On the rheological and sensory properties of a novel natural salivary substitute.

The prevalence of xerostomia, the sensation of dry mouth, is estimated at 20 % in the general population and up to 50 % in older adults. Saliva plays different roles during bolus formation: lubrication, mixing, coating, hydration, dissolution, and comminution of food particles. This study proposes and tests artificial saliva formulations mimicking human saliva rheological and sensory perceptions. Shear and extensional rheology were assessed to select the type of formulation closest to saliva rheological characteristics. After evaluating three alternative sources, an extract simulating saliva rheology was produced from flax seeds. Friction coefficient and rheological properties, such as flow curves, relaxation times, and Trouton ratios, were compared favorably with human saliva. The sensory evaluation demonstrated that flaxseed extracts induce perceived mouth hydration, slipperiness, and adhesion exceeding that of human saliva. The flaxseed extract proposed in this can i) be used to study in vitro food oral processing and ii) pave the way to novel natural salivary substitutes to alleviate the symptoms of xerostomia.

Identification and quantification of key phytochemicals in peas - Linking compounds with sensory attributes.

Pea protein isolates contain high-quality plant protein. However, they have sensory drawbacks, notably bitterness and astringency, that have limited their use in commercial foods. This study's aim was thus to identify the main phytochemicals in pea-based samples and to examine associations with sensory attributes. The phytochemical profiles of pea flour, pea protein isolates, and pea protein isolate fractions were characterized via UHPLC-DAD-MS. A total of 48 phytochemicals have been revealed: 6 phenolic acids, 5 flavonoids, and 1 saponin were identified and quantified, while another 9 phenolic acids, 10 flavonoids, and 6 saponins were tentatively identified. The impacts of protein extraction and fractionation were studied. These processes appear to have caused some compound degradation. It was found that 29 compounds were correlated with perceived bitterness and/or astringency. Therefore, these results show that certain phytochemicals can lead to negative sensory attributes in pea-protein-based products.

Gaining deeper insight into aroma perception: An integrative study of the oral processing of breads with different structures.

The objective of this study was to investigate for the first time the influence of bread structure, volatile compounds, and oral processing on aroma perception. 3 types of French baguette were created using the same raw ingredients but different bread-making processes; they consequently varied in their crumb and crust structures. We characterized the initial volatile profiles of two bread structural subtypes-namely bread crumb and bread crumb with crust-using proton transfer reaction-mass spectrometry (PTR-MS) headspace analysis. Three types of bread were characterized by thirty-nine ion fragments from m/z 45 to 139. We then conducted a study in which 8 participants scored aroma attribute intensities for the different bread types and subtypes at 3 key stages of oral processing (10, 40, and 100% of individual swallowing time). At these 3 time points, we collected boli from the participants and characterized their volatile profiles using PTR-MS headspace analysis. The results suggest saliva addition dilutes volatile compounds, reducing volatile release during oral processing. Thus, a bread with high porosity and high hydration capacity was characterized by a low volatile release above boli. We examined the relationships between 4 aroma attributes of bread crumb with crust and 24 discriminatory fragment ions found in boli headspace. This study demonstrated for the first time that the perceived aroma of crumb with crust was influenced more by volatile profiles than by crumb texture. It thus contributes to our understanding of aroma perception dynamics and the mechanisms driving volatile release during oral processing in bread.

Identifying the ideal profile of French yogurts for different clusters of consumers.

Identifying the sensory properties that affect consumer preferences for food products is an important feature of product development. Different methods, such as external preference mapping or partial least squares regression, are used to establish relationships between sensory data and consumer preferences and to identify sensory attributes that drive consumer preferences, by highlighting optimum products. Plain French yogurts were evaluated by a sensory profiling method performed by 12 trained judges. In parallel, 180 consumers were asked to score their overall liking and complete a cognitive restraint questionnaire. After hierarchical cluster analysis on the liking scores, preference mapping using a quadratic regression model was performed. Five clusters of consumers were identified as a function of different preference patterns. Contrary to our expectations, fat levels were not discriminating. For each cluster, the results of preference mapping enabled the identification of optimum products. A comparison of the 5 sensory profiles revealed numerous differences between key sensory attributes. For example, one consumer cluster had a strong preference for products perceived as very thick, grainy, but with a less flowing texture, less sticky, whey presence and color, in contrast to other clusters. In addition, each segment of consumers was characterized according to the results of the cognitive restraint questionnaire.

Breakdown pathways during oral processing of different breads: impact of crumb and crust structures.

