9 research outputs found
Study of changing of adhesion between pans and cereal products during baking according to the surface properties of pan.
Les revĂȘtements perfluorĂ©s sont utilisĂ©s comme anti-adhĂ©sifs dans des moules de cuisson pour pains de mie. Ils font lâobjet de diverses interrogations relatives Ă leur vieillissement. Dans ce contexte, la problĂ©matique de ce travail a portĂ© sur lâĂ©tude des consĂ©quences du vieillissement de revĂȘtements perfluoroalkoxy (PFA) sur leurs performances anti-adhĂ©sives. De plus, les consĂ©quences de la perte des propriĂ©tĂ©s anti-adhĂ©sives des revĂȘtements ont Ă©tĂ© Ă©valuĂ©es en termes de risque chimique. La production de nĂ©oformĂ©s dans la croĂ»te de pain au contact des moules a donc Ă©tĂ© Ă©tudiĂ©e. Pour rĂ©pondre Ă la problĂ©matique, des moules ont Ă©tĂ© vieillis en conditions industrielles, puis Ă partir dâun protocole mis au point spĂ©cifiquement dans le cadre de cette Ă©tude, des mesures de forces ont pu ĂȘtre rĂ©alisĂ©es pendant le dĂ©moulage des pains. Par ailleurs, plusieurs formules de pains de mie ont Ă©tĂ© testĂ©es. Il sâagissait dâĂ©tudier dâune part lâeffet de lâĂ©tat physique des lipides sur le dĂ©moulage. De plus, lâeffet dâautres constituants tels que protĂ©ines et fibres a Ă©tĂ© Ă©tudiĂ© (utilisation de farine complĂšte).Le vieillissement en conditions industrielles nâaffecterait que les propriĂ©tĂ©s physiques (rugositĂ©) des revĂȘtements PFA. Ces modifications de surface nâont cependant pas entraĂźnĂ© de problĂšme de dĂ©moulage en fin de cuisson. Par ailleurs, les marqueurs choisis de la rĂ©activitĂ© (furane, acrylamide et CML) Ă©voluent peu avec le vieillissement, et ce quelle que soit la formule. La CML montre toutefois une tendance Ă augmenter avec le vieillissement, ce qui pourrait malgrĂ© tout indiquer un effet du vieillissement des revĂȘtements sur la rĂ©activitĂ© du produit.Par ailleurs, pour caractĂ©riser plus spĂ©cifiquement lâadhĂ©sion de pĂątes de farine au cours de la cuisson, une mĂ©thodologie basĂ©e sur des tests dâadhĂ©rence en simulateur expĂ©rimental sur rhĂ©omĂštre a Ă©tĂ© mise au point. Ces tests dâadhĂ©rence ont Ă©tĂ© effectuĂ©s avec des surfaces modĂšles en verre, choisies pour ĂȘtre reprĂ©sentatives des propriĂ©tĂ©s chimiques des revĂȘtements PFA. Il apparaĂźt que les propriĂ©tĂ©s adhĂ©sives des pĂątes Ă©voluent de la mĂȘme façon que les propriĂ©tĂ©s viscoĂ©lastiques en fonction de la tempĂ©rature. Par ailleurs, les propriĂ©tĂ©s interfaciales contribuent pour une part Ă lâĂ©volution dâadhĂ©sion des pĂątes avec la tempĂ©rature. Les pĂątes tendent Ă adhĂ©rer plus facilement sur des surfaces hydrophiles. Dâailleurs, sur ces surfaces, les ruptures peuvent devenir cohĂ©sives au-delĂ dâune certaine tempĂ©rature, indiquant une diminution de leur hydrophobicitĂ© de surface.Perfluorinated coatings used as anti-adhesive coatings in bread pans are subjected questions relating to their aging. In this context, the objective of this work was to focus on the consequences of aging of perfluoroalkoxy (PFA) coatings on their anti-adhesive performance. The consequences of loss of anti-adhesive properties were studied in terms of chemical risks and neoformed compounds in bread crust during baking in contact with a pan were investigated. To do so, pans were aged under industrial conditions, then a method was specifically developed for this study to measure forces during depanning step. Moreover, several bread formulas were tested. The aim was to determine the impact of physical state of lipids (rapeseed oil versus concrete fat) and of other components as proteins and fibers (by adding whole-wheat flour) on depanning step.Aging in industrial conditions seems to only affect physical properties (roughness) of PFA coatings. These modifications of the pan surface did not led to depanning problem at the end of the baking step. Moreover, the chosen reactivity markers evolve slightly with aging, whatever the bread formula used, even if a slightly increase of CML quantity with aged pan was highlighted.Furthermore, in order to characterize the adhesion of wheat dough depending on the temperature, a new methodology was developed. It consisted in measuring the adherence forces under experimental simulations on rheometer. We selected model glass surfaces which had chemical properties close to the properties of PFA coatings. We showed that adhesion and viscoelastic properties evolve in the same way with temperature, and interfacial properties also contribute to evolution of dough adhesion. Wheat dough tend to adhere more easily on hydrophilic surfaces. Anyway, on these surfaces, failure may become cohesive from a specific temperature, showing a decrease of the dough surface hydrophobicity
