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1.
Soil extracts usually contain large quantities of dissolved humified organic material, typically reflected by high polyphenolic content. Since polyphenols seriously confound quantification of extracted protein, minimising this interference is important to ensure measurements are representative. Although the Bradford colorimetric assay is used routinely in soil science for rapid quantification protein in soil-extracts, it has several limitations. We therefore investigated an alternative colorimetric technique based on the Lowry assay (frequently used to measure protein and humic substances as distinct pools in microbial biofilms). The accuracies of both the Bradford assay and a modified Lowry microplate method were compared in factorial combination. Protein was quantified in soil-extracts (extracted with citrate), including standard additions of model protein (BSA) and polyphenol (Sigma H1675-2). Using the Lowry microplate assay described, no interfering effects of citrate were detected even with concentrations up to 5 times greater than are typically used to extract soil protein. Moreover, the Bradford assay was found to be highly susceptible to two simultaneous and confounding artefacts: 1) the colour development due to added protein was greatly inhibited by polyphenol concentration, and 2) substantial colour development was caused directly by the polyphenol addition. In contrast, the Lowry method enabled distinction between colour development from protein and non-protein origin, providing a more accurate quantitative analysis. These results suggest that the modified-Lowry method is a more suitable measure of extract protein (defined by standard equivalents) because it is less confounded by the high polyphenolic content which is so typical of soil extracts.  相似文献   

2.
大孔树脂分离纯化玫瑰果多酚及其抗氧化性   总被引：1，自引：2，他引：1  
为了研究大孔树脂对玫瑰果多酚的纯化效果,该试验以玫瑰果多酚粗提液为原料,利用大孔树脂吸附法对其进行纯化,并对其体外抗氧化活性进行了研究。结果表明,大孔吸附树脂纯化较佳工艺为:在20℃条件下,用质量浓度为0.80 mg/m L的玫瑰果多酚粗提液(p H值5.8)以1 m L/min的流速上样200 m L;吸附平衡后用少量蒸馏水洗至洗脱液无色,后用70 m L体积分数为70%的乙醇溶液,以1.5 m L/min的流速进行动态洗脱,洗脱峰相对集中、对称,无拖尾。纯化后,总酚质量分数由纯化前的122.90 mg/g提高到399.42 mg/g。体外抗氧化活性的研究表明:清除1,1-二苯基-2-苦基肼自由基的作用效果顺序为维生素C纯化多酚2,6-二叔丁基-4-甲基苯酚(Butylated hydroxytoluene,BHT)粗多酚;清除超氧阴离子自由基的作用效果顺序为维生素CBHT纯化多酚粗多酚;清除羟基自由基的作用效果顺序为维生素C纯化多酚BHT粗多酚。研究结果为玫瑰果多酚的进一步利用提供依据。  相似文献   

3.
Virgin olive oils were subjected to simulated common domestic processing, including frying, microwave heating, and boiling with water in a pressure cooker. The impact of these processes on polyphenol content and physicochemical characteristics of oils was assessed. Thermal oxidation of oils at 180 degrees C caused a significant decrease in hydroxytyrosol- and tyrosol-like substances. In contrast, oils heated for 25 h still retained a high proportion of the lignans 1-acetoxypinoresinol and pinoresinol. Thermal oxidation also resulted in a rapid degradation of alpha-tocopherol and the glyceridic fraction of oils. Microwave heating of oils for 10 min caused only minor losses in polyphenols, and the oil degradation was lower than that in thermoxidation assays. Again, lignans were the least affected polyphenols and did not change during microwave heating. Boiling a mixture of virgin olive oil and water in a pressure cooker for 30 min provoked the hydrolysis of the secoiridoid aglycons and the diffusion of the free phenolics hydroxytyrosol and tyrosol from the oil to the water phase. Losses of polyphenols were detected only at pH lower than 6. Moreover, alpha-tocopherol and the glyceridic fraction of oils were not modified during this process. It is worth noting that all the heating methods assayed resulted in more severe polyphenols losses and oil degradation for Arbequina than for Picual oil, which could be related to the lower content in polyunsaturated fatty acids of the latter olive cultivar. These findings may be relevant to the choice of cooking method and olive oil cultivar to increase the intake of olive polyphenols.  相似文献   

