Ascorbate,not urate,modulates the plasma antioxidant capacity after strawberry intake

The consumption of antioxidant-rich foods has already been associated with acute significant increases in plasma total antioxidant capacity (TAC) in humans, but there is no consensus among different literature reports. Furthermore, the acute rise in plasma TAC observed after consumption of several non-berry fruits seems not to be necessarily related to the absorption of dietary antioxidants, such as micronutrients and phenolic substances, but is attributed to the relevant increase of endogenous urate in serum. In this study, we first compared the nutritional quality of strawberry fruits from different genotypes, all cultivated in the same experimental field. Significant genotype-to-genotype differences were observed in the antioxidant capacity and in the vitamin C, folate and phenolic contents of the fruits. Second, in order to investigate the individual effects of the selected strawberry genotypes on the post-prandial plasma antioxidant status in humans, we assessed the acute effects of a single dose of strawberries in healthy subjects. The variation of plasma TAC through the FRAP and TEAC assays, and any eventual changes in ascorbate and urate levels in serum, were measured during the three hours following the strawberry intake. The acute intake of strawberries resulted in a significant increase in plasma FRAP values in all the subjects, independently of the individual TAC baseline levels. Interestingly, the lowest increases in plasma TAC and in serum ascorbate levels were associated with consumption of the nutritionally-poorest cultivars. In addition, significant increases in ascorbate, but not in urate, concentrations were observed in serum. These findings suggested that the fructose-dependent hyperuremic effect, observed after the intake of non-berry fruits, is not responsible for the plasma antioxidant changes following strawberry consumption.     

ORAC and TEAC assays comparison to measure the antioxidant capacity of food products

Oxygen radical antioxidant capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) assays were compared to estimate the total antioxidant capacity (TAC) of orange juice, milk, and an orange juice-milk beverage. When the TEAC method was used with this beverage, an increase in the concentration of orange juice corresponded to an increase in TAC, but increasing the percentage of milk did not increase the TAC value. When the ORAC method was applied, it was seen that increased concentrations of juice or milk corresponded to greater antioxidant capacity. An evaluation was also made of the influence of certain compounds (ascorbic acid, gallic acid, β-carotene, lutein, zeaxanthin and albumin) with antioxidant capacity that were present in the samples studied.     

Changes in strawberry phenolics, anthocyanins, and antioxidant capacity in response to high oxygen treatments

Changes in fruit quality, decay, phenolic and anthocyanin content, and antioxidant capacity of strawberries (Fragaria × ananassa Duch. cv. Allstar) stored under air and high oxygen atmospheres at 5 °C were investigated. Freshly harvested strawberries were placed in jars and ventilated continuously with air or with 40, 60, 80, or 100 kPa O₂ at 5 °C for up to 14 days. Samples were taken initially, and after 3, 7, 10 and 14 days of storage. While fruit quality parameters such as titratable acidity, total soluble solids and surface color were only slightly affected by differing levels of O₂, the higher oxygen concentration treatments significantly reduced decay. Oxygen concentrations higher than 60 kPa also promoted increases in ORAC values, total phenolics and total anthocyanins as well as individual phenolic compounds analysed by HPLC during the initial 7 days of storage. However, this effect diminished with prolonged storage. No significant differences in ORAC values, total phenolics, total anthocyanins, or the individual phenolic compounds were observed among the high O₂ and air-stored fruits after 14 days of storage. These results indicate that high oxygen treatments exert the most effects on fruit quality and antioxidant capacity of strawberry fruit in the first 7 days of storage.     

