【作者】 任雪峰；

【导师】 杨正银；

【作者基本信息】 兰州大学 ， 无机化学， 2012， 硕士

【摘要】 本论文以湿法消化和干法灰化两种方法紫甘薯样品进行预处理,采用火焰原子吸收光谱比较了两种处理方法所得样品中11种金属元素的含量,并对仪器工作条件进行了优化；采用湿法消化处理了甘肃三地产人参果,采用火焰原子吸收光谱比较了三地产人参果样品中11种金属元素的含量,并对仪器工作条件进行了优化；应用超声波辅助法对紫甘薯花色素进行了提取研究,在单因素试验的基础上,采用响应面法对影响紫甘薯花色素提取率的乙醇浓度、料液比、超声时间和超声温度四个因素进行优化组合,并在最佳提取工艺条件下进行了验证试验；对超声辅助法提取的紫甘薯色素对光照、pH值、金属离子及食品添加剂的稳定性进行了研究；以紫甘薯色素提取液为研究对象,抗坏血酸为对照,采用·OH自由基、DPPH·自由基、NO2-自由基和Fe3+体系,考察了紫甘薯色素的体外抗氧化性。研究结果如下：1.不同消化方法对测定各种金属离子有显著影响,采用湿法消化处理所得样品中K、Ca、Na、Mg、Zn、Fe、Cu、Mn、Pb、Cr和Cd的含量分别为16896.36、2003.56、152.13、1032.15、138.92、90.67、9.94、1.98、1.96和1.53μg·g-1,采用干法灰化所得样品中各元素的含量分别为15058.04、966.65、129.71、1100.96、107.11、72.30、7.35、4.32、2.04、1.38和1.46,μg·g-1,采用湿法消化处理样品更加有利于样品的氧化分解,消化的更为完全。方法的加标回收率在96.14%～104.31%之间,各元素测定值的精密度在0.12%-3.56%之间,说明该方法准确、可靠,可以作为测定紫甘薯中金属元素测定的方法之一。2.凉州区、天祝县、甘州区的人参果中Na、Ca、Mg、Mn、Cu、K、Zn、 Fe、Cr、Cd和Pb的含量分别为164.82、2273.14、1287.95、5.27、10.60、23558.10、154.88、87.57、2.10、2.67、2.19,125.79、877.65、1424.14、5.24、8.25、20867.55、149.43、50.66、2.33、2.93、2.25和240.35、1413.83、1382.65、5.86、6.86、19844.45、153.75、135.74、1.97、2.25、2.09μg·g-1。加标回收率为97.26%-104.82%,相对标准偏差(n=9)为：0.10%～5.15%,测定方法简单易行,方便快捷。3.在单因素试验的基础上,应用响应面分析法优化紫甘薯色素的提取工艺。结果表明：超声温度、乙醇浓度二次方项、料液比二次方项、超声温度二次方项和超声时问二次方项对紫甘薯色素提取率的影响极显著(P<0.0001),说明乙醇浓度、料液比、超声温度和超声时间在紫甘薯色素的提取率影响中不是简单的线性关系,而是存在交互作用。最佳提取工艺条件为：乙醇浓度为72%,料液比1：88,超声温度55℃,超声时间29min。在此条件下,紫甘薯色素的吸光度值可达0.861,与理论值相差0.38%,RSD(n=5)为0.38%,说明采用响应面法得到的工艺参数可靠,可以对紫甘薯色素的提取工艺进行模拟。4.紫甘薯色素在酸性条件下比在碱性条件下稳定,受热性较强,可以在70℃以下可以稳定保存；紫薯色素对光照不稳定；金属离子Na+、K+、Mg2+、Ca2+、Zn2+以及低浓度的Fe3+和Cu2+对紫薯色素有辅色作用,可以作为色素的护色剂；A13+和高浓度的Fe3+及Cu2+会对紫甘薯色素造成降解；氯化钠和蔗糖对紫甘薯色素具有增色作用,柠檬酸对紫甘薯色素稳定性没有影响；当苯甲酸钠浓度低于0.01%,抗坏血酸和山梨酸钾浓度低于0.05%,紫甘薯色素的稳定性基本保持不变。5.在实验所选的4种体外抗氧化活性评价方法中,从对·OH、DPPH·和N02-自由基的清除率值看,紫甘薯色素各种溶剂提取物对DPPH·的清除作用远大于·OH和NO2-自由基的清除作用,而NO2-自由基的清除作用又优于·OH的。在同一抗氧化评价指标中,不同溶剂提取物的抗氧化能力存在较大差异,在DPPH·和NO2-自由基的清除实验中,醇提物的各部分萃取物清除效果随着萃取溶剂极性的增大而增强,且抗坏血酸表现出较好的清除效果；而在·OH的清除实验中,醇提物的各部分萃取物清除效果随着萃取溶剂极性的增加而减弱,抗坏血酸的清除效果远优于各部分萃取物的。在Fe3+还原能力大小的测定实验中,正丁醇部分和乙酸乙酯部分有比较强的还原力,且还原力与质量浓度呈量效关系。更多还原

