Thickened beverages are commonly used to enhance swallowing safety in individuals with dysphagia, however, this modification can adversely affect palatability and reduce patient acceptance. This study examined the influence of drink formulation, specifically the choice of thickening agents, on texture perception by integrating sensory evaluation with a trained sensory panel along with rheological and tribological measurements using a tongue-mimicking surface. The friction coefficient at an in vivo-relevant sliding velocity of 3.5 mms-1 exhibited a strong correlation with perceived graininess. Furthermore, viscosity at a characteristic shear rate of 179 s-1 was identified as a reliable predictor of perceived thickness. Sensory findings were interpreted within the International Dysphagia Diet Standardization Initiative (IDDSI) framework. The results demonstrate that beverages classified within the same IDDSI consistency level can display significantly different rheological and tribological behaviors, and that such differences are perceptible to consumers.

This study investigates the influence of proteins and arabinoxylans contents of wheat grain on the dough extensional properties, critical determinants of bread quality. Thirty-seven wheat samples (37) were selected from an initial set of 150 wheats, according to technological criteria, including water absorption (WA), to assess the impact of natural variability of several protein and arabinoxylan (AX)-related features on dough behaviour. Dough were prepared at the hydration level determined by the WA Farinograph tests. TD-NMR results showed that, for all samples, the dough reached an optimal hydration state, reflected by a four-peak time distribution. Rheological tests were performed on dough samples at low deformation with Dynamic Mechanical Thermal Analysis (DMTA), and at large deformation, using Lubricated Squeezing Flow test (LSF). Results indicate that the maximum storage moduli E'max determined by DMTA, at temperature close to 70 degrees C, is primarily influenced by initial gluten network cross-linking. E'max decreased between 1.1 MPa and 0.6 MPa, with increasing wet gluten content from 17.2 to 40 g/100g. At large deformation, the extensional viscosity of all doughs followed a power law, from which was derived the consistency index K. Surprisingly, K increased from 11,100 to 22,200 Pa.sn when the intrinsic viscosity of water extractable arabinoxylans increased from 420 to 820 mL/g, n being the flow index of the dough. Results showed that the extensional viscosity is more closely affected by the AX characteristics than by protein characteristics. These results were interpreted in terms of supramolecular distribution of the gluten network and the entangled arabinoxylans in the liquid phase, and discussed for their possible impact on bread making for a wide range of wheats.

A capillary pre-shearing rheometer, Rheoplast®, allowing for simulation of an extrusion process, was used to determine the viscosity of 60/40 pea protein isolate/gluten blends previously extruded at different temperatures (130 °C, 140 °C, 150 °C) and moisture contents (50%, 55%, 60% w/w). Electronic microscopy and mechanical testing showed that the materials displayed distinct anisotropic and fibrous structures. Pressure profiles were determined over an apparent shear rate range of 10–104 s−1, using capillary dies with length/diameter (L/D) ratios 8, 16, and 32 (D = 1 mm). For all materials, the pressure profiles are regular, suggesting the absence of wall slip. All flow curves could be fitted with the Ostwald–de Waele model. The values of consistency index (K), ranging from 480 to 5000 Pa.sn, and those of the flow index (n), from 0.25 to 0.7, were inversely correlated, reflecting the effect of material structuring. Furthermore, the time-temperature superposition principle was extended to account for the influence of water content by introducing the glass transition temperature (Tg) of the protein mixture with curve shift factors depending linearly on Tg/T. All results can then be fitted using a Carreau model, describing the viscous behavior within the range [1, 105 s−1] with plateau viscosity (η0) values varying between 240 and 1050 Pa.s. Finally, by extrapolating Bagley plots to L/D = 0, entry pressure was derived, and, consequently, apparent elongational viscosity was determined, leading to Trouton number values around 100. Results are interpreted by structural differences and the viscosity model can be used for computer simulation of flow in the die.

