Lead contamination in Portuguese red wines from the Douro region: from the vineyard to the final product

To quantify lead contamination in wines and to try to identify major lead sources, two winemaking processes were followed during one annual cycle of wine production. Two vineyards from the Douro Portuguese region and two types of wine, one red table wine, which has been produced in a very modern winery, and one red fortified wine (similar to Port), which has been produced by a traditional vinification process, were selected for this study. Aerosols from the vineyards atmosphere, vineyard soil, vine leaves, grapes, and samples from the intermediary and final wine product were collected. Suitable pretreatments, namely, high-pressure microwave assisted digestion (soil, leaves, and grapes) and UV-irradiation (grape juices and samples from the different steps of the vinification processes), were used. The samples were analyzed in terms of lead total concentration and respective isotope ratios by using inductively coupled plasma mass spectrometry and atomic absorption spectrophotometry with electrothermal atomization. It was observed that the major sources of lead were in the vinification system, the more traditional one introducing more lead than the modern one. For the fortified wine, the lead concentration increased from 4.7 microg L(-1), in the grape juice, to 17.2 microg L(-1), in the final product, while for the table wine the increase was from 4.1 to 13.1 microg L(-)(1). Therefore, only about 1/4 (fortified wine) and 1/3 (table wine) of the lead total content of the final products came from soil and atmospheric deposition. Therefore, it is expected that marked reductions of the lead content in the wines would occur if the sources of lead were removed from the tubes and containers used in the vinification system, particularly by using welding alloys and small fittings free of lead. The lead levels in the vine leaves (global mean of 0.43 microg g(dry leave)(-1)) and grapes (global mean of 35 ng g(dry grape)(-1)) were similar in both vineyards.     

葡萄枝条资源化利用研究现状及进展

中国是葡萄生产大国，随着葡萄产业的发展，每年修剪产生大量葡萄残枝，因葡萄枝条资源化利用率低而引起资源浪费和环境污染等突出问题。因此，葡萄枝条作为可再生生物质资源，其开发利用既可以减轻环境污染，改善生态环境，创造新的经济增长点，推进美丽乡村建设，也符合"双碳"发展目标，是实现资源、环境和经济可持续发展的有效途径。该研究围绕葡萄枝条资源化开发利用总目标，从肥料化、燃料化、原料化3个方面对葡萄枝条资源化综合利用现状和研究进展做了系统分析，总结了现有发展存在的问题，并对未来前景进行了展望，以期为葡萄枝条高值高效资源化综合利用和农业绿色可持续发展提供参考。     

(E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene: a potent grape-derived odorant in wine

(E)-1-(2,3,6-Trimethylphenyl)buta-1,3-diene (TPB) was identified as a potent odorant in acid hydrolysates of crude glycoconjugate fractions isolated from grapes and grape vine leaves. TPB was also identified in a Semillon wine, using gas chromatography/mass spectrometry, by co-injection with an authentic sample. TPB had an aroma detection threshold of 40 ng/L in a neutral white wine and the concentration of TPB in four out of five white wines analyzed ranged from 50 to 210 ng/L.     

基于迁移学习的葡萄叶片病害识别及移动端应用

为解决已有的卷积神经网络在小样本葡萄病害叶片识别的问题中出现的收敛速度慢,易产生过拟合现象等问题,提出了一种葡萄叶片病害识别模型(Grape-VGG-16,GV),并针对该模型提出基于迁移学习的模型训练方式。将VGG-16网络在ImageNet图像数据集上学习的知识迁移到本模型中,并设计全新的全连接层。对收集到的葡萄叶片图像使用数据增强技术扩充数据集。基于扩充前后的数据集,对全新学习、训练全连接层的迁移学习、训练最后一个卷积层和全连接层的迁移学习3种学习方式进行了试验。试验结果表明,1)迁移学习的2种训练方式相比于全新学习准确率增加了10～13个百分点,并在仅训练25轮达到收敛,该方法有效提升了模型分类性能,缩短模型的收敛时间;2)数据扩充有助于增加数据的多样性,并随着训练次数的增加,训练与测试准确率同步上升,有效缓解了过拟合现象。在迁移学习结合数据扩充的方式下,所构建的葡萄叶片病害识别模型(GV)对葡萄叶片病害的识别准确率能达到96.48%,对健康叶、褐斑病、轮斑病和黑腐病的识别准确率分别达到98.04%、98.04%、95.83%和94.00%。最后,将最终的研究模型部署到移动端,实现了田间葡萄叶片病害的智能检测,为葡萄病害的智能诊断提供参考。     

