Effects of exogenous abscisic acid on antioxidant capacities,anthocyanins, and flavonol contents of muscadine grape (Vitis rotundifolia) skins

The objective of this study was to evaluate the effect of exogenous abscisic acid (ABA) on the antioxidant capacity and phenolic content of muscadine grape skins (cvs. Noble and Alachua). ABA was applied on grapes during and after veraison. Average berry weight, total soluble solids (⁰Brix) and pH of the juice from both cultivars were not affected by the ABA treatment. Antioxidant capacity was enhanced by 38% and 18% in treated Noble at the first and second sampling, respectively. High performance liquid chromatography analysis revealed a significant increase in individual anthocyanins in treated Noble grapes at both sampling times. However, increase in the content of ellagic acid, myricetin, quercetin and kaempferol was observed at first sampling only. No effects of ABA treatment were seen in Alachua grapes. Our results indicate that exogenous application of ABA enhances the antioxidant capacity, anthocyanins and phenolic content of muscadine grapes but these effects may vary depending upon the cultivar.     

Determination of anthocyanin content in C.V Monastrell grapes during ripening period using several procedures

The accumulation of anthocyanins in grape skin and their evolution during ripening were evaluated in Monastrell grapes grown at four different sites growing season. Of the different techniques used for this purpose, we used one chromatographic [high‐performance liquid chromatography (HPLC)] and three spectrophotometric (Saint‐Cricq, Fragoso‐García and Lamadon) methods. The grapes from two of the sites (Agüeros and Rubializas) presented much higher values of anthocyanin (1279 and 1207 mg kg^?1 respectively) compounds than the grapes from the other two sites. Of the different methods used, HPLC proved to be an invaluable tool for identifying and quantifying individual anthocyanins in a sample, while the Fragoso‐García technique was the best of the spectrophotometric methods for laboratories that do not have access to HPLC equipment. Application of principal component determination (PCA) to our experimental data resulted satisfactory classification of wines in terms of their geographical origin. High correlation coefficients were observed among the different spectrophotometric techniques (0.88 between Fragoso‐García and Saint Cricq; and 0.92 between Lamadon and Saint Cricq) and lower coefficients between HPLC and the spectrophotometric techniques.     

Original article: Prediction of the colour and polyphenolic composition of the young red wines from the phenolic potential of the grapes

The phenolic potential of the grapes of Tannat, Cabernet Sauvignon and Merlot produced in the south region of Uruguay was analysed in four years. The grapes of Tannat had the highest total phenolic richness (A280 = 80.0), total anthocyanin potential (ApH1 = 2540 mg L^?1) and extractable anthocyanin potential (ApH3.2 = 1269 mg L^?1), although there were important differences between the years. Representative winemaking of each vineyard was carried out. The differences verified in the grapes phenolic indexes were related to the colour and polyphenolic composition of the wines. The correlations between the phenolic indexes of the grapes and the colour and polyphenolic composition of the wines were very high. The estimation of the polyphenolic richness and the extractability of the anthocyanins of the grapes allow to improve the management of the winemaking and the prediction of the chromatic characteristics and the global polyphenolic composition of the wines.     

Red clover isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice

Isoflavonoid extracts from red clover (Trifolium pratense) leaves were found to enhance overall color and stability of anthocyanin 3,5-diglucosides present in muscadine grape (Vitis rotundifolia) juice and wine through intermolecular copigmentation reactions. Predominant isoflavonoids present in red clover included formononetin, biochanin A, and prunetin and were the major polyphenolics identified to influence anthocyanin color and stability. Since red clover isoflavonoids have poor water solubility characteristics, this allowed for removal of extraneous non-isoflavonoid compounds using hot water and subsequent extraction with ethanol. Isoflavonoid solubility was evaluated as a function of ethanol concentration with recoveries up to 57% found in 20% solutions. Changes in maximum absorbance, total soluble phenolics, isoflavonoids, and anthocyanins were evaluated in muscadine juice and wine following the addition of isoflavonoid extracts with maximum color enhancement found at an anthocyanin to cofactor ratio of 1:8, after which their solubility was prohibitive. Additionally, dried leaves and ethanolic extracts of red clover were added prior to and following fermentation of muscadine wine (11% ethanol) stimulating the natural copigmentation that takes place during red wine fermentation and aging processes. Once fermentation was complete, finished wines were evaluated over a 9-week storage period at 20 and 37 °C. Despite low levels of isoflavonoids present, color improvement and anthocyanin stability was observed in the wines during storage. Little information is available on copigmentation reactions occurring in actual food systems, yet red clover isoflavonoids proved to be novel and effective color enhancing compounds when used in low concentrations in young muscadine wines.     

