Simultaneous Adsorption Of Organic Acid And Total Phenols In Ice Grape Juices And Icewines Using D354 Resin

The quality of ice grapes directly affects the quality of icewines.Ice grape growing area location,environmental conditions,altitude have a very important role in its quality.The ice grapes in some planting areas of Liaoning Huanren have high acidity and post-bitter problems after being squeezed and fermented into wine.Therefore,it is necessary to establish a kind of acid and bitterness for ice grape juices and icewines.The method solves the above problems of icewines and further enhances the quality of icewines to achieve international high quality.In this study,ice grape juices and icewines with higher acidity and bitterness were studied,and D354 weak alkaline anion exchange resin(hereinafter referred to as "D354 resin")was used to treat ice grapes at 0°C,10°C and 20°C,respectively.Static adsorption experiments of organic acid and total phenols in juices and icewines directly affecting the acidity and bitterness of the organic acid and total phenols.The static adsorption kinetics,thermodynamics and isotherms of D354 resin on total acid and total phenols in ice grape juices and icewines were investigated.The mechanism and the variation of the main six organic acids in ice grape juices and icewines with the static adsorption process of the resin were explored.The results show that:(1)Study on static adsorption curve of D354 resin on ice grape juices and icewinesThe adsorption rate of D354 resin on organic acids and total phenolss in ice grape juices and icewines was significantly improved With the increase of adsorption temperature.At 0°C,10°C and 20°C,the equilibrium adsorption capacity of D354 resin on total acid of ice grape juices was 151.69 mg/g,190.09 mg/g and 222.16 mg/g,respectively.The amounts were 3.65 mg/g,4.20 mg/g,and 4.67 mg/g,respectively.The equilibrium adsorption capacities of D354 resin for total ice acid were 144.00 mg/g,189.20 mg/g,and 219.22 mg/g,respectively.The equilibrium adsorption capacities were 2.35 mg/g,2.70 mg/g,and 2.99 mg/g,respectively.It can be seen that with the increase of adsorption temperature,the maximum equilibrium adsorption capacity of D354 resin on total acid and total phenols in ice grape juices and icewines is also increasing.(2)Static adsorption kinetics of D354 resin on ice grape juices and icewinesThe pseudo-first-order kinetic model and the pseudo-second-order kinetic model were fitted to the data of static adsorption of total acid and total phenols in ice grape juices and icewines of D354 resin.The results show that the fitting effect of the second-order dynamic model is better.The theoretical equilibrium adsorption amount obtained by fitting is very similar to the actual adsorption amount.The process of adsorption of total acid and total phenols in ice grape juices and icewines by D354 resin accords with the pseudo-second-order kinetic model,and the Elovich fitting model further validates the conclusion.The quasi-second-order kinetic equations of D354 resin for total acid and total phenols in ice grape juices and icewines were determined.The W-M kinetic model was used to fit the static adsorption experimental data,and the fitting effect was good.The adsorption process is controlled by both intragranular diffusion and liquid film diffusion.(3)Thermodynamics and isotherms of static adsorption of D354 resin on ice grape juices and icewinesThe adsorption isotherm data of total acid and total phenols in D354 resin adsorbed in ice grape juices and icewines were mixed.The results showed that the adsorption process of D354 resin adsorbing ice grape juices and icewines total acid and total phenols was more consistent with Langmuir isotherm model;The Langmuir isotherm model parameters show that the adsorption process of D354 resin on total acid and total phenols in ice grape juices and icewines is endothermic reaction,and the reaction is easier to carry out,further verifying the conclusion of static adsorption kinetics;The thermodynamic parameters of static adsorption of resin were calculated and analyzed.Among them,adsorption enthalpy change ΔH>0,adsorption free energy change ΔG<0,adsorption entropy change ΔS>0,indicating the adsorption of D354 resin on total acid and total phenols in ice grape juices and icewines.The process is spontaneous and the reaction proceeds more easily as the temperature increases.(4)Adsorption of D354 resin on single organic acid of ice grape juices and icewinesThe experiment analyzed six major organic acids in ice grape juices and icewines,including tartaric acid,malic acid,citric acid,acetic acid,lactic acid and succinic acid.The samples were highly efficient by static adsorption experiments on D354 resin on ice grape juices and icewines.The liquid chromatography was used to analyze the changes of six main organic acids in ice grape juices and icewines with D354 resin.The results showed that D354 resin adsorbed six organic acids 5 minutes before adsorption.The acid content of the machine was significantly reduced.As the adsorption progressed further,since the six organic acids of the ice grape juices and the icewines had different affinities from the adsorption sites of the D354 resin,the resin was present between the six organic acids throughout the static adsorption process.The displacement phenomenon at the active site makes the variation of the six organic acids in the static adsorption process at different temperatures exhibit diversity.