The Reparation Of Capsaicin/lutein Microcapsules Based On Protein-esterified Starch Emulsions And Their Properties

Capsaicin and lutein are two important carotenoids with bright color,high safety and great advantages in biological functions.There are many functions in the capsaicin,such as weight loss,beauty,anti-aging and radiation protection.Capsaicin is listed as class A pigment by the Food and Agriculture Organization of the United Nations(FAO)and the World Health Organization(WHO)and there is no limit in use;Lutein is the main pigment in the macular area of the retina of eyes,which could reduce the incidence of cataracts and night blindness.However,the multiple conjugated double bonds in the structure resulted in the poor water solubility and stability of capsaicin and lutein,which limited the application in industry.Microencapsulation technology could use natural or synthetic materials as wall materials,and encapsulate gas,liquid or solid materials(core material)into small particles,which could reduce environmental interference,weaken the direct stimulation of the body,cover or delay the release of flavor substances,improve the stability of the core material and transform into easy-to-handle solid materials.In our study,starches were modified using three esterification methods(octenyl succinic anhydride,acetic acid and citric acid esterification).Different ratios of proteins(whey protein and sodium caseinate)to esterified starch(10:0,9:1,7:3,5:5,3:7,1:9 and 0:10)were used as emulsifiers to prepare oil-in-water capsaicin/lutein emulsions,then microcapsules were prepared by spray drying technology.The effects of the protein and esterified starch ratios on microcapsule microstructure,physicochemical properties and storage stability were investigated.It provided reference for expanding the application of capsaicin/lutein in food,biological,pharmaceutical and other industries,and improved the stability and water dispersion of other lipid-soluble active ingredients.All results are as follows:(1)The emulsifying effect of single modified starch as emulsifier was poor,and the oil-in-water emulsion system presented larger droplets and aggregates.The surface of most microcapsule particles was smooth and relatively complete.The surface of microcapsules with high modified starch content appeared holes and damage,while the system with high protein content had no obvious cracks or pores.(2)The yield of microcapsules was up to 82.18%,which decreased with the decrease of protein content in the wall material;the water content was lower than the maximum water content of dry powder applied in the food field of 3.00%-4.00%,reaching a low level.After microencapsulation of capsaicin and lutein,the solubility of capsaicin and lutein increased significantly to more than 49.71%,and the solubility increased gradually with the decrease of modified starch content in the wall material.In our study,the soaking time of the three wall materials in water was:sodium caseinate>modified starch>whey protein.The product with the highest modified starch content in microcapsules presented lower load rates,and the addition of protein was helpful to improve the overall load rate of microcapsules and improve the embedding effect.The lightness L*value of microcapsule powder products with higher load rate was also higher.The average particle size of capsaicin microcapsules and lutein microcapsules ranged from 1-60?m and 1-180?m,respectively.The average particle size of microcapsules with higher protein content in the wall material was smaller,and the values of d_(4,3)and d_(3,2)were closer.The glass transition temperatures of microcapsules were all higher than room temperature,thus the microcapsules could be kept in a relatively stable state under general storage conditions.Moreover,the addition of protein was helpful to improve the thermodynamic stability of microcapsules.The emulsion systems were typical non-Newtonian fluids,K(25°C)>K(50°C)and n(25°C)<n(50°C).(3)Light and high temperature could significantly affect the stability of capsaicin and lutein microcapsules.Among the three capsaicin microcapsules,the microcapsules constructed by combining whey protein with OSA potato starch had higher retention rate and better storage stability.Among the three kinds of lutein microcapsules,the lutein microcapsules using sodium caseinate and acetate mung bean starch composite as wall material processed better storage stability and higher retention rate after 15 days of storage.