Uncoupling the Impact of Fracture Properties and Composition on Sensory Perception of Emulsion-Filled Gels

The aim of the study is to investigate the effect of fracture properties and composition of emulsion-filled gels on dynamic texture perception. Twelve emulsion-filled gels varying in fracture stress (High/Low) and strain (High/Low) were prepared from three binary gel mixtures. Mechanical properties, syneresis, friction properties, microstructure, melting behavior, oral breakdown and texture perception of the gels were determined. Gels varying in composition but exhibiting similar fracture properties were obtained. Serum release, melting in mouth and friction varied between gels differing in composition. Fracture properties and melting of gels impacted oral breakdown. Fracture properties impacted perception of texture attributes at first bite and during chew down. Melting and syneresis impacted chew down perception of gels. We conclude that fracture stress mainly impacted texture perception at first bite, whereas fracture strain impacted perception of chew down texture attributes with high fracture strain gels being perceived creamy. The composition of gels impacted properties such as melting and serum release, which accounted for high variations in perception of moistness and creaminess between samples. Practical Applications: Fracture properties of food are known to impact the perception of first bite texture attributes. Moreover, they are known to control breakdown of food during oral processing. However, little is known about the impact of fracture properties on perception of chew down texture attributes. The current study highlights the impact of fracture properties on chew down texture perception. It identifies other gel properties depending on gels composition that account for variation in perception between gels. The use of emulsion-filled gels enabled the investigation of sensory attributes related to fat perception. Such knowledge can be used for food reformulation, for instance formulation of low fat soft solid foods. This study indicates which mechanical properties should be controlled to obtain a desired texture profile of soft solid foods.</p

Analysis of oral breakdown of food gels using image analysis

Characterizing the dynamics of food oral breakdown is of interest to understand the temporal perception of food products. Several studies aimed at characterizing bolus properties through the determination of particle size distribution, saliva uptake and rheological properties. For soft and heterogeneous foods, it is difficult to have a description of the evolution of food breakdown in the mouth, because the concept of individual particles is not clear and the bolus texture is not always homogeneous. For this reason, it is convenient to examine the possible utilization of other analytical techniques. The present work aimed at studying the possible contribution of artificial vision for studying bolus formation. Four emulsion-filled gels were prepared from two concentrations of agar and gelatin. By combining two different layers of these gels, four samples of homogeneous composition and 6 samples of heterogeneous composition were prepared. The layers were colored independently in order to study their breakdown and mixing during oral processing. Images of spat out boluses were collected at different stages of the chewing process and studied by different image analysis methods: grey-level histograms, histogram of shape area, mathematical morphology and grey level co-occurrence matrix. Methods were compared for their ability in discriminating boluses as function of homogeneous gel composition and mastication time. Three methods were found to be relevant and mathematical morphology providing the best results. Using this method, we further analyzed the impact of heterogeneous gels composition on the evolution of boluses properties. Results showed that when two gel layers of different composition were combined, the agar layer dominated bolus properties and that the presence of gelatin impacted the dynamics of gel breakdown. The results were in agreement with results obtained previously when characterizing the physical properties of the boluses. This study showed that artificial vision provides reliable tools for evaluating the dynamics of bolus formation, which is complementary to the methods commonly used in literature while avoiding extensive manipulation of boluses

Investigation of oral gels breakdown using image analysis

International audienceCharacterizing the dynamics of food oral breakdown is of interest to understand the temporal perception of food products. The present work aimed at studying the possible contribution of artificial vision for studying bolus formation. Four emulsion-filled gels were prepared from two concentrations of agar and gelatin. By combining two different layers of these gels, four samples of homogeneous composition and 6 samples of heterogeneous composition were prepared. The layers were colored independently in order to study their breakdown and mixing during oral processing. Images of spat out boluses were collected at different stages of the chewing process and studied by different image analysis methods: gray-level histograms, histogram of shape area, mathematical morphology and gray level co-occurrence matrix. Methods were compared for their ability in discriminating boluses as function of homogeneous gel composition and mastication time. Three methods were found to be relevant and mathematical morphology provided the best results. Using this method, we further analyzed the impact of heterogeneous gels composition on the evolution of boluses properties. Results showed that when two gel layers of different composition were combined, the agar layer dominated bolus properties and that the presence of gelatin impacted the dynamics of gel breakdown. The results were in agreement with results obtained previously when characterizing the physical properties of the boluses. This study showed that artificial vision provides reliable tools for evaluating the dynamics of bolus formation, which is complementary to the methods commonly used in literature while avoiding extensive manipulation of boluses

Assessment of the interactions between pea and salivary proteins in aqueous dispersions

To understand and limit the unpleasant oral sensation of astringency felt during the consumption of pea-based drinks, we investigated the interaction between mixtures of salivary and pea proteins, as compared to mixtures where HEPES buffer (at pH 6.8) was used as a negative control for saliva. Since astringent compounds have the ability to bind with salivary proteins, mixes of freshly collected whole unstimulated saliva and a pea protein isolate (PPI) (a dispersion at 3.5% w/v) were prepared in ratios 95:5 and 1:1 saliva:PPI, to allow different stoichiometries to occur in the mouth. Samples were incubated at 37 °C during 30 min, after centrifugation at 16000g during 20 min to separate pellet from supernatant. Using techniques such as SEC, Native-PAGE and LC-MS, 7 pea proteins were identified as being capable of forming aggregates with at least 7 saliva proteins, some of which have been previously connected to astringency