Twenty-five years of total antioxidant capacity measurement of foods and biological fluids: merits and limitations

This review summarises 25 years of investigations on antioxidants research in foods and biological fluids and critically analyses the merits and limitations of using the total antioxidant capacity (TAC) measurement in the metabolomic era. An enormous bulk of knowledge was produced regarding the antioxidant capacity of foods and large TAC databases were developed. A direct link between a food TAC value and any health benefit is erroneous and has led to several cases of consumer deception. However, the striking epidemiological evidence associating a high dietary TAC with some disease prevention and the availability of well-constructed TAC databases deserve attention and must be taken into account to establish the usefulness of measuring TAC in both foods and biological samples. The in vivo TAC measurement, usually performed in plasma, is influenced by many external factors, such as dietary habits, as well as environmental and behavioural factors, which are integrated towards homeostatic control by fine physiological mechanisms with high inter-individual variability. Therefore, plasma TAC cannot be considered as a unique biomarker of individual antioxidant status. However, the combined evaluation of plasma TAC with known markers of disease, individual metabolism, inflammation and genetics, as well as with markers of gut microbiota composition and activity, may lead to the identification of populations that are more responsive to food/diet TAC. In this framework, the appropriate use of TAC measurement both in food and in vivo can still provide support for the interpretation of complex phenomena and be a tool for sample screening when making a quick decision toward in-depth research investigations. © 2018 Society of Chemical Industry     

Antioxidant stability of small fruits in postharvest storage at room and refrigerator temperatures

Strawberries (Fragaria ananassa), raspberries (Rubus idaeus) and red currants (Ribes rubrum), as well as two drupes, cherries (Prunus avium), and sour cherries (Prunus cerasus), were subjected to two storage temperatures (4 °C and 25 °C) and phytochemicals concentrations (total phenols, flavonoids and anthocyanins) as well as antioxidant capacity (DPPH, ABTS and FRAP assays) were monitored until the fruit visually spoiled. Red currants and strawberries exhibited the highest initial total phenol (TP) contents (322.40 ± 5.56 and 335.47 ± 6.12 mg GAE/100 g FW, respectively) and maintained the highest TP contents throughout storage at both temperatures. Storage of at 25 °C as opposed to 4 °C, facilitated faster spoilage of analyzed fruits. In addition, most fruits stored at 4 °C, exhibited slightly higher antioxidant activity values at the end of storage according to all three antioxidant activity assays as opposed to fruits stored at 25 °C. The dynamic evolution of antioxidant capacity at both temperatures reflected the transient changes in phytochemical composition of small fruits in storage.     

Influence of environmental and genetic factors on health-related compounds in strawberry

Strawberry (Fragaria × ananassa, Duch.) represents a relevant source of micronutrients and phenolic substances, most of which are natural antioxidants and contribute to the high nutritional quality (NQ) of the fruit. Despite its proven health benefits, strawberries also contain allergenic compounds. In particular protein Fra a 1 is considered the main cause of allergic reactions after consumption of these fruits. However, there is a dearth of literature data on the genetic and seasonal influences on the Fra a 1 accumulation in strawberries, and on the quantitative variation of this allergen during fruit ripening.     

The effects of organic and conventional nutrient amendments on strawberry cultivation: Fruit yield and quality

BACKGROUND: The nutrition of food is increasingly important to consumers. The popularity of organic food rests partly on the assumption that these products are healthier despite a lack of conclusive evidence. The effects of organic and inorganic fertilizer amendments on parameters of strawberry fruit quality, in terms of sugar, macro‐ and micro‐nutrients concentrations, and total antioxidant capacity were compared. RESULTS: Treatments did not affect sugar content or total antioxidant capacity. Inorganic fertilizer treatments increased S and Mn content of berries compared to organic treatments. The K and P content of berries differed among years. CONCLUSIONS: Organic amendments did not increase the fruit quality of strawberries compared to inorganic amendments. Copyright © 2008 Society of Chemical Industry     

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings. RESULTS: The order of TAC (mmol Trolox g^?1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety. CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry     