不同啶虫脒剂型对烟粉虱的毒力差异及原因分析

为探讨农药剂型对烟粉虱的毒力差异,分别以甘蓝和黄瓜叶片作为生物测定载体,比较了啶虫脒乳油(EC)、微乳剂(ME)、可溶性液剂(SL)、可溶性粉剂(SP)及可湿性粉剂(WP)等5种剂型对烟粉虱成虫的毒力,并通过对植物叶片临界表面张力、啶虫脒药液表面张力、动态接触角及叶片持液量的测定,分析了不同啶虫脒剂型间毒力差异形成的原因。结果表明:以甘蓝叶片为生物测定载体,不同啶虫脒剂型间对烟粉虱的毒力差异明显;以黄瓜叶片为生物测定载体,不同剂型间毒力差异不明显。啶虫脒SL、SP、WP在两种生物测定载体间的毒力差异大于EC和ME。甘蓝和黄瓜叶片的临界表面张力值分别为30.73 mN.m 1和57.91~63.30 mN.m 1。啶虫脒有效成分浓度大于7.81 mg.L 1时,啶虫脒EC和ME溶液表面张力即小于甘蓝和黄瓜叶片的临界表面张力;啶虫脒有效成分浓度大于500 mg.L 1时,啶虫脒SL、SP、WP溶液的表面张力才小于甘蓝叶片的临界表面张力。啶虫脒ME溶液液滴接触两种植物叶片的瞬间(0 s),液滴与叶片间的接触角就明显小于90°。甘蓝叶片对低浓度的啶虫脒ME和EC溶液的持液量高于其他3种剂型,黄瓜叶片对啶虫脒各剂型溶液的持液量无明显差异。植物叶片表面性质和不同剂型溶液表面张力的差异是导致剂型间产生毒力变化的重要原因。     

红叶葡萄品种叶片花色苷种类的鉴定与分析

为解决葡萄园中由葡萄修剪产生的大量叶片残留问题,提高修剪产生的叶片的利用价值,本试验以8612、玫瑰香、红鸡心3个红叶葡萄品种和葡萄园皇后、玫瑰露、秋红3个绿叶葡萄品种不同发育时期的叶片为研究对象,利用MATLAB软件对整张叶片的图像数据进行提取,计算色差值;利用超高效液相-质谱法(LC-MS)检测花色苷的成分和含量,探讨不同发育时期叶片中花色苷不同组分的变化规律。结果表明,不同发育时期的红色和绿色叶片色差指数L^*、a^*、b^*变化趋势明显不同,共检测到18种花色苷组分,包括花青素类(4种)、甲基花青素类(4种)、花翠素类(4种)、甲基花翠素类(2种)和二甲基花翠素类(4种)。以上5类花色苷在红色叶片中均被检测到,绿叶品种中未发现花翠素类和甲基花翠素类花色苷。花色苷定量结果显示,红色叶片不同发育时期花色苷含量为123.468~855.001 mg·100g^-1,绿色叶片花色苷含量为4.407~44.517 mg·100g^-1。甲基化类花色苷占比随叶片发育均逐渐增大。花色苷酰化修饰类型分析结果发现,香豆酰化类型花色苷含量高于其他酰化类型花色苷,在花色苷总含量中所占比例较高,而阿魏酰化和糖酰化类花色苷含量非常少。色差和不同类型花色苷成分的相关性分析结果表明,红色叶片的色差指数与更多类型的花色苷含量存在相关关系。红色葡萄叶片中花色苷种类丰富、含量较高,是花色苷类化合物的潜在来源,具有很大的利用价值。本研究通过对叶片中花色苷成分和含量进行了详细调查,为今后葡萄园中叶片的加工再利用提供了依据。     

Grape response to phosphorus fertilizer: Petiole to blade P ratio as a guide for fertilizer application

Abstract

A two‐year fertilizer study on a mature vineyard of grapes (Vitis vinifera L., cv. ‘Cabernet Sauvignon’ and ‘Sauvignon blanc') was conducted on a White House sandy loam (fine, mixed, thermic Ustollic Haplargid) soil at the University of Arizona Oracle Agricultural Center. Two cultivars were grown and treated with different levels of N and P fertilizer and tested for total P and NO₃‐N content of plant tissues.

