Stability,Separation And Purification Of Betaxanthin From Beta Vulgaris Var.Lutea

The color in yellow beets was not effectively utilized.It is of great significance to develop it into a natural water-soluble yellow color.In this study,yellow beet was taken as the subject,the extraction conditions of betaxanthin,the stability of betaxanthin under different conditions and the separation and purification of betaxanthin by macroporous resin were systematically studied.Main research contents and results are as follows:(1)In the extraction experiment of betaxanthin,the maximum absorption wavelength of betaxanthin was 480 nm,and the stability of betaxanthin could be maintained to the maximum when the extraction solution p H was 4.0.Compared with the pressing method,the acid water extraction can reduce the oxidation degree of the betaxanthin,and better maintain the color of the yellow beet solution.The betaxanthin is easily soluble in organic solvents that are mutually soluble with water.Using 50%methanol solution for extraction,the yellow beet color solution with higher concentration(51.92±1.92 mg/L)can be obtained with less impurity content and high clarification degree.Ethyl acetate has a better separation effect on non-polar substances in yellow beet solution,and the ethyl acetate primary extraction could retain the betaxanthin to the maximum.(2)In the experiment of the stability of betaxanthin under different conditions,the influence of the yellow beet color at different temperature is very huge,the pseudo-first-order kinetics model better fit the yellow beet color under different temperature of thermal degradation kinetics,the correlation coefficients all above 0.83.The reaction rate constant of degree of change is proportional to the trend of the rise of temperature.The reaction activation energy Ea of thermal degradation of yellow beet color calculated by Arrhenius formula was 45.10 k J/mol.The sensitivity of betaxanthin to temperature was relatively high among natural colors.According to the temperature entropy Q₁₀,the effect of temperature on the degradation rate of yellow beet color mainly occurred at 40-50^oC,it may be related to enzymatic hydrolysis.Seven kinds of metal ions with different molar amount were studied.It was found that 0.01mol/L K⁺could maintain the color and stability of betaxanthin.The pseudo-first-order kinetic model could better fit the effects of nine acid additives and two sugar additives on the stability of betaxanthin,and the effect of gallic acid was better in the acid additive,the effect of ferulic acid was the worst,and the effect of chitosan was better in the sugar additive.The results of preservative and antioxidant experiments showed that the stability of betaxanthin could be enhanced to some extent by adding 0.2%V_C and using 1.0%potassium sorbate for cold storage in a short time.(3)In macroporous resin purification betaxanthin experiment,through the static adsorption and desorption experiment according to the six kinds of resin adsorption resin screening,and three resins XAD-4(2.879±0.156 mg/g),XAD-16(4.025±0.142 mg/g),LH-17(4.438±0.119 mg/g)were selected for static adsorption isotherm experiments.Langmuir equation can better fit static adsorption behavior of the three resins(correlation coefficient is 0.9883,0.9903,0.9808,respectively).The adsorption behavior of the three resins for betaxanthin was more inclined to monolayer adsorption.Moreover,according to the maximum adsorption capacity Q_max(10.941 mg/g),LH-17 resin is more conducive to the recovery of betaxanthin from the crude extract of yellow beet solution,and the pseudo-first-order kinetic model can well fit the kinetic behavior of the three resins adsorbing betaxanthin.By dynamic adsorption experiments,when the flow rate of adsorption and desorption is 1 BV/h can get higher utilization rate of the resins and the concentration of eluent,and LH-17 resin regeneration effect was better than the other two kinds of resin,which can be used in continuous production use.After one round of operation,betaxanthin recovery ratio was 37.03%,and the purity was 2.18%,which is72.4%higher than that of the yellow beet extracts.