Scielo RSS <![CDATA[South African Journal of Enology and Viticulture]]> http://www.scielo.org.za/rss.php?pid=2224-790420190002&lang=en vol. 40 num. 2 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Editorial Letter</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Chemical and Sensorial Characterization of Tropical Syrah Wines Produced at Different Altitudes in Northeast of the Brazil</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200002&lng=en&nrm=iso&tlng=en Over the years, viticulture has expanded to new regions outside the temperate zones, such as Northeast Brazil, India, Thailand, Myanmar, Vietnam, Bangladesh and Venezuela, characterized by the production of tropical wines. It is important for the productive sector to comprehend the effects of grapevine interaction with the characteristics of each new region on wines composition. In this study, the composition of wines of Syrah from two regions with different altitudes in Northeast Brazil were analyzed by different methodologies to characterize chemical compounds as sugar, acids, minerals, phenolics (anthocyanins, fla-vonols, stilbenes and condensed tannins) and the sensory profile. The wines of the Bahia region (1100 m of altitude) obtained high concentrations for chemical parameters related to color, monomeric anthocyanins, stilbenes and monomelic and oligomeric tannins. Wines of the low altitude region, Pernambuco (350 m of altitude) were characterized by higher concentrations of flavonols (kaempferol, isorhamnetin, quercetin and rutin) and polymerized tannins. The chemical composition of wines from the two studied regions was influenced by altitude. A trend towards higher concentrations in most for phenolic compounds analyzed was observed in wines from the higher altitude region during the two years of study. Regarding the sensory profile, fruity, floral, herbaceous and empyreumatic attributes aromatic obtained highest scores in wines of the 350 m altitude region, the other attributes were dependent on the year of harvest. <![CDATA[<b>Comparative Anatomy and Morphology of the Leaves of Grenache Noir and Syrah Grapevine Cultivars</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200003&lng=en&nrm=iso&tlng=en Grenache Noir and Syrah are two of the grapevine (Vitis vinifera L.) cultivars used to a great extent worldwide. They have very different leaf morphologies from an ampelographic (botanical) point of view. This might also be related to differences in the anatomy and micro-morphology of their leaves. The goal of the present work was to compare these cultivars' leaf anatomy and morphology. Adult leaves from both cultivars were characterised using a range of microscopy techniques. Grenache Noir had a significantly smaller leaf surface area, but a significantly thicker leaf blade, than Syrah. It also had significantly larger stomata and a larger stomatal index than Syrah. The distribution of mesophyll tissues was similar in both cultivars, but the upper epidermis was significantly thicker in Grenache Noir, and the palisade parenchyma cells were longer in Syrah. The mesophyll tissues of both cultivars contained abundant idioblasts carrying crystals of calcium oxalate and mucilage. This work reveals quantitative and qualitative differences in the anatomy and morphology of mature Grenache Noir and Syrah leaves. Further work is needed to determine how these anatomical and morphological differences may be connected with different responses at the functional level. <![CDATA[<b>Cost-effective Ultrasonic Extraction of Bioactive Polyphenols from Vine and Wine Waste in Serbia</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200004&lng=en&nrm=iso&tlng=en By using cost-effective ultrasonic extraction techniques, bioactive phenolic extracts were obtained from Merlot and Vranac (Vitis vinifera L.) vine and wine waste produced in Serbian wineries. These wastes include vine leaves, grape pomace, seeds, skins and stems, which can find further use in the food and pharmacology industries as preservatives against microbes. The extracts showed strong scavenging free radical activity (EC50 from 0.37 to 2.02 mg/L), which was in very good correlation with the total polyphenol content. Strong antimicrobial activity was found against six Gram-positive and five Gram-negative bacterial strains, and against the yeast Candida albicans. The principal component and agglomerative hierarchical clustering analyses performed were shown to be good for grouping and distinguishing the results from the vine and wine by-products (leaves and seeds) from both investigated grape varieties based on the content of various polyphenolic classes, and antioxidant and antimicrobial activities. The valorisation of the grape by-products is consistent with the concept of a sustainable and environmentally oriented wine industry and provides an important economic advantage. <![CDATA[<b>Nitrogen and Sulphur Foliar Fertilisation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200005&lng=en&nrm=iso&tlng=en The effects of fertilisation can reverberate from grapes through to wines. In wine, non-volatile compounds mainly influence the taste and flavour of wines, while volatile compounds