4.
The efficacy of enzyme-assisted ensiling (ENLAC) in the recovery of polyphenols from rosemary and sage was tested. Fresh rosemary and sage were chopped and ensiled in 0.5-L anaerobic jars. Treatments comprised control (no additives), 0.5% glucose and lactic acid bacteria, and 1% cellulase plus 1% hemicellulase plus pectinase. Following storage at room temperature for 45 days (experiment 1) and 26 days (experiment 2), polyphenols were extracted from the silages in ethanol either by direct blending or by cold extraction. The enzyme treatment resulted in silages with the lowest pH values, lowest fiber content, highest water-soluble sugar content, and highest polyphenol recovery; this treatment resulted in increased polyphenol recovery from rosemary and sage, by 100 and 20%, respectively. Comparison between direct blending and cold extraction revealed similar efficiency of polyphenol recovery.  相似文献   

5.
Aim of this study was to evaluate the total antioxidant activity (TAA) of extra virgin olive oil (EVOO) and the effect of heating on the alpha-tocopherol content and TAA in relation to the presence of polyphenols, heating time, and temperature. Experiments included the measurement by ABTS decolorization assay of antioxidant capacity of alpha-tocopherol and 14 simple phenolic compounds present in EVOO, either dissolved in ethanol or added to refined olive oil, and the evaluation of TAA, total phenols, and alpha-tocopherol of six commercial EVOO and three olive oils. Finally, four experimental oils were prepared from refined olive oil containing a fixed amount (300 ppm) of alpha-tocopherol and increasing amounts of polyphenols (25, 125, 225, and 326 ppm) extracted from EVOO. The thermal stability of experimental oils under domestic heating conditions (heating time from 30 to 120 min, heating temperature from 160 to 190 degrees C) was studied by evaluating the loss of alpha-tocopherol and TAA according to a Latin square design. Results indicate that TAA of commercial oils is mainly due to their phenol and alpha-tocopherol content. Heating experiments suggest that polyphenols from EVOO are effective stabilizers of alpha-tocopherol during olive oil heating, thus contributing to the nutritional value of cooked foods.  相似文献   

6.
The aim of the present study was to determine the effect of animal-based organic nutrition and environmental parameters on tomato fruit quality, as well as to establish relations among colour and morphological values performed by the Tomato Analyzer (TA) software application. Organic tomato fruits produced by three organic nutrient solutions, which consisted of different mixtures of several OMRI certified nitrogen fertilizers and one inorganic nutrient solution (Steiner’s solution) as the control, were evaluated for their polyphenol and carotenoid content. We used Tomato Analyzer (TA) to evaluate fruit size and shape. Moreover, we implemented a digital image analysis tool, Color Test (CT), as part of the TA software application to collect and analyse fruit colour parameters. The application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. The high air temperature (>30°C) and sub-optimal light intensity negatively affected the carotene content of tomato fruits, as well as their morphological and colour attributes. Plants fed with organic solutions containing ASA + ASB + NK2SO4 showed comparable morphology and fruit colour attributes to those of the control plants that received Steiner’s nutrient solution. The results indicated that the application of organic fertilizers positively affected the total hydrolysable and condensed polyphenols of tomato fruits compared to the control. Plants fed with the Steiner’s nutrient solution exhibited the highest carotenoid content in tomato fruits. Organically produced tomatoes through animal-based fertilizer application displayed similar fruit morphology and colour attributes compared to conventionally produced tomatoes.  相似文献   

