Rheological characterisation of juices obtained from transgenic pectate lyase-silenced strawberry fruits

The present study is focused on the characteristics of juice made from transgenic strawberry fruits with a 90% reduction on pectate lyase mRNA expression. No differences of soluble solids, pH or solid volume fraction were found between control and transgenic juices. Total sugar content of the serum fraction was also similar but a slightly higher content of large molecular mass polyuronides was observed in transgenic juice. The solid fraction of transgenic juice contained larger particles than did the control. The dynamic shear analysis of the juices showed higher values of the storage (G′) and loss (G′′) moduli versus strain for the transgenic samples, with G′ over G′′ within the linear viscoelastic range (LVR). For both samples, G′ and G′′ increased with frequency, showing a weak-gel response, whereas complex viscosity (η^∗) decreased with frequency, denoting a shear-thinning behaviour. Overall, the transgenic juices showed higher values of G′, G′′ and complex viscosity than did the control within the frequency range assayed and a more solid-like character. These results suggest that effects of pectate lyase-silencing in tissue integrity increased the content of large particles in juice, its viscoelastic properties being modified and its viscosity increased.     

Comparative study of polyphenolic content and antiradical activity of cloudy and clear apple juices

Clear and cloudy apple juices from Idared and Champion varieties were studied for their radical‐scavenging effects. The polyphenolic content and composition of the juices before and after thiolysis were determined by high‐performance liquid chromatography with diode array detection. Cloudy juices, especially that prepared from Champion variety, had a higher content of procyanidins than clear juices. Radical‐scavenging activity was measured by electron paramagnetic resonance (EPR) spectroscopy using the stable 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical. All juices showed long‐lasting radical‐scavenging activity, and EPR spectra were recorded over time to follow the reaction kinetics. Scavenging of DPPH showed pseudo‐first‐order kinetics, which might be expected in the presence of polymerised antioxidants that prevent closer contact between the DPPH radical and hydroxyl groups. The content of polymeric procyanidins showed a linear dependence on the rate constant, suggesting that these compounds are mainly responsible for time‐extended radical‐scavenging activity. The antioxidant properties of apple juices were much better reproduced by EPR spectroscopy than by UV–visible measurements. The former method is especially sensitive to the concentration of polymerised or bound procyanidins, whilst the latter method requires transparent (clear) samples. Apple juices, especially cloudy ones, are a rich source of natural antioxidants that may be used in the pharmaceutical or food industry. Copyright © 2006 Society of Chemical Industry     

Evidence of frequent integration of non-T-DNA vector backbone sequences in transgenic strawberry plant

We have studied the occurrence of the integration of non-T-DNA sequences in transgenic strawberry plants obtained through Agrobacterium inoculation. DNA from these plants was subjected to PCR amplification of the sequence of the gene trfA, which is located outside the T-DNA. The percentage of trfA-positive plants varied from 40% to 90%, with a mean of 65.7%. Backbone sequences were confirmed by Southern blot analysis.     

Bioactive compounds and quantification of total ellagic acid in strawberries (Fragaria x ananassa Duch.)

Strawberries are one of the most popular edible fruits in Brazil and their consumption has increased with the development of new varieties available at almost all seasons. Fruit of seven full-ripened strawberry cultivars (Dover, Camp Dover, Camarosa, Sweet Charlie, Toyonoka, Oso Grande and Piedade) were characterized in relation to the total phenolics, vitamin C, flavonoids, free and total ellagic acid contents and antioxidant capacity. Camp Dover had the lowest values for anthocyanins and total phenolics but the highest total flavonoid content. Dover presented the highest anthocyanin, total phenolics and ellagic acid contents and also elevated antioxidant capacity. The best conditions for the determination of the total ellagic acid content in strawberries were also optimized and the results showed that the extraction with 80% acetone, and hydrolysis using 2 N TFA at 120 °C for 60 min allowed a 99% recovery.     

