甘蔗抗氧化物质的提取与分离

实验中以简单可靠DPPH法作为抗氧化活性的评价方法，分别选择D201，D204，D301，D750等树脂，以不同浓度比例的碱盐溶液以及乙醇作为洗脱剂，对甘蔗抗氧化物质的提取工艺进行了研究。结果表明，当选用D204大孔吸附树脂，用碱性NaCl作为洗脱液时，可以使提取物抗氧化活性达到最高。在此提取条件下对甘蔗制糖过程中的多种原料进行活性物质提取，发现均具有良好的抗氧化活性，同时，也发现制糖终产物废蜜的抗氧化能力也较高。     

DPPH法测甘蔗提取物抗氧化活性研究

本研究对甘蔗制糖过程中的各种原料进行活性物质的提取，并用DPPH（二苯代苦味酰基自由基）法测定其抗氧化活性，同时探讨了pH、加热温度、加热时间对自由基清除率的影响。结果表明各种原料均具有较强的抗氧化活性；pH值对抗氧化活性影响很大，而加热时间温度对抗氧化活性无显著影响。初步推断该活性物质属酚类。     

紫皮甘蔗天然红色素功能活性研究

从紫皮甘蔗中提取甘蔗红色素,研究该色素对超氧阴离子自由基、羟自由基、DPPH 自由基及NO2 的清除作用,以及在动物油和植物油中的抗氧化能力,以此来评价红色素的功能活性。结果表明：甘蔗红色素对超氧阴离子自由基、羟自由基和DPPH 自由基均有良好的清除作用,对NO2 的清除作用不太显著;在油脂中具有一定的抗氧化能力,在猪油中的抗氧化能力强于在豆油中的抗氧化能力。     

葡萄皮色素提取工艺的优化与抗氧化活性的分析

目的研究优化葡萄皮色素的提取工艺及其抗氧化活性。方法用正交实验优化影响色素提取率的主要因素；用DPPH＊自由基清除法研究葡萄皮色素的抗氧化活性及抗氧化能力的相关物质。结果最佳提取工艺为料液比1：5，温度40℃，时间30min，乙醇浓度50％，超声波提取色价高于微波提取。葡萄皮色素对自由基DPPH＊有一定的清除作用。结论确定了葡萄皮色素的最佳提取工艺；葡萄皮色素有较强的抗氧化活性。     

天然红心鸭蛋中色素物质的提取研究

探讨了天然红心鸭蛋中色素物质的提取及抗氧化活性。结果表明:天然红心鸭蛋中的红色物质呈现类胡萝卜素的特征反应,故其色素中主要成分为类胡萝卜素类物质。以冻干红心蛋粉为原料提取红心蛋黄中的色素物质的最优提取条件为:以石油醚∶丙酮=2∶1为溶剂,温度4O℃,3次提取,每次提取时间60min,料液比为1∶4。     

葡萄皮色素提取工艺的优化与抗氧化活性的分析

目的 研究优化葡萄皮色素的提取工艺及其抗氧化活性.方法 用正交实验优化影响色素提取率的主要因素;用DPPH自由基清除法研究葡萄皮色素的抗氧化活性及抗氧化能力的相关物质.结果 最佳提取工艺为料液比1∶5,温度40,时间30 min,乙醇浓度50%,超声波提取色价高于微波提取.葡萄皮色素对自由基DPPH有一定的清除作用.结论 确定了葡萄皮色素的最佳提取工艺;葡萄皮色素有较强的抗氧化活性.     

荷叶膳食纤维抗氧化物质提取研究

荷叶经粉碎、乙醇提取两次、蒸发浓缩、石油醚脱脂、再次浓缩后，得到抗氧化活性物质粗产物，再进行定性实验，并研究了荷叶提取物粗黄酮在猪油中的抗氧化性．结果表明，用正交实验得出抗氧化物的最佳提取工艺为：浸提时间4h，浸提温度为70℃，加入乙醇的固液比为：1：20；从荷叶中得到抗氧化活性物质粗产物为19g／100g；抗氧化活性物质粗产物进行定性检验的反应，反应均呈一定颜色，表明其中含有黄酮类化合物；本实验提取过程步骤简单易行，所用溶剂成本较低，所得粗提物的抗氧化性也较强，对于荷叶中类黄酮的开发利用具有一定的实际意义。     

