Studies On Content And Extraction Of Active Components From Falling Citrus Fruit

There are many falling fruit during the developmental period of citrus fruit, which contain active components. But it hasn't been utilized completely. The new-tech supercritical fluid extraction (SFE) has many excellences. However, it can not still be used widely at large scale because of its high pressure operation and other problems. In order to solve these problems, ultrasound was used to enhance the SFE process of active components from falling fruit in this dissertation. Firstly, the active components in falling fruit of citrus were studied, the factors effecting SFE and ultrasound assisted SFE (USFE) were investigated in detail. Based on these, two extraction methods mentioned above were compared and their technical parameters were optimized. Then, the mathematical model of USFE was studied. The conclusions were made as follows.Hesperidin and synephrine were the main active components in falling fruit of Satsuma mandarins, Sweet orange, Navel orange, Bingtang orange ,Ponkan, and their contents varied with the citrus varieties. In falling fruit of thirteen samples, the range of synephrine content was 0.47%-1.83%, and average was 0.93%. The range of hesperidin content was 9.02%-13.61%, and average was 11.33%. The RSD of synephrine content was higher than hesperidin content, and there was no linear correlation between them. Correspondence analysis was utilized to describe the relation among synephrine content, hesperidin content, variety and producing area efficaciously. In the chart of correspondence analysis, distribution of falling fruit and active components is shown easily. The falling fruit of citrus was the good raw material of active components.Based on the analyzing of the SFE equipment, a new ultrasonic apparatus used forenhancing SFE was designed and made. Assisted by CAE, the new solid horn wasfinished. New apparatus was composed with ultrasonic transducer, solid horn andgenerator. After debugged, it can run steadily, safely and is easy to control.Only synephrine could be extracted from citrus falling fruit by SFE, USFE, ethanolwas used at same time. The contents of synephrine in extracts of SFE,USFE were44.7%,51.2%, higher than extract of SE(4.6%). The factors, which affected SFE, USFE, were extraction temperature, pressure, MSD, supercritical fluid flow rate, modifier and ultrasonic power and so on. Experiments results indicated that the extraction yield increased with the adequate increasing of extraction temperature, pressure, MSD, fluid flow rate, modifier amount or ultrasonic power. A series of parameters for synephrine extraction by supercritical fluid, optimized by orthogonal experiment were: temperature 50℃, pressure 30MPa, SCF flow rate 12 L·h^-1, modifier 12%. For synephrine by SFE, the order of each factor's effectiveness on its extraction yield was: extraction temperature> extraction pressure > SCF flow rate> modifier. A series of parameters for synephrine extraction by USFE, optimized by uniform experiment were: ultrasonic power, temperature 45℃, pressure 20MPa, SCF flow rate 9L·h^-1, modifier 12%, extraction time 4.5h, extraction yield 43.9%. For SFE process, with the enhancement of ultrasound, extraction pressure, temperature, modifier usage and extraction time were decreased, however, the extraction yield were obviously higher. Ultrasound did not change the solvent or SCF's choice of active components. The molecular structure of active components was not affected by SFE or USFE.The mathematical model for USFE of active components from falling fruit of citrus was got as follows, based on uniform experiment result.y=-87.1944+3.1964x₂+2.0832x4+1 9.6721x₆-0.0315x₂²-0.1566x₄²-1 .7800x₆²+ 0.0020x1·x₄-0.0760x₂·x₆+0.0328x₄·x₅The prediction results of this model fit the experimental results well, and it could present the practical extraction process. Synthesis effect of two factors could be observed by response surface method.The structure of falling fruit were broken by ultrasound. The hole in aluminium foil indicated that there were ultrasonic cavitation phenomena in supercritical fluid. Intensity of cavitation decreased with distance extending and increased with time. Hence, the mechanism of ultrasound enhanced SFE were the cavitation effect, the mechanic effect and thermal effect. Owing to these effects, ultrasound could decrease resistance to internal diffusion, promote internal mass transfer. At the same time, ultrasound caused the on flow of SCF outside the raw material, and broke the stagnant layer of its surface, thinned layer of mass transfer, increased mass transfer coefficient, improved outside mass transfer. Moreover, ultrasound transferred its energy to solutes o that it enhanced the movement of solute molecule and speeded up its dissolution. Thus, ultrasound could enhance SFE.In the dissertation, ultrasonic technique and supercritical fluid technique were combined to extract active components from falling fruit of citrus. It has important theoretical and practical significance in enriching the theory of ultrasonic, promoting the application of ultrasonic and supercritical fluid technique, and developing active components from plant.