【作者】 吴彩娥；

【导师】 李元瑞；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2005， 博士

【摘要】 本研究以猕猴桃籽为原料,利用超临界CO2 萃取精馏技术、分子蒸馏技术、尿素包合技术、微胶囊技术等现代高新食品工程技术,从猕猴桃籽中提取猕猴桃籽油、富集纯化猕猴桃籽油a-亚麻酸,并对猕猴桃籽油进行了微胶囊化。重点研究了猕猴桃籽油及其脂肪酸酯在超临界CO2 中的溶解度以及富集纯化的各个工艺条件对猕猴桃籽油a-亚麻酸含量的影响,系统地研究“气流式锐孔法”和喷雾干燥法制作的猕猴桃籽油微胶囊的工艺技术,并探讨了猕猴桃籽油微胶囊的理化性质、贮藏稳定性和释放特性。主要研究结果如下:　1.压力是影响猕猴桃籽油在超临界CO2 中溶解度的最主要因素。超临界CO2 萃取猕猴桃籽油的转变压力约为27.8MPa。当压力小于27.8MPa 时,溶解度随温度的升高而减小,因而要尽可能采取临界温度以上的较低的萃取温度,以获得较高的溶解度;当压力大于27.8MPa时,溶解度随温度的升高而增加。压力在30MPa和35MPa时温度从40℃升高到45℃,猕猴桃籽油在超临界CO2 中的溶解度增加不明显,较合适的萃取条件为温度压力30~35MPa 温度40℃;水分含量对猕猴桃籽油的溶解度有一定的影响,超临界CO2 萃取猕猴桃籽油时物料的水分含量不能过低或过高,应保持5~7%的水分含量;在试验条件下,猕猴桃籽油脂肪酸乙酯在超临界CO2 中的溶解度差异显著,可以通过改变温度和压力将不同的猕猴桃油乙酯分离。2.温度、压力、CO2 流量等条件对猕猴桃籽油的超临界CO2 精馏效果有很大影响。单因素试验结果表明,超临界CO2 精馏富集猕猴桃籽油脂肪酸时精馏温度梯度40-55-70-85、精馏柱压力15MPa、CO2 流量3000 g/h、萃取压力20MPa、萃取温度35℃是较适宜的操作工艺条件,在此条件下经过精馏后可使猕猴桃籽油中a-亚麻酸的含量达到69.91%;程序升压可使猕猴桃籽油中a-亚麻酸的含量达到73.53%;尿素包合和银离子络合与超临界CO2 精馏结合分别使猕猴桃籽油a-亚麻酸的含量由单独精馏的69.91%提高至72.30%和75.59%。对超临界CO2 连续进料精馏浓缩猕猴桃籽油a-亚麻酸的工艺进行了初步研究。在物料流量为3.3~5.1g/min、CO2 流量为3000 g/h、精馏压力为15MPa 的条件下,可以将猕猴桃籽油a-亚麻酸提高至70.35~75.18%。3.单级分子蒸馏适宜的分离条件为:蒸馏温度110℃,蒸馏压力3.5Pa,物料流量30~40 滴/min;刮膜器转速400r/min,进料温度55℃。采用单级分子蒸馏可使猕猴桃籽油原料中的a-亚麻酸由原来的61.82%提高至70%以上;多级操作方式适宜的分离条件为,蒸馏温度90~120℃,蒸馏压力3.0~4.0Pa,物料流量30 滴/min,刮膜器转速400r/min,进料温度55℃。经过四级分子蒸馏,可以将猕猴桃籽油原料中的a-亚麻酸由原来的更多还原

