【作者】 陈德经；

【导师】 岳田利； 刘邻渭；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2006， 硕士

【摘要】 板栗(Castanea Mollissima Blume)在加工中易褐变,但板栗仁黄色素如何变化,未见文献报道。对新鲜板栗在45℃烘12h,破壳、除衣、粉碎,分别用乙醇、丙酮、乙醚、氯仿、石油醚等溶剂提取,用紫外分光光度仪对乙醚提取液进行200-700nm扫描,在可见光区最大吸收波长为441nm,在此波长下测定不同溶剂提取液的吸光度,确定乙醚为最佳提取溶剂。以料液比、时间、温度、pH值进行黄色素提取(L934)正交试验,最佳提取工艺为料液比1:3,1.5h,35℃,pH值为7,板栗仁色素的粗含量为2.8%。对板栗仁切薄片,从内片径三分之二处分开,用乙醚提取等量板栗仁的外部和内部的色素,外部提取液的吸光度是内部的2倍,板栗仁黄色素在外部的含量大于内部。板栗仁黄色素为脂溶性色素,溶于有机溶剂,不溶于水,在溶液中显黄色,黏稠液时显棕黄色。板栗仁色素在可见光内主要吸收波长为416 nm、441 nm、470 nm,在紫外区吸收波长为240 nm、296 nm;在310 nm、340nm有一定的荧光特性;光线对色素有一定的褪色作用。温度对色素影响不大,但超过100℃对色素影响明显;pH值从1到14使色素由棕色变为橙黄色,在强酸条件下,显绿色。金属离子Cu2+、Fe3+、Ca2+、Al2+、Sn2+、Mn2+、Zn2+对色素影响不显著,但Pb2+影响较大。食品添加剂柠檬酸、蔗糖、维生素C随浓度增大影响色素的稳定性,但亚硫酸钠、氯化钠浓度增大对色素稳定性有促进作用。微波、超声波处理对色素具有一定破坏作用。褐变板栗提取的色素比未褐变板栗色素的吸光度大,板栗褐变不是板栗仁色素的褐变,而是板栗其它褐变物对板栗仁黄色素的掩蔽作用。板栗仁色素提取物,经过硅胶和三氧化二铝(3:1,m/m)柱层析,用正已烷、二氯甲烷、甲醇洗脱分别收集的非极、弱极和性极三个馏分,对极性馏分甲基化,分别进行GC-MS检测,共检测出68种化合物。非极性馏分检测出19种化合物,主要是烷烃和烯烃类化合物,其中正二十七烷、三十一烯、二十九烯相对含量分别为29.937%、23.945%、22.196%。这些化合物中,角鲨烯有6个异戊二烯双键组成的共轭烯烃,属于三萜类化合物,具有发色基团,其余18种不具有显色作用。弱极性馏分测出29种化合物,主要是醛和酯类,其中亚油酸乙酯、油酸、油酸乙酯相对含量分别为19.216%、16.406%、11.976%,在这些化合物中,共轭脂肪酸及酯本身无色,但可与黄色素结合呈黄色,同时还检测出亚油酸、豆甾醇、β-生育酚、黄酮等功能成分。极性馏分检出20种化合物,主要是有机酸类,其中壬酸、棕榈酸、辛酸相对含量分别为25.5147%、15.2833%、14.8311%,这一类物质没有发色基团。GG-MS未检测出类胡萝卜类及其它色素类化合物。高速逆流色谱(HSCCC)分离板栗仁黄色素,溶剂系统为正已烷-乙酸乙酯-乙醇-水(6:1:6:1,V/V),分离中有三大峰,分别占64.62%,19.07%,13.91%,通过紫外检测和观察,第一峰段收集液为无色,λmax:220nm;第二峰段收集液为黄色,λmax:444 nm、473nm、220 nm;第三峰段收集液为无色,λmax:296 nm;固定相收集液为黄色,λmax:423nm、446nm、471nm、220nm、296nm。经硅胶薄层层析(TLC),用正已烷-乙醚(1:2.5,V/V)展开,提取物和HSCCC分离各峰段液展开,有2个黄色点,R?1为0.38,R?2为0.96。经PHLC分析,板栗仁黄色素中含有β-胡萝卜素和叶黄素,叶黄素的含量是0.42mg/100mg,β-胡萝卜素的含量是0.16mg/100mg。经过紫外光谱测定、薄层鉴定、气质联用仪和高效液相分析,初步确定板栗仁色素由β-类胡萝卜素和叶黄素两种黄色素组成。更多还原