Available P was evaluated with two extracting methods (Olsen and Bray P₁). Relationships between soil pH, extractable Al, Fe, Mn, and Zn with the availability indexes of soil P were also examined. Furthermore, the effects of P rates and placement on the P content of plant tissue, grape yield, and petiole to blade P ratios were investigated. Three fertilizer placements (0, 25, and 50 cm depths) at rates of 88 g P and 80 g N per vine were used for both cultivars in 1987, whereas, in 1988, three P rates (0, 88, and 176 g P per vine) and 207 g of N per vine were applied.

The results of this investigation indicated that fertilizer placement did not have a significant effect on grape yield nor the P content of petioles or leaf blades. Nevertheless, P fertilization of grapes resulted in a significant increase in plant P content and grape yield. Petiole to blade P ratio proved to be a suitable indicator for diagnosis of P status of grape plants.     

Effects of vine or bunch shading on the glycosylated flavor precursors in grapes of Vitis vinifera L. Cv. syrah

Effects of the modification of vine or bunch environment on glycoconjugates were studied in Syrah berries over two years. Vines were shaded from berry set to maturity, with black polyethylene nets of different mesh size to obtain 30 and 50% of the direct sunlight. Bunches were naturally shaded by the leaves or artificially with 90% shade bags. Sun-exposed berries were chosen as control berries. A quantitative decrease in levels of glycoconjugates was observed in shaded bunches, particularly for phenolic and C(13)-norisoprenoidic glycosides. In the same way, vine shading caused a decrease in the contents of glycosides of terpenols, phenols, and C(13)-norisoprenoids in berries, but the grape environment (microclimate) affected the berry composition more than the vine environment. A cluster thinning experiment confirmed the independence of grapes with regard to the plant for the biosynthesis of the C(13)-norisoprenoid glycosides.     

Identification of monomenthyl succinate in natural mint extracts by LC-ESI-MS-MS and GC-MS

Fresh and dried mint leaves Mentha piperita (peppermint) and Mentha spicata (spearmint) were extracted in two different ways and the extracts investigated by high performance liquid chromatography-tandem mass spectrometry. All the ethanolic extracts prepared with Soxhlet apparatus were used in the identification of monomenthyl succinate as previously reported. The highest level was found in fresh spearmint leaves. The analysis of the extractions, prepared under mild conditions using a fluorinated solvent (HFC 134-a), confirmed the natural occurrence of monomenthyl succinate in the leaves, ruling out the hypothesis that this constituent could be an artifact of the Soxhlet extraction process. A method for identifying this compound in such a fluorinated solvent extract of mint leaf using preliminary esterification with diazomethane and then GC-MS is described.     

Vineyard and fermentation studies to elucidate the origin of 1,8-cineole in Australian red wine

Preliminary investigations revealed that the proximity of Eucalyptus trees to grapevines can directly influence the concentration of the aroma compound 1,8-cineole present in the corresponding red wines. For two different vineyards, the closer the grapevines were to the trees, the greater was the amount of 1,8-cineole in the wines elaborated from those grapes. This led us to carry out further studies to quantify the levels of 1,8-cineole found in grape berries, leaves, and stems at set distances from Eucalyptus trees over multiple vintages. Generally, the highest concentration of 1,8-cineole was found in the grapevine leaves, followed by grape stems and then grapes. In each sample type, we observed greater concentrations of 1,8-cineole in samples closer to the trees. Various fermentation treatments carried out with Shiraz grapes showed that matter other than grapes (MOG, e.g., Eucalyptus or grape leaves) could contribute significant amounts of 1,8-cineole to the finished wines. These studies confirmed that vineyard position and winemaking conditions can determine the 1,8-cineole concentration in red wine. The fermentation study also showed for the first time that the concentration of rotundone in red wine can be strongly influenced by grapevine leaves and stems in the ferment.     

