Effects of repeated frying on physicochemical characteristics,oxidative stress,and free radical scavenging potential of canola oil and ghee

The repeated use of cooking oils and ghee for the deep frying of food materials may affect their nutritional quality. The present study evaluated the effect of repeated frying on the physicochemical characteristics and antiradical potential of canola oil and ghee. The oil and ghee were used for frying of fish and chicken for 2, 4, 6, 8, and 10 frying cycles followed by the analysis of physicochemical, oxidative stress, and antiradical parameters. Regression analysis of the data showed a frying cycle-dependent significant linear increase in saponification (R² = 0.9507–0.9748), peroxide and acid values (R² = 0.956–0.9915), and malondialdehyde (MDA) production (R² = 0.9058–0.9557) of canola oil and ghee subjected to fish and chicken frying but exponential increase in saponification value (R² = 0.9778) and MDA production (R² = 0.7407) of canola oil and ghee used for fish frying. The increase in the number of frying cycles linearly decreased the iodine value (R² = 0.9781–0.9924), and 1, 1-diphenyl-2-picrylhydrazyl, hydroxyl, and 2, 2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging potential (R² = 0.9089–0.9979) of canola oil and ghee. Repeated frying in cooking oil and ghee increases oxidative stress and decreases their physicochemical and antioxidant qualities. Canola oil was comparatively more oxidative resistant than canola ghee. The regression equations derived from regression analysis will guide researchers to conduct similar types of univariate studies.     

Effect of bamboo oil on antioxidative activity and nitrite scavenging activity

The purposes of this study were to investigate the effects of the bamboo oil on antioxidative activity and nitrite scavenging activity in vitro and in vivo. When the bamboo oil concentration was increased from 10 to 90 μL/mL, the DPPH scavenging rate increased from 15.6 to 98.2%. However, at bamboo oil concentrations above 110 μL/mL, it was not increased. The superoxide anion radical scavenging rate increased from 54.8 to 89.1% when the bamboo oil concentration increased from 110 to 150 μL/mL. When the bamboo oil was incubated for 20 h, the linoleic acid scavenging rate was approximately 91.2%, similar to that of ascorbic acid. The glutathione production using bamboo oil in vivo was 59.0 μM/g of liver, which was about 6.5-fold higher than that of the control. In the case of the activities of glutathione peroxidase and catalase, they were 16.8 U/mg of protein and 295 KU/mg of protein, respectively, approximately 5.6-fold higher and 3.0-fold higher than that of the control. The nitrite scavenging activity was increased from 60.1 to 93.9% at pH of 1.2 when the saturation time was increased from 2 months to 8 months. However, at more than 10 months of saturation, this level was not increased. These results suggest that the bamboo oil of Phyllostachys nigra var. henonis can be used in bioactive and functional materials.     

Antioxidant activity of crude tannins of canola and rapeseed hulls

The antioxidant activity of crude tannins of canola and rapeseed hulls was evaluated by β-carotene-linoleate, α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, and reducing power assays. Crude tannins were extracted from three samples of Cyclone canola (high-tannin) hulls and Kolner, Ligaret, and Leo Polish rapeseed (low-tannin) hulls with 70% (vol/vol) acetone. The total phenolic content in crude tannin extracts ranged between 128 and 296 mg of sinapic acid equivalents per 1 g of extract. The ultraviolet spectra of methanolic solution of canola extracts showed two absorption maxima (282 and 309 nm), whereas those of rapeseed extracts exhibited a single maximum (326 nm). Crude tannins isolated from canola hulls exerted significantly (P<0.025) greater antioxidant activity than those from rapeseed in all three assays. The scavenging effect of all crude tannins, at a dose of 1 mg, on the DPPH radical ranged from 35.2 to 50.5%. The reducing power of Cyclone canola hull extracts on potassium ferricyanide was significantly (P≤0.0025) greater than that of rapeseed hull extracts, and the observed data correlated well (r=0.966; P=0.002) with the total content of phenolics present.     