Water absorption in wheat flour is a crucial parameter for optimizing bread-making processes. The determinants of wheat flour water absorption were investigated through the analysis of 28 compositional and technological properties of 150 wheats grown in France. A multiple linear regression approach was used to predict the water absorption, selecting the best model through successive examination of Bayesian Information Criterion, Variance Inflation Factor and minimizing the total number of variables. A model with protein content, soluble starch, damaged starch and specific viscosity from water extractable arabinoxylans was identified as the best trade-off between the number of variables and the predictive performances among all possible models. Soluble Starch, varying between 1.11 and 6.21 g/100 g flour a new criterion measured alongside water-extractable arabinoxylans content, varying between 0.26 and 0.86 g/100 g flour, shows significant potential to predict water absorption compared to damaged starch.

Wheat flour doughs were prepared from four commercial wheat flours at different mixing times and hydration levels in order to obtain variations in their rheological properties and gluten network structure. Their rheological behavior was assessed by Dynamic Mechanical Analysis (DMA) for their viscoelastic properties and by Lubricated Squeezing Flow (LSF) for their extensional properties. Gluten network structure was determined by quantitative analysis of confocal microscopy (CLSM) images. Among the rheological properties, the consistency index (k) derived from the extensional viscosity and the elastic modulus ratio (E ' Max/E ' Min) varied between 10 and 42 kPa. sn, and 4 and 26, respectively. They were found to be consistently linked to the gluten network structure. This structure was primarily described by the morphological descriptor, "protein width", which defines the thickness of protein strands, the average value of which varied between 1.7 and 2.5 mu m. Both rheological properties and morphological criteria were significantly influenced by dough hydration rather than by mixing time, whereas the flour characteristics did not play a major role. Interpretation of these results, supported by previous 1H time domain nuclear magnetic resonance (TD-NMR) results concerning water distribution profiles, showed that an optimal dough is defined by a high dough consistency index (k) and a highly cross-linked gluten network (low E'Max/E'Min ratio), presenting thin protein strands.

The survival rate of mesenchymal stem cells (MSC), a crucial factor in tissue engineering, is highly dependent on glucose supply. The purpose of this paper is to study the potential of starch foams as glucose suppliers. It is investigated through in vitro hydrolysis by amyloglucosidase in conditions that respect physiological constraints (37 degrees C and pH 7.4), including a duration of 21 days, and no stirring. Nine extruded starch foams with amylose contents ranging from 0 to 74 %, with various cell wall thicknesses (50 to 300 mu m), and different crystallinities (0-30 %) were hydrolysed. These kinetics were fitted by a model which shows that the maximum rate of hydrolysis varies from 7 to 100 %, and which allows the rate of hydrolysis at 21 days to be calculated precisely. The results reveal the major role of amylose in glucose delivery kinetics, and the secondary roles of crystallinity and cell wall thickness of the foams. Additional hydrolysis of starch films revealed that thickness positively influences the amylose chain reorganisation during hydrolysis, which, in slows down and limits glucose delivery. A simple glucose delivery kinetics analysis procedure is proposed to select samples for testing as MSC glucose suppliers.

A procedure to assess dough behaviour at mixing is established and its results are correlated with flour specifications and results from empirical rheological tests. A total of 36 wheat flours obtained from two types of cultivations, conventional (C) or sustainable (S), were used in this work. They were processed on a lab-scale spiral mixer under same kinematics and hydration conditions. The power supplied by the mixer along time, P(t), was recorded. The resulting time-series were treated in two ways: (1) nine parameters were directly derived from the data and (2) a four-parameters Gauss model was used to fit the data (R2mean = 0.97), including the standard deviation (SD). The Gauss model parameters better explained the variability of the mixing curves of the flours. Furthermore, PLS modelling of SD evidenced two clusters in relation to the extensibility capacities of the dough (P/L from the Chopin alveograph), hence providing information on the tolerance of the flour to mixing. These results enhanced the contribution of dough extensional properties during mixing and open prospect to improve the assessment of its rheological behavior during processing by a simple mixing test.