7.
Polyphenols are an important functional minor component of virgin olive oils that are responsible for the key sensory characteristics of bitterness, pungency, and astringency. Polyphenols were isolated from virgin olive oils by using liquid/liquid extraction and then separated by using reverse phase HPLC followed by fraction collection. The sensory qualities of the isolated polyphenols were evaluated, and almost all fractions containing polyphenols were described as bitter and astringent. However, the fraction containing deacetoxy-ligstroside aglycon produced a strong burning pungent sensation at the back of the throat. In contrast, the fraction containing the analogous deacetoxy-oleuropein aglycon, at an equivalent concentration, produced only a slight burning/numbing sensation, which was perceived more on the tongue. No other polyphenol fractions from the analyzed oils produced the intense burning sensation; thus, deacetoxy-ligstroside aglycon is the polyphenol responsible for the majority of the burning pungent sensation found in pungent extra virgin olive oils.  相似文献   

8.
The individual evolution of phenolic compounds has been studied during the natural fermentation of black olives for the first time. Cyanidin 3-rutinoside and cyanidin 3-glucoside were the main anthocyanins identified in fresh olives, and they were not detected after 1 month of storage either in brine or in olive. The fruit colors were different when aerobic or anaerobic conditions were used and as a consequence of the different anthocyanin polymerizations that took place. At time zero, the polyphenols observed in the olive juice were hydroxytyrosol-4-beta-glucoside, oleuropein, hydroxytyrosol, tyrosol, salidroside, and verbascoside and, after 12 months, the main phenol was hydroxytyrosol. The polyphenol content in the oil phase of olives was also analyzed. The dialdehydic form of elenolic acid linked to hydroxytyrosol and tyrosol, oleuropein aglycon, and ligstroside aglycon were the main compounds found at the beginning of fermentation but were not detected after 3 months. In contrast, hydroxytyrosol, hydroxytyrosol acetate, tyrosol, and tyrosol acetate were the main polyphenols detected in the oil phase of the final product. The acid hydrolysis of the initial glucosides (in olive juice) and the aglycons (in oil phase) was, therefore, the main reaction that took place during fermentation.  相似文献   

9.
A new spectrophotometric assay for the determination of the polyphenolic content of olive oil is presented. It is a substrate-recycling assay for phenolic compounds that employs tyrosinase in the presence of excess NADH. The reaction of various phenols with the enzyme produces an o-quinone, which is detected by recycling between reactions with the enzyme and NADH. The method offers some advantages over the classical methods employed to determine the polyphenolic content of olive oil, that is, ease and reproducibility of the analysis, highly increased sensitivity, and selectivity toward phenolic compounds. The amount of total polyphenols was determined in virgin olive oils both with the Folin-Ciocalteu reagent and with the proposed enzymatic method. The results suggest a better estimation of the polyphenol content, as compared with the colorimetric method. This has to be attributed to the different reactivities of the two methods toward phenols and catechols. Finally, the enzymatic method demonstrates that there is a linear relationship between the olive oil phenolic content and the antioxidative capacity of oil extracts.  相似文献   

10.
The ability of a degraded soil to respond to successive additions of a toxic organic waste (olive-mill solid waste) and its vermicompost was studied in a controlled incubation experiment for 32 weeks. Hydrolytic enzyme activities (phosphatase, β-glucosidase), oxidoreductase activities (dehydrogenase, o-diphenol oxidase) and indole acetic acid production, were used as measures of soil perturbation. No microbial activity, indicated by the total lack of dehydrogenase activity, was detected when the olive-mill solid waste was added to the soil. However, after 16 weeks, the activity returned to the original soil levels (1.35 μg INTF g−1 h−1). The addition of vermicomposted olive-mill solid waste increased the original soil dehydrogenase activity by five-fold, indicating a loss of toxicity of the waste during the vermicomposting process; the activity remained high throughout the experiment. At week 21, a second addition of olive solid waste, was made to both olive waste and vermicompost-amended soils, when the soil originally amended with olive waste had reached the activity measured in soil amended with vermicompost. Dehydrogenase activity recovered immediately, reaching levels up to seven-fold higher than the background levels of the soil. The ability of soil to respond to a toxic waste clearly differed after a period of exposure to the waste. The faster response was probably related to the increased pool of stabilized organic matter present in soil, arising from the stabilization of added olive waste in the soil or through the amended vermicompost. The amplitude (period of recovery to the initial state after disturbance) and the elasticity (speed of recovery) of the soil could also be monitored by o-diphenol oxidase and β-glucosidase activities. However, indole-3-acetic acid production proved to be a useful measure of perturbation only following the second addition of the olive waste.  相似文献   