play an important role in the aromatic expression. This review includes information on the presence of non-volatile and volatile compounds reportedly affected by nitrogen and sulphure foliar fertilisation, (bio)synthesis, and evolution throughout winemaking, their chemical properties, and their implications. The second part presents the status of the research on elucidating the influence and contribution of foliar fertilisation practices on the chemical compounds throughout winemaking, from the grape to the wine. <![CDATA[<b>Survival of vine mealybug, <i>Planococcus ficus </i>(Signoret) (Hemip-tera: Pseudococcidae), on grapevine root remnants in soil in the Western Cape Province, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200006&lng=en&nrm=iso&tlng=en Grapevine leafroll is the most damaging grapevine virus disease in South Africa, and the primary vector of Grapevine leafroll-associated virus 3 (GLRaV-3) is vine mealybug, Planococcus ficus (Signoret). Preventing re-infection of newly planted, virus-free grapevines is critical to control and prevent the spread of leafroll disease. Results from a previous survey raised concern that mealybugs surviving on leafroll-infected root remnants in the soil could transmit the virus to newly planted grapevines. This study aimed to determine if P. ficus commonly occurs on grapevine roots in the Western Cape Province of South Africa, if and for how long it can survive on remnant roots in soil, and if it can transmit GLRaV-3 to healthy grapevines after surviving on remnant roots. Surveys to determine the occurrence of mealybugs on grapevine roots were conducted at different times of the growing season in vineyards near Robertson, McGregor, Montagu, Somerset West and Malmesbury over three seasons. A field trial was conducted on a sand-clay-loam soil with 23% clay and a sandy-loam soil with 10% clay over 12 months to determine survival of different life stages of vine mealybug confined on root sections from leafroll-infected Pinotage/R110 grapevines. Results indicate that P. ficus does not readily occur on grapevine roots in the Western Cape, and that it does not survive well on root remnants of grapevines for any length of time. Implications for planting virus-free grapevines in soil where leafroll-infected vines were removed, are discussed. <![CDATA[Grape Must Profiling And Cultivar Discrimination Based On Amino Acid Composition And General Discriminant Analysis With Best Subset]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200007&lng=en&nrm=iso&tlng=en The present study aimed to elucidate the amino acid profile of a number of grapevine cultivars relevant to the South African wine industry using 738 grape must samples obtained during the 2016 and 2017 harvests. Proline and arginine were found to be the most abundant amino acids, with an average of 697.69 mg/L for proline (range 33.22-3445.43 mg/L) and 388.35 mg/L for arginine (range 13.56-1616.56 mg/L) across all vintages, regions, and cultivars. At the other extreme, ornithine (2.01 mg/L), glycine (3.28 mg/L), methionine (3.64 mg/L) and lysine (3.91 mg/L) were found to have the lowest concentrations, both in terms of the overall average, as well as per cultivar. Furthermore, the data were used to demonstrate how characteristic the amino acid profile is of a particular group (red or white) or cultivar. Cultivars were predicted based on their average amino acid concentrations using general discriminant analysis (GDA) and the best subset principle. For white musts, Chardonnay showed the highest prediction accuracy (100%), and Pinotage (75%) for red cultivars. Overall, the white cultivars included in this study were more accurately distinguished from one another (75.6%) compared to the red (60.1%). This predictive ability was subsequently compared to the accuracy of predicting cultivars based on only the arginine and proline concentrations as well as the ratio between the two. The use of only these amino acids as well as the addition of the proline/arginine ratio as a predictor variable did not offer satisfactory discriminatory power between either white or red cultivars. <![CDATA[<b>Modulation of Yeast-Derived Volatile Aromas by Oleic Acid and Sterols</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200008&lng=en&nrm=iso&tlng=en Unsaturated fatty acids and sterols are essential constituents of the yeast plasma membrane. Recently, their contribution to modulating the production of yeast-derived volatile compounds has received significant attention. The objective of this study was to determine how sterol and lipid supplementation, including ergosterol, plant sterols or oleic acid, differentially influenced yeast growth as well as the production of fermentative aromas when added individually or in combinations. Oleic acid significantly altered the volatile profiles produced and lowered yeast growth. Generally, phytosterol (β-sitosterol) and ergosterol supplementation resulted in similar responses regarding the production of aromas, however, they differed in the magnitude of the response in the case of medium chain fatty acids and acetate esters synthesis. The combinations of sterols with oleic acid resulted in a