ABSTRACT Cassava crops have always been fundamental in human nutrition and industry. Nowadays, the development of new cultivars with specific properties has become a major research area. In this research, amylose-free cassava starch (WXCS) extracted from clone AM206-5 was evaluated with respect to its physicochemical, morphological, and thermorheological properties. The waxy nature of cassava starch was verified (0.54 ± 0.09% w/w amylose), showing a 16.92±0.20 µm average granule size and elliptical or spherical truncated shapes without granule aggregation. There were significant differences in the pasting profiles evaluated, with WXCS being thermally less stable (Breakdown = 698±2 cP) generating less viscous final pastes (731±16 cP) compared to a commercial amylose-free corn starch. The WXCS shear viscosity was determined in a capillary rheometer (Rheoplast®), showing an inverse linear temperature dependence, decreasing by a factor larger than 3 when the temperature changed from 100 to 120 °C, with a pseudoplastic flow described by the power law (n: 0.25-0.40), consistency index (32607 - 6695 Pa.s) and specific mechanical energy (124 - 75 J/g). The extensional viscosity was always higher than the shear viscosity, where increasing the strain rate and temperature enlarged the Trouton number (25-145). Complete WXCS transformation under real process conditions was achieved with a 30% w/w moisture content and 100 °C, which induced full granular integrity loss and crystalline structure destruction. The results confirmed a potential utilization for this new starch to obtain extruded-type food products or to serve as a biothickening agent.

Pea flour and a blend of pea starch and protein isolate with a starch-to-protein ratio close to 2/1 were processed using co-rotating twin-screw extruders. Different extruder scales operated at a moisture content of 18-35% and a screw speed of 120-700 rpm resulted in large intervals of melt temperature T (95-165 degrees C) and specific mechanical energy SME (150-2000 kJ/kg). With increasing T and SME, starch solubility in water increased due to starch melting and depolymerisation, and protein solubility in SDS decreased due to formation of protein aggregates linked by disulphide bonds. Extruded foods' morphology was studied by CLSM. Protein cross-linking increased the median size of protein ag-gregates; starch destructuration increased the area of the starch phase to the detriment of the protein one. Melt shear viscosity was determined using a pre-shearing capillary rhe-ometer. The melts exhibited shear-thinning behaviour according to a power-law model, with values close to those of model parameters observed for pea flour and SP 2/1 blend. The rheological model was implemented in a 1D global extrusion model to simulate pea ingredient extrusion. Satisfactory correlations between predicted extrusion variables (T, SME) and biopolymer transformation suggested that products with target structure can be obtained using simulation to tune extrusion conditions.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Biopolymer composites based on pea starch-protein blends and pea flour are processed using extrusion at various levels of specific mechanical energy (SME). Their morphology was a continuous matrix phase of starch with embedded protein particles, as revealed by Confocal Laser Scanning Microscopy (CLSM). The motivation is to correlate the local Young's modulus (E) in starch and protein phases, as well as their interphase, through nanoindentation tests to macroscopic three-point bending testing results of starch-protein composites. The differences between E of starch and protein phases and interphase were significant and their values were found to vary in the ranges of 4.2–7, 3–6.9 and 4–6.9 GPa, respectively. The local E can be tuned by the protein content and composite morphology, the latter depending on the level of transformation of the biopolymers during extrusion (SME). Pea flour composites have larger modulus values, which can be attributed to the presence of fibres.

