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.     

不同品种染色葡萄转色期花色苷积累的差异性研究

该研究探究了三个染色葡萄品种烟73、Kolor和Tintorera在转色期其果皮和果肉中花色苷积累的差异。 通过利用高效液相色 谱-离子阱质谱联用仪（HPLC-ITMS）对花色苷的检测发现,各染色葡萄品种花色苷含量和比例存在组织特异性。 果皮和果肉中含量最 高的花色苷分别为二甲花翠素-3-O-葡萄糖苷和甲基花青素-3-O-葡糖苷,果皮和果肉中所占比例最高的花色苷分别为3',4',5'-羟基取 代花色苷和3',4'-羟基取代花色苷。 此外,基于各类花色苷的含量主成分分析（PCA）也能明显区分三个品种的果皮和果肉。 就不同品 种而言,烟73和Tintorera花色苷组成相似,而与Kolor存在明显差异（P＜0.05）。 该研究为探究染色葡萄不同组织中花色苷的合成机理 提供了基础,并且为染色葡萄在葡萄酒调色中的应用提供了理论依据。     

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.     

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.     

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.     

Volatile aroma constituents of Noble muscadine grapes

The volatile components of Noble muscadine grapes were analysed with a combined gas chromatograph-mass spectrometer. Over twenty-five peaks were separated, of which fifteen were identified. A gas chromatogram of the grape extract is presented, along with a Table of compounds and their associated mass spectral data.     

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％。     

鲤鱼组织中氯霉素的代谢速率及其色谱-质谱的表征方法研究

目的:研究氯霉素在鲤鱼体内的药物代谢动力学规律,并用色谱-质谱方法对代谢过程中残留的氯霉素进行结构表征。方法:以鲤鱼为实验动物,按80mg/kgbw剂量进行背部肌肉注射,用药代动力学参数描述氯霉素在鱼体内的代谢消除行为;在优化的反相色谱与电喷雾电离质谱(HPLC-ESI-MS)联用系统条件下,采用负离子检测模式,对鱼肌肉氯霉素进行结构分析。结果:氯霉素在鱼肌肉的残留呈现多峰特点,其消除半衰期为17.81h。同时,通过HPLC-ESI-MS联用技术,可清晰地获得氯霉素的母离子峰和相关的碎片离子信息。结论:氯霉素在鲤鱼体内具有较长的残留时间,HPLC-ESI-MS联用技术可用于水产样品中氯霉素残留的确证分析。     

Enzymatic vegetable extract with bio‐ active components: Influence of fertiliser on the colour and anthocyanins of red grapes

BACKGROUND: The obtention and physicochemical characterization of an enzymatic vegetable extract (EVE) from agroindustrial wastes by a proteolytic extraction is described. The main components of EVE are nitrogen (peptides and free amino acids) and phytohormones (auxins, gibberellins, cytokinins), as functional components. The effect of EVE as fertilizer/biostimulant on several parameters of red grapes, such as colour and anthocyanins, was also evaluated. RESULTS: Its application induced high anthocyanin content with the specific induction of petunidin. Tristimulus colorimetry was applied in order to study the colour of musts. Grape juice with significant and perceptible differences in colour characteristics was obtained using EVE. The colour points were located around redder hues (h_ab) on the (a*b*)‐plane and lightness (L*) was lower. CONCLUSION: The fertilization with biostimulant shows a promising future in the functional plant nutrition linked with an increase in the organoleptic and quality food parameters. Copyright © 2007 Society of Chemical Industry     

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。     

液相色谱-串联质谱法测定饮料中16种邻苯二甲酸酯

建立同时检测饮料中16种邻苯二甲酸酯的液相色谱-质谱联用检测方法。用甲醇提取饮料中的邻苯二甲酸酯,采用Aglilent Eclipse plus C18柱(2.1mm×150mm,3.5μm),以0.1%甲酸的甲醇溶液＋0.1%甲酸溶液作为流动相,梯度洗脱,质谱检测器检测,多反应监测定量。方法检出限为0.005～0.051mg/kg,回收率为89.1%～105.1%,相对标准偏差为0.8%～4.1%,可以满足饮料中邻苯二甲酸酯的检测要求。     

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.     

Copigmentation potential of overripe seeds from sun-dried white grapes on anthocyanins colour and stability by differential colorimetry

Overripe seeds are wine by-products from grapes submitted to postharvest sun drying, which induce phenolic biosynthesis and polymerisation. Overripe seeds from Pedro Ximénez (PX) and Moscatel (MO) sun-dried grapes were compared as copigments sources to modulate grape anthocyanin (GA) colour and stability in simulated wine conditions. RRLC/MS analysis proved that overripe seeds contain specific phenolic mixtures capable of inducing positive quantitative and qualitative colour changes in GAs, evidenced by differential colorimetry. Copigmentation effects significantly varied depending on the overripe seed variety, related to their qualitative phenolic composition and content. MO extracts richer in gallic acid, catechin and procyanidin B1 led to the stronger colour intensification and perceptible qualitative changes. PX extracts richer in epicatechin, procyanidins B2, B2-GAL and B7 behaved as weak copigments. Overripe seed copigments preserved better GAs colour stability during storage leading to the formation of new anthocyanin-derived pigments, being the stabilising effect stronger with those of MO variety.     

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.