| Lemon, a wide range of resource, is a kind of fruit with high beauty and officinal value. In recent years, the deep processing industry of lemon has developed rapidly,resulting in a great deal of lemon pomace. They were all discarded as garbage in traditional processing method, which not only wasted resource, but also polluted the environment. Lemon pomace contains a variety of active components. If it is used reasonably, it will be beneficial for economy and environment.In this study, with lemon pomace as raw material, the effect of ultrasonic frequency , ethanol volume, solvent and material ratio , time and temperature were investigated with extraction yield of limonin as an indicator. Meanwhile, compared with the extraction effect without ultrasound, the results of dual-frequency ultrasonic extraction had an significant advantage over that without ultrasound.. The optimum dual-frequency extraction conditions were as follows: ultrasonic temperature 50?, liquid-solid ratio 25:1(mL:g), ultrasonic time 61 min and ultrasonic power 560 W, and the extraction yield reached 2.80%.HPD722 macroporous resin was applied to the purification of limonin extracted from lemon pomace. The optimal absorption equilibrium time was 4h and the desorption equilibrium time was 3h respectively. The static absorption experiments showed that the suitable concentration of sample solution was 0.25mg/mL, pH was 7,ethanol concentration was 80% and pH of desorption solution was 6. In the .process dynamic adsorption and desorption, the optimal flow rate was 1 .OmL/min and elution flow rate was 0.5mL/min. The purity of limonin was 52.03% after purification.The stability and antioxidant activity of limonin were studied, the results showed that limonin was unstable and easy to degrade in high temperature, acid and alkaline conditions or lighting environment. The reduction ability, DPPH scavenging ability and hydroxyl radical scavenging ability of sample and BHT were analysised and compared, it could be found that the reduction capacity of the sample is stronger than that of BHT in the concentration range of 10-50 ?g/mL. At 50ug/mL, the sample's absorbance value was 0.35 at the maximum absorption wavelength, which indicated that it had a certain reduction ability, during 10-40ug/mL, the scavenging rate was higher than that of BHT. However, the sanple's scavenging ability of hydroxyl radical(·OH) was weaker than that of BHT, the scavenging rate was 43.70% when the concentration was 300ug/mL, afterwords, the -OH removal efficiency became slow.Adopting saturated water solution method, the limonin was embedded with P-CD,through the single factor and orthogonal experiments, the optimum conditions were as follows:temperature 50?, stirring time 30 min and the ratio of wall to core material 15:1. Microcapsule product is white loose power with no lumps and slightly bitter.The moisture content, solubility and density were 2.67%, 32.86% and 0.655 g/cm3 respectively. The phase identification of microcapsules showed that the absorption peak position, intensity and characteristic absorption wavelength of microcapsule and limonin's ultraviolet spectrum were almost the same. The differential scanning results of ?-CD and embedding material showed that ?-CD had two absorption peaks at 118? and 230?, but the embedding material appeared one peak at 116?. There was no absorption pear at 230 ? , which indicated the the intermolecular interaction between limonin and ?-CD had occured, changing the cavity structure of P-CD, thus confirmed the formation of embedded objects. |
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