response more closely associated with the oleic acid control treatment, showing lower levels of acetate ester production. <![CDATA[<b>Recent Developments in Seedless Grapevine Breeding</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200009&lng=en&nrm=iso&tlng=en Grapes are one of the most commonly produced fruit crops in the world and are consumed as table grapes, wine grapes and dried grapes. In line with consumer demands, seedlessness continues to be an important feature that increases the chances of marketing grapes. Nearly all of the dried grapes that are offered to the world markets are seedless grapes. In addition, the demand for seedless varieties has increased steadily in the table grape trade over the years. Therefore, the production of new seedless grape varieties with large berries that are suitable for table consumption is one of the important goals of breeding studies in viticulture. In this study, recently bred and released new seedless grape varieties are briefly introduced, seedless grape breeding methods are summarised, and the latest developments in breeding methods are explained. <![CDATA[<b>The Impact of Different Tannin to Anthocyanin Ratios and of Oxygen on the Phenolic Polymerisation Over Time in a Wine-like Solution</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200010&lng=en&nrm=iso&tlng=en Colour and phenolic stability during ageing are influenced by the levels of distinct classes of phenolics in young red wines. The ratios between different classes of phenolic compounds also determine the colour and phenolic development of red wines. The present study evaluated the impact of forced oxidation on different anthocyanin/tannin (A/T) extracts and its consequent effect on the colour and phenolic evolution over time. The results showed that higher contents of seed tannins could enhance phenolic polymer formation, especially in the presence of oxygen. The addition of oxygen seemed to favour certain polymerisation reactions between tannins, leading to higher concentrations of monomeric anthocyanins in solution. A slower oxygen consumption was also observed as the phenolic composition of the wine-like extract evolved over time. <![CDATA[<b>Hydric behaviour and gas exchange in different grapevine varieties <i>(Vitis vinifera </i>L.) from the Maule Valley (Chile)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200011&lng=en&nrm=iso&tlng=en In the near future, stomatal behaviour will be crucial to counteract conditions arising from climate change. Grapevine varieties are classified as either isohydric or anisohydric, depending on the sensitivity of sto-mata to water deficit and on their water potential homeostasis. However, the great variability observed in different studies indicates that a continuum exists in the range of stomatal sensitivity to water stress. Thus, more knowledge about the hydric behaviour and the gas exchange of isohydric and anisohydric grapevine varieties under different water conditions could lead to the development of irrigation strategies oriented at improving water-use efficiency, yield and berry composition. In this study, research was conducted in order to characterise the stomatal regulation of four different Vitis vinifera L. varieties, namely Pinot noir, Sauvignon blanc, Chardonnay and Merlot, according to soil water status. Measurements of leaf gas exchange, together with measurements of stem water potential (Ψ$) and leaf water potential (Ψ1), were taken during two seasons. Under conditions of water stress, Chardonnay and Merlot reached a minimum Ψ$ of -1.67 and -1.68 MPa respectively, and higher levels of water-use efficiency (A N/g), of 62.3 and 69.7 μmol C0(2/)mol H(2)0 respectively. In Sauvignon blanc and Pinot noir, the minimum Ψ$ was -1.26 and -1.40 MPa respectively, with lower levels of A N/g s (53.1 and 50.5 μmol C0(2/)mol H(2)0, respectively). Under conditions of water stress (Ψ1 < -0.9 MPa and *Fs < -0.6 MPa), all varieties had a significantly increased A^g¹, despite a significant reduction in gas exchange. Therefore, the hydric behaviour and gas exchange observed in this study suggest that Chardonnay and Merlot could be characterised as anisohydric varieties, as they present less sensitive stomatal control, while Pinot noir can be classified as a near-anisohydric variety and Sauvignon blanc as an isohydric variety. New investigations should consider other characteristics of the varieties to classify them better. <![CDATA[<b>Profiling Potentially Smoke Tainted Red Wines: Volatile Phenols and Aroma Attributes</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200012&lng=en&nrm=iso&tlng=en Malodourous compounds, including volatile phenols (VPs) are frequently found at concentrations below their odour thresholds in wine, and may therefore be considered to present no threat to wine quality. Most investigations into smoke taint quantify compounds by chemical/analytical means, or investigate sensory effects of supra- and peri-threshold contamination in model wine. In this project, twelve wines (submitted by the South African industry as potentially smoke tainted) were screened for VPs using GC-MS, and characterized using descriptive analysis (DA) by