11.
Grapes and red wine prepared from Vitis vinifera L. contain a variety of polyphenols. Some information is available about the polyphenols of the seeds and leaves of grapevine, but considerably less is known about the polyphenols of woody stems. In this paper, we describe the results of a study of polyphenolic compounds in grapevine stems. We demonstrate how a combination of reversed phase high-performance liquid chromatography with ultraviolet-diode array detection and electrospray ionization-tandem mass spectrometry ion-trap detection enables characterization of a phytochemical mixture of considerable complexity. As the polyphenol source, the stems of three frost-hardy grapevine varieties [Hasaine (Hasansky) sladki, Zilga, and Yubilei Novgoroda] were used. The main group of methanol-extractable polyphenols of stems consists of trans-resveratrol and its derivatives including oligomers and glucosides. As minor components of the extract, stilbenoid piceatannol as well as a number of nonstilbenoid polyphenols, mostly flavan-3-ols and phenolic acids glucosides, were determined. The total polyphenol content of the grapevine stems depends on the variety, whereby the stems of cultivar Yubilei Novgoroda with white grapes contain significantly less of both groups of polyphenols.  相似文献   

12.
Rapid determination of polyphenols and vitamin C in plant-derived products   总被引：5，自引：0，他引：5  
Polyphenols, widely spread in our diet by the consumption of plant food products, are commonly determined using Folin-Ciocalteu reagent that interacts with other different reducing nonphenolic substances and leads to an overestimation of polyphenol content. In this paper we report an optimized Folin-Ciocalteu method to specifically determine the contents of total polyphenols and vitamin C. After the optimal conditions for the colorimetric assay were set, solid-phase extraction (Oasis HLB (hydrophilic-lipophilic balance)) was carried out to eliminate the water-soluble reducing interferences including vitamin C. Colorimetric correction was thus performed by subtracting interfering substances contained in the water washing extract from the raw extract. Moreover, vitamin C present in the water washing extract can be destroyed by heating and thus colorimetrically deduced. This procedure was set up with synthetic solutions and validated on different extracts from fruit products.  相似文献   

13.
In S Spain, the Andalusian olive oil industry generates annually 2.5–3.0 million tons of olive mill pomace, a by‐product which is comprised of the residues from the two‐phase oil‐extraction process. The agricultural policies of the EU have led to widespread interest in recycling these agricultural by‐products. Olive mill pomace might be evaluated as an organic fertilizer after composting, however, before wider use of composted olive mill pomace is advocated, characterization of the final product is needed. In this study, the physico‐chemical characteristics, net N mineralization, and the potential for N leaching of 7 out of the 11 olive‐mill‐pomace composts currently produced in the Andalusian olive mills were investigated. Compost of olive mill pomace differed in the proportions of raw materials co‐composted with the olive mill pomace, such as olive leaf material, manure, and straw. In all the composts tested, organic matter, total C and K were high with 60.5%, 30.7%, and 1.7% on average, respectively, whereas total P was low (0.4%) and with intermediate levels of N (1.5%). Compost pH (8.03), electrical conductivity (2.85 dS m–1), and germination index (65% on average) were adequate for agricultural use. Furthermore, principal component analyses revealed a clear relationship between the quality of the composts and the proportion of manure mixed with the raw materials. Net N mineralization was negative on average (–20 μg IN g–1) after 1 y, but positive after 2 y of incubation with up to 94% of available N from the total N added and the short‐term potential N leaching after compost application was negligible (less than 3.9% of added N) and much lower than the other N fertilizer with up to 80% added N leached. Overall, results of this study clearly show that these currently produced composts of olive mill pomace are suitable as soil improvers for agricultural purposes, but may not contribute significantly as a N fertilizer for up to 2 y after application.  相似文献   