筛选和评价天然抗氧化剂的方法-DPPH法

从植物中筛选和提取天然抗氧化剂是食品科学研究的热点,用于筛选抗氧化剂、评价抗氧化活性的方法也随之增多。DPPH法是普遍采用的方法之一,此法使用稳定的自由基DPPH筛选抗氧化剂、评价抗氧化效果。本文对DPPH法的原理、操作过程、表示测定结果的方法及该法的特点及应用进行了概括,并对影响测定结果的因素进行了探讨。     

不同果皮颜色高粱抗氧化活性研究

通过对6种不同果皮颜色高粱的总酚含量测定,以及其清除DPPH自由基和ABTS自由基能力评价,分析高粱果皮颜色对其总酚含量的影响;以及高粱总酚含量与其清除DPPH自由基清除能力和ABTS自由基清除能力之间关系。结果表明,高粱果皮颜色深浅不是其总酚含量高低的可信指标。高粱总酚含量越高,其清除DPPH自由基和ABTS自由基能力越强,总酚含量与DPPH自由基清除能力之间呈线性正相关,相关系数为0.883 1;总酚含量与ABTS自由基清除能力之间也具有线性正相关特性,相关系数是0.915 1。     

异形玉叶金花果实不同提取部位抗氧化活性研究

以乙醇为溶剂提取异形玉叶金花果实,经减压浓缩后,依次用乙酸乙酯和正丁醇进行萃取。用DPPH自由鼙的清除能力来评价两个部位的抗氧化活性。结果表明,己酸乙酯部位浓度为283．20μg/mL时自由基清除率大于50％,IC50=304．85μg／mL,正丁醇部位浓度为17760μg／mL．时自由基清除率大于50％,IC50-224．07μg／mL。正丁醇部位抗氧化能力比乙酸乙酯部位更好。     

Chromatographic separation of glucopyranosyl sinapate from canola meal

The compound 1-O-β-D glucopyranosyl sinapate (GPS), a phenolic glycoside, was separated from ethanolic extracts of defatted canola meal by a two-step chromatographic method. The first step involved Sephadex LH-20 chromatography with methanol as the eluting solvent. The solvent from the fraction containing GPS was evaporated, and glucopyranosyl sinapate was subsequently separated by a semi-preparative high-performance liquid chromatography method with an RP-18 column and a mobile phase consisting of water/acetonitrile/acetic acid (88∶10∶2, vol/vol/vol).     

Structure–activity relationship for dihydromyricetin as a new natural antioxidant in polymer

Dihydromyricetin (DMY), a natural product, was used as antioxidant in ethylene vinyl acetate copolymer (EVA) in our laboratory. Oxidation induction temperature (OIT) of EVA with the antioxidant of DMY and effect of pH on OIT was measured by means of differential scanning calorimeter (DSC). The mechanism on that antioxidation of DMY in EVA is produced on basis of determination of UV–Vis absorption, nuclear magnetic resonance (NMR) and the experiment of reacting the pyrogallic (PA) and DMY, respectively, with the DPPH. The result shows that the ortho‐trihydroxyl group (B ring) in DMY has mainly antioxidative activity and hydroxyl group of 7‐position (A ring) not only displayed reversibility to acidic or alkaline medium but also affected in some extent the antioxidative ability in EVA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Stability and radical‐scavenging activity of heated olive oil and other vegetable oils

The effect of heating at 180 °C on the antioxidant activity of virgin olive oil (VOO), refined olive oil (ROO) and other vegetable oil samples (sunflower, soybean, cottonseed oils, and a commercial blend specially produced for frying) was determined by measuring the radical‐scavenging activity (RSA) toward 1,1‐diphenyl‐2‐picrylhydrazyl radical (DPPH^?). The RSA of the soluble (polar) and insoluble (non‐polar) in methanol/water fractions of olive oil samples was also measured. The stability of heated oils was assessed by determining their total polar compound (TPC) content. VOO was the most thermostable oil. Total polar phenol content and the RSA of VOO heated for 2.5 h decreased by up to 70 and 78%, respectively, of their initial values; an up to 84% reduction in RSA of VOO polar and non‐polar fractions also occurred. Similar changes were observed in the RSA of ROO and its non‐polar fraction after 2.5 h of heating. The other oils retained their RSA to a relatively high extent (up to 40%) after 10 h of heating, but in the meantime they reached the rejection point (25–27% TPC). The results demonstrate that VOO has a remarkable thermal stability, but when a healthful effect is expected from the presence of phenolic compounds, heating has to be restricted as much as possible.     

