Scielo RSS <![CDATA[South African Journal of Enology and Viticulture]]> vol. 42 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>A Review of Tannin Determination Methods Using Spectro-photometric Detection in Red Wines and Their Ability to Predict Astringency</b>]]> Astringency is an important sensory attribute that influences red wine quality. The astringent sensation inside the mouth is caused by a group of molecules called tannins. These molecules in wine can be determined and analysed by spectrophotometric, analytical and recently electrochemical methodologies. This article focuses on the three methods most frequently used by the wine industry: Bate Smith or acid hydrolysis method, Adams Harbertson assay or BSA tannin assay, and methylcellulose precipitation (MCP) method. These methods differ on the principle upon which they are based, as well as on the kind of tannin that they can determine. The purpose of this article is to present the main advantages and disadvantages of the three spectrophotometric methods acid hydrolysis, BSA assay and MCP methods for tannin determination in red wine, in order to review their efficacy, group of tannins each method can determine, and their suitability for astringency prediction. <![CDATA[<b>Selection of Grass and Broadleaf Crops as Catch Crops where Winery Wastewater is Used for Irrigation: A Review</b>]]> Winery wastewater contains high levels of elements such as sodium, phosphorus, potassium, as well as chemical oxygen demand, sodium adsorption ratio and pH. This may raise concerns regarding the pollution of the surrounding environment. Environmentally friendly methods such as recycling, i.e. treatment and re-use, where treated or partially treated and diluted wastewater is used for irrigation of agricultural crops, are essential. Irrigation with winery wastewater, which is rich in nutrients, can be beneficial to overall soil fertility as an alternative to conventional fertilizers. However, long-term applications of wastewater may have a negative effect on soil physicochemical properties. A selection of crops with nutrient interception abilities, preferably for salts, may be ideal for the removal of excess elements from the soil whilst reducing leaching and excess run off. The use of perennial grasses, annual winter growing grains and winter growing broadleaf nitrogen-fixing annuals as winter cover crops in the South African wine industry has been extensively documented but their use as summer catch crops intercepting elements applied via wastewater irrigation has not yet been well researched. <![CDATA[<b>Phenolic Compounds in Cork-Closed Bottle-Fermented Sparkling Wines</b>]]> Bottle fermented sparkling wine in South Africa is known as Méthode Cap Classique which is based on the method used in France for Champagne. The use of cork, instead of a crown cap during the second fermentation in sparkling wine was investigated for its effect on the phenolic profile of wines. Phenolic acids susceptible to migration from cork into wine were studied in two-disc corks from three different commercial suppliers, coded as Cork A, Cork R and Cork C and a crown cap closure. Gallic, caftaric, caffeic and p-coumaric acids were quantified in all samples using a liquid chromatographic technique. