尚待开发的一类天然食品抗氧剂─—黄酮类化合物

天然食品抗氧剂很受大众的信赖和欢迎，目前在食品中已经广泛使用的天然抗氧剂主要有生育酚、抗坏血酸及其衍生物。除此之外，还有一些天然化合物也具有抗氧作用，或许在不久的将来会在商业上开发利用。从最近的研究结果分析，其中最有希望的可能就是广泛存在于植物体中的黄酮类化合物（黄烷醇、异黄酮、黄酮、黄烷酮）以及黄酮类化合物的前体物（酚酸和儿茶酸等）。1黄酮类化合物黄酮类化合物是植物光合作用产生的一大类化合物，包括以黄酮（2-苯基色原酮）为母核的一类黄色色素和黄酮的同分异构体（异黄酮）及其还原产物（黄烷酮）。黄酮…     

网上酒屋

葡萄酒有无酒精 均有益健康 专家研究表明：去掉酒精的红葡萄酒，其健康成分犹在。这项研究测出了无酒精葡萄酒中所含的对人有益成分──血液中的焦儿茶酸。这种成分可以降低癌症和心脏病的危险性。试验志愿者有的领了两杯正规的红葡萄酒，有的领了两杯去掉了酒精的红葡萄酒。研究人员发现，在葡萄酒和无酒精葡萄酒之间，二者的焦儿茶酸没有明显的不同。 焦儿茶酸，也称黄烷类，有预防冠状心脏病和某些癌症的功效，也可以从新鲜水果和蔬菜中得到。黄烷类也有改善免疫系统的作用。低剂量饮葡萄酒对心脏病有好处已广为人知，现在证实了无酒精…     

椪柑、温州蜜桔果皮中酚类物质组成及抗氧化能力研究

目的:研究椪柑、温州蜜桔果皮中酚酸与黄烷酮糖苷组成及其抗氧化能力。方法:高效液相法测定椪柑、温州蜜桔果皮中九种酚酸和两种黄烷酮糖苷的组成与含量。用福林酚法、ABTS法和FRAP法对椪柑、温州蜜桔果皮甲醇提取液抗氧化能力进行评价。结果:柑橘果皮中可溶酯化酚酸部分所占比例最大,肉桂酸型酚酸是柑橘皮中的主要酚酸,且主要以酯化形式存在,其含量排列顺序一般为:阿魏酸>对香豆酸>芥子酸>咖啡酸。温州蜜桔果皮中有较高总酚酸含量(p<0.05)。椪柑果皮主要含橙皮苷,温州蜜桔果皮含橙皮苷和少量柚皮芸香苷。温州蜜桔果皮中总黄烷酮糖苷含量高于椪柑(p<0.05)。总的来说椪柑果皮提取液抗氧化活性略高于温州蜜桔。结论:HPLC测定柑橘皮中酚酸与黄烷酮糖苷可取得良好结果,抗氧化实验表明柑橘皮具有一定的抗氧化能力。     

举步艰难的非营养型甜味剂——二氢查耳酮(Dihydrochalcone)

0 引言三十多年前,人们首次从柑桔黄烷酮、柚苷和新橙皮苷中获得具有甜味的二氢查耳酮。从此,人们合成了大量的该甜味剂的衍生物,其中有些只是在结构上作了些微小的改变,有些则作了较大的改变。所有这些,都是为了进一步了解其结构与风味的关系,或是为了提高质量、提高溶解度及降低毒性等。从实用的观点来看,一种新合成的     

石榴汁中部分多酚类物质的分离鉴定

目的:分离鉴定天然石榴汁中主要多酚类物质.方法:采用乙酸乙酯、正丁醇萃取多酚类物质,并应用液质联用分析方法,对其有关成分进行鉴定.结果:初步分析结果表明,石榴汁中含有鞣花酸、石榴素、芹菜配基、芹菜配基-7-O-β-D-吡喃葡萄糖苷、芦丁、3,3\,4',5,7-五羟基黄烷酮、3,3',4',5,7-五羟基黄烷酮-6-D-吡喃葡萄糖苷.结论:石榴汁中多酚类物质含量丰富,有必要进行深入研究,以明确其主要功能成分.     