Ătude de lâĂ©volution des contacts moules / pains de mie au cours de la cuisson en fonction des propriĂ©tĂ©s de surface des moules
Perfluorinated coatings used as anti-adhesive coatings in bread pans are subjected questions relating to their aging. In this context, the objective of this work was to focus on the consequences of aging of perfluoroalkoxy (PFA) coatings on their anti-adhesive performance. The consequences of loss of anti-adhesive properties were studied in terms of chemical risks and neoformed compounds in bread crust during baking in contact with a pan were investigated. To do so, pans were aged under industrial conditions, then a method was specifically developed for this study to measure forces during depanning step. Moreover, several bread formulas were tested. The aim was to determine the impact of physical state of lipids (rapeseed oil versus concrete fat) and of other components as proteins and fibers (by adding whole-wheat flour) on depanning step.Aging in industrial conditions seems to only affect physical properties (roughness) of PFA coatings. These modifications of the pan surface did not led to depanning problem at the end of the baking step. Moreover, the chosen reactivity markers evolve slightly with aging, whatever the bread formula used, even if a slightly increase of CML quantity with aged pan was highlighted.Furthermore, in order to characterize the adhesion of wheat dough depending on the temperature, a new methodology was developed. It consisted in measuring the adherence forces under experimental simulations on rheometer. We selected model glass surfaces which had chemical properties close to the properties of PFA coatings. We showed that adhesion and viscoelastic properties evolve in the same way with temperature, and interfacial properties also contribute to evolution of dough adhesion. Wheat dough tend to adhere more easily on hydrophilic surfaces. Anyway, on these surfaces, failure may become cohesive from a specific temperature, showing a decrease of the dough surface hydrophobicity.Les revĂȘtements perfluorĂ©s sont utilisĂ©s comme anti-adhĂ©sifs dans des moules de cuisson pour pains de mie. Ils font lâobjet de diverses interrogations relatives Ă leur vieillissement. Dans ce contexte, la problĂ©matique de ce travail a portĂ© sur lâĂ©tude des consĂ©quences du vieillissement de revĂȘtements perfluoroalkoxy (PFA) sur leurs performances anti-adhĂ©sives. De plus, les consĂ©quences de la perte des propriĂ©tĂ©s anti-adhĂ©sives des revĂȘtements ont Ă©tĂ© Ă©valuĂ©es en termes de risque chimique. La production de nĂ©oformĂ©s dans la croĂ»te de pain au contact des moules a donc Ă©tĂ© Ă©tudiĂ©e. Pour rĂ©pondre Ă la problĂ©matique, des moules ont Ă©tĂ© vieillis en conditions industrielles, puis Ă partir dâun protocole mis au point spĂ©cifiquement dans le cadre de cette Ă©tude, des mesures de forces ont pu ĂȘtre rĂ©alisĂ©es pendant le dĂ©moulage des pains. Par ailleurs, plusieurs formules de pains de mie ont Ă©tĂ© testĂ©es. Il sâagissait dâĂ©tudier dâune part lâeffet de lâĂ©tat physique des lipides sur le dĂ©moulage. De plus, lâeffet dâautres constituants tels que protĂ©ines et fibres a Ă©tĂ© Ă©tudiĂ© (utilisation de farine complĂšte).Le vieillissement en conditions industrielles nâaffecterait que les propriĂ©tĂ©s physiques (rugositĂ©) des revĂȘtements PFA. Ces modifications de surface nâont cependant pas entraĂźnĂ© de problĂšme de dĂ©moulage en fin de cuisson. Par ailleurs, les marqueurs choisis de la rĂ©activitĂ© (furane, acrylamide et CML) Ă©voluent peu avec le vieillissement, et ce quelle que soit la formule. La CML montre toutefois une tendance Ă augmenter avec le vieillissement, ce qui pourrait malgrĂ© tout indiquer un effet du vieillissement des revĂȘtements sur la rĂ©activitĂ© du produit.Par ailleurs, pour caractĂ©riser plus spĂ©cifiquement lâadhĂ©sion de pĂątes de farine au cours de la cuisson, une mĂ©thodologie basĂ©e sur des tests dâadhĂ©rence en simulateur expĂ©rimental sur rhĂ©omĂštre a Ă©tĂ© mise au point. Ces tests dâadhĂ©rence ont Ă©tĂ© effectuĂ©s avec des surfaces modĂšles en verre, choisies pour ĂȘtre reprĂ©sentatives des propriĂ©tĂ©s chimiques des revĂȘtements PFA. Il apparaĂźt que les propriĂ©tĂ©s adhĂ©sives des pĂątes Ă©voluent de la mĂȘme façon que les propriĂ©tĂ©s viscoĂ©lastiques en fonction de la tempĂ©rature. Par ailleurs, les propriĂ©tĂ©s interfaciales contribuent pour une part Ă lâĂ©volution dâadhĂ©sion des pĂątes avec la tempĂ©rature. Les pĂątes tendent Ă adhĂ©rer plus facilement sur des surfaces hydrophiles. Dâailleurs, sur ces surfaces, les ruptures peuvent devenir cohĂ©sives au-delĂ dâune certaine tempĂ©rature, indiquant une diminution de leur hydrophobicitĂ© de surface