Antioxidant properties and bioactive components of Norton (Vitis aestivalis) and Cabernet Franc (Vitis vinifera) wine grapes

Three wine grapes, Norton (Vitis aestivalis), Cabernet Franc clone1, and Cabernet Franc clone313 (Vitis vinifera), collected from a Virginia vineyard were evaluated and compared for their antioxidant properties and phenolic profile. All grape extracts exerted remarkable antioxidant activities. Their oxygen radical absorbance capacity (ORAC) values were not significantly different from one another, ranging from 22.9 to 26.7 μmol TE/g of fresh weight. The Cabernet Franc clone1 had the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging activity (8.8 μmol TE/g) compared to the Norton or Cabernet Franc clone313 grape extracts (7.9 μmol TE/g and 5.4 μmol TE/g, respectively). The Norton grape contained significantly higher total phenolic, anthocyanin, and flavonoid content than the Cabernet Franc grapes (p < 0.05). The hydroxybenzoic acids, in particular gallic acid, were the major phenolic acids in all the grape extracts. The Norton grape variety was found to be rich in malvidin-diglucoside and malvidin-glucoside, while the malvidin-diglucoside was negligible in the Cabernet Franc grapes. The results suggest a remarkable impact of grape genotype on its antioxidant properties and phenolic composition in Virginia-grown wine grapes.     

HPLC-ESI-MS/MS测定动物性食品中19种喹诺酮类药物残留的研究

本研究建立了同时检测动物性食品中思诺沙星、环丙沙星、诺氟沙星、氧氟沙星、氟甲喹、恶喹酸、双氟沙星、沙拉沙星、司帕沙星、丹诺沙星、氟罗沙星、马波沙星、伊诺沙星、奥比沙星、培氟沙星、萘啶酸、吡哌酸、洛美沙星和西诺沙星19种喹诺酮类药物的HPLC．ESI．MS／MS检测方法。动物组织样品用乙腈提取,采用甲酸水溶液．甲醇体系作为流动相,梯度洗脱,质谱检测器检测。方法的线性范围为0．3～50μg／kg,相关系数（r）大于0．9956,检出限为0．3μg／kg,19种喹诺酮类药物在鸡肉和鱼肉的平均回收率分别为75．3％~96．3％、79．7％～94．2％,日内和日间变异系数均小于10％。     

Colour stability of anthocyanins from Isabel grapes (Vitis labrusca L.) in model systems

The influence of temperature, pH, the presence or absence of light, the presence or absence of oxygen and the presence or absence of tannic acid on the colour stability of anthocyanins from crude extract of Isabel grapes (Vitis labrusca L.) in food and model systems was studied. The spectrophotometric results (Δλ, ΔA) revealed interaction between the anthocyanins of the crude extract and tannic acid, suggesting copigmentation. In a model system, temperature, pH, the presence or absence of light, the presence or absence of oxygen and the presence or absence of tannic acid, significantly affected the half-life time of anthocyanins. The long half-time of the anthocyanins from Isabel grapes in a yoghurt model system indicates that these pigments are relatively stable in this food. In a rehydrated beverage model system at 4±1 °C, the presence of tannic acid (1:1, w/v) increased the half-life time by 187 h compared to the control samples.     

花青素酰基化作用研究进展

花青素是一类非常重要的天然食用色素,酰基化花青素因其具有较高的稳定性而成为各国食品科学家的研究热点,本文介绍了酰基化花青素的植物来源、稳定机制以及花青素发展趋势。     

Chemical characterization and antioxidant evaluation of muscadine grape pomace extract

Concentrated muscadine pomace extract was chromatographically analyzed for its individual phenolic, flavonoid, and anthocyanidin compounds. This extract was also characterized regarding its total phenolic content (TPC), total flavonoid content (TFC), antioxidative activities in terms of scavenging DPPH free radicals, reducing ferric, and chelating Fe²⁺. The TPC of this product was 34.1 ± 1.8 mg of gallic acid equivalents(GAE)/g of extract, and TFC was 3.0 ± 0.3 mg of quercetin equivalents/g of extract. Some phenolic compounds including ellagic acid, gallic acid, (−)-epicatechin, (−)-epigallocatechin, catechin, myricetin, quercetin, and kaempferol were identified. Some anthocyanidins including delphinidin, cyanidin, petunidin, peonidin, and malvidin were also identified in the extract by using a combination of retention and spectral properties on a reverse-phase HPLC–PDA. In addition, 3,3′,4,4′5,5′-hexahydroxystilbene-a resveratrol analogue present in the extract was identified for the first time by LC–MS. The results from this study demonstrate that the muscadine pomace extract is rich of natural antioxidants such as phenolics, flavonoids and anthocyanins, and possesses strong antioxidant properties. Besides, the developed methods can be used for routine quality control of the muscadine products for manufacturing efficiency and consistency.     