柑橘香橙素生成途径关键酶黄烷酮-3-羟化酶特性分析及原核表达

香橙素是柑橘类黄酮的重要组成,黄烷酮-3-羟化酶是香橙素生成途径中的关键作用酶。对黄烷酮-3-羟化酶的特点进行总结与分析并在大肠杆菌中进行表达。首先从NCBI数据库筛选了来自柑橘、陆地棉、玉米、水母雪莲和欧芹的5种f3h,对其进行理化性质、蛋白质二三级结构、序列比对等生物信息学分析并以大肠杆菌为宿主进行表达。发现5种来源的f3h,其基因开放阅读框为1032~1119 bp,编码343~372个氨基酸,蛋白分子质量为38.89~41.45 kDa,理论等电点在5.43~5.96,且不同物种F3H的理化性质、结构域和蛋白质结构也有一定的相似性。通过构建大肠杆菌表达体系发现:黄烷酮-3-羟化酶均能进行原核表达,除去来源于水母雪莲的F3H未检测到香橙素的生成,其余4种F3H均能将柚皮素转化为香橙素且产物生成量不同,其中ZmF3H生成量最高达20.12 mg/L。     

有“第七类营养素”之称的多酚类物质

在许多天然植物中含有黄酮类化合物（黄酮、异黄酮、黄酮醇、黄烷酮、黄烷醇、花色素苷等）、绿原酸、没合子酸和鞣花酸等多酚类单体及其衍生物,以及花色素原、没食子单宁、鞣花单宁等低聚或多聚类多酚。这些物质都有一定量的Ｒ·ＯＨ基,能形成有抗氧化作用的氢自由基（Ｈ·）,以消除超氧阴离子（Ｏ_２~－·）和羟自由基（ＯＨ·）等自由基的活性,从而保护组织免受氧化作用的损害,以及提高免疫功能、抗癌、抗衰老等作用。因此被称为是“第七类营养素”。 本文介绍了部分国际上市售的多酚类制品,包括甘草油性提取物、洋葱提取物、芸香普及其酚解物、大豆多酚、杨梅提取物、蓝莓提取物、葡萄籽提取物、生苹果提取物、松树提取物、月见草提取物、紫地丁提取物、甜菜多酚等,它们的基本功能和市场情况     

白藜芦醇在大鼠体内的吸收代谢分析

目的:高效液相色谱及气质联用法同时分析大鼠血浆和尿中白藜芦醇及白藜芦醇苷含量。方法:6w龄Wistar大鼠10只,适应性喂养1w后,分装于10个代谢笼中。实验前禁食10h,按体重灌胃给予大鼠50mg/kg白藜芦醇。高效液相色谱法检测大鼠血浆和尿中白藜芦醇及白藜芦醇苷的含量,并通过气质联用仪探索性分析不同时间血浆中代谢产物的种类。结果:白藜芦醇及白藜芦醇苷在0~10mg/L浓度范围内线性较好,其R2分别为0.9995及0.999 6。白藜芦醇灌饲1h后血浆中白藜芦醇浓度达到最大值,约4.79μg/m L,而白藜芦醇苷则到3h后才达到峰值,且其浓度达到白藜芦醇原型含量的5倍,约23.78μg/m L。白藜芦醇及其糖基化衍生物可在白藜芦醇摄入后24h内经尿液大量排泄到体外,排泄率超过摄入量的一半,其中原型占90%以上。气质联用分析进一步发现,机体摄入白藜芦醇3h后血浆中代谢物种类及含量均达到峰值。结论:白藜芦醇进入大鼠体内后在血浆中主要以衍生物形式存在,且代谢主要在摄入后前3h内,摄入后24h内主要以原型形式经尿液排出。     