【Abstract】 It is not seen in literature how the color of pigment in chestnut (Castanea mollissima Blume) change when chestnuts occur to brown in processing. In our experiments, fresh chestnuts were dried at 45℃for 12h, with shells decorticated and coats removed, and the kernels were crushed and extracted pigment from chestnut kernels with ethanol, acetone, ether, chloroform, and petroleum respectively. All the crude extracts were scanned through an ultraviolet spectrometer in the range of 200 - 700 nm. The highest absorbing wavelength was shown at 441 nm, under which all the crude extracts were measured for efficiency of different solvents, and the results demonstrated that ether was the best extracting solvent. Then an orthogonal design (L934) was adopted and corresponding experiments were conducted among such factors as the ratio between materials and solvent (R), duration (D), temperature (T) and pH for the best extracting conditions, and the results suggested the following: R = 1:3, D = 1.5 h, T = 35℃, and pH = 7. Finally the content of crude pigments in chestnut kernels was indicated at 2.8% by the experiments. The distribution of pigment in outer chestnut are 2 times as much as the inner ones by examining ABS of extracting solution from same mass which sliced chestnut from the diameter of two and third.The yellow pigments in chestnut kernels were fat-soluble, dissolvable in organic solvents but not in water. Crude extracts were yellow in color, but brownish yellow if thickened. Their absorbing wavelength was chiefly at 416, 441, and 470nm in visible light, and 240 and 296nm in UV; they also exhibited a weak fluorescence at 310 and 340 nm. Lights faded the pigments; temperature showed no apparent effect on stability of the pigments, but affected remarkably when exceeding 100℃. The acidity in terms of pH from 1 to 14 made the color turn from brownish yellow to orange, and to green in extremely acid solutions. Metal ions such as Cu2+、Fe3+、Ca2+、Al2+、Sn2+、Mn2+、Zn2+ had no significant effects on the pigments, but Pb2+ did. Food additives such as citric acid, sucrose, and Vc influenced the stability of the pigments as their concentrations increased. Both sodium sulfite and sodium chloride stabilized the pigments with their density increment. The treatment with microwave and ultrasonic wave displayed some destruction on the pigments. The extract of the browned chestnuts absorbed more lights than the normal one, meaning that the browning of the chestnut kernels was not due to the yellow pigments of the kernels themselves but to other materials that masked the normal yellow color.The crude extracts of chestnut kernels were isolated via a column chromatography filled with silica gel and alumina (3:1, M/M), and washed sequentially with n-hexane, dichloromethane, and methanol to obtain non-polar, weak-polar, and polar fractions, and the polar fraction was then methylated. All the fractions, including the methylated one, were subject to a gas chromatography-mass spectrometry (GC-MS) analysis, and a total of 68 compounds were found. There were 19 compounds in the non-polar fraction, mainly Alkanes and Olefins, among which Heptacosane accounted for 29.937%, Hentriacontene for 23.945%, and Nonacosene for 22.196%. Squalene, one of the 19 compounds in the non-polar fraction, contains conjugated double bonds composed of six units of isoprene that belong to triterpene compounds with chromophores; whereas the others have no this kind of chromophore. Weak-polar fraction consisted of 29 compounds, mostly aldehydes and esters, among which the relative amounts of Linoleic acid ethyl ester, 9-Octadecenoic acid, and Ethyl Oleate were 19.216%, 16.406%, and 11.976% respectively. Conjugated linoleic acids and esters themselves are colorless, but they can show colors when combined with other pigments. Meanwhile, functional ingredients of Linoleic acids, Stigmastans,β-Tocopherols and Flavonoids were also found. Inside polar fraction there were 20 compounds found, mainly organic acids, among which were Nonanoic acid (25.514%), Hexadecanoic acid (15.2833%), Octanoic acid (14.8311%), etc. These kinds of compounds do not have chromophore. Carotenoids and other pigment compounds were not found by GC-MS.High-speed Countercurrent Chromatography (HSCCC) was used to isolate the yellow pigments, with the mixed solvents of n-hexane, ethyl acetate, ethanol, and water (6:1:6:1, V/V) as the washing reagent. Three main peaks appeared, accounting for 64.62%, 19.07%, and 13.91% respectively. When examined under UV, the first peak was colorless,λmax :220 nm; the second, yellow,λmax = 444 nm, 473nm,220nm; and the third, colorless,λmax :296 nm; the fixed phase with the remaining solvent mixtures showed a yellow color,λmax: 423 nm ,446 nm,471 nm.,220 nm,296 nm。A silica thin layer chromatography, with spreading solvents of n-hexane and ether (1:2.5, V/V), was employed to examine the components of both the crude extracts and the fractions isolated by HSCCC. Two yellow spots were obtained, with R?1 = 0.38,and R?2 = 0.96. HPLC analysis indicated that the yellow pigments in chestnut kernels containedβ-carotene and lutein; the second peak of HSCCC, R?1, were lutein; the fixed phase with the remaining solvent mixtures and R?2 wereβ-carotene. The content of lutein in fresh chestnuts is 0.42mg/100g,β-carotene`s contents is 0.16mg/100g.Therefore, the yellow pigments in chestnut kernels are composed ofβ-carotene and lutein by analyzing with UV,TLC,GC-MS, and, HPLC.更多还原