【Abstract】 Using kiwifruits seed as raw materials and applying modern high-tech food engineering technology, mainly supercritical CO2 extraction-distillation technology, molecular distillation technology, urea inclusion technology, microencapsulation technology etc, kiwifruit seed oil was extracted from kiwifruits seed, a-linolenic acid of kiwifruit seed oil was enriched and kiwifruit seed oil was microencapsulated. The solubility of kiwifruit seed oil and its fatty acids ethyl esters in supercritical CO2 were studied. The conditions and effects of enrichment purified technological on kiwifruit seed oil a-linolenic acids contents were investigated. The technology for kiwifruit seed oil microcapsule which made by “air stream tiny hole”and spray dry method were systematically researched. The physicochemical property, storage stability and release property of kiwifruit seed oil microcapsules were also covered. The main results of this study were as follows: 1. Pressure is the major factor affecting the solubility of kiwifruit seed oil in supercritical CO2. The transforming pressure for extracting kiwifruit seed oil by supercritical CO2 extraction is approximately 27.8Mpa. When the pressure is less than this value, solubility will decrease as temperature rising, therefore, a lower extraction temperature above supercritical point should be adopted to achieve a higher solubility; while the pressure is more than 27.8Mpa, solubility will increase with the temperature rising; with the condition of 30MPa and 35MPa, extraction temperature rise to 45℃from 40℃, solubility of kiwifruit seed oil in supercritical CO2 will not increase significantly. Thus, the suitable extraction conditions are pressure 30~35 MPa, temperature 40℃; Water contents will affect solubility of kiwifruit seed oil, water content of materials should neither too high nor too low. 5~7% of water content should be maintained when the kiwifruit seed oil is extracted by supercritical CO2. Solubility of fatty acids ethyl esters of kiwifruit seed oil in supercritical CO2 are significantly different in the test conditions. Different fatty acids ethyl esters of kiwifruit seed oil can be separated by varying temperature and pressure. 2. Temperature, pressure, CO2 flow have a great impact on fractionation effectiveness of kiwifruit seed oil by supercritical CO2. Single factor experimental result indicates that, when fatty acids of kiwifruit seed oil are separated by supercritical CO2 extractive distillation, the optimum conditions are that fractionation column operating on temperature gradients of 40-55-70-85, pressure 15MPa, CO2 flow rate 3000g/h, and extracting pressure 20MPa, extracting temperature 35℃. Under this operation condition content of a-linolenic acid in the kiwifruit seed oil will reach 69.91% after fractionation. Content of a-linolenic acid in kiwifruit seed oil will reach 73.53% by increasing pressure in accordance with procedure. The combination of urine inclusion and Ag+ complex with supercritical CO2 fractionation can respectively increase linolenic acid content of kiwifruit seed oil to 72.30~75.99% from the 69.91% of single fractionation. A preliminary research on technology of continuous concentration kiwifruit seed oil a-linolenic acid by supercritical CO2 fractionation was produced. At oil feed flow rate 3.3~5.1g/min, CO2 flow rate 3000g/h, column pressure 15MPa, a-linolenic acid of kiwifruit seed oil can be increased to 75.35~75.18%. 3. The optimum condition of molecular distillation separation on kiwifruit seed oil are temperature 110℃, pressure 3.5Pa, and oil feed flow rate 30~40 drops/min, rotational speed of membrane stripper 400r/min, feed temperature 55℃. Single step molecular distillation increased the level of a-linolenic acid in kiwifruit seed oil from 61.82% to70%. The most suitable separations conditions of multistsge operation method are distillation temp 90~120℃, pressure 3.0~4.0Pa, oil feed flow rate 30 drops/min, rotational speed of membrane stripper 400r/min, feed temp 55℃. The concentration of a-linolenic acid in kiwifruit seed oil can be increased to 84.33% from the previous 67.5% by 4 steps molecular distillation. 4. This study aims to develop higher content of a-linolenic produce with kiwifruit seed oil, provides a new direction of healthy products. The study shows that the best conditions of urea inclusion technology enrichment a-linolenic acid are mass ratio of fatty acid, urine, 95% of alcohol is 1:3:7, temperature –15℃, inclusion time 15h. Under these conditions, a-linolenic contents can reach 87.2%. Using urine inclusion to enrich a-linolenic acid in kiwifruit seed oil is a method of mild temper, simple, low cost; it is an effective way for preparation of high content a-linolenic acid of kiwifruit oil. 5. When spray dry method is used to prepare kiwifruit seed oil microcapsules, proper wall material combination is soybean protein isolate and maltodextrin. The best emulsion formula for spray dry kiwifruit seed oil: soybean separated albumen/maltodextrin is 1:1, core/wall is 1:1.5, concentration of emulsion is 25%. The optimum technological condition on spray dry method is: entering air temperature 180℃, homogening pressure 30 MPa, air outlet temperature 82℃; On this condition, kiwifruit seed oil encapsulation efficiency can get 85~90% and it has better test reproducibility. 6. The formulation for preparation of kiwifruit seed oil microcapsule using “air stream tiny hole”is sodium alginate concentration 2.5%, the best proportion of wall material, sodium alginate, and core material, kiwifruit seed oil, is 1:1, emulsifying agent is 0.2% tween80+0.1%stearin, CaCl2 concentration is 2.0%.The proper spray dry technical parameters are material flow speed 20 ml/min, spray air pressure 0.05MPa, spray distance 40cm.Encapsulation efficiency of kiwifruit seed oil is up to 93.05% in this condition. It becomes possible to industrialization production of microcapsules by the means of “air stream tiny hole”microencapsulation. 7. The quality of kiwifruit seed oil microcapsules made by “air stream tiny hole”and spray dry method accords with that of quality requirement of ordinary microcapsules; kiwifruit seed oil microcapsules prepared by these two methods have different size distribution and different solubility and have extensive uses; during storage, oxidizing speed of kiwifruit seed oil that microencapsulated is obviously lower than that without microencapsulated. During storage kiwifruit seed oil content declines slowly, and core material preservation is higher. Microencapsulation can prevent kiwifruit seed oil from volatilizing, reduce oxidizing speed rate, thus to prolong the preservation period of kiwifruit seed oil. 8. Kiwifruit seed oil microcapsules release slowly in man-made gastric juice and release fast in man-made intestinal juice, hence it has a good controlled release and enteric solubility, it is conforms with the requirements of ordinary microcapsules products on control release; kiwifruit seed oil microcapsules prepared by different method has different properties, and it can meet the needs of different control release; kiwifruit seed oil microcapsule’s release speed rate follows First Order Reaction Dynamic Model, namely, release speed rate is in direct proportion to microcapsules core surplus mass, linear equation. The bigger the particle is, the smaller the constant of release speed rate is.更多还原