【作者】 周鸣谦；

【导师】 王仁才；

【作者基本信息】 湖南农业大学 ， 果树学， 2008， 博士

【摘要】 在柑橘果实发育过程中，会产生大量的生理落果。湖南是我国柑橘生产的主要省份，每年产生的柑橘落果。目前，对于这些落果的开发利用十分不足。超临界流体萃取技术虽然具有诸多优点，但是因其高压操作，萃取效率相对较低等问题，限制了它的广泛应用。本论文以极具开发价值的柑橘落果活性成分为提取对象，采用超声强化超临界CO₂萃取技术对柑橘落果进行提取研究。在对柑橘落果中的活性成分进行分析研究的基础上，对超临界流体萃取法和超声强化超临界流体萃取法提取落果活性成分的影响因素及超声强化的效果进行了详细的研究，对两种方法提取的工艺参数进行了优化，构建了超声强化超临界流体萃取落果活性成分过程的数学模型，并进一步研究了超声强化超临界流体萃取的机理。通过研究表明：（1）温州蜜柑、哈姆林甜橙、冰糖橙、脐橙、椪柑落果中的活性成分以辛弗林与橙皮苷为主，辛弗林含量范围为0．47％～1．83％，平均含量为0．93％；橙皮苷含量范围为9．02％～13．60％，平均含量为11．33％；辛弗林含量相对标准偏差（36．47％）高于橙皮苷相对标准偏差（11．58％）；柑橘落果中橙皮苷、辛弗林含量均随着粒径的增大减少；相关分析表明，辛弗林、橙皮苷含量无线性相关关系；柑橘落果中活性成分含量随产地、品种变化较大，多元对应分析可以直观地描述活性成分含量与产地、品种之间的规律；柑橘落果可作为提取橙皮苷、辛弗林的优质原料。（2）对超声强化超临界流体萃取装置进行了改进，借助于计算机辅助分析设计了高性能的超声系统核心部件变幅杆。由超声波换能器、变幅杆和超声波发生器组成的超声强化装置与超临界萃取装置合理组装构成超声强化超临界流体萃取装置。经实际操作，该系统运行稳定，强化效果好。（3）以乙醇作为夹带剂的超临界CO₂萃取与超声强化超临界CO₂萃取能够提取出柑橘落果中的活性成分辛弗林，但不能萃取出橙皮苷等黄酮类物质；两者提取物中辛弗林的含量（44．7％、51．2％）远高于溶剂提取物（4．6％）。（4）萃取温度、萃取压力、物料颗粒度、流体流量、夹带剂含量、超声功率等因素对超临界CO₂萃取及超声强化超临界CO₂萃取过程产生影响。实验条件下，随着物料颗粒度、萃取温度、萃取压力、流体流量、夹带剂量、超声功率的适量增加，辛弗林提取率提高。采用正交设计对超临界萃取过程进行了工艺优化，优化后的工艺参数为：萃取温度50℃、萃取压力30MPa、流体流量12 L·h^-1、夹带剂含量为12％，此条件下辛弗林提取率可达35．8％。各因素对于超临界CO₂萃取柑橘落果活性成分影响程度为：萃取温度>萃取压力>流体流量>夹带剂。采用均匀设计对超声强化超临界CO₂萃取过程进行了优化，优化后的工艺参数为：超声功率250W、萃取温度45℃、萃取压力20MPa、流体流量9L·h^-1、夹带剂含量12％、萃取时间4．5h。以上述条件进行验证试验，辛弗林提取率达到43．9％。超声强化超临界CO₂萃取过程，降低了萃取系统的压力、温度以及夹带剂用量和萃取时间，而且萃取率也明显提高。超声场的加入没有改变超临界CO₂对活性成分的选择性，对提取物的分析也表明超声强化对于活性成分的结构没有影响。对于均匀设计的试验结果进行回归分析，构建了超声强化超临界流体萃取过程的数学模型：y=-87．1944+3．1964x₂+2．0832x₄+19．6721x₆-0．0315x₂²-0．1566x₄²-1．7800x₆²+0．0020x₁·x₄-0．0760x₂·x₆+0．0328x₄·x₅该模型的预测结果与实验数据拟合较好，能够反映萃取的实际过程，并能通过对其进行响应面分析研究两因素对于辛弗林提取率的综合影响。（5）显微观察显示，超声对超临界流体中的原料产生一定的破坏作用；在超声强化超临界状态下铝箔被腐蚀，证明存在超声波的空化效应；空化强度随着距声源距离加大而逐渐减小；随着超声处理时间的增加而逐渐增加。超声强化超临界流体萃取的机理可能是超声空化、机械波动效应与热效应的共同作用结果，并能使原料细胞破碎，从而强化分离过程。由于这些效应，超声可有效地减小内扩散阻力，加速内扩散，强化物料内部的传质；同时，超声对颗粒外部的流体造成湍动作用，破坏颗粒表面滞留层，减薄传质边界层，提高传质系数，促进颗粒外部的传质；另外，超声能的传递可使溶质活化，降低过程的能垒，增大溶质分子的运动，加速其溶解，从而对SFE过程产生强化效应。本论文对柑橘落果中的活性成分进行了研究，并将新兴的超声技术与超临界流体技术结合起来，协同提取其中的活性成分，为柑橘落果资源的充分利用提供了新的思路，对于超声技术与超临界流体技术的结合与应用也具有重要的理论意义与实际意义。更多还原

【Abstract】 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.更多还原