The enhancement of bioactive potential in Vitis vinifera leaves by application of microspheres loaded with biological and chemical agents

An overview of a research on Vitis vinifera plants treated with a chemical (calcium and magnesium ions) and biological (Trichoderma viride) agents simultaneously loaded in alginate microspheres was presented. Microspheres were applied at two growth stages: before flowering and berries pea-size. Physicochemical characteristics of leaves after the two growth stages and grapes were measured in terms of bioactive components content and antioxidant activity. After the treatments, vine leaves reached a significant increase in almost all measured parameters (polyphenols, antioxidant capacity, β-carotene, and chlorophyll) compared to the control. The highest total chlorophyll content was found after the treatment with microspheres containing Mg²⁺/Ca²⁺ cations, and T. viride. The treatments enhanced Vitis vinifera leaves in terms of bioactive potential and can be further used as a functional food. As compared to the control, somewhat elevated values of total polyphenols and antioxidant activity were found on the grape samples.     

Associations between the sensory attributes and volatile composition of Cabernet Sauvignon wines and the volatile composition of the grapes used for their production

The sensory properties of wine are influenced by the chemical composition of the grapes used to produce them. Identification of grape and wine chemical markers associated with the attributes perceived by the consumer of the wine will enable better prediction of the potential of a parcel of grapes to produce wine of a certain flavor. This study explores the relationships between Cabernet Sauvignon grape volatile composition and wine volatile profiles with the sensory properties of wines. Twenty grape samples were obtained from nine vineyard sites across three vintages and wines vinified from these parcels using controlled winemaking methods. The volatile composition of the grapes were analyzed by SBSE-GCMS, the wines were analyzed by SPME-GCMS, and these data sets were compared to that obtained from the sensory analysis of the wines. Statistical treatment of the data to account for vintage and region effects allowed underlying relationships to be seen between wine sensory attributes and wine or grape volatile components. The observed associations between grape or wine volatile compounds and wine sensory attributes has revealed target compounds and pathways whose levels may reflect the biochemical effects on grape composition by differing growth conditions during berry development and ripening. The compounds identified in this study may be useful grape or wine markers for potential wine sensory characteristics.     

Prediction of wine color attributes from the phenolic profiles of red grapes (Vitis vinifera)

Knowledge about the relation between grape and wine phenolics is of key interest for the wine industry with respect to being able to predict wine quality from analyses of grapes. Prediction of the phenolic composition and color of experimentally produced red wines from the detailed phenolic composition of the corresponding grapes was investigated using a multivariate approach. Grape extracts and wines were produced from 55 different grape samples, covering 8 different Vitis vinifera cultivars: Alicante, Merlot, Syrah, Cinsault, Grenache, Carignan, Cabernet Sauvignon, and Mourvedre. The phenolic composition of the grapes and wines showed that the average ratios between wine and grape phenolics ranged from 0.25 to 7.9 for the different phenolic compounds. Most interestingly, the average ratios were low for anthocyanins (0.31) and tannins (0.32), intermediate for (+)-catechin (0.75) and polymeric pigments (0.98), and high for gallic acid (7.9). Individual wine phenolics in general correlated well with several grape phenolics, indicating that a multivariate approach might be advantageous for prediction of wine phenolics from grape phenolics analysis. However the use of multivariate prediction of individual wine phenolics from the complete grape phenolic composition only improved the prediction of wine polymeric pigments, whereas wine anthocyanins were predicted with the same precision as from the direct relation with grape anthocyanins. Prediction of color attributes of pH normalized experimental wines from the phenolic profiles of grapes was accomplished using a multivariate approach. The correlation between predicted and measured total wine color was high ( r = 0.958) but was very similar to the correlation coefficient obtained for the direct relation between grape anthocyanins and total wine color ( r = 0.961). Color due to copigmentation, color due to anthocyanins, and color intensity were also predicted well.     