Antiradical activity of extracts of almond and its by-products

Antioxidant activities of ethanolic extracts of whole almond seed, brown skin, and green shell cover were evaluated using different free radical trapping assays. Trolox equivalent antioxidant capacity assay revealed that the total antioxidant capacities of brown skin and green shell cover extracts were 13 and 10 times greater than that of the whole seed extract at the same extract concentration. The free radical-scavenging activity of extracts of brown skin and green shell cover also exceeded that of the whole seed. The scavenging activity of superoxide radical by different almond extracts ranged from 76 to 97% at 100 ppm and 85 to 99% at 200 ppm. The corresponding reduction of hydrogen peroxide concentration was 59–66% (100 ppm) and 86–91% (200 ppm). The hydroxyl radical-scavenging capacities at 100 and 200 ppm were 16 and 42% for whole seed, 57 and 100% for brown skin, and 40 and 56% for green shell extracts, respectively. A 100% scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was observed for brown skin and green shell extracts at 100 and 200 ppm concentrations, respectively, and whole seed extracts scavenged 21 (at 100 ppm) and 73% (at 200 ppm) of the DPPH radical.     

新型分子内复合抗氧剂清除自由基的性能

以DPPH?为研究对象,采用紫外-可见光分光光度计研究了新型分子内复合抗氧剂对自由基的清除能力,并与市售抗氧剂1076和BHT进行对比。结果表明,相同条件下,该新型分子内复合抗氧剂清除自由基的能力优于市售抗氧剂1076和BHT;且清除自由基的能力随抗氧剂浓度的增加而增大,随清除反应时间的延长先增大后趋于稳定。清除反应温度对清除能力影响不大,表明该清除反应的反应活化能较低,该清除反应可在室温下快速进行。熔体流变速率和氧化诱导期测得的结果也证实了新型分子内复合抗氧剂的抗氧化能力优于市售抗氧剂BHT和1076。     

ABTS•+ scavenging activity of polypyrrole,polyaniline and poly(3,4‐ethylenedioxythiophene)

Although many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS^?+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4‐ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as‐prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry     

Free radical scavenging activity of cellulase‐treated chitosan

Partially N‐acetylated chitosan was hydrolyzed by the cheap, commercially available, and efficient cellulase. The products, with different molecular weight, were comparatively investigated by GPC, FT‐IR, XRD, and NMR. The results show that the decrease of molecular weight led to transformation of crystal structure and increase of water‐solubility, but the chemical structures of residues were not modified. Superoxide anion radical and hydroxyl radical quenching assay were used for the evaluation of free radical scavenging activity of cellulase‐treated chitosan in vitro. Low molecular weight chitosan (LMWC3, M_w 1.7 × 10³) exhibited high scavenging activity against free radical. It scavenged 79.3% superoxide radical at 0.1 mg mL^?1. At 2.0 mg mL^?1, scavenging percentage of initial chitiosan, LMWC1 (M_w 27.3 × 10³), LMWC2 (M_w 5.9 × 10³), and LMWC3 (M_w 1.7 × 10³) against hydroxyl radical was 14.3%, 33.1%, 47.4%, and 65.9%, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

龙眼果皮不同方法提取物对自由基的清除作用

用超声波、微波、冷凝回流及常温浸泡4种方法,用φ(C2H5OH)=95%的乙醇提取龙眼果皮,分别得到超声波提取物(UE)、微波提取物(ME)、热提物(RE)和浸提物(DE)。然后采用二苯代苦味酰肼自由基(DPPH)法对不同质量浓度的各提取物进行了自由基清除实验。结果表明,龙眼果皮乙醇提取物对自由基有很强的清除作用,清除能力远远优于3,5-二叔丁基-4-羟基甲苯(BHT);不同的提取方法所得提取物对自由基的清除作用有显著差别,其中以ME的效果最佳,当其质量浓度为1.2 mg/mL时,最大清除率高达83.11%。     

Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin

Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.     