Comparison of phenolic composition and antioxidant properties of two native Chilean and one domestic strawberry genotypes

The phenolic composition of extracts from the forms chiloensis and patagonica of Fragaria chiloensis were compared with that of the commercial strawberry Fragaria × ananassa cv. Chandler by high performance liquid chromatography with diode-array detector (HPLC–DAD) and high performance liquid chromatography with electrospray ionization mass spectroscopy detector (HPLC–ESI–MS). The phenolic constituents in the three species were mainly proanthocyanidins, hydrolysable tannins, anthocyanins and flavonol glycosides. In both native strawberry species the main flavonol glycoside was quercetin 3-O-glucuronide and the minor anthocyanins identified were cyanidin-malonyl-glucoside and pelargonidin-malonyl-glucoside. The highest anthocyanin content was found in the commercial red strawberry while ellagic acid was the main phenolic in the native white strawberry. From the methanolic fruit extract of the native Chilean strawberry Fragaria chiloensis ssp. chiloensis f. chiloensis four known antioxidants were isolated by selective fractionation using the bleaching of the free radical scavenger 1,1-diphenyl-2-picrylhydrazyl (DPPH) as the guiding assay. The antioxidant properties (measured as the bleaching of the DPPH radical) were determined for methanol extracts of the three fruits, for fractions of F. chiloensis ssp. chiloensis f. chiloensis, and for the isolated compounds cyanidin-3-glucoside, pelargonidin-3-glucoside, quercetin-3-glucuronide and ellagic acid. This study allows a clear chemical differentiation between the commercial strawberry and the Chilean white strawberry.     

Effect of l-ascorbic acid, sugar, pectin and freeze-thaw treatment on polyphenol content of frozen strawberries

The stability of phenolic compounds of three strawberry cultivars was evaluated for changes during prefreezing treatments, storage and various freezing and thawing conditions. Polyphenol content was determined by HPLC-DAD-FL. The sum of assayed polyphenolic (proanthocyanidin and monomeric flavan-3-ols, anthocyanins, ellagic acid, p-coumaric acid) represented 2858.4 mg/kg in Kent, 2893.1 mg/kg in Elkat, and 2438.0 mg/kg in Senga Sengana. After freezing, 4.5-33.6% of polyphenols were lost; protective effects of prefreezing treatments were seen on anthocyanidins and proanthocyanidins: ascorbic acid was the most effective pretreatment, allowing retention of 3.9-27.5% of anthocyanins, and almost total recovery (3.9-23.9%) when associated with liquid nitrogen freezing. Pectin and sugar only allowed retention of 3.0-25.1% and 5.5-25.4% of the antocyanins, respectively. Thawing of the strawberries in a microwave oven (instead of 20 h at 20 °C) had a further positive effect on retention of anthocyanins, proanthocyanins, (+)-catechin and ellagic acid.     

Evaluation of the phenolic content,antioxidant activity and colour of Slovenian honey

Honey samples from the seven most common honey types in Slovenia were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using the ferric reducing antioxidant power (FRAP) assay and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method for antiradical activity. In addition the colour characteristics of honey samples were analysed. The results of the study showed that total phenolic content, antioxidant activity and colour parameters differ widely among different honey types. Phenolic content expressed as gallic acid equivalent ranged from 44.8 mg/kg in acacia honey to 241.4 mg/kg in fir honey. Antioxidant activity was the lowest in the brightest acacia and lime honeys and the highest in darker honeys, namely fir, spruce and forest. The colour of the Slovenian honeys, analysed in this study was very variable and ranged from pale yellow to dark brown. Correlations between the parameters analysed were found to be statistically significant (p < 0.05).     

Impact of germination on phenolic content and antioxidant activity of 13 edible seed species