Identification of ellagic acid conjugates and other polyphenolics in muscadine grapes by HPLC-ESI-MS

Ellagic acid, ellagic acid glycosides, and ellagitannins found in various fruits and nuts, including muscadine grape, are reported to have potential health-promoting benefits and antioxidant properties. This study isolated and identified several ellagic acid derivatives present in muscadine grapes and determined their relative antioxidant properties (AOX). Compounds were extracted from grape skins and pulp using methanol, and the solvent was evaporated. Isolates were dissolved in citric acid buffer (pH 3.5) and absorbed onto C18 cartridges. Nonretained polyphenolics were collected separately and again partitioned from Sephadex LH-20, whereas retained polyphenolics were first eluted with ethyl acetate followed by methanol. Ellagic acid derivatives were identified on the basis of UV and mass spectra, and the presence of ellagitannins was confirmed by a significant increase in free ellagic acid with HPLC followed by acid hydrolysis. Muscadine grapes contained phenolic acids, flavonols, anthocyanins, ellagic acid, and numerous ellagic acid derivatives. AOX varied in the order ethyl acetate > methanol > C18 nonretained fractions; each correlated to both total phenolics (r = 0.90) and total ellagic acid (r = 0.99) contents. Results of this study revealed previously unidentified ellagic acid derivatives in muscadine grapes.     

Extraction of rutin from buckwheat (Fagopyrum esculentumMoench) seeds and determination by capillary electrophoresis.

The content of the flavonoid rutin was determined in different milling fractions of buckwheat seeds and in buckwheat stems, leaves, and flowers. The extraction was performed by using a solvent containing 60% of ethanol and 5% of ammonia in water. The extracts were analyzed by capillary electrophoresis (running buffer of 50 mM borate (pH 9.3), 100 mM sodium dodecyl sulfate; determination at 380 nm). In bran fractions the concentration of rutin was 131-476 ppm, and in flour fractions 19-168 ppm. On average, about 300, 1000, and 46000 ppm of rutin were found in leaves, stems, and flowers, respectively. The results indicate that buckwheat could be an important nutritional source of flavonoids, especially in countries with a low mean daily flavonoid intake.     

Antioxidant properties of various solvent extracts of total phenolic constituents from three different agroclimatic origins of drumstick tree (Moringa oleifera Lam.) leaves

Water, aqueous methanol, and aqueous ethanol extracts of freeze-dried leaves of Moringa oleifera Lam. from different agroclimatic regions were examined for radical scavenging capacities and antioxidant activities. All leaf extracts were capable of scavenging peroxyl and superoxyl radicals. Similar scavenging activities for different solvent extracts of each collection were found for the stable 1,1-diphenyl 2-picrylhydrazyl (DPPH(*)) radical. Among the three different moringa samples, both methanol and ethanol extracts of Indian origins showed the highest antioxidant activities, 65.1 and 66.8%, respectively, in the beta-carotene-linoleic acid system. Nonetheless, increasing concentration of all the extracts had significantly (P < 0.05) increased reducing power, which may in part be responsible for their antioxidant activity. The major bioactive compounds of phenolics were found to be flavonoid groups such as quercetin and kaempferol. On the basis of the results obtained, moringa leaves are found to be a potential source of natural antioxidants due to their marked antioxidant activity. This is the first report on the antioxidant properties of the extracts from freeze-dried moringa leaves. Overall, both methanol (80%) and ethanol (70%) were found to be the best solvents for the extraction of antioxidant compounds from moringa leaves.     

Anthocyanin quantification and radical scavenging capacity of Concord, Norton, and Marechal Foch grapes and wines