红枣色素中活性成分含量与抗氧化活性的相关性

为明确红枣色素抗氧化作用的物质基础,测定碱提、超声辅助碱提、酶-超声辅助碱提色素中总多酚、花色苷和总黄酮含量,采用还原能力、O-2·和DPPH·清除能力评价其抗氧化活性,并分析色素活性成分含量与抗氧化活性之间的关系。结果表明:不同方法提取色素活性成分含量存在显著差异(p0.05),以碱提色素最高;不同方法提取色素均具有较强抗氧化活性,且清除O-2·、DPPH·能力差异显著(p0.05);相关性研究显示总多酚、总黄酮含量与清除O-2·、DPPH·能力呈显著正相关(p0.05),花色苷含量与清除DPPH·(r=0.874)能力呈明显正相关,表明多酚和黄酮可能是红枣色素抗氧化作用的主要物质基础。     

市售有色糖中色素类物质的提取和抗氧化性评价

采用芳香族大孔吸附树脂分级提取市售有色糖中的色素,并测定其总酚含量。利用邻苯三酚自氧化法评价分级提取色素的抗氧化性,分析色素解吸液中总酚含量与抗氧化能力之间的相关性。结果表明:60%的乙醇对SD300芳香族大孔吸附树脂吸附解吸分离得到的色素中总酚含量最高;使用60%乙醇作解吸剂,市售有色糖色素中酚类物质含量大小顺序是糖蜜赤砂糖冰片糖黄冰糖,抗氧化能力由强到弱的顺序是糖蜜赤砂糖冰片糖黄冰糖。     

酱油渣所含抗氧化成分的价值

通过对各种大豆发酵食品的抗氧化性进行研究，发现豆酱中具有很强抗氧化能力的成分是o-二羟基异黄酮（ODD，其产生在接种和制曲过程中。人体内产生的活性氧自由基和自动氧化物质引起疾病、致癌和老化现象。利用食物中的抗氧化物质抑制氧化引起的不良反应，例如在食物中添加抗氧化物质，采用生物工程提高食物中抗氧化成分的含量等，有助于预防疾病。近年来发现酱油渣中含有的成分具有较强的生理活性，研究人员试图将其提取出来用于保健食品、化妆品以及医药等。     

Pressurized liquid extraction of flavonoids from spinach

ABSTRACT:  Pressurized liquid extraction (PLE) using water and a 70:30 mixture of ethanol and water over the temperature range of 50 to 190 °C was used to extract flavonoids from dried spinach. The total phenolic content, antioxidant capacity, color, and browning indices of the extracts were also evaluated. PLE using a 70:30 mixture of ethanol and water was more effective than water in extracting flavonoids from spinach. Flavonoids were effectively extracted over the temperature band of 50 to 130 °C with water and 50 to 150 °C with ethanolic solvent. Levels of total phenolics and ORAC values increased with increasing extraction temperature, indicating that flavonoids were minor contributors to antioxidant capacity at elevated extraction temperatures. Browning of ethanolic extracts correlated highly with ORAC values over the temperature range of 50 to 190 °C, and the ORAC values of the large molecular weight fraction (> 1000 Da) increased linearly over the temperature range, indicating that Maillard polymers were the major contributors to antioxidant capacity. The results illustrate that PLE temperatures of < 130 °C for water or < 150 °C for ethanolic solvent may be used to extract flavonoids, followed by a high temperature (> 170 °C) extraction to generate antioxidant-rich moieties.     

Chemical and economic evaluation of natural antioxidant extracts obtained by ultrasound-assisted and agitated bed extraction from jussara pulp (Euterpe edulis)

This work aimed to evaluate the influence of ultrasonic and agitated bed extractions on the chemical composition and manufacturing costs of extracts obtained from jussara (Euterpe edulis) pulp. The effects of extraction time (5–180 min), temperature (25–55 °C), ethanol concentration (0–90% in acidified water) and solvent/pulp ratio (5–30 mL/g) on the extraction yield, phenolic content, anthocyanin content, antioxidant capacity and manufacturing costs were assessed. The yields provided by the ultrasound-assisted and agitated bed extractions were not significantly different. The anthocyanins and phenolic compound yields were significantly affected by the extraction time, the ethanol concentration in water and the solvent/feed ratio, but not by the temperature. In general, the antioxidant capacity of the extracts displayed tendencies similar to the anthocyanin and phenolic compound yields. The production of crude extracts obtained by ultrasound and agitated bed extraction incurred greater manufacturing costs compared to the market prices of assai extracts.     

