Study On Interaction Between Konjac Glucomannan And Tanninc Acid And Its Application

Under the background that a single component of food has been revealed,the interaction between food components,the mechanisms,and their effects on food processing and nutritional properties have attracted much attention in the field of food science in recent years.The research of the interaction between konjac glucomannan and polyphenols is still rare and the complex formation process and product properties are still unknown.The topic used tannic acid as a representative polyphenol and the interaction between konjac glucomannan and tannic acid was discussed.In order to use the interaction of food components to obtain the functional properties that can not be achieved by a single component and provide reference for improving food performance and developing new food ingredients,influence of related factors on the interaction were explored to reveal its mechanism of interaction.The main research contents and results are as follows:1.The TA-KGM complex system was studied.The effects of pH and polysaccharide concentration on the turbidity and particle size of the composite system were studied.The influence of ionic strength,urea concentration and temperature on the TA binding capacity of KGM was explored.The interaction was investigated by XRD,DSC,and FT-IR.The thermodynamic change of the interaction when tannic acid was added dropwise to KGM was studied by isothermal calorimetric analysis.As shown,at low pH,the interaction was strong.As the KGM concentration increased,the particle size of the complex became larger and the complex appeared as a uniformly dispersed spherical particle in the solution.The ionic strength had no significant effect on the amount of TA that KGM combined.Increasing the temperature or the concentration of urea will lead to a significant decrease in the amount of KGM-bound tannic acid,indicating that the main driving force for the interaction may be hydrogen bond.XRD,DSC,and FT-IR analysis further demonstrated the interaction.Isothermal titration calorimetry results show that thecombination is an exothermic reaction and the heat of reaction is gradually increased with the addition of tannic acid.2.The KGM was sonicated.The GPC results showed that the molecular weight of the KGM reduced as sonication time increased.The infrared analysis revealed that the ultrasound treatment did not change the chemical structure of KGM.The samples were prepared by controlling the mass ratio of TA-KGM.The turbidity revealed that KGM and TA could form complex depending on the solution pH.And the DLS and TEM results indicated that the TA-KGM complexes organized into large and uniform colloidal particles and would lead to precipitate with the change of weight ratio.And the complex with the lower KGM molecular weight tended to precipitate at lower TA-KGM weight ratio.The effect of molecular weight,pH and temperature on thermodynamic changes in the formation of the complex were also examined by ITC,the titration profiles exhibited the two distinct zones at 25 ? where the first stage corresponded to soluble complex formation,while the second stage represented aggregation between complexes.The intensities of heat flow of KGM with lower molecular weight was higher and the transition between the first and two zones shifted into lower mass ratio which was in line with the DLS and TEM results.And the increasing pH and temperature weakened the thermal changes of interaction which indicated that the main driving force of the first stage was hydrogen bonds and the main driving force of the second stage was hydrophobic interaction.Molecular weight can regulate the size of the particles.3.TA-KGM complex was used as an antioxidant for the Tween-80 stable emulsion.The radical scavenging capacity of the TA-KGM complex was first determined using the ABTS method and the DPPH method.It was found that the complexes had increasing free radical scavenging activity compared with free tannic acid and KGM.And nanoemulsions were prepared with different KGM and tannic acid concentrations.Emulsions prepared with four conditions were found with a single peak distribution and had good emulsion stability.The oxidation degree of the oils was measured by TBARS method and PV method.The oxidation stability of the four emulsions was compared.Itwas found that the emulsions with the complexes has the strongest antioxidant capacity compared with the other three emulsions...