The anthocyanin content and the radical scavenging capacity of three non-Vitis vinifera grapes (Marechal Foch, Norton, and Concord varieties) were determined. Analyses of anthocyanins in the skin (S) and wine (W) of these grape varieties were performed by spectrophotometry, HPLC with electrochemical detection, and matrix-assisted laser desorption ionization (MALDI). The total anthocyanin contents of S samples were 258 +/- 37 mg/100 g of wet weight for Foch, 888 +/- 78 mg/100 g for Norton, and 326 +/- 5.9 mg/100 g for Concord grapes. The malvidin 3,5-diglucoside content quantified by HPLC indicated that Norton S had the highest amount of the compound (327 +/- 110 mg/100 g). The MALDI mass spectrometric analysis indicated an abundance of malvidin glucosides in W of Foch grapes and in S and W of Norton grapes and of cyanidin aglycon in S and W of Concord grapes. S samples were subjected to a radical scavenging capacity test using the 2,2-diphenyl-1-picrylhydrazyl radical and compared to Trolox. The radical scavenging capacity for Foch S was 0.78 mM Trolox equiv, that of Concord S, 0.80 Trolox equiv, and that of Norton S was highest at 0.95 Trolox equiv. The higher concentrations of malvidin 3,5-diglucoside in S of grape varieties were associated with greater radical scavenging capacity.     

Contribution of dimethyl sulfide to the aroma of Syrah and Grenache Noir wines and estimation of its potential in grapes of these varieties

The contribution of dimethyl sulfide (DMS) to the aroma of Syrah and Grenache Noir wines from the Rhone Valley of France was investigated by sensory analysis, and its levels in these wines were measured. The potential DMS in the corresponding grapes and wines, susceptible to release during wine aging, was evaluated. Free DMS and potential DMS assessed by a heat-alkaline treatment were measured in grape juices and wines by SPME-GC-MS using methods previously reported and slightly modified. A relationship between potential DMS from grapes and the total DMS levels in wine was demonstrated. Furthermore, a linear regression between the ratio of free DMS levels to these total DMS levels in wine and time of storage was found. Free and potential DMS levels in grapes and wines depended on grape variety, vintage, and vine location. DMS imparted a noticeable and complex contribution to the aroma of the wines investigated, depending on the mode of sensory perception used, either before or after glass swirling. It significantly enhanced the fruity notes of the wines, and additional truffle and black olive notes.     

Study of amine composition of botrytized grape berries

Aliphatic primary and biogenic amines of grape varieties from two vintages were studied. We established that appearance and/or increase of both primary aliphatic and biogenic amines is due to microbiota living in/on grape berries. Aszú, gray rotten grapes infected mainly with Botrytis cinerea, grape berries infected mainly with Penicillium species, and intact grape berries were compared on the basis of amine composition using t-test, analysis of variance, and multivariate statistical analysis (principal component analysis and linear discriminant analysis). The amine composition and amine content of Aszú grapes were significantly different (p < 0.05) from those of intact grapes despite the effect of the vineyards and the vintages. Grape samples coming from the same growing location, intact, Aszú grapes, and grape berries infected mainly with Penicillium species could be separated from each other with multivariate statistical analysis. We distinguished intact, Aszú (noble rotten), and gray rotten berries from each other as well. Evaluating amine values of grape samples independently of the place of origin, the Aszú and green rotten berries could not be differentiated. The varieties and vineyards have affected the amine composition of Aszú grapes, while these effects on intact grapes appeared only slightly.     

Influence of vineyard location and vine water status on fruit maturation of nonirrigated cv. Agiorgitiko (Vitis vinifera L.). Effects on wine phenolic and aroma components

The influence of site on grape and wine composition was investigated for Vitis vinifera L. cv. Agiorgitiko in the Nemea appellation area in southern Greece. Three nonirrigated plots were studied during the 1997 and 1998 vintages, which were typically very hot and without summer rainfall. Vines were subjected to different water regimens as a result of the variation of soil water-holding capacity and evaporative demand. Vine water status was determined by means of predawn leaf water potential. Differences in vine water status between sites were highly correlated with the earliness of shoot growth cessation and veraison. Grape composition was monitored during fruit ripening. Water deficit accelerated sugar accumulation and malic acid breakdown in the juice. Early water deficit during the growth period was demonstrated to have beneficial effects on the concentration of anthocyanins and total phenolics in berry skins. A similar pattern was observed for the phenolic content of wines elaborated after vinification of grapes harvested on each plot, in both seasons. Limited water availability seemed to increase glycoconjugates of the main aromatic components of grapes as a quantitative increase in levels of bound volatile compounds of the experimental wines was observed under water deficit in both years. Wines produced from grapes of stressed vineyards were also preferred in tasting trials.