黄酮类化合物的保健作用

黄酮类化合物(Flavonoids),又称生物类黄酮(Bioflavonoids),早期是指具有乙一苯基吡喃酮结构的一类黄色素,现指具有色酮环与苯环为基本结构的一类化合物的总称。可以分类为:黄酮类、黄酮醇类、异黄酮类、黄烷酮类等,广义的范围还包括查耳酮、嗅酮、异黄烷酮、双黄酮(Biflavonoids)及茶多酚(儿茶素的结构、性质及作用与类黄酮相似,也可归于黄酮类化合物中),其中黄酮醇是重要的一类。一、黄酮类化合物的摄入量及在食物中的含量(一)类黄酮在部分食物中的含量果蔬中黄酮类化合物几乎以配糖体形式存在,且含量较低,如洋葱、土豆、包心菜、芹菜、…     

生物类黄酮在贮藏加工中的变化

生物类黄酮(Bioflavonoids),即黄酮类化合物,属植物次生代谢产物,广泛分布于豆类、谷类、水果、蔬菜、啤酒、果酒以及许多药用植物中。从其结构上看,属于γ-吡喃酮的衍生物,依据其C环的饱和度和B环的连接位置可将黄酮类化合物分为黄酮(flavones)、黄酮醇(flavonols)、黄烷酮(flavanones)、异黄酮(isoflavones)、查尔酮(chalcones)等多种化合物。 现代医学和大量的流行病学调查结果显示,生物类     

薏苡仁油在不同存放条件下的氧化与氧化稳定性

薏苡仁油富含不饱和脂肪酸,具有较高的营养与药用价值。以酸价和过氧化值为指标对不同温度、光线、空气和抗氧化剂存放条件下的薏苡仁油进行氧化稳定性研究。结果表明：温度、光线和空气均可加速薏苡仁油的氧化,其中温度对薏苡仁油的氧化影响最大;添加抗氧化剂可明显提高薏苡仁油的稳定性,其抗氧化效果VE 强于TBHQ。     

Inhibition of β-carotene degradation in oil-in-water nanoemulsions: Influence of oil-soluble and water-soluble antioxidants

The utilisation of carotenoids as functional ingredients (pigments and nutraceuticals) in many food and beverage products is currently limited because of their poor water-solubility, high melting point, chemical instability, and low bioavailability. This study examined the impact of antioxidants on the chemical degradation of β-carotene encapsulated within nanoemulsions suitable for oral ingestion. β-Carotene was incorporated into oil-in-water nanoemulsions stabilized by either a globular protein (β-lactoglobulin) or a non-ionic surfactant (Tween 20). Nanoemulsions were then stored at neutral pH and their physical and chemical stability were monitored under accelerated stress storage conditions (55 °C). β-Carotene degradation was monitored non-destructively using colour reflectance measurements. The rate of β-carotene degradation decreased upon addition of water-soluble (EDTA and ascorbic acid) or oil-soluble (vitamin E acetate or Coenzyme Q10) antioxidants. EDTA was more effective than ascorbic acid, and Coenzyme Q10 was more effective than vitamin E acetate. The utilisation of water-soluble and oil-soluble antioxidants in combination (EDTA and vitamin E acetate) was less effective than using them individually. Emulsions stabilized by β-lactoglobulin were more stable to colour fading than those stabilized by Tween 20. These results provide useful information for designing effective nanoemulsion-based delivery systems that retard the chemical degradation of encapsulated carotenoids during long term storage.     