Physicochemical and phytochemical properties of cold and hot water extraction from Hibiscus sabdariffa

Hibiscus cold (25 °C) and hot (90 °C) water extracts were prepared in various time-temperature combinations to determine equivalent extraction conditions regarding their physicochemical and phytochemical properties. Equivalent anthocyanins concentration was obtained at 25 °C for 240 min and 90 °C for 16 min. Total phenolics were better extracted with hot water that also resulted in a higher antioxidant capacity in these extracts. Similar polyphenolic profiles were observed between fresh and dried hibiscus extracts. Hibiscus acid and 2 derivatives were found in all extracts. Hydroxybenzoic acids, caffeoylquinic acids, flavonols, and anthocyanins constituted the polyphenolic compounds identified in hibiscus extracts. Two major anthocyanins were found in both cold and hot extracts: delphynidin-3-sambubioside and cyanidin-3-sambubioside. In general, both cold and hot extractions yielded similar phytochemical properties; however, under cold extraction, color degradation was significantly lower and extraction times were 15-fold longer. PRACTICAL APPLICATION: Hibiscus beverages are prepared from fresh or dried calyces by a hot extraction and pasteurized, which can change organoleptic, nutritional, and color attributes. Nonthermal technologies such as dense phase carbon dioxide may maintain their fresh-like color, flavor, and nutrients. This research compares the physicochemical and phytochemical changes resulting from a cold and hot extraction of fresh and dried hibiscus calyces and adds to the knowledge of work done on color, quality attributes, and antioxidant capacity of unique tropical products. In addition, the research shows how these changes could lead to alternative nonthermal processes for hibiscus.     

Reutilization of mango byproducts: study of the effect of extraction solvent and temperature on their antioxidant properties

Mango biowastes, obtained after processing, contain large amounts of compounds with antioxidant activity that can be reused to reduce their environmental impact. The present study evaluates the effect of solvent (methanol, ethanol, acetone, water, methanol:water [1:1], ethanol:water [1:1], and acetone:water [1:1]), and temperature (25, 50, and 75 °C) on the efficiency of the extraction of antioxidants from mango peel and seed. Among the factors optimized, extraction solvent was the most important. The solvents that best obtained extracts with high antioxidant capacity were methanol, methanol:water, ethanol:water, and acetone:water (β-carotene test, antioxidant activity coefficient 173 to 926; thiobarbituric acid reactive substances test, inhibition ratio 15% to 89%; 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid ABTS(·+); and 2,2-diphenyl-1-picrylhydrazyl DPPH· scavenging, 7 to 22 and 8 to 28 g trolox equivalent antioxidant capacity [TE] per 100 g mango biowaste on a dry matter basis [DW]). Similarly, the flavonoid (0.21 to 1.4 g (+)-catechin equivalents per 100 g DW), tannin (3.8 to 14 g tannic acid equivalents per 100 g DW), and proanthocyanidin (0.23 to 7.8 g leucoanthocyanidin equivalents per 100 g DW) content was highest in the peel extracts obtained with methanol, ethanol:water, or acetone:water and in the seed extracts obtained with methanol or acetone:water. From the perspective of food security, it is advisable to choose ethanol (which also has a notable antioxidant content), ethanol:water, or acetone:water, as they are all solvents that can be used in compliance with good manufacturing practice. In general, increasing temperature improves the capacity of the extracts obtained from mango peel and seed to inhibit lipid peroxidation; however, its effect on the extraction of phytochemical compounds or on the capacity of the extracts to scavenge free radicals was negligible in comparison to that of the solvent. PRACTICAL APPLICATION: There are many antioxidant compounds in mango peel and seed, and they could be used as a natural and very inexpensive alternative to synthetic food additives. However, the conditions in which the antioxidants are extracted must be optimized. This work proves that conditions such as extraction solvent or temperature have a crucial impact on obtaining extracts rich in antioxidants from mango biowastes.     

Extraction kinetics modeling of antioxidants from grape stalk (Vitis vinifera var. Bobal): Influence of drying conditions

The use of antioxidant extracts obtained from natural products is highly relevant in the food, chemical and pharmaceutical industry. The mathematical analysis of the antioxidant extraction could contribute to a better understanding of the process and is fundamental for optimization tasks. However, the high complexity of natural matrixes makes modeling difficult. The main aim of this work was to model the antioxidant extraction process from grape stalk in order to quantify the influence of the previous drying operation on extraction kinetics. The antioxidant extraction kinetics for freeze dried and hot air dried samples at several temperatures (40, 55, 70, 85, 100 and 115 °C) were carried out, using the FRAP method to measure the antioxidant capacity in the extracts. A diffusion model was developed that took significant external resistance as well as the complex geometry of grape stalk into consideration. From the modeling results, the influence of the drying conditions on the antioxidant concentration of the dry stalk, the antioxidant effective diffusivity and the mass transfer coefficient were identified.     

