Heat treatment of milk may cause whey proteins and caseins to form aggregates. These soluble and micellar aggregates and their other properties (size, composition, shape, etc.) can affect the techno-functionalities to...Heat treatment of milk may cause whey proteins and caseins to form aggregates. These soluble and micellar aggregates and their other properties (size, composition, shape, etc.) can affect the techno-functionalities to the milk, conferring interesting or negative features depending on the application in dairy industries. In this study, we propose a new approach to characterise those protein aggregates. SDS-agarose electrophoresis is followed by the calculation of a retention factor (Rf) for each protein spot. Rf allows milk aggregates to be compared qualitatively under the same conditions. This method could be transposed to the dairy industry for a better knowledge of the milk subsequent to heat treatment.展开更多
The effect of enzymatic crosslinking by microbial transglutaminase on the physico-chemical properties of gelatin-based films incorporated with lysozyme were investigated.Increase in the crosslinking degree of gelatin ...The effect of enzymatic crosslinking by microbial transglutaminase on the physico-chemical properties of gelatin-based films incorporated with lysozyme were investigated.Increase in the crosslinking degree of gelatin with microbial transglutaminase concentration in film-forming suspensions was correlated with a decrease of films thickness.Moreover,the enhancement in crosslinking resulted in a decrease of the solubility in water,as well as of the extent of swelling degree,and of the water vapor permeability of films and in an increase of films tensile strength.The kinetics of release at 4◦C of lysozyme from control non-reticulated films and reticulated films to either sodium acetate buffer,or 2%(w/v)agar gels in direct contact were compared.Interestingly,the kinetics of release of lysozyme were always slower from crosslinked films than from control films.This difference was higher for lysozyme release to agar gels,which was dominated by Fickian diffusion.Enzymatic crosslinking by microbial transglutaminase of gelatin-based films incorporated with lysozyme can thus effectively control the release of this food preservative.展开更多
In this study,the interaction of exopolysaccharides from Leuconostoc mesenteroides P35(EPS-LM)with Escherichia coli heat-labile enterotoxin B-pentamer(LTB)was investigated at different concentrations and temperatures ...In this study,the interaction of exopolysaccharides from Leuconostoc mesenteroides P35(EPS-LM)with Escherichia coli heat-labile enterotoxin B-pentamer(LTB)was investigated at different concentrations and temperatures by using surface plasmon resonance(SPR)and molecular docking approaches.FT-IR spectral analysis together with HPTLC analysis revealing that glucose is the only constitutive monosaccharide of EPS-LM suggests that its structure is composed of dextran withα-D(1→6)glycosidic linkages.SPR analysis revealed the high affinity of EPS-LM for immobilized LTB toxin(KA=(2.05±0.04)×10^(6) mol.L−1 at 37℃).The binding process was spontaneous(ΔG<0),endothermic(ΔH>0),and entropy-driven(ΔS>0)with an increase of KA with temperature.This suggests that EPS-LM-LTB interaction is dominated by hydrophobic forces.The binding affinity of EPS-LM to LTB had negligible dependence on enthalpy(ΔH=0.084 kJ mol−1).Further,molecular docking results suggested the presence of some binding sites of EPS-LM on the LTB through hydrophobic forces(Lys,Asp,Arg,Glu)and also hydrogen bonding(Glu)in the hydrophobic core of LTB.Besides autodock studies,Schiffer-Edmundson helical wheel diagrams of LTB inα-helix domain suggested that LTB hydrophobic core is a highly effective region,which was able to form favorable non-polar interactions of the protein's binding surface(with amino acids residues such as Tyr,Leu,Ile)with EPS-LM.This study provided thus further insights into the interactions between EPS-LM and LTB,suggesting that EPS produced by some LAB,such as EPS produced by Ln.mesenteroides P35 strain are good candidates to inhibit E.coli toxin activity.展开更多
文摘Heat treatment of milk may cause whey proteins and caseins to form aggregates. These soluble and micellar aggregates and their other properties (size, composition, shape, etc.) can affect the techno-functionalities to the milk, conferring interesting or negative features depending on the application in dairy industries. In this study, we propose a new approach to characterise those protein aggregates. SDS-agarose electrophoresis is followed by the calculation of a retention factor (Rf) for each protein spot. Rf allows milk aggregates to be compared qualitatively under the same conditions. This method could be transposed to the dairy industry for a better knowledge of the milk subsequent to heat treatment.
文摘The effect of enzymatic crosslinking by microbial transglutaminase on the physico-chemical properties of gelatin-based films incorporated with lysozyme were investigated.Increase in the crosslinking degree of gelatin with microbial transglutaminase concentration in film-forming suspensions was correlated with a decrease of films thickness.Moreover,the enhancement in crosslinking resulted in a decrease of the solubility in water,as well as of the extent of swelling degree,and of the water vapor permeability of films and in an increase of films tensile strength.The kinetics of release at 4◦C of lysozyme from control non-reticulated films and reticulated films to either sodium acetate buffer,or 2%(w/v)agar gels in direct contact were compared.Interestingly,the kinetics of release of lysozyme were always slower from crosslinked films than from control films.This difference was higher for lysozyme release to agar gels,which was dominated by Fickian diffusion.Enzymatic crosslinking by microbial transglutaminase of gelatin-based films incorporated with lysozyme can thus effectively control the release of this food preservative.
基金the Minist`ere des Affaires Etrang`eres(France)and the Ministry of Research,Science and Technology(Iran)for financing double PhD scholarship joint-supervision program between France and Iran for Mojtaba AZARI-ANPARThe authors are indebted to Conseil D´epartemental de l’Ain and Bourg en Bresse Agglom´eration for the financial support of BioDyMIA research unit activities.
文摘In this study,the interaction of exopolysaccharides from Leuconostoc mesenteroides P35(EPS-LM)with Escherichia coli heat-labile enterotoxin B-pentamer(LTB)was investigated at different concentrations and temperatures by using surface plasmon resonance(SPR)and molecular docking approaches.FT-IR spectral analysis together with HPTLC analysis revealing that glucose is the only constitutive monosaccharide of EPS-LM suggests that its structure is composed of dextran withα-D(1→6)glycosidic linkages.SPR analysis revealed the high affinity of EPS-LM for immobilized LTB toxin(KA=(2.05±0.04)×10^(6) mol.L−1 at 37℃).The binding process was spontaneous(ΔG<0),endothermic(ΔH>0),and entropy-driven(ΔS>0)with an increase of KA with temperature.This suggests that EPS-LM-LTB interaction is dominated by hydrophobic forces.The binding affinity of EPS-LM to LTB had negligible dependence on enthalpy(ΔH=0.084 kJ mol−1).Further,molecular docking results suggested the presence of some binding sites of EPS-LM on the LTB through hydrophobic forces(Lys,Asp,Arg,Glu)and also hydrogen bonding(Glu)in the hydrophobic core of LTB.Besides autodock studies,Schiffer-Edmundson helical wheel diagrams of LTB inα-helix domain suggested that LTB hydrophobic core is a highly effective region,which was able to form favorable non-polar interactions of the protein's binding surface(with amino acids residues such as Tyr,Leu,Ile)with EPS-LM.This study provided thus further insights into the interactions between EPS-LM and LTB,suggesting that EPS produced by some LAB,such as EPS produced by Ln.mesenteroides P35 strain are good candidates to inhibit E.coli toxin activity.