米糠提取物超声辅助提取工艺及抗氧化活性

以乙醇为提取溶剂,采用响应面法对米糠提取物的超声辅助最佳提取工艺进行探讨。米糠提取物的总酚含量及抗氧化活性分别采用Folin-Ciocalteu 法和 Trolox 等价抗氧化能力(TEAC)方法测定。结果表明：总抗氧化活性随着总酚含量的增加而增大,但其活性高低并不完全取决于总酚物质。米糠提取物最佳提取工艺条件为乙醇体积分数90%(V/V),提取温度55℃,提取时间97min。在此条件下,米糠提取物的总酚含量为(2.76 ± 0.17)mg GAE/g米糠(n=3),总抗氧化活性为(2.99 ± 0.24)μmol TEAC/g 米糠(n=3)。     

Combining quality and antioxidant attributes in the strawberry: The role of genotype

The nutritional value of fruit has been widely studied and is demanded by consumers, especially for protection against cardiovascular disorder, cancer and other diseases, as well as for general health benefits. These benefits can also be ascribed to the total antioxidant capacity (TAC) of fruit.Fruit nutritional quality can be described by a standard quality parameter and the analyses of nutritional parameters, such as antioxidant capacity (and specific related compounds). In this study, firmness, colour, soluble solids content and titratable acidity were considered as quality parameters and TAC and total phenolic content as nutritional parameters. All these attributes were screened in 20 strawberry genotypes (cultivars and selections) for the selection of new improved genetic material (offspring) originating from different cross combinations, including an F1 Fragaria virginiana spp. glauca among parents.Results indicate that the effect of the genotype on strawberry nutritional quality is stronger than that of the cultivation conditions. However, commercial cultivation did not show a high range of variation of fruit nutritional quality, particularly for the nutritional parameters.The study of offspring originating from different cross combinations showed that fruit nutritional quality can be considered an inheritable trait and that the variability of fruit nutritional quality among commercial cultivars can be improved by breeding.Finally, results demonstrate the role of F. virginiana spp. glauca as an important genetic source of the fruit nutritional quality.     

Antioxidant and antiglycation properties of Passiflora alata and Passiflora edulis extracts

The leaves of Passiflora alata Dryander and Passiflora edulis Sims, traditionally used in American countries to treat both anxiety and nervousness by folk medicine, are rich in polyphenols, which have been reported as natural antioxidants. In this study, the antioxidant activities of P. edulis and P. alata hydroalcoholic leaf extracts were verified in in vitro and ex vivo assays. P. alata showed a higher total reactive antioxidant potential than did P. edulis. The antioxidant activities of both extracts were significantly correlated with polyphenol contents. In addition, both extracts attenuated ex vivo iron-induced cell death, quantified by lactate dehydrogenase leakage, and effectively protected against protein damage induced by iron and glucose. These findings demonstrate that the P. alata and P. edulis leaf extracts have potent in vitro and ex vivo antioxidant properties and might be considered as possible new sources of natural antioxidants.     

Comparison of the 2,2'-azinobis-3-ethylbenzotiazo-line-6-sulfonic acid (ABTS) and ferric reducing anti-oxidant power (FRAP) methods to asses the total antioxidant capacity in extracts of fruit and vegetables

A comparison was made on the use of two spectrophotometric methods, the ferric reducing antioxidant power (FRAP) method and the 2,2'-azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) method, for the measurement of the total antioxidant capacity (TAC) of plant foods. The correlations of TAC measured by the two methods were highly significant in both water-soluble (r2= 0.90) and water-insoluble extracts (r2= 0.98) from 13 strawberry samples. Also a corresponding comparison of TAC in extracts from 14 plant species showed high correlation coefficients, r2= 0.98 for water-soluble extracts and r2= 0.88 for water-insoluble extracts. The ratio of TAC values obtained with the two methods (ABTS/FRAP) varied between 0.7 and 3.3 for different plant extracts indicating that they contained antioxidants with varying reactivity in the two methods. TACs in six pure antioxidant substances were ranked in the following order by both methods: quercetin > ferulic acid > catechin > rutin > caffeic acid > Trolox = chlorogenic acid. The two methods showed similar TAC values for quercetin, rutin, caffeic acid and chlorogenic acid while ferulic acid and catechin gave higher results with the ABTS method than with the FRAP method, and such differences probably explain the varying ratios of ABTS/FRAP obtained in foods. Regarding storage TAC in water-soluble strawberry extracts stored at -20 or -80 degrees C was stable for at least five months while storage at 4 degrees C decreased the TAC value with 40% during five weeks of storage. The study showed that both the ABTS and FRAP methods can be used for convenient monitoring of the antioxidant capacities in fruit and vegetables, and that different antioxidants had varying reactivity in the two methods.     

