【作者】 刘释文；

【导师】 陈绍军；

【作者基本信息】 福建农林大学 ， 农产品加工及贮藏工程， 2008， 硕士

【摘要】 龙眼（Dimocarpus Longan Lour）为无患子科的果实,为我国著名的亚热带水果。在我国已有2000多年栽培历史,是重要的南亚热带常绿长寿果树,为岭南四大佳果之一。龙眼成熟于高温季节,鲜果采后生理代谢旺盛,在常温下很容易失水、褐变和腐烂,影响了龙眼的贮藏和销售。目前,龙眼保鲜技术还不成熟,随着龙眼酒、龙眼罐头、桂圆干及龙眼其他深加工产品的出现,龙眼核、肉分离,作为加工废弃物的龙眼核目前的利用率不高,利用水平低下。本论文对龙眼核主要营养成分进行了测定,对龙眼核棕色素的提取工艺和特性以及龙眼核棕色素的抗氧化活性进行了研究,主要研究结果如下:（1）龙眼核含有丰富的淀粉、还原糖、粗纤维、蛋白质、果胶等,黄酮含量也较高,同时还含有多种矿物元素、维生素以及人体必须氨基酸等营养素,是一种具有较大开发潜力的资源。龙眼核中淀粉含量高达60.88%,还原糖含量为9.67%,粗纤维含量为6.85%,蛋白质含量为5.58%,果胶含量为5.19%,单宁含量为4.72%,脂肪含量为3.23%,灰分含量为2.05%以及黄酮的含量为0.14%。（2）蒸馏水和60%乙醇溶液对龙眼核棕色素的提取效果较好,提取率分别为0.1301%和0.1303%,是较适宜的龙眼核棕色素溶剂,甲醇和丙酮的提取效果较差。正交试验结果表明,龙眼核棕色素的最佳提取工艺为乙醇浓度60%、浸提温度30℃、浸提时间为12h。在龙眼核棕色素提取中乙醇浓度起主要作用,其次是浸提温度,最后是浸提时间。应用matlab7.01软件对乙醇浓度、浸提温度和浸提时间三因素进行分析,得出龙眼核棕色素的最佳提取工艺为乙醇浓度60%、浸提温度37℃、浸提时间12h,与正交试验结果基本一致。验证试验结果表明,龙眼核棕色素的最佳提取工艺为乙醇浓度60%、浸提温度37℃、浸提时间12h。（3）龙眼核棕色素在紫外光区有一强一弱两个吸收峰,最大吸收波长λ_max=240nm,在波长为350nm处有一个弱的吸收峰;龙眼核棕色素是水溶性色素,易溶于极性溶剂,不溶于非极性溶剂;对光、热稳定性良好;在中性和碱性介质中稳定性良好,碱性条件下吸光度上升,分子中存在可逆结构;具有较好的抗氧化性和抗还原性且抗氧化性强于抗还原性,H₂O₂和Na₂SO₃的加入均导致原最大吸收峰的位移,λ_msx从240nm移到270nm:对K⁺、Na⁺、Mg²⁺、Ba²⁺⁴种金属离子较稳定,加入CuSO₄和FeCl₃时发生明显的颜色变化,Al³⁺和Ca²⁺离子对色素有增色作用,Zn²⁺浓度当量为乙酸锌质量浓度2.5%时,龙眼核色素的吸光度下降最大;部分常用食品添加剂的除柠檬酸和Vc外,对色素溶液吸光度的影响不大,柠檬酸和Vc的加入,使色素的吸光度下降;龙眼核棕色素为黄酮类化合物,是黄酮类色素和花青素的混合物。（4）龙眼核棕色素对NaNO₂的清除率为78.0%,对O₂^-的清除率达到90.23%,对·OH的清除率为86.54%;温度对龙眼核棕色素清除超氧阴离子自由基（O₂^-）的影响不大;放置时间对龙眼核棕色素清除超氧阴离子自由基（O₂^-）的能力有较大影响,随着放置时间的延长而下降明显;Vc对龙眼核棕色素清除超氧阴离子自由基（O₂^-）的有增效作用;NaCl、MgCl₂对龙眼核棕色素清除超氧阴离子自由基（O₂^-）的能力影响不明显,而AlCl₃、CaCl₂却能导致龙眼核提取物清除超氧阴离子自由基（O₂^-）的能力下降。更多还原