Artificial boluses were prepared from sponge cake by grinding the food to a given particle size and hydrating with artificial saliva. The shear viscosity of the artificial food bolus was then measured by capillary rheometry, and its variations with shear rate were studied as a function of four main factors: bolus water content, particle size, temperature and saliva viscosity. The flow curves can be fitted according to the Herschel-Bulkley model, which allows for the derivation of two main properties: yield stress and consistency. Saliva plasticizing coefficients are defined by the variations of these properties as a function of the water content. Their value, close to 12, is in good agreement with values obtained for molten starch (10 < α < 20). Particle size has little influence, whereas the effect of temperature and saliva viscosity is not monotonous. They underline the complexity of the structure of the bolus and the interplay between the saliva, acting as a lubricant and a swelling agent. Finally, the extensional viscosity of the artificial bolus is also determined by capillary rheometry, and it is shown to be of importance when comparing the viscous properties of the artificial bolus with those of real ones from literature.

The baking industry performs common technological (empirical) tests. Unfortunately, the results hardly predict the dough behavior online. This paper first reviews the most common methods to assess the rheological properties of the dough, including empirical tests, small and large deformations methods. A second section describes the relations between rheological properties and dough behavior at the critical step of dough mixing. We put forward a tentative interpretation of these relations based on dough structural changes supported by results from imaging or spectroscopic methods. Finally, a review of simple models consistent with the physical understanding of the dough behavior is presented as tools that scientist and engineers can use to interpret experimental data, perform system analysis and anticipate the product properties.

The properties of artificial food bolus are studied by dynamic oscillatory and capillary rheometry as functions of bolus water content (WC), in the usual range of saliva hydration, for four cereal products: sponge cake, extruded flat bread and their counterpart enriched in legume proteins. All boluses followed the same rheological behavior characterized by (1) solid -like in the linear viscoelastic domain and (2) Herschel-Bulkley model for large shear strain. Hence, four characteristic rheological properties are determined: modulus at viscoelastic plateau, characteristic stress at transition to flow, yield stress and consistency in the flow regime. The decrease of these properties with WC was fitted by an exponential decay function, from which was extracted a coefficient alpha (5 = alpha < 30), defined as a coefficient of interaction of the food with water. The values of alpha are of the same order of magnitude as the plasticization coefficient of starch by water. They were larger for the extruded pea based (EFP, alpha >= 15), and were lower for the sponge cake (SC, alpha < 15). The variations for the different rheological properties are discussed in terms of matter state, envisioning bolus as a suspension of soft swellable particles. The comparison of these values with those encountered for real boluses from similar foods suggests that these results contribute to define a coefficient of interaction of food with saliva.

As the elderly population is growing steadily, more age-friendly food products that allow them to cover their nutritional needs and are enjoyable need to be designed. Since their oral physiology is considerably altered, the study of Food Oral Processing has become an essential discipline in food development, as it takes into consideration the complex interactions between food structure, oral processing, physiology and perception. Cereals are staple foods in many countries, and their consumption as bakery products is popular among the elderly population. In addition, when fortified with pulse proteins, they can help meet the protein needs of seniors and help fight against sarcopenia. For these reasons, this chapter presents an overview of the various aspects involved in the oral processing and formulation of soft cereal foods, translating them into challenges and opportunities that are of relevance to the design of realistic soft cereal foods targeted for the elderly that are nutritious and sensory appealing. This review focuses on the healthy elderly population and does not intend to cover the needs of the dependent elderly suffering from chronical diseases.

The structure of cereals and snack foods during processing is developed according to structural changes at various levels of matter organization. At macroscopic scale, two main consecutive mechanisms rule these changes: (1) the transition from a powder (the flour) to a viscoelastic liquid (the dough, the paste) and (2) the transition from a liquid to a solid, soft or rigid. At mesoscopic scale, these changes can be first captured through state diagrams that represent the material rheological properties as functions of the composition. These diagrams and functions can be enriched with the paths followed by the food product along processing. All together, these representations, called basic knowledge models, can provide scientists and engineers with a comprehensive basis to predict the development of structure and final properties of the food. In this chapter, we will strive to apply basic knowledge models for predicting texture properties to several types of airy cereal and snack foods (bread, biscuits, cakes, and extruded snacks taken as examples). A specific effort is devoted to build a generic approach of structure development that can be applied to the design of cereal foods with targeted sensory and nutritional properties.