Cadmium in roadside grapes

The concentration of cadmium in unwashed wine grapes and leaves is considered as a function of the distance from the suspected source, an isolated straight road. Cadmium levels were determined by a.a.s. with electrothermal atomisation in a graphite furnace. The grape and leaf samples display an asymptotic decrease in cadmium concentration (c) according to the distance (d) from the edge of the road. The observed data can be fitted with the exponential function c=A+B exp (-Cd), the parameters being estimated by least-squares non-linear regression. The simple model allows the determination of the cadmium level at d→∞ (A) and at d=0 (A+B). The results obtained indicate that the effect of the presence of the road is not detectable beyond a distance of 50 m.     

Anthocyanin profiles of major red grape (Vitis vinifera L.) varieties cultivated in Greece and their relationship with in vitro antioxidant characteristics

A range of fourty‐six red grape (Vitis vinifera spp.) samples, originating from six widely cultivated varieties and covering major parts of the Hellenic vineyard, were assayed for their content in six principal anthocyanin pigments. Representative in vitro antioxidant parameters were also determined, including antiradical activity (A_AR), reducing power (P_R) and hydroxyl free radical scavenging activity (SA_HFR). Quantitative determination using high performance liquid chromatography showed that the prevalent pigment was malvidin 3‐O‐glucoside (average content 82.53 mg per 100 g fresh berry weight), followed by its coumarate derivative (29.26 mg per 100 g), paeonidin 3‐O‐glucoside (10.84 mg per 100 g), petunidin 3‐O‐glucoside (7.80 mg per 100 g) cyanidin 3‐O‐glucoside (5.67 mg per 100 g) and delphinidin 3‐O‐glucoside (1.28 mg per 100 g). The richest variety was Syrah, with total average anthocyanin content of 186.02 mg per 100 g, whereas the Hellenic native variety Xinomavro had the lowest average anthocyanin level (38.70 mg per 100 g). The establishment of correlations of individual and total anthocyanin contents with the values from the antioxidant test was accomplished with linear regression. The links of total anthocyanins were significant with all antioxidant parameters (P < 0.001), but more importantly with SA_HFR (R² = 0.740). Malvidin 3‐O‐glucoside content had the higher correlation with SA_HFR compared with all other anthocyanins (R² = 0.698, P < 0.001).     

Influence of pressing method on juice stilbene content in muscadine and bunch grapes

ABSTRACT:  Juice stilbene contents of 2 muscadine ( Vitis rotundifolia) cultivars, Noble and Carlos, and 2 bunch grape ( Vitis labrusca) cultivars, Mid South and Miss Blanc were evaluated after crushing and pressing. Four commercial pressing methods were used to produce juice: (1) cold press of fresh berries (CP); (2) hot press of fresh berries (HP); (3) cold press of frozen and thawed berries (FCP); and (4) cold press of pectolytic enzyme treated berries (ECP). Free run juice (FRJ) from the crusher without pressing was also tested. An HPLC with a UV detector was used to verify the presence and quantity of resveratrol, piceid, and their isomers. For the muscadine juices, total stilbenes were greater for HP and FCP than for FRJ and CP treatments. Trans -resveratrol was only detected in HP juices of the muscadines at levels near the detection limits. The bunch grape cultivars behaved similar to the muscadines in the processing treatments. HP juice had the greatest total stilbene levels and was significantly greater than FRJ, CP, and FCP. Total stilbene levels in juices from the 2 bunch grape cultivars, were higher (up to 5 times greater depending on pressing method) than for the muscadine grape cultivars. Total stilbene levels in muscadine juices treated with pectinase before pressing (ECP) were similar to those of the FCP samples. Juice from FCP and ECP treated Noble muscadine had total stilbene levels greater than FRJ and CP but less than HP levels. Juices from HP-, ECP-, and FCP-treated Carlos muscadine had total stilbene levels greater than for FRJ and CP juices.     

Microwave assisted extraction of anthocyanins from grape skins

A new method for the analysis of anthocyanins in grapes based on a systematic study of the extractability of eleven anthocyanins from grapes has been developed. Microwave assisted extraction was applied as a prior stage to the chromatographic determination of anthocyanins in the extracts. The stability of anthocyanins under the extraction conditions was checked using a standardised extract from grape skins. Temperatures from 50 °C up to 150 °C were evaluated. A fractional factorial experimental design was developed to analyse the influence on the extraction process of six different extraction variables: solvent (mixtures of methanol and water), stirring, extraction temperature, extraction time, microwave power and extraction volume. The extraction solvent was the most important variable for the recovery of most anthocyanins from grapes. Finally, the influence of the extraction time was also studied. With this new method, anthocyanins can be extracted from grapes in 5 min, using 100 °C as extraction temperature and 40% methanol in water as the extraction solvent. Repeatability and reproducibility were also checked, the resulting RSDs (n = 9) were lower than 7% for glucosides, the main components, and lower than 9% for the acyl derivatives, the compounds found in the lowest concentrations.     

