Methods are described for the extraction and analysis of hydrophilic and lipophilic antioxidants, using modifications of the oxygen radical absorbing capacity (ORACFL) procedure. These methods ...provide, for the first time, the ability to obtain a measure of “total antioxidant capacity” in the protein free plasma, using the same peroxyl radical generator for both lipophilic and hydrophilic antioxidants. Separation of the lipophilic and hydrophilic antioxidant fractions from plasma was accomplished by extracting with hexane after adding water and ethanol to the plasma (hexane/plasma/ethanol/water, 4:1:2:1, v/v). Lipophilic and hydrophilic antioxidants were efficiently partitioned between hexane and aqueous solvents. Conditions for controlling temperature effects and decreasing assay variability using fluorescein as the fluorescent probe were validated in different laboratories. Incubation (37 °C for at least 30 min) of the buffer to which AAPH was dissolved was critical in decreasing assay variability. Lipophilic antioxidants represented 33.1 ± 1.5 and 38.2 ± 1.9% of the total antioxidant capacity of the protein free plasma in two independent studies of 6 and 10 subjects, respectively. Methods are described for application of the assay techniques to other types of biological and food samples. Keywords: ORACFL; phenolics; antioxidant; free radical; lipophilic; hydrophilic; blueberry; fruit juices
The objective of this work was to investigate the effect of processing frying conditions, simulating possible home and catering practices, in order to optimize the process to obtain a good final ...product limiting the acrylamide (AA) formation. Experiments were performed using commercially frozen pre-fried potato strips, a fixed initial frying temperature of 180
°C, two different fryers for domestic (A) and catering (B) use, and two potato-to-oil ratios (1/4 and 1/8
w/v). Several batches were fried at different fixed times, and for each batch the temperature of oil and stick surface were acquired by thermocouples. Analysis of AA and other quality characteristics (water and oil content, color, texture) of French fries were carried out. In all adopted frying conditions the increase of oil and potato surface temperature was faster in fryer A than in fryer B due to its peculiar manufacturing characteristics and employment mode. As a consequence, higher AA levels and a more cooked product were obtained using fryer A. With the immersion of a lower potato quantity (1/8
w/v), higher oil temperatures and AA levels and a more cooked product were obtained in shorter time in both fryers. Considering quality parameter results, the best quality characteristics were obtained in potatoes from fryer B between 10 and 13
min of frying with a product-to-oil ratio of 1/4 (around 250
±
20
μg
kg
−1 of AA), and after about 7
min of processing with a product-to-oil ratio of 1/8 (around 260
±
50
μg
kg
−1 of AA).
The molecular components of a phenolic fraction (P2), obtained from liquid chromatography of a Swiss Chard (
Beta vulgaris subsp.
cycla) extract, were identified using HPLC-ESI-MS/MS. The primary P2 ...components were: vitexin-2″
O-rhamnoside, its demethylated form 2″-xylosylvitexin, isorhamnetin 3-gentiobioside, and rutin. P2 “in toto” and the single components were characterized for antioxidant capacity, antimitotic activity on MCF-7 human breast cancer cells and for toxicity to human lymphocytes and macrophages. P2 inhibited MCF-7 cell proliferation (IC
50 value=9
μg/ml) without inducing apoptosis, showed no toxicity to human lymphocytes and slight toxicity to macrophages. Vitexin-2″
O-rhamnoside strongly inhibited DNA synthesis in MCF-7 cells, whereas 2″-xylosylvitexin and isorhamnetin 3-gentiobioside were activators; combinations of activators and inhibitors maintained the over-all inhibitory effect.
Antioxidant capacity of extra‐virgin olive oils Ninfali, Paolino; Aluigi, Gianfranca; Bacchiocca, Mara ...
