洋葱皮中黄酮化合物的超声提取与光谱分析

采用超声波法从洋葱皮中提取黄酮类化合物并探讨出最佳提取条件,建立了洋葱皮中黄酮化合物的光谱分析方法.实验结果表明:此光谱分析法的回收率为99.6%～102.1%,变异系数小于0.18%。     

洋葱皮中黄酮类物质的提取及分离纯化研究

采用超声波辅助法提取洋葱皮中黄酮类物质,通过柱层析等方法进行分离纯化,利用高效液相色谱对黄酮类物质进行检测,在超声波辅助萃取洋葱皮中总黄酮的研究中,确定乙醇浓度80%、料液比1∶10、超声时间20min条件下对总黄酮提取率最高。获得总黄酮物质后采用萃取、聚酰胺柱层析进行分离纯化,获得不同浓度乙醇洗脱组分,建立HPLC方法为进样量5μL、检测波长360nm、甲醇∶水（含0.1%冰乙酸）=45∶55、柱温为室温。分离纯化中得到结晶,通过质谱、核磁共振鉴定此晶体物质为槲皮素。     

富黄酮洋葱酒中黄酮类化合物稳定性研究

目的研究不同因素对洋葱酒中总黄酮化合物的影响。方法以富黄酮洋葱为试验材料,分别测定温度、p H、氧化剂、还原剂、常用的食品添加剂及金属离子对洋葱发酵酒的黄酮含量影响。结果低温对洋葱黄酮影响不大,升高温度可能导致黄酮分解;p H对黄酮影响较大,应尽可能在酸性范围内贮存富黄酮洋葱酒;洋葱黄酮对氧化还原剂较稳定,具有良好的抗氧化能力,但还原剂可能导致黄酮含量减小,应避免接触;在不同浓度的食品添加剂中,黄酮含量较稳定,可以添加常见添加剂调整富黄酮洋葱酒风味;金属离子对其影响较大。结论本研究优化的储藏条件为富黄酮洋葱酒的开发与保存提供了方法与依据。     

洋葱中黄酮类化合物的提取与测定

采用乙醇提取洋葱中的黄酮类化合物,用紫外-可见分光光度法测定提取的黄酮类化合物的质量。考察乙醇浓度、料液比、提取时间、提取温度对黄酮类化合物提取量的影响。结果表明,测定波长为504 nm,芦丁检测浓度在0.080 mg/mL~0.400 mg/mL范围内与吸收度线性关系良好(R2=0.997 4);用乙醇提取洋葱中黄酮类化合物的工艺条件为乙醇浓度60%,料液比1∶18(g/mL),提取时间2.5 h,提取温度77℃。在此工艺条件下,从6.00 g洋葱中提取黄酮类化合物的量为25.40 mg。     

洋葱中黄酮类化合物的分布及其抗氧化活性的研究

洋葱是黄酮类化合物含量较高的蔬菜之一,本研究对新疆产的红皮洋葱、黄皮洋葱和白皮洋葱等3个主要的洋葱品种分别采用浓度为95%和60%的乙醇溶液提取其中的黄酮类化合物,并比较了各种提取物对羟基自由基和DPPH自由基清除能力。结果表明,三个品种中的黄酮类化合物的含量以红洋葱最高,黄洋葱次之,白洋葱的含量最低,洋葱提取物的抗氧化能力与其中的黄酮类化合物的含量呈正相关关系。     

红黄紫洋葱皮中黄酮含量的测定及比较

采取硝酸铝-亚硝酸钠法分别测定并比较了上海红皮洋葱、日本黄皮洋葱和北京紫皮洋葱皮中的黄酮含量.结果表明,不同品种洋葱皮中总黄酮类含量有较大差异,北京紫皮洋葱皮总黄酮类含量最高,上海红皮洋葱皮次之,日本黄皮洋葱皮黄酮类含量最低,分别为:46.7,40.1,29.9 mg/g.     

洋葱中黄酮化合物的提取与光谱分析

采用超声波法从洋葱中提取黄酮类化合物并探讨了最佳提取条件,建立洋葱中黄酮化合物的光谱分析方法。实验结果表明:此光谱分析法的回收率为99.6%～102.1%,方法的准确度与精密度均较高。     

洋葱皮萃取物中黄酮类化合物的分析研究

本文对洋葱皮萃取物中黄酮类化合物的成分及含量进行了分析研究．从显色反应、紫外光谱、薄层色谱的分析结果表明，洋葱皮萃取物中黄酮类化合物的主要成分为游离的槲皮素及其衍生物。HPLC定量分析结果为萃取物中含游离槲皮素31．2％，总黄酮44．6％。     

洋葱中黄酮类化合物的提取方法的研究

目的：本文通过探究洋葱中黄酮类物质提取方法，确立提取方法的最优方案，通过纵向对比得出最佳提取方案。方法：热水浸提法、乙醇浸提法和酶解提取法。结果：酶解提取法提取效率最高；最佳提取工艺：酶解PH=5、酶解温度40℃、酶量2.7‰、酶解时间70min。在此工艺条件下，洋葱黄酮类物质质量可达到 5.8649 mg/g。结论：通过对三种方法提取效率进行纵向对比，确定酶解提取法为最佳提取方法。     

洋葱黄酮类化合物的水提工艺条件研究

采用水浸提法提取洋葱中的黄酮类化合物,用比色法测定洋葱中黄酮类化合物的含量,并对黄酮类化合物提取过程中各因素对收率的影响情况作了研究,其影响的主次顺序为料液比>浸提温度>浸提时间。     