a sensory panel highly trained in smoke taint evaluation. Results were compared statistically to elucidate relationships between chemical and sensory characteristics. It was demonstrated, using the combined dataset that concentration and composition of VPs in the wines correlated well with certain sensory attributes. Guaiacol was present in most samples at peri- or supra-threshold levels, but was not correlated with taint unless in combination with other phenols, in which case it was associated with 'smoky', 'ashy' and 'herbaceous' attributes. Wines with supra-threshold levels of VPs showed negative attributes ('chemical / plastic', 'tar / BR' and 'medicinal / Elastoplast™'). In some cases, sensory effects ('earthy / dusty / potato skin', 'mouldy / musty' and 'cooked vegetables (veg.)') could not be attributed to supra-threshold VP contamination, and therefore seemed to be due to combinations of VPs at subthreshold levels. Associations between negative attributes and historical bushfire events prior to harvest were found for a number of the wines. This study emphasizes the importance of understanding effects of VPs on wine aroma, and escalating awareness and sensitivity to these issues in the wine industry. <![CDATA[<b>Response of Soil Chemical Properties to Irrigation with Winery Wastewater on a Well-drained Sandy Soil</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200013&lng=en&nrm=iso&tlng=en Most wineries in South Africa dispose of their wastewater through land application. This is carried out by irrigating small areas of cultivated pasture with the wastewater or ponding, with the former being the more general practice. Land application of winery wastewater results in the accumulation of potassium (K+) and sodium (Na+) in the soil and leaching of calcium (Ca²+) and magnesium (Mg²+).This could lead to long term instability of soil structure. The objective of this study was to investigate the effect of irrigation with winery wastewater on chemical soil properties and potential environmental impacts. Therefore, an existing grazing paddock at a winery near Rawsonville was selected where wastewater had been applied for many years. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of cations, particular K+ and Na+, beyond 90 cm soil depth at the selected study site. These leached elements are likely to end up in natural water resources in the long run. Irrigation with winery wastewater did not have a pronounced effect on soil pH(KCl). This was probably due to the decomposition of organic matter, and the fact that the applied salts were leached beyond 90 cm depth. The study confirmed that disposal of winery wastewater through land application can only be recommended where wastewater application will not exceed the water requirement of the crop as well as the water holding capacity of the soil which is being irrigated. <![CDATA[<b>Effects of Different Harvest Times on the Maturity of Polyphenols in Two Red Wine Grape Cultivars <i>(Vitis vinifera </i>L</b><b>.</b><b>) in Qingtongxia (China)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200014&lng=en&nrm=iso&tlng=en Due to the special climate conditions in the Qingtongxia region, grapes are high in sugar and low in titratable acidity from the stages of ripening. Therefore, the common methods used for determining the maturity of grapes, which depend on the ratio of sugar and titratable acidity in other regions, are inappropriate in Qingtongxia. This research was done in order to seek for a simple and convenient method of determining the optimal harvest time of grapes, further providing some theoretical basis for improving the quality of wine in Qingtongxia. Phenolic contents and some basic physico-chemical parameters of Merlot and Pinot Noir were evaluated during different ripening stages. The results showed that a different harvest time significantly affects the phenolic contents and physico-chemical parameters of Merlot and Pinot Noir. The total contents of anthocyanins in skins and total contents of phenolic in seeds was screen out as two important indexes to evaluate the maturity of polyphenols, in order to better improve the quality of grape and wine. <![CDATA[<b>UV Light Acclimation Capacity of Leaf Photosynthetic and Photochemical Behaviour in Near-isohydric and Anisohydric Grapevines in Hot and Dry Environments</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200015&lng=en&nrm=iso&tlng=en The photosynthetic and photochemical adaptation of grapevine leaves to high UV radiation, under hot and dry summer conditions, was investigated in near-isohydric Cannonau (syn. Grenache) and near-anisohydric Bovale grande (syn. Carignan). From pea-size stage until harvest, vines with mild to moderate water deficit were subjected to UV-blocking treatment (-UV) and compared to a control exposed to sunlight (C). Canopy light and thermal microclimate, growth and density, maximum leaf gas exchange, primary photochemistry (PSII) and phenols were monitored. Average increments in canopy temperature under -UV tunnels during day-time and night-time were 3.3°C and 0.8°C in Bovale grande and 2.6°C and 1.1°C in Cannonau. Cultivars reached similar leaf area, intrinsic