【Abstract】 Longan（Dimocarpus Longan Lour）,is a famous sapindaceae fruit and have 2000 years in China.Longan is a very important south-asian tropic fruit.However longan will metabolize vehemence,loose moisture and browning because longan mature in the hot and humid period of the year,which influence the storage and distribution of longan.The storage tecniof longan is still unmature,with the develop of longan wine, longan cane,dried longan and other production of longan,the separation between pulp and seed of longan and the utilization ratio of longan seed are both low at present. This article is not only studing on the main nutrient components,the extraction processing and characteristic of longan seed’s brown pigment,but the antioxidant of longan seed’s brown pigment and The results are showed as follows:（1）The longan seed is full of amylum,reducing sugar,coarse-fibred,protein,pectic and flavone,meanwhile it contains multiform nutrient elements such as mineral elment,vitamin and amino acid ect,is a potential source.The content of amylum, reducing sugar,coarse-fibred,protein,pectic,tannic acid,fat,ash and flavone is 60.88%,9.67%,6.85%,5.58%,5.19%,4.72%,3.23%,2.05%and 0.14%.（2）The distilled water or 60%is good for extracting the longan seed’s brown pigment,the extraction rates was 0.1301%or 0.1303%,is appropriate for extracting the longan seed’s brown pigment,but the acetone or methanol is not.Orthogonal test results showed that the best technology for extracting the longan seed’s brown pigment is:60%ethanol,extract at 30℃for 12 h.In the extract flow of longan seed’s brown pigment by ethanol,the consentration of ethanol play a major role,followed by the extraction temperature,the last is extraction time.Application software matlab7.01 to study on three factors of concentration of alcohol,extraction temperature and extraction time,and it showed that the best technology for extracting the longan seed’s brown pigment is:60%ethanol,extract at 37℃for 12 h,basically the same with the orthogonal test results.Verification test results showed that the best technology for extracting the longan seed’s brown pigment is:60%ethanol,extract at 37℃for 12 h.（3）The longan brown pigment in UV sect have two absorption peak,one is strong, the other is weak.The best isλ_max=240nm,there is a weak absorption peak atλ=350nm The longan brown pigment is water color,which is easy dissolve in polar solvent and difficult in non-polar solvent;the stability against of light,heat,neutral and alkaline medium is good,in alkaline condition,absorbance will raise,and some reversible structure could be found in molecules.It has good oxidation resistance and anti-reduction and oxidation resistance is stronger than anti-reduction.Add H₂O₂ and Na₂SO₃ will let the original maximum absorption peak shift,that isλmax moved from 240 nm to 270 nm;It will keep stable when meet with 4 metal ions:K⁺,Na⁺,Mg²⁺, Ba²⁺,while adding CuSO₄ and FeCl₃,the color changes.Al³⁺and Ca²⁺can deepen the color of the pigment,when Zn²⁺is equivalent to 2.5%C₄H₆O₄Zn·2H₂O,The abosoption of longan seed’s brown pigment decline.Some common food additives have little effect on pigment’s absorbance except for citric acid and V_c,The abosoption of longan seed’s brown pigment decline as citric acid or V_c being added. Longan seed’s brown pigment is a mixture of flavonoid and anthocyanin.（4）The clearance of extraction of longan seed against NaNO₂,O₂^-,and.OH is 78.0%,90.23%and 86.54%respectively.The effect of factors on O₂^- eliminated by longan seed’s extract are different from each other,the temperature and NaCl, MgCl₂’effect is a little,while the effect of time is great,with the extension of time, the capability of the extraction declines;V_c can increase effectiveness of the extraction;There are no distinct impact on this capability with adding NaCl,MgCl₂; as for AlCl₃,CaCl₂,the capability of the extract decline obviously.更多还原