Oral processing during bread consumption is a key process related to the dynamics of texture perceptions, sensory stimuli release and starch digestion. The aim of this study was to determine the respective contribution of bread properties (composition and structure of crumb and crust) and of the oral physiology of subjects to the breakdown pathways in the mouth. The properties of the in vivo bread bolus obtained from eight healthy subjects were studied at three key points in time during their oral processing. The progressive lubrication and breakdown of bread were observed, as well as the beginning of the enzymatic degradation of starch. The study showed that "time" was the factor responsible for the greatest variability in bolus properties. Breakdown pathways were established for crumbs with and without crust. The presence of crust modified the oral processing, increasing, for instance, the heterogeneity of particle size at the middle of the oral processing sequence. Moreover, the hydration capacity of crust contributed to high starch degradation at swallowing time, in comparison with crumb alone. The main subject characteristics impacting bolus properties were the in-mouth duration, the individual masticatory index and the mouth volume, while the main bread properties explaining the bolus properties were the initial composition and the water-absorbing capacity. We concluded that both crumb and crust structures had an impact on the oral processing, affecting the capacity of hydration, the rheology and the breakdown degree of the bolus.

Respective impact of bread structure and oral processing on dynamic texture perceptions through statistical multiblock analysis.

Texture perception is a multidimensional and dynamic phenomenon resulting from both the initial structure of food and its breakdown during oral processing. The aim of this study is to identify the respective contribution of food and bolus properties to temporal changes in texture perceptions during bread consumption. For this purpose, the perception dynamics of three French baguettes with dif\ferent structures were assessed through Temporal Dominance of Sensations and Progressive Profiling. Samples of crumb with and without crust were tasted by trained panelists. The intensities of nine texture attributes were evaluated at three key stages of oral processing (10%, 40% and 100% of individual swallowing time) using the Progressive Profiling method. Six of them were related with a Multiblock Partial Least Squares (MB-PLS) regression to the initial bread properties and to some bolus properties measured at these three stages. The evolution during oral processing of some attributes such as "soft", "dry", "doughy" and "sticky" was more influenced by modifications of bolus properties than by the initial characteristics of the breads. Among bolus properties, the MB-PLS highlighted that the hydration and texture properties of the bolus had a greater impact on texture perceptions than bolus structure. The "aerated" perception was more affected by the crumb structure, while the "heterogeneousness" and the "crispiness" were more affected by the presence of crust. This study thus contributes to improving our understanding of dynamic texture perceptions through a statistical model that takes the physical properties of bread and bolus during oral processing into account.

Quality changes in yogurt during storage in different packaging materials.

The influence of packaging polymers (polypropylene or polystyrene) on the sensory and physicochemical characteristics of flavoured stirred yogurts with either 0% or 4%-fat content was investigated during the 28 days of storage at 4°C. Regardless of the packaging type, complex viscosity and thickness perception increased during storage due to exopolysaccharide production, whereas the pH of yogurts decreased. Packaging type had a greater impact on 0%-fat yogurts than on 4%-fat yogurts for both sensory and physicochemical characteristics. During storage, 0%-fat yogurt conditioned in glass displayed the lowest aroma quantity decrease of the three types of packaging, in accordance with the olfactory properties. However, between the two polymer types, polystyrene packaging seemed to be preferable for limiting aroma compound losses and subsequent fruity note intensities, and for avoiding the development of odour and aroma defects. Less significant packaging effect was observed for 4%-fat yogurts.

Influence of proteins on the perception of flavored stirred yogurts.

Among yogurt dairy components, protein type is known to modify the texture of the products and the volatility of odorous volatile organic compounds. The aim of this study was to investigate the impact of 3 protein ratios (caseinate to total protein) on the sensory properties of 4% fat, strawberry-flavored stirred yogurts. A sensory methodology study was therefore investigated to choose the most efficient method in terms of sensitivity, quantification, and ease with which the panel could distinguish slight differences in olfactory property between the yogurts. Three kinds of product presentation procedures were compared: a monadic presentation, a comparative presentation, and a comparative presentation with a reference. The results showed that the 3 presentation methods emphasized some important texture differences between the yogurts in the same way. However, the comparative procedure with a reference was the only one to reveal clear olfactory property differences between the yogurts. The main effect of protein ratio variation in yogurt concerned the texture properties, which greatly differed between the 3 yogurts and was confirmed by complex viscosity measurements. Olfactory differences between the yogurts were more subtle. Overall, the flavor intensity and the fruity notes were less intense in the yogurts with the high caseinate ratio than in those with the low ratio. This result was in agreement with the physicochemical measurements, which showed a higher retention of a large majority of aroma compounds of the strawberry flavor in the yogurts with a high caseinate ratio.