Journal of the American Oil Chemists' Society,
March 2001, Letnik:
78, Številka:
3
Journal Article
Recenzirano
In this study, the oxygen radical absorbance capacity (ORAC) of vegetable oils was investigated using a spectrofluorometric method, which measures the protection of the phenolic substances of the oil ...on the β‐phycoerythrin fluorescence decay in comparison with Trolox. More than 97% of the phenolic substances was extracted from the oil using methanol, and the methanolic extract was then used for the ORAC and the total phenolics assay. We found a significant correlation between ORAC values of different olive oils and the total amount of phenolics. For extra‐virgin olive oils, maximal ORAC values reached 6.20±0.31 μmol Trolox equivalent/g, while refined and seed oils showed values in the 1–1.5 μmol Trolox equivalent/g range. Our method is useful to assess the quality of olive oils and to predict, in combination with the rancidity tests, their stability against oxidation.
Vegetables are the most important sources of phenolics in the Mediterranean diet. Phenolics, especially flavonoids, are suggested as being essential bioactive compounds providing health benefits. In ...this study, twenty-seven vegetables, fifteen aromatic herbs and some spices consumed in Central Italy (the Marches region) were studied to reveal total phenolic, flavonoid and flavanol content as well as their antioxidant capacity measured by the oxygen radical absorbance capacity (ORAC) method. A comparison in terms of antioxidant capacity was made between different salads, as well as between salads to which aromatic herbs had been added. Lemon balm and marjoram at a concentration of 1·5 % w/w increased by 150 % and 200 % respectively the antioxidant capacity of a salad portion. A 200 g portion of a salad enriched with marjoram corresponded to an intake of 200 (sd 10) mg phenolics and 4000 (sd 300) ORAC units (μmol Trolox equivalents). Olive oils and wine or apple vinegars were the salad dressings that provided the highest increase in antioxidant capacity. Among the spices tested, cumin and fresh ginger made the most significant contribution to the antioxidant capacity. The results are useful in surveying the antioxidant parameters of vegetables, herbs and spices produced and consumed in our geographical area as well as in quantifying the daily intake of phenolics and ORAC units. The results can be used in public health campaigns to stimulate the consumption of vegetables able to provide significant health protection in order to prevent chronic diseases.
The phenolic and oxygen radical absorbance capacity (ORAC) values have been measured in six fresh and frozen vegetables (beet green, spinach, broccoli, carrot, onion, and celery) from the same ...cultivar by analyzing the whole juice (WJ) and the acetonic extract of the squeezed pulp. To exploit the effect of the acid environment on the stability and recovery of the phenolics, perchloric acid (PCA) was added directly to WJ and to the pulp before the extraction with acetone. In both fresh and frozen vegetables, PCA markedly increased the recovery of phenolics extracted from the pulp, but PCA had no effect on the WJ. Four of six frozen vegetables showed lower phenolic and ORAC values than the fresh vegetables, whereas in the other two cases, values were significantly higher compared to fresh samples. Among the fresh vegetables, beet green showed the highest ORAC and phenolic values; however, when measured in two different cultivars of beet green, the ORAC value showed as much as 4.5-fold variation, whereas total phenolics and flavonoids showed 1.2- and 3.5-fold variations, respectively. The results show that total phenolics and ORAC, compared in fresh and frozen vegetables, represent an index of the mildness of blanching in the industry of frozen vegetables and provide a measure of the gap in antioxidants in the diet of people who consume frozen instead of fresh vegetables. The plant genotype is an important source of variabilty in the ORAC value, which can be conveniently used to increase the intake of antioxidants from vegetables. Keywords: Vegetable juices; antioxidants; phenolic compounds; oxygen radical absorbance capacity (ORAC); fresh and frozen vegetables