Comparison of antioxidant capacity of commonly consumed youth beverages in the United States

Epidemiological evidence supports that polyphenol‐rich foods with high antioxidant potency promote health and may influence various metabolic diseases' development. Often beverage products claim to have antioxidant potency based on the perceived polyphenol content; however, few studies have examined the antioxidant potency of beverages with none reporting on commonly consumed youth beverages. This study's purpose was to measure total antioxidant capacity (TAC), expressed in Trolox equivalents (μmol mL^?1), in a variety of youth beverages, including juices, vitamin enhanced waters, sport drinks, energy drinks and various milk products. Significantly higher TAC (3.8–6.7 μmol mL^?1) was measured in 100% juices, while vitamin enhanced waters varied by brand (0.2–3.1 μmol mL^?1). Soda, energy and sports drinks measured the least activity (0.0–0.3 μmol mL^?1), whereas other milk types (strawberry, organic, regular and soya) measured no activity, except chocolate milk (3.0 μmol mL^?1). These results may improve beverage selection practices for youth, parents and dietitians to increase TAC of the paediatric diet.     

A Comparative Study of Phenolic Antioxidant Activity and Flavonoid Biosynthesis‐Related Gene Expression Between Summer and Winter Strawberry Cultivars

Strawberry (Fragaria ananassa Duch.) possesses good antioxidant properties. Phenolic compounds in strawberries, such as anthocyanins and ellagic acid, mainly act as antioxidants. This study aimed to compare the phenolic content and expression patterns of genes involved in flavonoid biosynthesis between summer and winter strawberry cultivars affected by seasonal variation, degree of ripeness, and genotype. Antioxidant activity and the total content of phenols and flavonoids decreased with fruit ripening. Most notably, summer strawberry cultivars showed higher antioxidant activity than winter cultivars. The expression patterns of flavonoid biosynthetic genes tested were cultivar‐dependent and were also affected by ripening. These results help us understand the nutritional and physiological characteristics of selected cultivars and provide a range of information for strawberry consumption.     

Influence of Storage Temperature on the Kinetics of the Changes in Anthocyanins, Vitamin C, and Antioxidant Capacity in Fresh-Cut Strawberries Stored under High-Oxygen Atmospheres

ABSTRACT:  Changes in the main antioxidant properties of fresh-cut strawberries stored under high-oxygen atmospheres (80 kPa O₂) were studied at selected temperatures (5 to 20 °C). The suitability of zero- and 1st-order kinetics as well as a model based on Weibull distribution function to describe changes in experimental data is discussed. A non-Arrhenius approach was used to determine the temperature dependence of the estimated rate constants. A Weibull kinetic model most accurately  ( R ²_adj≥ 0.800)  estimated changes in anthocyanins and antioxidant capacity of fresh-cut strawberries throughout the storage period, whereas a 1st-order model adequately fitted  ( R ²_adj≥ 0.982)  the variation of vitamin C. The temperature dependency of the kinetic rate constants for each antioxidant property was successfully modeled through the non-Arrhenius approach  ( R ²_adj≥ 0.709)  . The T_c obtained for anthocyanins, vitamin C, and antioxidant capacity degradation were 290, 284, and 289 K, respectively, indicating the temperature at which a marked acceleration of the losses in the antioxidant potential of strawberry wedges occurs. These findings will help to describe the variation of the antioxidant potential of fresh-cut strawberries upon storage time and temperature.     