Food antioxidant capacity determined by chemical methods may underestimate the physiological antioxidant capacity

Antioxidant capacity assays are of growing interest in the study of dietary antioxidant properties since they are able to analyse a complex mixture of antioxidants and its synergistic interactions. However, most of the antioxidant capacity assays in the literature are limited by the antioxidant extraction technique, since some antioxidants may remain associated in the extraction residues. The objective of this work was to compare an in vitro physiological procedure for antioxidant extraction with a methanol/acetone/water extraction (chemical procedure). Enzymatic digestions and in vitro colonic fermentations were used on solid plant foods daily consumed in the Spanish diet to estimate the total antioxidant capacity released during the entire digestion process. The in vitro physiological procedure yielded a higher antioxidant capacity than the chemical procedure (7000 and 900 μmol trolox equivalents measured by ABTS, respectively). Our results suggest that determination of antioxidant capacity in food chemical extracts may underestimate the real antioxidant capacity that may be in close contact with the intestinal lumen.     

不同超声频率对温州蜜柑皮总酚和抗氧化能力的影响

对比分析20、60、100kHz 3种超声频率条件下超声参数(超声时间、提取温度、超声能量)对温州蜜柑皮中总酚及抗氧化能力的影响。结果表明：3种超声频率作用下,随着超声时间、提取温度、超声能量的增加,总酚和抗氧化能力呈显著增加趋势,但是总酚和抗氧化能力的最佳超声条件是各不相同的。此外,60kHz的超声频率处理得到温州蜜柑皮提取物总酚和抗氧化能力均高于20、100kHz处理。超声处理后提取物中总酚和抗氧化性呈现出良好的相关性。在20、60、100kHz 3种频率作用下,15℃超声处理后,相关系数R2依次为0.8228、0.8354、0.8435;在30℃时,R2依次为0.7706、0.8735、0.8895;在40℃时,R2依次为0.8626、0.9248、0.8622;在3.2、8、30、56W的超声能量水平下,R2依次为0.9143、0.9958、0.7971,表明在低频超声范围内超声波技术能有效地增强温州蜜柑皮提取物的抗氧化性。     

Evaluation of antioxidative performance of tomato extracts obtained by different methods

BACKGROUND: Two extraction methods employing tetrahydrofuran and phosphate buffer (pH 7.4) respectively were used to process tomatoes. The antioxidant contents and antioxidative properties of extracts of four tomato cultivars were measured. To evaluate the overall antioxidative capacity of the tomato extracts, an antioxidative performance index (API) was used, defined as the average of four antioxidative assays, i.e. relative reducing power, ferrous ion‐chelating ability, 2,2‐diphenyl‐1‐picrylhydrazyl free radical‐scavenging activity and superoxide radical‐scavenging activity. RESULTS: A linear correlation between the total antioxidant content (TAC) and API of tomato extracts was found that was independent of the extraction method and tomato cultivar. CONCLUSION: The concept of representing multiple antioxidant activities by a single index is useful for evaluating the overall antioxidative capacity of antioxidants in tomatoes. Copyright © 2007 Society of Chemical Industry     

High antioxidant activity of coffee silverskin extracts obtained by the treatment of coffee silverskin with subcritical water

Coffee silverskin (CS) is a thin tegument of the outer layer of green coffee beans and a major by-product of the roasting process to produce roasted coffee beans. CS extracts obtained by the treatment of CS with subcritical water at 25-270°C were investigated for their antioxidant activity using hydrophilic oxygen radical absorption capacity (H-ORAC) and DPPH radical scavenging capacity assays. The antioxidant activity increased with increasing the extraction temperature and the highest activity was observed with the extracts obtained at 270°C. The H-ORAC and DPPH values of the extracts were 2629±193 and 379±36μmol TE/g of CS extract, respectively. High correlation (R=0.999) was observed between H-ORAC and DPPH values for the CS extracts. High correlation of the antioxidant activity was also observed with protein and phenolic contents in the extracts. The CS extracts could be useful as a good source of antioxidative materials.     

黑木耳花青素提取工艺的优化及其抗氧化活性研究

为探讨黑木耳中花青素类物质最优提取工艺,以花青素提取率为考察指标,以提取试剂、温度、时间和液料比为提取因素,单因素试验基础上设计正交优化试验,研究黑木耳中花青素的最佳提取工艺;进一步利用大孔树脂对花青素粗提物进行纯化,纯化产物经自由基清除试验和抗菌试验等评价其生理学活性。结果表明,黑木耳花青素最佳提取条件为:提取剂酸化乙醇、液料比20∶1(mL/g)、温度60℃、时间60 min,且花青素提取物的抗氧化能力明显高于等浓度抗坏血酸;同时黑木耳花青素提取物对大肠杆菌和金黄色葡萄球菌具有较好的抑制作用。