洋葱皮黄酮微胶囊技术研究

通过制备洋葱皮黄酮微胶囊,以提高洋葱皮黄酮的稳定性。实验以β-环糊精为壁材,研究了分子包埋法制备微胶囊工艺中不同因素对微胶囊化包埋率的影响。结果表明:芯材与壁材的最佳配比为1∶11.49,搅拌时间60.6min,搅拌温度61℃。在此条件下,产品微胶囊化效率达到41.26%。     

Food content, processing, absorption and metabolism of onion flavonoids

The question as to how far the development of chronic diseases in humans depends on diet still remains open. Simultaneously, epidemiological studies suggest the consumption of a flavonoids rich diet might decrease the risk of degenerative changes and certain diseases. The intake of this group of compounds as to quality and quantity depends on dietary habits and a widespread presence of quercetin in the diet makes this compound one of the key factors. Onion, one of the richest and most common quercetin sources, was particularly often studied in different aspects. Quercetin is present in onion mainly as glycosides, of which the distribution within the onion bulb changes in onion processing, and biological activities attracted a lot of attention. Especially antioxidative activity demonstrated in vitro was initially associated with most of the beneficial effects of quercetin on the human body. However, after ingestion quercetin undergoes extensive metabolism and microbial action resulting in its altered or degraded structure; therefore, most of the effects shown in in vitro experiments with the pure compound cannot be directly extrapolated to in vivo systems. Yet, this does not mean that quercetin simultaneously loses its positive impact on consumer health. Even after being metabolized it may still affect the redox balance by inducing antioxidative and detoxifying enzymes or compounds which may be involved in sustaining homeostasis.     

Antimicrobial and antioxidant activity of crude onion (Allium cepa,L.) extracts

Antioxidant and antimicrobial activity of the ethyl acetate and water subfractions of methanolic extracts of three Spanish onion varieties were assayed. Flavonoids were mainly present in ethyl acetate subfraction being 34.92 ± 0.75, 7.95 ± 0.16, 0.38 ± 0.01 μmol of rutin eq. g^?1 D.W. and its antioxidant capacity was 74.86 ± 1.77, 24.59 ± 0.67, 4.55 ± 0.44 μmol Trolox g^?1 D.W. of Grano de Oro, Fuentes de Ebro and Calçot de Valls varieties, respectively. The antimicrobial activity of flavonol standards and onion extracts was evaluated against some food spoiler microorganisms. Quercetin and kaempferol were inhibitory against gram positive bacteria such as Bacillus cereus, Staphylococcus aureus, Microcroccus luteus and Listeria monocytogenes. Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa were less sensible to the antimicrobial effect of both flavonol standards and Candida albicans was totally resistant. Among the onion extracts tested only ethyl acetate subfraction showed antimicrobial inhibition.     

新疆药桑叶中黄酮类化合物的分离与鉴定

采用色谱分离技术从药桑叶醇提物的乙酸乙酯萃取部分分离黄酮类化合物,通过核磁共振（NMR）和高效液相-串联质谱（HPLC-MS-MS）鉴定其结构。分离得到四个黄酮类化合物,结构表征为芦丁（1）、槲皮素-3-O-葡萄糖苷（2）、金丝桃苷（3）、山奈酚-3-O-β-D-吡喃葡萄糖（4）。其中化合物（3）、（4）首次从新疆药桑叶中分离得到。      

Radical scavenging compounds in onion skin

Two major flavonols (F_I and F_II) in onion skin were isolated. According to the ultraviolet–visible absorption spectra, F_I and F_II fractions were thought to be 3,5,7,3′-OH and 3 (5),7,3′,4′-OH of flavonol, respectively. After acid hydrolysis of the two fractions, F_I was found to consist of quercetin and glucose, but F_II only contained quercetin. F_I and F_II were confirmed by fast atom bombardment as quercetin 4′-glucoside and quercetin, respectively. The F_I and F_II fractions exhibited potent radical scavenging activity against DPPH, superoxide anion (O₂·^-) , and hydroxyl (·OH) radicals.     

三种洋葱营养成分分析

对三种洋葱的主要营养成分、矿物质和黄酮类化合物含量进行分析研究,并探讨黄酮类化合物含量与抗氧化的关系。三种洋葱中水分含量为88.3%～92.7%,碳水化合物为7.73%～8.56%,蛋白质为1.12%～1.71%,脂肪为0.23%～0.41%,其中,白皮洋葱的脂肪含量较高,适合作为提取洋葱油的原料。三种洋葱中黄酮类化合物含量为592.3～913.2mg/kg,紫皮洋葱的黄酮类化合物含量最高,适合作为提取黄酮类化合物的原料,而且紫皮洋葱的产量较高,种植面积较大,很有开发前景;三种洋葱的黄酮类化合物含量与总的抗氧化能力没有相关性。三种洋葱矿物质元素组成相似,钾含量最高,铜含量最低。     

分光光度法测定火龙果茎中黄酮类化合物的含量

火龙果是仙人掌三角柱属多年生植物,其果具有丰富的营养价值,可作为水果直接食用,花也可以作为蔬菜,而火龙果茎却未被利用.本文研究了火龙果茎中黄酮类化合物的分离提取和测定方法.采用单因素实验和正交试验对黄酮类化合物的分光光度法测定条件和火龙果茎中黄酮类化合物的分离提取条件进行优化.实验结果表明,以芦丁为标样,黄酮含量在6.6444.8mg/L范围内服从比尔定律,回归方程为A=0.333ρ-5.14×10-3,相关系数R=0.9999;火龙果茎中黄酮类化合物的分离提取条件为:70%的乙醇溶液为提取溶剂,料液比为1 : 40,提取温度为75℃,提取时间3h.方法回收率为96.1%102.2%,相对标准偏差(RSD)为3.3%(n=5).火龙果茎干品中黄酮类化合物的含量为0.49%.