【作者】 杨柏崇；

【导师】 李元瑞；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2003， 硕士

【摘要】 本研究利用超临界CO₂萃取技术，对影响猕猴桃籽油萃取的工艺条件，如原料前处理及萃取工艺条件等进行了深入系统的研究，以单因素试验结果为依据，对萃取的工艺条件进行了优化，并与溶剂法浸提的猕猴桃籽油进行了品质上的比较。结合流体动力学原理对超临界CO₂萃取猕猴桃籽油的机理进行了探讨。气相色谱分析表明猕猴桃籽油富含α—亚麻酸，是一种具有极高应用价值的功能性油脂。研究了超临界CO₂萃取一精馏联用技术富集α—亚麻酸的工艺条件，取得了一定的结果，为以后的开发利用积累了经验。研究结果表明： 在粉碎度一定的条件下，投料量对超临界CO₂萃取效果有明显的影响，本试验范围以300g加料量为佳；物料粒径大小选择很重要，采用40～60目粉碎度，有利于流体向物料内部渗透，提高萃取率。 萃取压力和萃取温度是影响萃取过程的主要参数。在温度一定的条件下，超临界CO₂的溶解能力随压力升高而上升，但二者并非线性关系，在35Mpa之后萃取率增加缓慢，从经济角度来看，高压下操作费用将大大增加，因而压力有一个最佳值。萃取温度的影响与压力选择有关，系统的转变压为27Mpa，当萃取压力小于系统的转变压力时，溶解度随着温度的升高而减小，反之，随着温度升高而增加。CO₂流量对超临界CO₂的萃取能力有双重作用，因此也有一个最佳值。以萃取压力、萃取温度、CO₂流量作为Box-Behnken试验设计的变量，进行响应曲面分析得到优化工艺条件为萃取压力=35Mpa，萃取温度：45℃，CO₂流量=27Kg/hr。各因素对油脂萃取率影响顺序为萃取压力＞萃取温度＞CO₂流量，并且各因素之间有明显的交互作用。 萃取时间的长短在一定范围内依赖于CO₂流量以及压力的大小，本试验萃取时间120～150分钟即可达到完全萃取。 基于流体动力学原理对萃取过程的机理进行了分析，收缩核模型可以很好的描述超临界CO₂萃取猕猴桃籽油的萃取过程。 与石油醚萃取的猕猴桃籽油相比，超临界CO₂萃取工艺简单，时间短，完成了油脂的脱胶，部分起到脱色、脱酸效果。萃取产品中α—亚麻酸含量超过60％，是富含α—亚麻酸的功能性油脂，具有较高的开发利用价值。油脂的氧化稳定性试验表明超临界CO₂萃取的猕猴桃籽油氧化稳定性较差，需进行深入研究。 采用超临界CO₂萃取一精馏技术富集α—亚麻酸的初步研究表明，精馏柱温度梯度较大，控温段数多，则精馏效果好，CO₂流量加大相应减少了萃取时间。在精馏柱压力为13Mpa，二氧化碳流量15kg/hr，温度梯度分布为40-55-70-85℃时，α—亚麻酸含量提高到70％。更多还原

【Abstract】 The various factors that had effects on the extraction efficiency of the kiwi fruit seed oil, such as operative parameters and pie-treatment of raw material etc, were systematically studied with supercritical carbon dioxide fluid extraction(SCFE-CO2) technology. According as the results of single factor experiments, the operative parameters (extraction pressure, extraction temperature,CO2 flow rate) were optimized. The mechanism is analysed for processing kiwi fruit seed oil with SCFE-CO2 ,which is based on the principle of the fluid kinetics. The oil with SCFE-CO2 under optimal conditions was compared to crude oil extracted by petroleum ether. GC analysis showed that kiwi fruit seed oil contained plent of a-linolenic acid(a-LNA) which has a great potential as a functional oil source. The conditions that concentrating a-LNA from kiwi fruit seed oil by SC-CO2 extraction-fractionation technology was studied. It was available for further studying and exploiting.At the same granularity of raw material, the amount of influx had great effect on extraction efficiency. In the range of experiment, 300g was the optimal amount of influx. Granularity of raw material is also important to extraction, 40-60mu is of benefit to improving extraction efficiency.Extraction pressure and temperature were principal factors for SCFE-CO2. In a certain temperature, the density of SC-CO2 was increased with increasing extraction pressure, and the capability that SCF solved kiwi fruit seed oil was also enhanced, but it didn’t show liner relationship. When exceeding 35Mpa,the increase of extraction efficiency was very low with the raise of extraction pressure. However, working with higher pressure is not practical (very high investing and operating costs), therefore extraction pressure had a optimal value. The influence of temperature was related to the extraction pressure. The transformation pressure of SCFE-CO2 of kiwi fruit seed oil was 27Mpa. Under this transformation pressure, the solubility of oil decreased with the raise of temperature. When the extraction pressure surpassed 27Mpa. The case is just opposite. The CO2 flow rate has two different effects on extraction efficiency, so it has also a optimal value. Taking the extraction pressure, extraction temperature and CO2 flow rate as the variables of Box-Behnken Design, the results of response surface analysis(RSA) showed that the effect sequence of the above three factors was extraction pressure, extraction temperature, CO2 flow rate. And these variables had evident crossing action. The optimum parameters ofSCFE-CO2 were extraction pressure 35Mpa, extraction temperature 45 , CO2 flow rate 27kg/hr.Within the operating conditions, the extraction time depended on the extraction pressure and CO2 flow rate. The kiwi fruit seed oil can be extracted fully for 120-150min.Based on the principle of fluid kinetics, the mechanism of SCFE-CO2 was discussed. Shrinking Core model can well describe the process of SCFE-CO2.Comparing to the effect of extraction with petroleum ether, SCFE-CO2 had several virtues. The technology is simpler, operating time is shorter, moreover, it gained better color and lower acid value and didn’t need degumming. The a-LNA contents was more than 60% in the oil, so kiwi fruit seed oil has available value in exploitation and utilization. The oxidative stability of oil with SCFE-CO2 was not good, so we must do more research work in the future.Enrichment of a-LNA from kiwi fruit seed oil by SC-CO2 extraction-fractionation technology indicated that fractionation efficiency will be improved with the increase of temperature gradient of fraction column and stages of controlling temperature. The fractionation time will decreased with the increase of CO2 flow rate. When fraction column pressure was 13 Mpa,CO2 flow rate was 15kg/hr and temperature range was 40-55-70-85 , a-LNA contents reached 70%.更多还原