The objective of this work was to understand, in the elderly, the mechanisms of oral breakdown and bolus formation for two cereal foods (brioche and sponge cake) enriched with pulse proteins (pea and faba bean), in order to develop foods acceptable for the elderly population. The food oral processing (FOP) of these two food products has been studied by imaging and rheology, in connection with the perception of in-mouth comfort and with the oral physiology of seniors. It has been shown that the salivary flow has a major influence on the viscosity of the food bolus, which is itself strongly linked to the perception of comfort for non enriched products. The impact of enrichment on texture depends on the product considered. It modifies the mechanisms of FOP and perception of oral comfort. For sponge cake, this impact can be reduced by adapting the process, with apparently, small impact on protein digestibility evaluated in vitro. This interdisciplinary study therefore leads to recommendations for developing realistic cereal foods, with acceptable sensory properties and meeting the elderly people's nutritional needs. (C) 2020 Societe francaise de nutrition. Published by Elsevier Masson SAS. All rights reserved.

The structure of extruded pea flour can affect chewing performances. Our objective was to relate the bolus properties (fragmentation, moisture content and viscosity) of chewed extruded pea snacks to their structure. In order to have control over oral physiological parameters, we opted for an in vitro approach using a chewing simulator, the variables of which were the flow rate of artificial salivary fluid and chewing time. The structure of the extruded pea snacks was characterized by its density and protein solubility in dithioerythritol (DTE), which reflected the amount of protein aggregates cross-linked by disulphide bonds. The particle size distribution and median width (D50) of the bolus fragments were determined by imaging technique. Bolus viscosity and saliva uptake (ΔWC) were respectively determined by capillary rheometry and gravimetric method. Extruded snacks were persistently reduced to small particles (~ 2 mm) during chewing process following a unique curve of D50 = f (chewing time) fitted by a power function. ΔWC evolution during chewing process was expressed as a function of the structure index, defined as the product of the snacks’ relative density by protein solubility in DTE. The boluses’ viscosity exhibited a shear thinning behaviour the consistency index of which was negatively correlated to the saliva uptake (ΔWC) through a plasticization coefficient (α). α values (< 2) were much smaller than those reported for cereal products (15–30) and depended on protein solubility in DTE.

Extrusion has been fully described in detail formerly in various books, which explain well the process and the changes of the material structure, either from biomass or from petrol. In this chapter, we focus on the two main mechanisms—melting and expansion—promoted by extrusion, according to the latest scientific results available. We will also show how the changes of recipe may be tackled, using experimental methods and modeling, especially relevant for the extrusion process, provided the main physical properties of the recipe are known. Finally, this approach is illustrated by specific examples from real application in breakfast cereal manufacturing by extrusion cooking.

This paper presents a digital learning tool, MESTRAL ("Modelisation Et Simulation des TRansformations ALi-mentaires", "Modelling and Simulating Food Processing" in English), that can provide educators with a tool to teach food processing using simulators and a broad range of models derived from research in food science & engineering. It was built using electronic knowledge books (eK-book). The eK-book represents knowledge in the form of concept maps and knowledge sheets, connected via a network of hypertext links. MESTRAL encompasses 15 modules, that cover approximately 150 h of teaching and a broad range of real systems, from a single unit operation (e.g., frying a banana) to a logistic chain (e.g., ham cold chain). Each module conveys information on a food product or a food process, and includes a simulator based on a published scientific model. Altogether, the models address various scale of systems and are based on different theoretical frameworks. For each simulator, the model inputs and outputs are stored in a database. Outputs are visualized through abacuses, which can be used for virtual practice. MESTRAL modules also include training exercises and tests to help students to assess the knowledge they have acquired during consultation of the modules. Finally, MESTRAL has already been successfully tested by different audiences according to various learning forms.