•In vitro digestion of biscuits carried out using a dynamic and multi-compartmental system.•Comparison of the kinetics of digestion between enrichments in proteins, fibres and both of them.•Following ...proteolysis upon digestion through the different gut compartments.•Following amylolysis upon digestion through the different gut compartments.
The influence of protein and/or fibre enrichment on the nutritional properties of biscuits was studied in terms of proteolysis and amylolysis. Biscuits were digested using a multi-compartmental and dynamic system that simulates the main physiological digestive functions of the upper tract of healthy adult humans: the TIM-1. A control biscuit and three biscuits enriched in proteins and/or fibres were digested under the same conditions. Samples were collected in each compartment of the TIM-1 (stomach, duodenum, jejunum and ileum) at different times of digestion and analysed in terms of proteolysis and amylolysis. Results indicate that both formulation and processing impacted the digestive fate of the biscuits. Incorporating proteins or fibres in biscuits lowered or delayed proteolysis. Moreover a protein-plus-fibre additional or synergic effect was observed. Biscuits enriched in proteins and/or fibres displayed a higher amylolysis degree than the control biscuit, probably due to lower starch amounts and higher gelatinization degrees.
•In vitro digestion of biscuits using a dynamic and multi-compartmental system.•Comparison between proteins, fibres and both of them enrichments.•Modelling digestion through the different gut ...compartments.•Following viscosity evolution during digestion.•Prediction of the viscosity upon digestion in stomach and small intestine.
The effects of biscuit composition on the viscosity generated during digestion were investigated. A control biscuit, one with proteins, one with fibres, and one with both proteins and fibres were digested under the same conditions, using the TNO intestinal model (TIM-1). The TIM-1 is a multi-compartmental and dynamic in vitro system, simulating digestion in the upper tract (stomach and small intestine) of healthy adult humans. Digesta were collected at different times, in the different compartments of the TIM-1 (stomach, duodenum, jejunum and ileum) and viscosity was measured with a dynamic rheometer. Results showed a marked effect of biscuit composition on chyme viscosity. Highest viscosity was obtained with biscuits containing viscous soluble fibres, followed by those enriched in both proteins and fibres, then by protein-enriched and control biscuits. The viscosity was maintained throughout the gut up to the ileal compartment. A prediction of the evolution of the chyme viscosity in each compartment of the TIM-1 was built, based on model curves describing the evolution of the viscosity as a function of biscuit concentration, and on dilution factors measured by spectrophotometry on a blank digestion.
The investigation dealt with the effect of the replacement of a part of wheat flour by pea flour on the properties of batters and cakes. As the protein composition of pea flour differs from that of ...wheat, the effect of its incorporation on batter formation and cake properties was monitored throughout the different steps of cake processing. The incorporation of air, which influences the cell structure and density of the cake, was the subject of particular attention. Four orders of incorporation were first investigated to identify their effects on a standard recipe made with 100% wheat flour. Mixing first egg and sugar together allows introducing air, but most of it is lost after oil and flour introduction. Whatever the order of incorporation, the density of the batter ends around 1.1 ± 0.2 g.cm
−1
. However, batter consistencies are significantly different and resulting cakes show different crumb structures. These results are discussed in terms of physicochemical mechanisms, and a schematic representation of the phenomena occurring at the different steps of mixing depending on the order of ingredient incorporation is proposed. When 20 and 40% of the wheat flour was replaced by pea flour using the two most energy-efficient orders of incorporation, more air was incorporated into the batter. However, the resulting cakes were denser, but surprisingly softer. Differences in cell structure explain this apparent contradiction.
Aggregation of egg and wheat proteins during cake mixing and baking was monitored by SE-HPLC after sequential extraction of dough and baked cakes in SDS-buffer first and then in SDS/DTE buffer. Three ...cake recipes were compared, including either only egg, only flour, or both flour and egg proteins. Dough mixing did not result in any changes in protein solubility or size distribution. Baking promoted protein aggregation and quickly resulted in the solubility loss of all proteins within the first extracting solvent with the exception of wheat omega gliadins. Upon baking similar kinetics of proteins solubility loss in SDS-buffer were observed regardless of cake recipes. Extraction of the remaining SDS-insoluble proteins with SDS/DTE buffer allowed total protein recovery but only in the case of cakes made on the basis of only flour. For cakes including eggs and despite the presence of DTE a disulfide reducing agent, very large polymers were release into solution, contrarily to the only flour cakes where only small polypeptides (>70,000 g/mol) were mostly recovered. Protein sequential extraction combined with SE-HPLC analysis highlighted the critical role of egg proteins in triggering wheat and egg proteins complexation into SDS-insoluble aggregates stabilized through disulfide but also non-reducible covalent bonds.
•Cake protein aggregation during processing was studied using SE-HPLC.•Dough mixing does not impact the size distribution of egg and flour proteins.•Egg and flour proteins formed mixed aggregates upon baking.•Mixed aggregates are stabilized by thiol/disulfide and iso-peptide bonds.•Eggs proteins contribute to strengthen the cake protein network.
Demand for health-oriented bakery products with low sugar, low fat and high fibre contents is increasing. Incorporating dietary fibre in biscuit dough tends to require some increase in its hydration ...level depending on fibre types and contents. This correction is usually managed empirically by skilled operators or bakers. In order to improve the understanding of the impact of dietary fibre on dough processing and properties, two complementary approaches are proposed. The first is a sensory description that helps formalize the hydration correction of biscuit dough enriched in fibre. The second focuses on the prediction of biscuit dough hydration, based on the evaluation of fibre and sugar water holding capacity (WHC) with the Farinograph. A polynomial model was used to describe the Farinograph water absorption versus the powder content. The WHC was computed from data obtained with the Farinograph, and it was used in biscuit dough in order to try to predict biscuit dough hydration. This model was compared to the actual added water, evaluated by the sensory methodology. A simple relationship was found between the actual and predicted amount of water. These two approaches are tools that help the formulation of biscuits with high dietary fibre content.