三种黄酮清除自由基活性的研究

为比较黄酮2、3位单双键不同及3'、4'邻位取代基不同对清除自由基活性的影响。采用UV-Vis光谱法测定了木犀草素、香叶木素及橙皮素对1,1-二苯基-2-三硝基苯肼自由基(DPPH·)、超氧阴离子自由基(O2-·)的清除作用。结果显示3种黄酮化合物对两种自由基都有一定的清除作用,清除效果随浓度的增大而增大。但对自由基清除能力表现为木犀草素远强于香叶木素、香叶木素与橙皮素无显著差别。说明具有B环3'、4'邻二羟基结构的黄酮清除自由基的能力明显强于具有B环3'羟基、4'甲氧基结构的黄酮;黄酮C环2、3位单双键不同对自由基清除能力影响不显著。     

帽蕊木抗氧化活性研究

用二苯代苦味肼基自由基(DPPH)、铁离子还原/抗氧化力测定法(FRAP)和2,2′-连氨-(3-乙基苯并噻唑啉-6-磺酸)二氨盐(ABTS)3种体外抗氧化活性分析方法,与阳性对照没食子酸丙酯(PG)、丁基羟基茴香醚(BHA)和二丁基羟基甲苯(BHT)比较,对帽蕊木进行了抗氧化活性评价。在帽蕊木叶和皮的6个提取物中,叶乙酸乙酯提取物清除DPPH和ABTS自由基的能力最强(IC50=2.24 mg/L和IC50=1.165 mg/L),强于阳性对照BHA(IC50=3.43 mg/L和IC50=1.675 mg/L)和BHT(IC50=18.79 mg/L和IC50=4.555 mg/L),弱于阳性对照PG(IC50=0.94 mg/L和IC50=0.885 mg/L);叶正丁醇提取物还原Fe3+能力最强(FRAP值=1 395.94μmol TE/g),皮正丁醇提取物次之(FRAP值=1 275.43μmol TE/g),都强于阳性对照BHT(FRAP值=238.11μmol TE/g),弱于阳性对照PG(5 159.97μmol TE/g)、BHA(2 573.96μmol TE/g)。结果表明,帽蕊木叶和皮的乙酸乙酯和正丁醇提取物都有很好的抗氧化活性,并且帽蕊木叶的活性强于茎皮。该文报道工作的新颖性已为河南大学图书馆2008年8月25日出具的第CX 2008007号《科技查新报告》所证实。     

Optimization of Microwave Assisted Extraction of Antioxidant Extract from Garcinia pedunculata Robx.

The process of microwave assisted extraction of antioxidants extract from Garcinia pedunculata Robx. was optimized using response surface methodology. A Box-Behnkem design was used to investigate the effects of three independent variables, namely solvent concentration(%), solvent to sample ratio(v/w), and radiation time(min) on total antioxidant activity by DPPH and ABTS radical scavenging activity. Optimal conditions for extraction of antioxidants concluded that the solvent concentration be 70.79%, solvent to sample ratio be 20:1, and irradiation time at 4.73 minutes. However, the antioxidant activity of the extract was found to reach upto 85.98% DPPH radical scavenging activity and 19.23 mg-trolox equivalent/g dry weight. FTIR study revealed that, the extraction of antioxidant extract was higher with increase in irradiation time, but the antioxidant activity of the extract was lower with increase in time. The structural changes in plant material after extractions observed by light microscopy provided visual evidence of the disruption effect.     

Micronization of taxifolin by supercritical antisolvent process and evaluation of radical scavenging activity

The aim of this study was to prepare micronized taxifolin powder using the supercritical antisolvent precipitation process to improve the dissolution rate of taxifolin. Ethanol was used as solvent and carbon dioxide was used as an antisolvent. The effects of process parameters, such as temperature (35-65 °C), pressure (10-25 MPa), solution flow rate (3-6 mL/min) and concentration of the liquid solution (5-20 mg/mL) on the precipitate crystals were investigated. With a lower temperature, a stronger pressure and a lower concentration of the liquid solution, the size of crystals decreased. The precipitation temperature, pressure and concentration of taxifolin solution had a significant effect. However, the solution flow rate had a negligible effect. It was concluded that the physicochemical properties and dissolution rate of crystalline taxifolin could be improved by physical modification such as particle size reduction using the supercritical antisolvent (SAS) process. Further, the SAS process was a powerful methodology for improving the physicochemical properties and radical scavenging activity of taxifolin.     

DPPH法评价大黄提取物的抗氧化活性

采用超声波法提取大黄抗氧化物质,以DPPH法评价大黄抗氧化活性。结果表明,大黄抗氧化物质最佳提取工艺为:以70%乙醇为溶剂,料液比为1∶40 g/mL,超声提取2次,每次提取30 min;大黄抗氧化活性物质主要分布于石油醚和乙酸乙酯提取物,为该药材的开发提供参考。