Ătude de lâĂ©volution des contacts moules / pains de mie au cours de la cuisson en fonction des propriĂ©tĂ©s de surface des moules
Perfluorinated coatings used as anti-adhesive coatings in bread pans are subjected questions relating to their aging. In this context, the objective of this work was to focus on the consequences of aging of perfluoroalkoxy (PFA) coatings on their anti-adhesive performance. The consequences of loss of anti-adhesive properties were studied in terms of chemical risks and neoformed compounds in bread crust during baking in contact with a pan were investigated. To do so, pans were aged under industrial conditions, then a method was specifically developed for this study to measure forces during depanning step. Moreover, several bread formulas were tested. The aim was to determine the impact of physical state of lipids (rapeseed oil versus concrete fat) and of other components as proteins and fibers (by adding whole-wheat flour) on depanning step.Aging in industrial conditions seems to only affect physical properties (roughness) of PFA coatings. These modifications of the pan surface did not led to depanning problem at the end of the baking step. Moreover, the chosen reactivity markers evolve slightly with aging, whatever the bread formula used, even if a slightly increase of CML quantity with aged pan was highlighted.Furthermore, in order to characterize the adhesion of wheat dough depending on the temperature, a new methodology was developed. It consisted in measuring the adherence forces under experimental simulations on rheometer. We selected model glass surfaces which had chemical properties close to the properties of PFA coatings. We showed that adhesion and viscoelastic properties evolve in the same way with temperature, and interfacial properties also contribute to evolution of dough adhesion. Wheat dough tend to adhere more easily on hydrophilic surfaces. Anyway, on these surfaces, failure may become cohesive from a specific temperature, showing a decrease of the dough surface hydrophobicity.Les revĂȘtements perfluorĂ©s sont utilisĂ©s comme anti-adhĂ©sifs dans des moules de cuisson pour pains de mie. Ils font lâobjet de diverses interrogations relatives Ă leur vieillissement. Dans ce contexte, la problĂ©matique de ce travail a portĂ© sur lâĂ©tude des consĂ©quences du vieillissement de revĂȘtements perfluoroalkoxy (PFA) sur leurs performances anti-adhĂ©sives. De plus, les consĂ©quences de la perte des propriĂ©tĂ©s anti-adhĂ©sives des revĂȘtements ont Ă©tĂ© Ă©valuĂ©es en termes de risque chimique. La production de nĂ©oformĂ©s dans la croĂ»te de pain au contact des moules a donc Ă©tĂ© Ă©tudiĂ©e. Pour rĂ©pondre Ă la problĂ©matique, des moules ont Ă©tĂ© vieillis en conditions industrielles, puis Ă partir dâun protocole mis au point spĂ©cifiquement dans le cadre de cette Ă©tude, des mesures de forces ont pu ĂȘtre rĂ©alisĂ©es pendant le dĂ©moulage des pains. Par ailleurs, plusieurs formules de pains de mie ont Ă©tĂ© testĂ©es. Il sâagissait dâĂ©tudier dâune part lâeffet de lâĂ©tat physique des lipides sur le dĂ©moulage. De plus, lâeffet dâautres constituants tels que protĂ©ines et fibres a Ă©tĂ© Ă©tudiĂ© (utilisation de farine complĂšte).Le vieillissement en conditions industrielles nâaffecterait que les propriĂ©tĂ©s physiques (rugositĂ©) des revĂȘtements PFA. Ces modifications de surface nâont cependant pas entraĂźnĂ© de problĂšme de dĂ©moulage en fin de cuisson. Par ailleurs, les marqueurs choisis de la rĂ©activitĂ© (furane, acrylamide et CML) Ă©voluent peu avec le vieillissement, et ce quelle que soit la formule. La CML montre toutefois une tendance Ă augmenter avec le vieillissement, ce qui pourrait malgrĂ© tout indiquer un effet du vieillissement des revĂȘtements sur la rĂ©activitĂ© du produit.Par ailleurs, pour caractĂ©riser plus spĂ©cifiquement lâadhĂ©sion de pĂątes de farine au cours de la cuisson, une mĂ©thodologie basĂ©e sur des tests dâadhĂ©rence en simulateur expĂ©rimental sur rhĂ©omĂštre a Ă©tĂ© mise au point. Ces tests