•An approach combining sensory and technological aspects of rotary dough.•A sensory tool to accelerate biscuit formulation.•Prediction of biscuits dough hydration enriched in fibres.•Sensory and technological approaches combined to optimise rotary moulding process.
Sponge cake is a cereal product characterized by an aerated crumb and appreciated for its softness. When formulating such product, it is interesting to be able to characterize the crumb structure ...using image analysis and to bring knowledge about the effects of the crumb cellular structure on its mechanical properties which contribute to softness. An image analysis method based on mathematical morphology was adapted from the one developed for bread crumb. In order to evaluate its ability to discriminate cellular structures, series of cakes were prepared using two rather similar emulsifiers but also using flours with different aging times before use. The mechanical properties of the crumbs of these different cakes were also characterized. It allowed a cell structure classification taking into account cell size and homogeneity, but also cell wall thickness and the number of holes in the walls. Interestingly, the cellular structure differences had a larger impact on the aerated crumb Young modulus than the wall firmness. Increasing the aging time of flour before use leads to the production of firmer crumbs due to coarser and inhomogeneous cellular structures. Changing the composition of the emulsifier may change the cellular structure and, depending on the type of the structural changes, have an impact on the firmness of the crumb.
Practical applications
Cellular structure rather than cell wall firmness was found to impact cake crumb firmness. The new fast and automated tool for cake crumb structure analysis allows detecting quickly any change in cell size or homogeneity but also cell wall thickness and number of holes in the walls (openness degree). To obtain a softer crumb, it seems that options are to decrease the cell size and the cell wall thickness and/or to increase the openness degree. It is then possible to easily evaluate the effects of ingredients (flour composition, emulsifier …) or change in the process on the crumb structure and thus its softness. Moreover, this image analysis is a very efficient tool for quality control.
In order to test the interest of coupling independent components analysis/ATR-MIR spectroscopy, a series of starch samples (native/pregelatinized, regular/waxy, potato/wheat/maize, modified or not) ...were selected and made into pastes in excess water. The evolution of the spectra during heating and cooling were monitored. Spectra could be decomposed into 8 source signals, the independent components (ICs) whose contributions vary with the type of starch sample and temperature. Of these independent components, five showed peaks at wavelengths often associated with starch in the literature (993, 1003, 1014, 1024 and 1047 cm−1). Four of them could be linked to the expected evolutions of the amorphous (993 and 1003 cm−1) and ordered (1014 and 1024 cm−1) starch molecules. By comparing the evolution of the proportions of the different source signals extracted from the starch samples with results described in the literature, it was possible to interpret the evolution of the organization of starch granule during thermal treatment.
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•Amylose and amylopectin supramolecular organisation was studied by ATR-MIR spectroscopy.•ATR-MIR spectroscopy results were analyzed using a chemometric method.•Independent Components Analysis simplified the interpretation of the ATR-MIR spectra.•Crystals and bound water were followed versus increasing and then decreasing temperature.
In vitro digestion of short-dough biscuits enriched in proteins and/or fibres using a multi-compartmental and dynamic system (2): Protein and starch hydrolyses Villemejane, C; S. DenisauthorClermont Universit, Universit dAuvergne, Centre de Recherche en Nutrition Humaine Auvergne, EA 4678, Conception Ingnierie et Dveloppement de lAliment et du Mdicament, CS 60032, F-63001 Clermont-Ferrand, France; A. Marsset-BaglieriauthorAgroParisTech, UMR914 Physiologie de la Nutrition et du Comportement Alimentaire, F-75005 Paris, FranceINRA, UMR914 Physiologie de la Nutrition et du Comportement Alimentaire, F-75005 Paris, France ...
2015
Journal Article
La perméabilisation cellulaire par l'intermédiaire de champs électriques est une des méthodes les plus sures pour le transfert de gènes et de molécules d'intérêt. La découverte des effets ...intra-cellulaires d'un nouveau type d'impulsions électriques - les nanopulses - a ouvert de nouvelles perspectives à l'application des impulsions électriques au vivant. La mise au point de nouveaux outils est indispensable avant de pouvoir appliquer ces techniques à l'homme. Aussi, notre but a été de mettre au point des systèmes d'exposition de cellules à ces impulsions et de montrer que de nouvelles applications thérapeutiques étaient possibles, en particulier en cancérologie. Une nouvelle méthode d'exposition de cellules ou de tissus basée sur l'utilisation d'électrodes isolées a été proposée permettant d'éviter tout risque de contamination ou brûlure électrochimique. A l'aide de cette nouvelle méthode, des expériences in vitro puis in vivo ont pu être menées et confirment la possibilité d'augmenter d'un facteur 3 à 6 la production de luciférase après un électrotransfert de ce gène. Enfin, l'exposition de tumeurs à ces impulsions en présence de bléomycine a permis d'obtenir des régressions tumorales complètes. Nous avons aussi conçu un biomicrosystème permettant d'étudier les effets de telles impulsions à l'échelle cellulaire sous microscope s'intégrant comme terminaison adaptée dans la chaîne d'exposition. L'ensemble des résultats présentés dans cette thèse montre qu'il est possible d'envisager l'utilisation de ces impulsions comme nouvel outil thérapeutique dans le traitement de cancers ou en thérapie génique.
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