Oxygen Radical Absorbance Capacity (ORAC), phenolic and flavonoid determinations were performed on ready-to-eat fresh or cooked vegetables, sprouts, frozen vegetables and fresh and dehydrated fruits. ...The peel and pulp of fresh fruit was compared as well. In the minimally processed vegetables, the reduction of phenolic and ORAC values ranged from 10 to 40% in comparison with fresh vegetables; a 80% reduction was found in frozen vegetables, depending on the texture of the vegetable and the consequent blanching time. Some sprouts were shown to possess a high ORAC and can be considered useful ingredients to increase the antioxidant capacity of salads. Dried fruits showed a 25-55% decrease in ORAC when compared with fresh fruits. In two cultivars of apple and pear, the ORAC value of the peel was 6-9 fold higher than the one of the pulp. The results are discussed from the standpoint of nutritional value and quality of the adopted processing technology
Questo lavoro presenta l'applicazione del metodo ORAC, ovvero della capacità di assorbimento dei radicali perossilici, da parte di estratti vegetali e frutti. La determinazione del parametro ORAC, della concentrazione di polifenoli e flavonoidi è stata effettuata su vegetali freschi o cotti pronti per l'uso, su germogli di vari semi, vegetali congelati, frutti disidratati e frutti freschi. Sui frutti freschi è stato effettuato un confronto fra la buccia e la polpa. I valori ORAC dei vegetali trasformati e pronti per l'uso mostravano un decremento variabile tra il 10 e il 40% rispetto ai vegetali freschi; nei vegetali surgelati il decremento massimo rilevato è stato dell'80%, a seconda della durezza del vegetale e del corrispondente tempo di blanching. I frutti disidratati mostravano un decremento di ORAC, rispetto ai freschi, variabile dal 25 al 55%. In due cultivar di mele e pere, l'ORAC della buccia era 6-9 volte più elevato del valore della polpa. I risultati sono discussi dal punto di vista del valore nutrizionale e della qualità della tecnologia di trasformazione
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Free radicals in olive oils were identified and quantified by EPR, by means of the spin-trapping technique making use of α-phenylbutylnitrone (PBN) as spin trap. The radical species were identified ...as PBN-trapped hydroxyl radicals (PBN-•OH) in the water microdroplets inside the fat medium. The largest radical concentration was 12.5 μM ≡ 100%. The following were the relative concentrations of the radicals under different conditions: (1) Two oils, produced by continuous centrifugation, aged for 1 year, showed a 25−30% increase in the radicals compared to nonaged oils; 1-year-old oil, produced by pressure, did not differ from the nonaged oil. (2) Radical production was markedly reduced by N2 bubbling; it was increased by heating, whereas it showed a biphasic pattern by air bubbling over time. (3) Radical concentration as a function of the UV irradiation time increased up to a maximum, after which it decreased and finally remained constant. The phenolic and oxygen contents were related to the radical content. This study demonstrates that the EPR technique is suitably applied to the detection of free radicals in olive oil and that storage, handling, and stress conditions of the oils significantly influence the radical concentration. Keywords: EPR; olive oil; hydroxyl radical; oil handling; oil storage
The induction period (IP), determined using accelerated methods such as the Rancimat test, is a parameter that has been used to predict the shelf life of virgin olive oil. The oxygen radical ...absorbance capacity (ORAC) has recently been proposed as a quality index of virgin olive oil because it measures the efficiency of phenolic compounds in the protection against peroxyl radicals. This study aims to investigate relationships between the ORAC and IP values and proposes ORAC as a new parameter of virgin olive oil stability. The concentrations of phenolics, o‐diphenols, tocopherol, β‐carotene, lutein, and ORAC and IP values were determined in 33 virgin olive oils. Regression analyses showed that both ORAC and IP values correlate with total phenols and o‐diphenols with highly significant indices, whereas the correlations of both ORAC and IP with tocopherols, β‐carotene, and lutein were not significant. The ORAC values correlate with the IP values with low but significant indices (R=0.42; P<0.02). The results confirm the key role of phenolic compounds in accounting for the shelf life of virgin olive oil and suggest that the ORAC parameter may be used as a new index of quality and stability.
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