【Abstract】 In this paper, samples of purple sweet potato were pretreated by methods of dry ashing and wet, the contents of11metal ion processed by two different methods were compared by Flame atomic absorption spectrometry(FAAS), and the work condition of instrument was optimalized. Pigement of purple sweet potato was extracted and researched by ultrasonic assistance, on the basis of single factor, four factors of ethanol concentration, ratio of solid material to liquid, ultrasonic time and ultrasonic temperature were organized with optimization by the approach of response surface, and the verification test was did under the optimal technology condition. The effects of light irradiation, pH, metal ion and food additive on the stability of pigment of purple sweet potato extracted by ultrasonic were discussed. Results show as follows:1. Differernt digestion methods has strong effect in the measurement of metal ions, the contents of K, Ca, Na, Mg, Zn, Fe, Cu, Mn, Pb, Cr, Cd in sample treated by wet digestion method were16896.36、2003.56、152.13、1032.15、138.92、90.67、9.94、1.98、1.96and1.53μg·g-1while the corresponding elements content treated by dry ashing method were15058.04、966.65、129.71、1100.96、107.11、72.30、7.35、4.32、2.04、1.38and1.46μg·g-1. The method of wet digestion is in favor of the sample’s oxygenolysis, The addition standard recovery was96.14%～104.31%and precision of measurement was0.12%～3.56%, it shows the method adopted here is accurate, reliable and can be regarded as a method for measuring metal ion in purple sweet potato.2. The analytical results of Na、Ca、Mg、Mn、Cu、K、Zn、Fe、Cr、Cd and Pb Solanum Muricatum from different habitats respectirely were164.82、2273.14、1287.95、5.27、10.60、23558.10、154.88、87.57、2.10、2.67、2.19,125.79、877.65、1424.14、5.24、8.25、20867.55、149.43、50.66、2.33、2.93、2.25and240.35、1413.83、1382.65、5.86、6.86、19844.45、153.75、135.74、1.97、2.25、2.09μg·g-1The results showed that recovery of standard addition was97.26%～104.82%, and the RSD(n=9) was0.10%-5.15%. The characteristic method is quick, simple and convenient, and the results are satisfactory.3. The extraction process is optimized by the response surface analysis method on the basis of single factor experiment. Results show the square of ultrasonic temperature.ethanol concentration, ratio of solid material with liquid and ultrasonic time has strong significance in the extraction of pigment of purple sweet potato(P<0.0001), it shows factors of ethanol concentration, ratio of solid material to liquid, ultrasonic temperature and time has an effect of being reciprocal but not linear. The optimized condition is:ethanol concentration is72%, ration of solid to liquid is1:88, ultrasonic temperature is55℃and ultrasonic time is29min, on the above condition, the absorbance of purple sweet potato is about0.861, which has a theory difference of0.38%, the relative standard deviation (RSD)is0.38%, it indicates the process parameters are reliable by the method of resonance surface, and the extraction process for pigment of purple sweet potato can be stimulated.4. Compared with basic condition, pigment of purple sweet potato is more stable in acidic condition, heating resistance is better, and can be preserved at70℃, pigment of purple sweet potato is unstable to light irradiation, metal ions of Na+、K+、Mg2+、 Ca2+、Zn2+and low ion concentration of Fe3+and Cu2+has Copigmentation effect for pigment of purple sweet potato, which can be used as color protect agent for pigment. Al3+and high concentration of Fe3+and Cu2+are helpful in the degradation of pigment of purple sweet potato, sodium chloride and sucrose has hyperchromic effect on PP’s pigment, but citric acid has no effect for the stability of pigment of purple sweet potato. When the concentration of sodium benzoate, ascorbic acid and potassium sorbate is lower than0.01%,0.05%and0.05%, the stability of pigment of purple sweet potato is unchanged.5. Antioxidant activities in vitro of pigment from Purple sweet potato using petroleum ether, chloroform, ethyl acetate or n-butanol were evaluated by salicylic acid,2,2-diphenyl-1-picrylhydrazyl(DPPH·),eliminating of NO2-and ferric reducing/antioxidant power(FRAP)assays under the reference of vitamin C. Results indicated that antioxidant activities of extracts exhibited an obvious difference due to different evaluation methods. Similarly, the antioxidant activities of extracts with different polarities measured by the identical assay method also exhibited a significant difference.更多还原