water-use efficiency and stem water potential under C and -UV. Cannonau showed lower stomatal conductance, maximum net assimilation and transpiration rates, but also faster recovery of PSII under heat and moderate water stress. UV radiation induced a stronger and longer impact on leaf assimilation, but the duration of elevated temperatures under -UV induced higher photoinhibition and lower photochemical efficiency. A similar degree of correlation between leaf temperature and gas exchange was found among cultivars and treatments. In Cannonau, leaf anthocyanin decreased due to heat-induced long-lasting PSII photoinactivation under C. Conversely, Bovale grande showed higher phenolic content stability, thus higher photoprotection and recovery of PSII functional units. Agronomical practices affecting leaf phenolic accumulation influence canopy acclimation to heat and high sunlight. Vineyard management must avoid excessive canopy sun exposure and duration of elevated temperatures to favour high assimilation, while reducing photoinactivation and heat damage. <![CDATA[<b>Potential of South African entomopathogenic nematodes to control the leaf miner, <i>Holocacista capensis </i>(Lepidoptera: Heliozelidae)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200016&lng=en&nrm=iso&tlng=en The Cape grapevine leafminer, Holocacista capensis, a sporadic pest of economic importance, is found in South African table and wine grape vineyards. The cocoon casings, constructed by the final instar larvae, can be found attached to grape bunches, posing a phytosanitary risk for table grape export markets. The current study aimed to determine the susceptibility of leaf-mining H. capensis larvae to seven entomopathogenic nematode (EPN) species belonging to Steinernematidae and Heterorhabditidae. To determine nematode virulence occupied leaf-mining galleries were extracted from infested leaves and inoculated with 200 infective juveniles (IJs) in 50 μ! of distilled water, for each of the EPNs screened. Concentration assays were conducted and and lethal dose was determined for the three most virulent species (Heterorhabditis baujardi, H. indica and H. noenieputensis), using concentrations of 0, 25, 50, 100, 200, and 400 IJs/leaf-mining larva. High mortality of leaf-mining larvae was obtained with H. baujardi (92%), H. noenieputensis (85%) and H. indica (83%). Almost double the number of H. noenieputensis (34 nematodes/insect) penetrated the insect larvae, in comparison with the other two EPNs. However, the relative potency of H. baujardi was 3.56 times higher than for H. indica, whilst that of H. indica was 2.57 times higher than it was for H. noenieputensis. The results obtained in the laboratory were found to be encouraging, especially with regard to the nematodes' ability to penetrate the leaf-mining galleries, and to infect the larvae successfully. <![CDATA[<b>Effect of Light Quality on Fruit Growth, Composition and the Sensory Impact of the Wines</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S2224-79042019000200017&lng=en&nrm=iso&tlng=en The stage at which grapes are harvested has an influence on the aromatic and phenolic composition of the berries and the resulting wines. The aim of this study was to evaluate wines harvested sequentially as outlined in the berry sugar accumulation model. Two vintages and treatments in which the light quality and quantity were altered at the fruit zone were compared. In 2010/2011, the grapes were harvested at two ripening stages after the sugar loading plateau was reached, namely the "fresh fruit" stage (20-25 days afterwards) and "pre-mature" stage (at approximately 35 days). In the 2011/2012 season, grapes were harvested 45 days after the sugar loading plateau was reached (the "mature fruit" stage). Vegetative aromas were synonymous with the "fresh fruit" stage in 2010/2011, while the 2011/2012 wines from the "mature fruit" harvest date were characterized by raisin, prune and spicy aromas. In both seasons, the control treatments were rated more intense in 'satin in the mouth' in and after expectoration. Wines in which the UV-B radiation was excluded during berry growth were rated the highest in the mouthfeel attribute 'coarseness' in both treatment seasons. Wines were analyzed chemically for phenolic content using HPLC, and sensorial using descriptive analysis with a trained panel. In the leaf removal treatments, higher acidity content enhanced the perception of astringency in the wine. Wines were analyzed chemically for phenolic content using HPLC and sensorial using descriptive analysis with a trained panel. Overall, the data showed that grape composition was altered by varying light quality, within a season, but seasonal variation overrode treatment effects. Flavonol concentration in 2011/2012 wine was higher in the exposed leaf removal treatment compared to the other treatments. High light intensities in 2011/2012 season increased anthocyanin concentration in the wine.. This study emphasizes the importance of the quality and quantity of light on the composition and quality of wines, and presents new findings regarding sensory attributes associated with harvesting at different ripening stages.