Factors in Various Fractions of Meat Homogenates That Affect the Oxidative Stability of Raw Chicken Breast and Beef Loin

ABSTRACT:  The fractions of meat homogenates were analyzed to find the factors that determine the susceptibility of raw chicken breast and beef loin to lipid oxidation. The fractions used in this study were meat homogenate, precipitate, and supernatant of homogenate after centrifugation, and high and low molecular weight fractions from the supernatant. Chicken breast showed greater oxidative stability than beef loin during 10-d storage ( P < 0.05). All fractions from chicken breast showed lower amounts of free ionic iron and myoglobin and higher total antioxidant capacity (TAC) than those from beef loin during storage. The TAC level of chicken breast maintained during storage. This suggested that the oxidative stability of chicken breast was ascribed to high, stable total antioxidant capacity with low level of catalysts for lipid oxidation. The water-soluble high molecular weight fraction, which contained myoglobin, was responsible for the high lipoxygenase-like activity and lipid oxidation potential (LOP) in beef loin. TAC in all fractions from beef loin decreased during storage. This suggested that high myoglobin content in beef loin caused the imbalance between pro- and antioxidant factors leading to the high susceptibility of beef loin to lipid oxidation. Myoglobin served a major source of catalysts, ferrylmyoglobin, hematin, and/or free ionic iron, for lipid oxidation.     

Cultivars, culture conditions, and harvest time influence phenolic and ascorbic acid contents and antioxidant capacity of strawberry (Fragaria x ananassa)

Strawberries are a good source of micronutrients, especially antioxidant phenolics. More information is needed to better exploit the health-promoting effect of such fruits. Several studies focused on the effects of genotype, cultural practices, and seasonal variation on the antioxidant potential of strawberries, but often yielding contradictory results and/or focusing on only 1 source of variability. In the present study, we showed that total phenolic compounds, ascorbic acid, and antioxidant capacity strongly differed between genotypes of strawberry. The precise results revealed the importance of genetic background for the antioxidant capacity and for the content of total phenolics (with up to 3.3-fold variations). Other parameters may also influence the antioxidant capacity in strawberry such as harvest time, culture conditions, and environmental factors. Moreover, in this study, the harvesting time (at the same ripening stage) appeared to be very important, more important than genotype. Variations of the antioxidant capacity of up to 4.1-folds were observed following the harvesting time of "Elsanta" cultivar. PRACTICAL APPLICATION: This article compares the antioxidant capacity and the content in ascorbic acid and phenolic compounds of strawberries of different varieties and of fruits harvested from April to December at the same ripening stage. The importance of strawberry antioxidant capacity resides in its benefits for human health.     

Characterization of antioxidant compounds of red and white rice and changes in total antioxidant capacity during processing

Although most rice cultivars have whitish kernel, some varieties have a red testa. Aim of this work was to compare the total antioxidant capacity (TAC) and the antioxidant chemical composition (namely tocols, gamma-oryzanols, and polyphenols) of red and white rices. In addition, the effect of milling and cooking on antioxidants was investigated in both rices. Dehulled red rice showed a TAC more than three times greater than dehulled white rice and its high TAC was essentially characterized by the presence of proanthocyanidins (PA) and associated phenolics. Milling caused a significant loss of TAC, even if red rice maintained a higher TAC. Cooking caused a further loss of antioxidants, but when there was a full uptake of cooking water by the grains ("risotto") this loss was limited. Thus, the consumption of whole or partially milled rice cooked as risotto would be preferred to preserve its nutritional properties.     