The aim of this work was to test 13 edible seeds for the levels of phenolic compounds and the antioxidant activity (TAC) at different germination states (dormant, imbibed and 7d sprouts). Selected seeds included mungbean, alfalfa, fava, fenugreek, mustard, wheat, broccoli, sunflower, soybean, radish, kale, lentil and onion. Accumulated phenolics (mg chlorogenic acid equivalent, CAE) and TAC (μg Trolox equivalent) on dry basis (DB) showed the general trend distribution of 7d sprouts > dormant seeds > imbibed seeds. In addition, the specific TAC (μg Trolox mg⁻¹ CAE) increased only for imbibed seeds indicating a possible protection effect of the phenolic antioxidants to the emerging sprouts. Phenolic contents of 7d sprouts (DB) ranged from 490 (lentil) to 5676 (mustard) mg CAE 100 g⁻¹. Seven day sunflower sprouts had higher TAC on a DB (40202 μg Trolox g⁻¹) compared to other seeds (1456–25991) and a blueberry reference (35232). Increases in phenolics (DB) from dormant seed to 7d sprout differ among seeds, ranging from 2010% (mungbean) to −11% (kale), while increases in TAC (DB) ranged from 1928% (mungbean) to 0% (lentil). This study shows that germinated edible seeds are an excellent source of dietary phenolic antioxidants.     

Flavonols, betacyanins content and antioxidant activity of cactus Opuntia macrorhiza fruits

Flavonols, betacyanins content and antioxidant activity of red-purple cactus Opuntia macrorhiza fruits, a promising cactus pear species, were evaluated in comparison to the well known cactus pear fruits of Opuntia ficus-indica. Flavonol profile was evaluated by HPLC-DAD prior to and after enzymatic hydrolysis (glycosides vs. aglycons). In addition betacyanins, responsible for the purple to red color of cactus pear fruits were also estimated and compared to Beta vulgaris ssp. (roots) and red O. ficus-indica fruits. In all cases, cactus fruit pulps showed no flavonols at all. While different derivatives of isorhamnetin glycosides were found in O. ficus-indica fruit's peel, isorhamnetin-3-O-rutinoside was the only compound in O. macrorhiza fruit. Correspondingly, antioxidant activity assays showed a high antioxidant activity of both, O. macrorhiza fruit's peel and pulp. With regard to betacyanins, O. macrorhiza fruit's peel and pulp provide a deep red-purple color, whose average impact is higher compared to red beet (B. vulgaris spp.) and about 8-fold higher than red fruits from O. ficus-indica. Supporting these results, estimation of color attributes (L*, a*, b*, C and H°) showed also a high color impact of both O. macrorhiza fruit's peel and pulp.     

Effect of mash maceration and ripening stage of apples on phenolic compounds and antioxidant power of cloudy juices: A study using chemometrics

The effects of different enzymatic preparations on total phenolic content, phenolic profile (HPLC), and ferric reducing antioxidant power (FRAP) of cloudy juices from Lis Gala and Fuji Suprema apples varieties, at three ripening stages (unripe, ripe and senescent) were investigated using Principal Component Analysis and Hierarchical Cluster Analysis. The commercial preparations enzymatic (Ultrazym^® AFPL; Pectinex^® Ultra Clear; Pectinex^® SMASH XXL; Panzym^® YieldMASH) increased the total phenolic compounds and ferric reducing capacity of the cloudy juice from unripe and ripe Lis Gala (respectively by 67 and 49% for unripe apples, and 28 and 33% for ripe apples) and unripe Fuji Suprema apples (23 and 55%), while for the ripe Fuji Suprema apples only Pectinex^® Ultra Clear and Panzym^® YieldMASH had this effect. No significant (p > 0.05) was observed on senescent stage, whatever the enzymatic preparation. Enzymatic preparations could increase phenolic compounds concentration and antioxidant capacity of cloudy apple juice, but this effect depended on the maturity of the apples.     

Identification and quantification of phenolic compounds and their effects on antioxidant activity in pomegranate juices of eight Iranian cultivars

Important health-promoting compounds, including six types of anthocyanins, phytoestrogenic flavonoids and ellagic acid were determined individually in pomegranate juices (Punica granatum L.) of eight Iranian cultivars by high performance liquid chromatography coupled to UV–vis detector (HPLC–UV) using individual calculation from the peak area based on standard curves of each component. Total phenolics and antioxidant activities were determined by Folin–Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods, respectively, and compared among the cultivars. The predominant anthocyanins were delphinidin 3,5-diglucoside (372–5301 mg/l) followed by cyanidin 3,5-diglucoside (242–2361 mg/l), delphinidin 3-glucoside (49–1042 mg/l) and pelargonidin 3,5-diglucoside (7–90 mg/l), respectively. The highest level of total tannins was found in Sweet Alak cultivar (3 mg/l). Saveh Black Leather showed the highest level of ellagic acid (160 mg/l). Antioxidant activity varied among the cultivars (18–42 Trolox equivalents antioxidant capacity) and was directly related to the total phenolics in each type of juice.     