14.
Composition and effects of additions of fibric (Oi) and hemic/sapric (Oe + Oa) layer extracts collected from a 20-year-old stand of radiata pine (Pinus radiata) on soil carbon dioxide (CO2) evolution were investigated in a 94-day aerobic incubation. The 13C nuclear magnetic resonance spectroscopy indicated that Oi layer extract contained greater concentrations of alkyl C while Oe + Oa layer extract was rich in carboxyl C. Extracts from Oi and Oe + Oa layers were added to a forest soil at two different polyphenol concentrations (43 and 85 μg g−1 soil) along with tannic acid (TA) and glucose solutions to evaluate effects on soil CO2 efflux. CO2 evolution was greater in amended soils than control (deionized water) indicating that water-soluble organic carbon (WSOC) was readily available to microbial degradation. However, addition of WSOC extracted from both Oi and Oe + Oa layers containing 85 μg polyphenols g−1 soil severely inhibited microbial activity. Soils amended with extracts containing lower concentrations of polyphenols (43 μg polyphenols g−1 soil), TA solutions, and glucose solutions released 2 to 22 times more CO2-C than added WSOC, indicating a strong positive priming effect. The differences in CO2 evolution rates were attributed to chemical composition of the forest floor extracts.  相似文献   

15.
Greek oregano is commonly used as a spice and in traditional medicine in Eurasia. The plant is rich in secondary metabolites, such as volatile organic compounds (VOC) and polyphenols. Chitosan oligosaccharides (COS) are used as a plant elicitor. The objectives of this study were to determine the effects of COS on the growth and content of secondary metabolites in Greek oregano. Four COS treatments (50, 200, 500, and 1000 ppm) were used in a field experiment. The 200 and 500 ppm COS treatments promoted plant height growth, whereas 50 and 200 ppm COS upregulated the content of polyphenols significantly (38 and 29%, respectively). The COS treatments induced H(2)O(2) generation in Greek oregano leaves; thus, the effect of H(2)O(2) treatment was studied to investigate the possible role of H(2)O(2) in growth and polyphenol production. A low concentration of H(2)O(2) also promoted plant height growth, but only tendencies to higher polyphenol content were seen.  相似文献   

16.
菜籽蛋白加工废液中多酚和多糖同步提取工艺优化   总被引：6，自引：4，他引：2  
为开发利用菜籽蛋白加工废液中的生理活性物质,该研究在单因素试验基础上,采用Box-Behnken响应面试验设计法,对菜籽蛋白加工废液中多酚和多糖提取工艺条件进行优化,同时探究两种物质的体外抗氧化活性。结果表明,影响菜籽蛋白加工废液中多酚和多糖得率的因素大小顺序为:乙醇体积分数浸提温度浸提时间,最佳提取工艺为:浸提温度60℃、乙醇体积分数65%、浸提时间31 min,在此条件下多酚得率为2.19%,多糖得率为8.14%;多酚提取物对DPPH·具有较强清除能力,其半抑制质量浓度为0.20 mg/mL,多糖提取物对DPPH·和·OH均具有较强的清除能力,其半抑制质量浓度分别为1.45、2.38 mg/mL;高效液相色谱法初步检测表明,菜籽蛋白加工废液中含有香豆酸、丁香酸、对香豆酸、芥子酸和苯甲酸。研究结果为菜籽蛋白加工废液的再利用提供参考。  相似文献   

17.
An extraction procedure and an analytical method have been developed to detect and quantify for the first time a series of ellagitannin derivatives formed in wine during aging in oak barrels. The method involves a preliminary purification step on XAD7 HP resin followed by a second purification step on TSK 40 HW gel. The resulting extract is analyzed for compound identification and quantitative determination by high-performance liquid chromatography-electrospray ionization-mass spectrometry in single ion recording mode. Reference compounds, which are accessible through hemisynthesis from the oak C-glycosidic ellagitannin vescalagin, were used to build calibration curves, and chlorogenic acid was selected as an internal standard. This method enabled us to estimate the content of four flavano-ellagitannins and that of another newly identified wine polyphenol, beta-1-O-ethylvescalagin, in a Bordeaux red wine aged for 18 months in oak barrels. All five ellagitannin derivatives are derived from the nucleophilic substitution reaction of vescalagin with the grape flavan-3-ols catechin and epicatechin or ethanol.  相似文献   

