Study On Extraction,purification And Application Of Tea Saponins From Camellia Seed Meal

China is rich in Camellia oleifera resources.Camellia seed meal,the by-product of Camellia oleifera seeds after oil extraction,has not been effectively utilized,leading to an enormous waste of the resources.Tea saponins in camellia seed meal have attracted widespread attention due to their good emulsifying properties and physiological activity.Currently,there are more studies on the extraction and purification of tea saponins,but traditional solvent extraction and a type of auxiliary extraction generally had low extraction rate,long extraction time,and low product purity.At the same time,tea saponins as natural surfactants were less studied in emulsion stabilization.In this study,aiming to improve the extraction efficiency and product purity,the ultrasonic-microwave method was used to assist the ethanol extraction of tea saponins using camellia seed meal as raw material,and then the macroporous resin was adopted to separate and purify tea saponins.The emulsifying properties and emulsions stability were compared between tea saponins and synthetic surfactants,and the influences of tea saponins on chiffon cake quality were explored.(1)Using camellia seed meal as raw material,the tea saponins were pre-treated by using an ultrasonic cell crusher at an ultrasonic intensity of 475 W,an ultrasonic time of 4 min,an operating interval on-time/off-time of 2s/2s.Following,the microwave reactor was adopted to extract the tea saponins.Based on a single-factor experiment,factors that had positive effects on the experimental indices were screened by Plackett-Burman design.Then the process parameters were optimized according to the Box-Behnken experiment.The results showed that the optimum extraction parameters were following ethanol concentration of 59%,extraction temperature of 59°C,microwave power of 480 W,microwave extraction time of 8min,extraction p H of 6.96,and solid-liquid ratio of 1:12(m/v).Under these parameters,the extraction rate and purity of tea saponins were 98.30% and 64.7%,respectively.(2)Aiming to study the adsorption characteristics of microporous resin on tea saponins,four resins D101,AB-8,NKA-2 and X-5,were screened by static adsorption,desorption tests and static adsorption kinetics to obtain the best adsorption resins.Then the optimal conditions were confirmed by dynamic adsorption and desorption tests.The results showed that X-5 resin was the best macroporous resin for purification of tea saponins,and the adsorption kinetics was highly consistent with the quasi-second-order dynamics model.The adsorption process of tea saponins on X-5 resin accorded with the Langmuir model.The optimum purification parameters of X-5 macroporous were as follows: the sample concentration of 5 mg/m L,the sample flow rate of 2.0 m L/min,a sample volume of 60 m L;eluent for ethanol solution,desorption velocity of 3.0 m L/min,the volume fraction of 80%,and the desorption fluid volume of 170 m L.After purification,the purity of tea saponins increased from 64.7% to90.19%.The purified samples showed the characteristic color reaction of tea saponins,and the UV and IR spectra of the purified samples showed similar characteristic peaks to the standard.Tea saponins showed a certain ability to scavenge DPPH and ABTS radicals,and tea saponins after purification showed a relatively high scavenging rate.(3)The emulsifying properties and emulsions stability of tea saponins and synthetic surfactants(Tween 80 and Sucrose Fatty Acid Esters)were compared.The results showed that tea saponins had good emulsifying properties and the ability to reduce the interfacial tension between oil and water.The influences of temperature on the stability of the emulsions were studied and the results showed that tea saponins emulsion(TSE)have good thermal stability.The Tween 80 emulsion(TWE)was stable at 30℃-70℃,and the particle size of the emulsion increased significantly and the stability decreased at 90℃.Sucrose Fatty Acid Esters emulsion(ZTE)had poor thermal stability.The influences of p H on the emulsions stabilities were investigated and the results showed that TSE had good stability in the p H range of 3.0-9.0,and the emulsion stratified at p H 2.0.TWE was less affected by p H.ZTE had poor stability in the p H range of 2.0-6.0,and the emulsion stratified in the p H range of 2.0-4.0.The influences of ionic strength on the emulsions stabilities were studied and the results showed that the TSE emulsion had good stability at lower ionic strength(<0.3 M Na Cl).The ionic strength had no effect on the stability of TWE.With the increase of ionic strength,the average particle size of ZTE increased significantly,and the emulsion stability got worse.Therefore,tea saponins had good emulsifying properties and could be used to enhance the stability of O/W emulsions under appropriate conditions.(4)The effect of tea saponins on the quality and shelf life of chiffon cake were studied.As the addition of tea saponins increased,the specific gravity of the chiffon cake batter and the baking loss of chiffon cake decreased while the specific volume increased from 4.64 to5.59 m L/g.With the addition of tea saponins increased,the hardness,adhesiveness,and chewiness of the chiffon cakes decreased,while springiness,cohesiveness,and resilience tended to increase first and then decrease.During storage,the total bacterial colony count,acid value of oils and fats,and peroxide value of chiffon cakes with tea saponins were lower than that of control.With the increase in the addition of tea saponins,the inhibition of tea saponins on the total number of bacteria,oil acid value,and peroxide value of cake were gradually enhanced.Therefore,it could be concluded that the addition of tea saponins not only resulted in a softer and more delicate structure of the chiffon cake,but also extended the shelf life of the cake to a certain extent.