Commercial antioxidants control lipid oxidation in mechanically deboned turkey meat

Effects of commercial rosemary antioxidants on oxidative stability of mechanically deboned turkey meat (MDTM) compared with Trolox C (vitamin E), ascorbic acid (vitamin C) and control without antioxidant were investigated. Antioxidants were added to meat at three levels. Thiobarbituric acid (TBA) assay and dynamic headspace gas chromatography were used to assess the effects of commercial antioxidants on lipid stability of MDTM during 7 months of frozen storage. Increased levels of TBA-reactive substances (TBARS) and volatile carbonyl compounds were noticed in all meat samples during storage, however most distinctly in meat without antioxidants. Retarding effect of antioxidants on the development of oxidation depended on the level and type antioxidants. Trolox C-a water soluble, synthetic derivative of vitamin E possessed the greatest antioxidative activity reflected by the lowest values of TBARS and volatile compounds. Ascorbic acid was less efficient than Trolox C and Biolox HT-W (rosemary), but more potent than most rosemary extracts in suppressing lipid oxidation especially in the long term frozen storage MDTM. The DPPH() method confirmed that antioxidant activity depends on the concentration of active compounds present in the samples available to scavenge the free radicals formed during the storage period. Supplementation of MDTM with antioxidants could be an alternative method to prevent oxidative degradation of the meat during frozen storage when vacuum packaging is not practical.     

Inhibition of cholesterol oxidation in marinated foods as affected by antioxidants during heating

Chinese marinated foods rich in cholesterol, such as eggs and pork, can be susceptible to formation of carcinogenic cholesterol oxidation products (COPs) during prolonged heating. The objectives of this study were to compare the effects of various antioxidants on the inhibition of COPs in marinated eggs, pork and juice. The various COPs in marinated food samples were analyzed by a GC–MS technique. The incorporation of antioxidants, vitamin C, vitamin E, BHA and trolox were all effective in inhibiting COPs formation, with vitamin C being the most pronounced in marinated eggs, and BHA in marinated pork and juice. The inhibition effect increased with increasing levels of BHA and trolox. However, vitamin E was more effective at a low level (0.02%) than at a high level (0.1%), probably because of prooxidant activity of the latter. The same phenomenon also occurred for 0.1% vitamin C in marinated eggs, but a reversed trend was observed in marinated pork and juice. The residual amounts of each antioxidant in marinated eggs, pork and juice were also determined by HPLC.     

Antioxidant effects of solvent extracts from the dried jujube (Zizyphus jujube) sarcocarp,seed, and leaf via sonication

Antioxidant effects of extracts from sarcocarp, seed, and leaf of dried jujube (Zizyphus jujube) were investigated. The highest amount of flavonoids and polyphenol was found in 80% methanol leaf extract at value of 43.04±0.34 and 324.75±6.01 mg/g, respectively. For 2,2′-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS) radical scavenging activity analysis at a concentration of 1,000 μg/mL, 70% ethanol seed extract (94.76±0.23%), and 80% methanol leaf extract (95.46±0.14%) were observed to have higher activity than those of controls, such as butylated hydroxyl anisole (BHA) (89.60±0.00%), butylated hydroxyl toluene (BHT) (84.07±0.50%), vitamin C (89.27±0.12%), and vitamin E (88.53±0.12%). All solvent extracts from leaf showed higher ABTS radical scavenging activity (over 98%) than those of controls with their activity values around 94% (500 g/mL). All extracts from sarcocarp and seed showed superoxide dismutase (SOD)-like activity of 24.46–34.84% on the concentrations (100–1,000 g/mL), and 80% methanol leaf extract showed the highest activity (43.66±0.37%) among samples. These results indicate that sarcocarp, seed of dried jujube are all excellent antioxidants, and especially leaf showed higher antioxidant effect than those of vitamin C and E.     

3种天然抗氧化剂对栀子果油氧化稳定性的影响

采用Schaal烘箱法,以过氧化值为指标,研究了3种天然抗氧化剂(维生素E、茶多酚、迷迭香提取物)以及2种增效剂(V_C和柠檬酸)对栀子果油氧化稳定性的影响。结果表明:3种天然抗氧化剂均能不同程度提高栀子果油的氧化稳定性,其中迷迭香提取物的效果最佳;柠檬酸和V_C对迷迭香提取物均表现出良好的抗氧化协同作用,且V_C对迷迭香提取物的协同作用明显优于柠檬酸;添加0.06%迷迭香提取物+0.02%V_C复合抗氧化剂的栀子果油的氧化稳定性明显优于添加0.005%TBHQ的栀子果油。     

