochemical and cognitive mechanisms contributed to perception.

Determination of taste-active compounds of a bitter Camembert cheese by omission tests

The taste-active compounds of a Camembert cheese selected for its intense bitterness defect were investigated. The water-soluble fraction (WSE) was extracted with pure water and fractionated by successive tangential ultrafiltrations and nanofiltration. The physicochemical assessment of these fractions led to the construction of a model WSE which was compared by sensory evaluation to the crude water-soluble extract, using a panel of 16 trained tasters. As no significant difference was perceived, this model WSE was then used directly or mixed with other cheese components for omission tests. Among the main taste characteristics of the WSE (salty, sour, umami and bitter), bitterness was found to be due to small peptides whose mass distribution was obtained by RPHPLC-MS (400-3000 Da) and whose taste properties are discussed.

IDENTIFICATION AND SENSORY EVALUATION OF THE CHARACTER-IMPACT COMPOUNDS OF GOAT CHEESE FLAVOUR

1 SUMMARY The volatile compounds of various goat cheeses have been isolated in order to identify the character-impact odorants by a combination of instrumental analyses and sensory studies. Different extraction procedures have been studied in order to obtain a volatile fraction representative of the cheeses. The most representative extract, as determined by sensory evaluation, has been submitted to GC-MS and to GC-olfactometry, using the aroma extract dilution analysis (AEDA) method. The volatile fatty acids have been found to be the most important compounds for the characteristic goat flavour. Among them, branched-chain fatty acids ( e.g. , 4-methyloctanoic and 4-ethyloctanoic) have been found to be particularly important. Finally, incorporation of volatile extracts and individual synthetic components into a cheese model allowed the flavour impact-compounds identified to be evaluated sensorially.

Relevance of omission tests to determine flavour-active compounds in food: application to cheese taste

One of the main problems to overcome in determining the flavour-active compounds of a food product is to point out a causative linkage which may exist between its composition obtained by physico-chemical analysis, and its flavour properties determined by a trained sensory panel. Starting with an overview of the strategies classically used to solve the problem and their limitations, this paper presents an alternative methodology based on omission tests. Through different applications concerning cheese taste studies, the main interests of this methodology are shown and discussed.

Interactions between non-volatile water-soluble molecules and aroma compounds in Camembert cheese

Abstract Interactions between selected aroma compounds and non-volatile water-soluble molecules were studied using dynamic headspace-gas chromatography. A model water-soluble extract (MWSE), previously constructed in gustatory and physico-chemical accordance with the crude Camembert cheese WSE, allowed the contribution of non-volatiles to the headspace composition of volatile compounds to be assessed. The presence of the MWSE increased the headspace concentration of 2-heptanone, 1-octen-3-ol and 3-methylbutanol, showing that these three volatile compounds were released by MWSE. Omission tests performed on MWSE allowed for the impact of each MWSE component on aroma compounds release to be determined. The releasing influence of minerals appeared as the main effect observed for the three volatiles, despite some retention phenomena due to other MWSE components also occurring. In the case of 2-undecanone, 2-nonanol, 2,4-dithiapentane and ethylhexanoate, which were not affected by the presence of MWSE, some significant compensatory effects were observed. Whereas amino acids had no significant effect, minerals might cause their release and the presence of peptides can either decrease or increase headspace concentration of aroma compounds. Possible antagonistic effects between MWSE components are discussed.

In Vivo Sodium Release and Saltiness Perception in Solid Lipoprotein Matrices. 2. Impact of Oral Parameters

This study aimed to investigate the relationships between sodium release, saltiness, and oral parameters during the eating of lipoprotein matrices (LPM). Sodium release and saltiness relative to 10 LPM were recorded during normal mastication by five subjects with differing oral parameters (chewing efficiency and salivary flow rate). The LPM samples varied in composition (dry matter, fat, salt, and pH levels) and represented a broad range of hardness. Mastication was recorded using electromyography simultaneously with sensory assessment. Differences in chewing behavior could explain most of the variability in sodium release and saltiness among subjects. Subjects with a higher chewing force and lower salivary flow rate experienced higher levels of sodium release and saltiness. In terms of the LPM, sodium release and saltiness were affected by either chewing behavior or food composition.