Analysis of phenolic compounds and antioxidant activity with H4IIE cells of three different rice grain varieties

The phenolic content and the antioxidant capacity of ethanolic extract of rice grains were examined using three different rice (Oryza sativa L. var. japonica) varieties, Jakwangchalbyeo (red pericarp glutinous rice), Hwasunchalbyeo (white pericarp glutinous rice), and Ilpumbyeo (white pericarp non-glutinous rice). Quantitative high performance liquid chromatography (HPLC) analyses showed that Jakwangchalbyeo contains the highest amount of total phenolic substances. Radical scavenging activities measured by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) assay were 87.5% (Jakwangchalbyeo), 45.0% (Hwasunchalbyeo), and 50.0% (Ilpumbyeo). The results suggest a positive correlation between the phenolic content and the antioxidation capacity. Antioxidant activity in the ethanolic extract of rice grain was further assessed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay and fluorescence-activated cell sorting (FACS) analysis of H4IIE cells treated with hydrogen peroxide (H₂O₂). Hwasunchalbyeo and Ilpumbyeo extracts showed no significant effects on H₂O₂-induced oxidative stress. Jakwangchalbyeo extract increased cell viability by up to 82% and 74% after 5- and 24-h treatments at 100 μg/mL, respectively. Consistent with the results of DPPH and MTT assays, dichlorofluorescein (DCF) fluorescence was further reduced when H₂O₂ was applied with Jakwangchalbyeo extract. In conclusion, red pericarp Jakwangchalbyeo grain extracts exerted significantly higher inhibitory effects on H₂O₂-induced oxidative stress in H4IIE cells than did other white pericarp rice grain extracts.     

The effect of postharvest ripening on strawberry bioactive composition and antioxidant potential

BACKGROUND: The aim of the present work was to evaluate the phytochemical profile and the antioxidant activity of strawberry fruit (cv. Camarosa) upon postharvest ripening at room temperature (20 °C) and to correlate them with qualitative attributes. RESULTS: ‘Camarosa’ fruit retained an appreciable postharvest performance for up to 1 day shelf life; thereafter substantial quality deterioration was observed. An increased phenolic content, mainly attributed to hydroxycinnamic acids, flavonols and anthocyanins, was monitored after 3 days maintenance at 20 °C. The chromatographic fingerprint of athocyanins showed that pelargonidin‐3‐glucoside was the major anthocyanin, which increased with the increase of shelf life period, while cyanidin‐3‐glucoside and pelargonidin‐3‐rutinoside were found at lower concentrations. The potent radical scavenging activity, evaluated with four in vitro assays, showed a higher antioxidant capacity after 3 and 1 days of shelf life. In addition, the antioxidant effect of strawberry fruit extracts on lipid substrates and on an emulsion system showed a significant inhibition in the formation of conjugated diene hyperoxides. Interestingly, no direct correlation between the phytochemical profile and the quality attributes exist. CONCLUSION: ‘Camarosa’ fruit had acceptable quality attributes for fresh consumption and at the same time a high phytochemical content up to 1 day shelf life. The over‐ripe fruit continued to be an excellent reservoir of natural antioxidants, pointing to its potential use as food antioxidant and nutritional supplement. Copyright © 2011 Society of Chemical Industry     

Antioxidant activity and total phenolic,organic acid and sugar content in commercial pomegranate juices

Pomegranate fruit and pomegranate juices (PJs) have taken great attention for their health benefits in the last years. The purpose of this study is to analyse the antioxidant activities, along with the organic acid and sugar contents of pomegranate juices sold in the Turkish markets. In the present study, we evaluated total phenolics (TPs), free radical scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing capacity of seven commercial PJs. Organic acid and sugar contents of juices were determined by capillary zone electrophoresis. The results showed that commercial pomegranate juices had markedly high total phenolic contents and antioxidant capacity. Fructose (F) and glucose (G) were found as the major sugars. The major acids were citric and malic. From the F/G ratio, organic acid profiles, TPs, and antioxidant capacity values, a possible adulteration was detected in one of the juices.     