葡萄籽低聚原花青素体外抗氧化活性研究

以实验室分离纯化得到的葡萄籽低聚原花青素为研究对象,水溶性维生素E和维生素C为对照,分别考察葡萄籽低聚原花青素对DPPH自由基、ABTS自由基、超氧阴离子自由基（O2-·）的清除能力以及铁离子还原能力（FRAP）。结果表明,葡萄籽低聚原花青素对DPPH自由基、ABTS自由基以及超氧阴离子自由基具有较高的清除能力,IC50值分别为23.52 μg/mL、51.38 μg/mL和684.46 μg/mL,具有较高的还原能力,且均优于对照水溶性维生素E。与维生素C相比,原花青素对ABTS自由基的清除能力以及还原能力均优于维生素C,两者DPPH自由基的清除能力相当,原花青素和水溶性维生素E在极低质量浓度（0.05～1.00 μg/mL）范围内,对超氧自由基具有清除能力,清除率为30%～40%,随着质量浓度的增加,维生素C的超氧阴离子自由基清除能力优于葡萄籽低聚原花青素。     

The scavenging capacity and synergistic effects of lycopene, vitamin E, vitamin C, and β-carotene mixtures on the DPPH free radical

The biological activity of lycopene can be enhanced by the presence of these other active antioxidants such as β-carotene, vitamin E, and vitamin C. Since many of these natural antioxidants are consumed together in foods, the potential for synergistic interactions is high in the human diet. The aim of this study was to determine what concentrations and combinations of antioxidants among lycopene, vitamin E, vitamin C, and β-carotene are capable of producing synergistic antioxidant effects, based on tomato-based food products. Solutions of the scavenging capacities of lycopene, vitamin E, vitamin C, and β-carotene, alone and in different combinations were measured using the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Three different levels of each antioxidant were used. A comparison of the scavenging capacity (antioxidant activity) of the combinations of antioxidants to the arithmetic sum of the scavenging capacities of the individual antioxidants was used to calculate the synergistic effects (SEs) between the antioxidants. The results showed that the mixture that had the highest SEs (P<0.01) was the solution combining lycopene (15 μmol/L), vitamin E (5.0 μmol/L), vitamin C (0.16 μmol/L), and β-carotene (10.83 μmol/L). The results suggest that the antioxidant property of this combination was substantially superior to the sum of the individual antioxidant effects, and these interactions can enhance the antioxidant effectiveness of natural antioxidants. The results could guide in the formulation and development of functional food products that have high antioxidant potential.     

葡萄籽提取物对葵花籽油抗氧化活性的研究

研究葡萄籽提取物对葵花籽油的抗氧化性能,实验证实葡萄籽提取物对油脂氧化有很好的抑制作用。在油脂中葡萄籽提取物的抗氧化性强于Vc、VE,预示其在粮油食品中具有广阔的应用前景。     

不同提取方式茶叶籽油脂肪酸及V_E组成分析与比较

以脱壳茶叶籽为原料,分别采用超临界CO2选择性萃取、压榨法及索氏法从茶叶籽中提取茶叶籽油,采用国标方法分析了不同提取方式得到的茶叶籽油的脂肪酸组成及VE组成。结果表明:采用三段式超临界CO2选择性萃取,不同萃取阶段得到的茶叶籽油脂肪酸组成存在一定变化规律,随着萃取压力及温度的升高,超临界CO2萃取出部分微量脂肪酸,包括:C14∶0、C16∶1、C20∶0,而这些脂肪酸在采用压榨法及索氏法提取得到的茶叶籽油中未检出。茶叶籽油中VE以α-VE为主,采用三段式超临界CO2选择性萃取茶叶籽油,VE主要在第一阶段被萃取出来,后呈逐段降低趋势,而且第一阶段茶叶籽油中VE含量高于压榨法及索氏法。