Petit suisse manufactured with cheese whey retentate and application of betalains and anthocyanins

Petit suisse cheese was elaborated with substitution of 30% milk volume for cheese whey retentate (volumetric reduction ratio=5.0) obtained by ultrafiltration (cheese 1) and 100% milk (cheese 2). These were evaluated regarding physicochemical composition: moisture, ash, total solids, lipids, total proteins, acidity in lactic acid and pH. Natural pigments were added to the cheeses: Cabernet Sauvignon (Vitis vinifera L.) grape anthocyanins or (Beta vulgaris L.) beetroot betalains. The cheese samples were maintained at 6±1 °C for 40 days in light-impermeable packaging and evaluated regarding pigment stability by determining half-life time and percentage color retention. The results of the physicochemical analyses demonstrated that significant differences occurred between cheeses 1 and 2 regarding total solid content, moisture, protein, lipids and carbohydrates. The half-life time and percentage color retention values obtained for the anthocyanin and betalain extracts added to the cheeses were adequate for the shelf life of this product.     

Colour implications of self-association processes of wine anthocyanins

Copigmentation processes have been indicated to be crucial to stabilise coloured forms of the anthocyanins and explain colour expression in young red wines. Several studies exist about copigmentation between anthocyanins and different phenolics in model solutions, but little information is available about interactions among anthocyanins themselves. In this work, the process of self-association has been investigated in wine-like model solutions containing different grape anthocyanins (the 3-glucosides of malvidin, delphinidin and peonidin). The results obtained confirmed the existence of anthocyanin self-association and its influence on the apparent hydration constant of the anthocyanins with subsequent modification in the colour of the solutions. It was observed that the greater the degree of methoxylation of the anthocyanin B-ring the greater was the magnitude of the self-association. Colour analyses in the CIELAB space showed that self-association produces changes, which are more important in quantitative parameters (chroma, C _ab^* and lightness, L ^*) than in qualitative ones (hue, h _ab). Self-association leads to an increase in C _ab^*, indicating a more intense colour of the solutions, and to a decrease in the psychometric index L ^*, meaning that a darkening is produced. The effects on the colour were more pronounced with the passage of time of storage of the solutions.     

Composition of anthocyanins in pomegranate flowers and their antioxidant activity

Anthocyanins in the flowers of pomegranate (Punica granatum L.) were extracted and separated by reverse-phase high-performance liquid chromatography and Sephadex LH-20 chromatography. Two anthocyanins were identified to be pelargonidin 3,5-diglucoside and pelargonidin 3-glucoside by spectral methods, ultraviolet–visible spectroscopy, ¹H nuclear magnetic resonance spectroscopy, mass spectroscopy and comparisons with the literature. These two anthocyanins were identified from pomegranate flowers for the first time. Furthermore, the antioxidant activities of purified anthocyanins were screened for their antioxidative potential using 2,2′-diphenyl-1-picryl hydrazyl (DPPH) and 3-ethyl-benzo-thiazoline-6-sulphonate (ABTS) systems. The purified anthocyanins showed strong radical scavenging activities. Pelargonidin 3-glucoside showed higher antioxidant activity (50% inhibition values of 19.56 μg/ml for DPPH and Trolox equivalents antioxidant activity of 2.39 μg/μg for ABTS) than pelargonidin 3,5-diglucoside.     

Possible use of texture characteristics of winegrapes as markers for zoning and their relationship with anthocyanin extractability index

Ribeira Sacra Denomination of Origin is a steep slope viticulture area located in Galicia (northwest of Spain), and it is divided into five different subzones. Taking into account that grape composition depends not only on the grape cultivar used but also on the environmental factors and cultural practices, texture analysis has been proposed to assess the grape mechanical properties of those subzones. With the aid of principal component analysis, berry skin break energy measured on bottom side and berry cohesiveness have been suggested as the best mechanical properties for the subzones differentiation. Moreover, significant correlations among mechanical parameters and anthocyanin extractability index were found. A regression hyperplane allowed estimating anthocyanin extractability from berry skin thickness and Young′s modulus measured on the lateral side of grapes. The speed of mechanical analysis facilitates the planning and management of pressing and maceration processes as a consequence of the drastic reduction in sample treatment time.