Preparation And Characterization Of Olive Oil Microcapsule By Complex Coacervation

Olive oil is recognized as a functional oil because it contains high unsaturated fatty acids, polyphenols and a variety of vitamins. Literature reports olive oil has the function of easy to digest, anti-cancer, cholesterol, slow down aging, olive oil has been used in textile, cosmetics and health products in new research. but it is easily oxidized and its nutrients are damaged, in addition, the grease of liquid has poor fluidity and solubili ty which are inconvenience to processing and storage. Microcapsule is a kind of technology that the core material are embedded by polymers which can protect sensitive components from the destruction of the environment and extend the storage time. Composite cohesion refers that the two kinds of colloidal solution which has opposite charge are separated spontaneously when they are attracted by each other. The G and GA are used mostly in present, but the gelatin are easy to gel itself at low temperature leading to the core material can not be embedded fully. In addition, the crosslinking agent used are poisonous formaldehyde and glutaraldehyde currently which limits the microcapsule application in food industry. The olive oil is embedded by using new walls and safe non-toxic firming agent in this paper, extend its application in the industria.The olive oil microcapsule was prepared using the method of complex coacervation which used the WPI and GA as the walls and use TG as curing agent in the study. The condensation of walls, olive oil microcapsule preparation and process optimization, the comparison of crosslinkin g agent, the determination of drying method, infrared analysis, thermal analysis, physicochemical properties of the microcapsule products, release an d storage stability are mainly studied in this paper.The Zeta potential of WPI and GA dispersions was studied under different p H, the results showed that he isoelectric point(p I) of WPI where the net charge is zero was detected at 4.6, The zeta potentials of WPI is positively charged below the isoelectric point(p H <4.6 and 22.40 m V at p H 3.0), and negatively charged above this p H(-36.90 mV at p H 7.0). The zeta potential of GA is negative within the pH range of 3.0~7.0. The cohesion between WPI and GA was studied using the method of single factor and response surface test with the condensation rate and the absorbance and turbidity as evaluation index, Best coagulation condition was: WPI: GA is 2:1,wall material concentration is 3%, pH 4.03.Basis on the wall material parameters, the parameters of the emulsion phase, condensed phase, curing stage which have effect on microcapsule preparation process was studied by determinin g the embedding rate, size and morphology under a microscope of the micocapsule. On the basis of single factor, the parameters of condensed stage and curing stage of microcapsule preparation was optimized by the response surface analysis. the optimum conditions of olive oil microcapsule preparation as follows: wall material concentration is 3%, wall to core is 2.82, emulsifying speed is 10000 rpm, emulsifying time is 3min, condensed p H is 4.0, coagulation time is 60 min, curing temperature is 15℃, curing time is 6.5h, curing agent concentration is 21.6U/g. Under this conditions the wet microcapsule was obtained which embedding rate of was 89%, the average particle size between 35 and 45μm, the multi-core elliptic ball.The differences of glut araldehyde and TG solidifying was studied with the embedding rate, particle size, the minro-form of microcapsule as evaluation index, the results shows that glutaraldehyde and TG solidifying effect was not significant difference, this prove that TG can be a good alternative to chemical curing agent was carried out on the compound condensing microcapsule crosslinking.The influence of spray drying and freeze drying on the condensation of microcapsules was studied with the embedding rate, particle size, the SEM morphology of microcapsule as evaluation index. The study found that the microcapsule with spray drying has better embedding rate, small size and microcapsules surface are rules without holes, therefore, the spray drying was chosen as the best drying methods in this paper.The basic physicochemical properties of microcapsule was studied, results show that the microcapsule moisture content is below 2.5%, both solubility and wettability are comfortable. TLC shows that chemical property of olive oil before and after embedding has not changed. DSC and TGA analysis of olive oil microcapsule shows that the olive oil microcapsule was stability in the normal temperature storage, but the microcapsules should not be stored at a high temperature 93 ℃. Infrared spectrum analysis proved that WPI condensed with GA are formed by physical action, not form a new chemical bonds. The release study of the microcapsule under different conditions shows that the release of olive oil microcapsule belongs to slow release, and the release in intestinal juice is greater than in the stomach, the olive oil was released mostly after stomach intestinal juice, release rate reach above 85%. The storage stability of the microcapsules which stored in different temperature, light, humidity was studied with peroxide value and acid value as evaluation index, the results show that nature olive oil with embedded and stored in low temperature, light free, low relative humidity environment is the most stable.