Contribution of amino acids to strawberry fruit quality and their relevance as stress indicators under NaCl salinity

Strawberry cvs Korona and Elsanta, differing in their sensitivity to salt stress, were exposed to 0, 40, or 80 mM NaCl in the root medium from the end of April to mid-August. Although fruits of both cultivars contained comparable amounts of Na⁺ and Cl⁻, fruit quality was more impaired in cv. Elsanta, as indicated by the larger reductions of fruit size and sugar/acid ratios. Malondialdehyde levels started to rise significantly at 40 mM NaCl in the more sensitive cv. Elsanta, but at 80 mM in cv. Korona. Total amino acid levels, especially contents of essential amino acids, rose significantly in both cvs. Salt stress also increased contents of free proline, asparagine, and glutamine. Their increases may contribute to osmotic adjustment. The results of the present study favour the interpretation that elevated levels of proline, asparagine and glutamine are indicative of salt stress damage.     

The phenolic profiles and antioxidant activity in different types of tea

Phenolics are suggested to be the major bioactive compounds responsible for the health benefits of tea. Seven types of tea were extracted using boiling water. The extraction kinetics was investigated. To more fully characterise the antioxidant profiles and possible associated health benefits of these tea types, the total water‐soluble solid content, phenolics, flavonoids, and antioxidant and antiproliferative activities were quantified. Green tea leaves (GTL) were found to have the highest phenolic content (128.7 ± 1.7 mg g^?1, P < 0.05), followed by teas of decaffeinated green tea bag (dGTB), green tea bag (GTB), black tea bag (BTB), decaffeinated BTB, black tea leaves and oolong tea leaves (OTL). Among the three leaf teas, GT displayed the greatest antioxidant activity (4850.2 ± 60.7 μmol g^?1, P < 0.05), followed by black tea (BT) and oolong tea (OT). As for the four bag teas, decaffeinated GT possessed the strongest antioxidant activity (4431.1 ± 335.0 μmol g^?1, P < 0.05), followed by GT, BT and decaffeinated BT. The results display that phenolic/flavonoid content well correlated with antioxidant activity. Proliferation of three human cancer cells was significantly inhibited in a dose‐dependent manner after exposure to some tea extracts. This may influence consumers in selecting the type of tea and tea brewing times, exhibiting greater health benefits.     

Changes in phenolic composition and antioxidant activity of white wine during bottle storage: Accelerated browning test versus bottle storage

Polyphenol content, antioxidant activity, reducing power, colour and changes during storage over nine months in bottles and after accelerated browning were studied in selected Hellenic varietal white wines. The following phenolic compounds were identified in the wines: Caftaric, coutaric, fertaric, ferulic, caffeic, p-coumaric and gallic acids, (+)-catechin and (−)-epicatechin. The results showed that the contents of most of the phenols diminished with time, with the exception of caffeic, ferulic and p-coumaric acids. Antioxidant activity increased with storage whereas reducing power remained significantly unaffected. Accelerated browning did not significantly alter the concentrations of tartaric acid esters but it increased the concentrations of the hydroxycinnamic and gallic acids. (+)-Catechin concentration was not affected while (−)-epicatechin decreased. Antioxidant activity did not show any significant change but reducing power was reduced after the end of the browning test. As for the absorbance at 420 nm, it remained unchanged during storage, but it was significantly increased after accelerated browning.     

Isolation,identification, and antioxidant activity of anthocyanin compounds in Camarosa strawberry

This paper explores the bioactive composition of strawberry (Camarosa variety) [Fragaria × ananassa (Rosaceae Family)] describing its anthocyanin composition and measuring the antioxidant activity (AA) of isolated pigments.