Abomasal infusion of essential fatty acids and conjugated linoleic acid during late pregnancy and early lactation affects immunohematological and oxidative stress markers in dairy cows

Oxidative stress and inflammation, as natural parts of metabolic adaptations during the transition from late gestation to early lactation, are critical indicators of dairy cows' metabolic health. This study was designed to investigate the effects of abomasal infusion of essential fatty acids (EFA), particularly α-linolenic acid, and conjugated linoleic acid (CLA) on plasma, erythrocyte, and liver markers of oxidative stress in dairy cows during the transition period. Rumen-cannulated German Holstein cows (n = 38) in their second lactation (11,101 ± 1,118 kg milk/305 d, mean ± standard deviation) were abomasally infused with one of the following treatments from d −63 antepartum until d 63 postpartum (PP): CTRL (n = 9; 76 g/d coconut oil); EFA (n = 9; 78 g/d linseed plus 4 g/d safflower oil); CLA (n = 10; isomers cis-9,trans-11 and trans-10,cis-12 CLA; 38 g/d); and EFA+CLA (n = 10; 120 g/d). Hematological parameters as well as markers of oxidative status were measured in plasma, erythrocytes, and liver before and after calving. Immunohematological parameters, including erythrocyte number, hematocrit, hemoglobin, mean corpuscular hemoglobin, leukocytes, and basophils, were affected by time, and their peak levels were observed on the day after calving. The oxidative stress markers glutathione peroxidase 1 and reactive oxygen metabolites in plasma and erythrocytes were both affected by time, exhibiting the highest levels on d 1 PP, whereas β-carotene, retinol, and tocopherol were at their lowest levels at the same time. Immunohematological parameters were only marginally affected by fatty acid treatment in a time-dependent manner. As such, lymphocyte and atypical lymphocyte counts were both significantly highest in the groups that received EFA at d 1 PP. Moreover, EFA supplementation increased the mean corpuscular volume and showed a trend for induction of mean corpuscular hemoglobin compared with the CLA group during the transition period. The PP mean thrombocyte volume was higher in the EFA than in the CLA group (except for d 28) and both EFA and CLA reduced number of thrombocytes and thrombocrit at distinct time points. Hepatic mRNA abundance of markers related to oxidative status, including glutathione peroxidase (GPX-1) and catalase (CAT), was lower (P < 0.05) in EFA-treated than non-EFA-treated cows at d 28 PP. Dairy cows at the onset of lactation were characterized by induced markers of both oxidative stress and inflammation. Supplementing EFA and CLA had minor and time-dependent effects on markers of oxidative stress in plasma, erythrocytes, and liver. A comparison of EFA supplementation with CLA or CTRL showed higher immunohematological response at d 1 PP and lower hepatic antioxidant levels by d 28 PP. Supplementation with EFA+CLA had only a minor effect on oxidative markers, which were more similar to those with the EFA treatment. Altogether, despite the time-dependent differences, the current findings show only minor effects of EFA and CLA supplementation in the prevention of early lactation-induced oxidative stress.     

Changes in the catechin and epicatechin content of grape seeds on storage under different water activity (aw) conditions

Storage effect on antioxidant content and capacity of grape seeds under different a_w conditions (a_w 0.33; 0.53; 0.75/50 days, 25 °C) was examined. Total phenol content (determined by the Folin–Ciocalteu method) decreased during storage though changes were trivial for samples stored at 33% or 53% RH. High level of humidity (75%) accelerated degradation and resulted in a ∼50% reduction of total phenol content. Minor loss of the DPPH radical scavenging activity (%RSA) of the extracts was observed. Catechin and epicatechin content monitored by RP-HPLC was reduced during storage, particularly at 75% RH. Epicatechin content proved to be less sensitive to water activity conditions than catechin content. Results of various in vitro assays (Folin–Ciocalteu, FRAP, DPPH, ABTS, CBA, ORAC and copper induced liposome oxidation) did not support difference in terms of resistance to oxidation. Based on the continuous release of gallic acid, our finding was related to hydrolytic reactions. Control of a_w of grape seeds can be of practical importance for the wine industry.