Isolation,Stability And Application Of Yellow Pigment From Gardenia Jasminoides

Gardenia yellow pigment（GYP）is a water-soluble natural pigment.The main active ingredients are Crocin and Crocetin.In actual production,it contains geniposide and other substances,which will cause discoloration,greening and other metamorphic phenomena.MCM-41（Mobil Composition Of Matter N.41）mesoporous molecular sieve is an excellent carrier for catalysis and adsorption industries.It has the advantages of ordered pores,uniform and adjustable pore size,and large specific surface area.The main principle of Ag⁺complexation extraction technology is to use the complexation reaction between silver ions and unsaturated organic C=C double bonds to achieve the purpose of separation.It has the advantages of strong selectivity,mild reaction conditions and low energy consumption.In this paper,MCM-41 was modified to obtain functionalized Ag/Fe₃O₄-MCM-41 mesoporous molecular sieve,which was used for the purification of gardenia yellow pigment by silver ion complexation.The main experimental contents and results are as follows:1.Preparation of mesoporous molecular sieve.MCM-41,Fe₃O₄-MCM-41 and Ag/Fe₃O₄-MCM-41 were successfully prepared,and the optimum concentration of silver nitrate was obtained.Through the analysis of the characterization results,it can be seen that Ag/Fe₃O₄-MCM-41 forms a’core shell’structure,its hysteresis loop shows obvious hysteresis loop and the adsorption isotherm belongs to type IV,indicating the existence of mesoporous structure.According to the element distribution map and scanning energy spectrum analysis map of the surface scanning area,Ag/Fe₃O₄-MCM-41 sample contains C,O,Fe,Ag and other elements,indicating that MCM-41 successfully loaded Fe and Ag.When the concentration of Fe₃O₄-MCM-41 impregnated Ag NO₃ exceeded 15mg/m L,the synthesized Ag/Fe₃O₄-MCM-41 showed agglomeration and adhesion,the specific surface area and pore size decreased,and the pore volume increased.Therefore,the Ag/Fe₃O₄-MCM-41 sample prepared by impregnating silver nitrate solution with a concentration of 15mg/m L has a better apparent structure.2.Purification of gardenia yellow pigment by Ag/Fe₃O₄-MCM-41.The optimum conditions for the adsorption of crocin by Ag/Fe₃O₄-MCM-41 were obtained by single factor and response surface experiments:C₀=10.17mg/m L,W=1.49g,V=15m L,T=27°C,t=30min;the adsorption is a spontaneous endothermic entropy increase process.The adsorption rate of crocin can be improved by increasing the temperature,the initial concentration of gardenia yellow,the specific surface area of Ag/Fe₃O₄-MCM-41 and the dispersed pore size.The optimum desorption conditions were as follows:ethanol volume fraction>65%,T=40°C,t=60min,solid-liquid ratio:1:10.After purification,no Ag was detected in gardenia yellow solution,and the safety was good.The adsorption rate of crocin on Ag/Fe₃O₄-MCM-41 was more than 65%after five times of use,indicating that it was reusable.3.Study on the purified gardenia yellow pigment.The color value of gardenia yellow pigment purified by Ag/Fe₃O₄-MCM-41 was significantly increased,which was 3.82 times higher than that of gardenia yellow.OD value decreased;the peak at440 nm increases,and the peak at 238 nm and 335 nm decreases.In addition,the antioxidant activity of gardenia yellow purified by Ag/Fe₃O₄-MCM-41 was significantly improved.But it is sensitive to strong acid,alkali and sunlight environment,and the loss rate is more than 15%.Temperature,indoor natural light,oxidant and reducing agent have little effect on its stability,and the loss rate does not exceed 10%.Therefore,Ag/Fe₃O₄-MCM-41 has a good purification effect on gardenia yellow.4.Preparation of gardenia yellow jelly.The purified gardenia yellow was used for jelly preparation to obtain the best formula for jelly preparation.Compared with the quality of commercial jelly,gardenia yellow jelly has better texture characteristics and sensory quality.The L*value of jelly products prepared by purified gardenia yellow decreased slowly,and the b*value decreased by 10.47%.The color of the jelly products prepared by unpurified gardenia yellow changed greatly and gradually tended to be green,and the gloss decreased,indicating that the purity of crocin in purified gardenia yellow pigment was high and the content of geniposide was low,which was beneficial to improve the quality of gardenia yellow jelly.