dâadhĂ©rence ont Ă©tĂ© effectuĂ©s avec des surfaces modĂšles en verre, choisies pour ĂȘtre reprĂ©sentatives des propriĂ©tĂ©s chimiques des revĂȘtements PFA. Il apparaĂźt que les propriĂ©tĂ©s adhĂ©sives des pĂątes Ă©voluent de la mĂȘme façon que les propriĂ©tĂ©s viscoĂ©lastiques en fonction de la tempĂ©rature. Par ailleurs, les propriĂ©tĂ©s interfaciales contribuent pour une part Ă lâĂ©volution dâadhĂ©sion des pĂątes avec la tempĂ©rature. Les pĂątes tendent Ă adhĂ©rer plus facilement sur des surfaces hydrophiles. Dâailleurs, sur ces surfaces, les ruptures peuvent devenir cohĂ©sives au-delĂ dâune certaine tempĂ©rature, indiquant une diminution de leur hydrophobicitĂ© de surface
Dosage du chlore dans un headspace d'eau de Javel par électrode spécifique
National audienc
Furan quantification in bread crust: development of a simple and sensitive method using headspace-trap GC-MS
To study reactivity in bread crust during the baking process in the pan, we followed furan mainly resulting from Maillard and caramelisation reactions in cereal products. Furan quantification is commonly performed with automatic HS-static GC-MS. However, we showed that the automatic HS-trap GC-MS method can improve the sensitivity of the furan quantification. Indeed, this method allowed the LOD to be decreased from 0.3 ng g(-1) with HS-static mode to 0.03 ng g(-1) with HS-trap mode under these conditions. After validation of this method for furan quantification in bread crust, a difference between the crust extracted from the bottom and from the sides of the bread was evident. The quantity of furan in the bottom crust was five times lower than in the side crust, revealing less reactivity on the bottom than on the sides of the bread during the baking process in the pan. Differences in water content may explain these variations in reactivity
Adhesion of bread dough to solid surfaces under controlled heating: balance between the rheological and interfacial properties of dough
International audienceThe adhesion of wheat dough affects many aspects of industrial baking, from kneading raw dough to the final baking process. In this work, an original method was developed to study the effect of temperature on the adhesive properties of bread dough in contact with a solid surface during heating. Using this approach, it will be possible to understand the factors that affect adhesion between dough and a baking surface, which will aid in developing methods to prevent dough from sticking. Overall, the dough's adhesion to a hydrophobic surface globally decreased with an increase in temperature from 35 to 97 degrees C, with the exception of the temperature range between 55 and 70 degrees C, in which the energy of adhesion increased slightly. Under these circumstances, the evolution of adhesion was primarily shaped by the rheological properties of the dough. However, when we used a solid surface with different surface energy, the results changed significantly, which suggests that the mechanisms of adhesion during heating are governed by a balance between the interfacial and bulk properties of the heated dough. The overall decrease in the adhesion of the dough to the hydrophobic glass surface may be explained by a decrease in dough hydrophobicity due to structural and chemical changes in the dough
Structural studies of adsorbed protein (betalactoglobulin) on natural clay (montmorillonite)
International audienceIn this work, the adsorption of a small globular protein (betalactoglobulin, BLG), on a natural montmorillonite clay (Mt) was investigated in acidic buffer (pH = 3). The combination of different characterization techniques such as zetametry, X-ray diffraction, transmission electronic microscopy, fluorescence and solid state nuclear magnetic resonance spectroscopies shed light on the interaction mechanism between the clay mineral and the proteins. For low BLG concentration, a slight increase of the interlayer spacing of the clay mineral was noticed as well as structural changes of the protein. In contrast, as the concentration of BLG increased, the adsorption led to a partial exfoliation of the clay mineral, accompanied with significant secondary structural changes of the protein characterized by a loss of ÎČ-sheet organization. Altogether, our results revealed an unexpected adsorption scheme where the increase of the BLG/Mt weight ratio of the hybrid material leads to a partial exfoliation of the Mt, but at the expense of the protein native structure