18.
Alpha-amylase inhibitor (alpha-AI) activity of Garcinia mangostana, commonly known as mangosteen, pericarp extracts was studied by assay guided fractionations from lipophilic to hydrophilic using combined solvent extraction and Amberlite XAD2 adsorption chromatography. Neither the lipophilic, xanthone containing fraction, nor the highly polar fraction, which has no affinity on Amberlite XAD2, showed any alpha-AI. The fraction that shows very high inhibitory activity contains primarily polyphenols and can be adsorbed on Amberlite XAD2. The IC50 of 5.4 microg/mL of this fraction is comparable to that of acarbose, a prescribed alpha-AI used in the control of type II diabetes, at 5.2 microg/mL. Total phenolic content (TPC) of each fraction was measured and the TPC has no correlation with the alpha-AI activity. The lipophilic fraction contains mainly xanthones as revealed by HPLC-MS analysis. Colorimetric analysis coupled with UV-vis and IR spectroscopic analysis demonstrated that the fractions with high alpha-AI activity are primarily oligomeric proanthocyanidins (OPCs) with little gallate moiety. There is also evidence to show that the alpha-AI by these OPCs is not purely by nonspecific protein complexation. Both tannic acid and G. mangostana OPCs precipitate BSA equally well but G. mangostana OPCs are 56 times more effective in inhibiting alpha-amylase.  相似文献   

19.
Chocolate is often labeled with percent cocoa solids content. It is assumed that higher cocoa solids contents are indicative of higher polyphenol concentrations, which have potential health benefits. However, cocoa solids include polyphenol-free cocoa butter and polyphenol-rich nonfat cocoa solids (NFCS). In this study the strength of the relationship between NFCS content (estimated by theobromine as a proxy) and polyphenol content was tested in chocolate samples with labeled cocoa solids contents in the range of 20-100%, grouped as dark (n = 46), milk (n = 8), and those chocolates containing inclusions such as wafers or nuts (n = 15). The relationship was calculated with regard to both total polyphenol content and individual polyphenols. In dark chocolates, NFCS is linearly related to total polyphenols (r2 = 0.73). Total polyphenol content appears to be systematically slightly higher for milk chocolates than estimated by the dark chocolate model, whereas for chocolates containing other ingredients, the estimates fall close to or slightly below the model results. This shows that extra components such as milk, wafers, or nuts might influence the measurements of both theobromine and polyphenol contents. For each of the six main polyphenols (as well as their sum), the relationship with the estimated NFCS was much lower than for total polyphenols (r2 < 0.40), but these relationships were independent of the nature of the chocolate type, indicating that they might still have some predictive capabilities.  相似文献   

20.
The effect of natural phenolic compounds on the antioxidant and prooxidant activity of lactoferrin was studied in liposomes and oil-in-water emulsions containing iron. The antioxidants tested with lactoferrin were alpha-tocopherol, ferulic acid, coumaric acid, tyrosol, and natural phenolic extracts obtained from three different extra-virgin olive oils and olive mill wastewater. The natural extracts of olive oils and mill wastewaters were composed mainly of polyphenols and simple phenolics, respectively. Lipid oxidation at 30 degrees C was determined by the formation of hydroperoxides and fluorescent compounds resulting from oxidized lipid interactions. All phenolic compounds showed synergistic properties in reinforcing the antioxidant activity of lactoferrin in lipid systems containing iron. The highest synergistic effects were observed for the phenolic extracts rich in polyphenols of extra-virgin olive oils and lactoferrin. This synergistic effect was higher in liposomes than in emulsions.  相似文献   

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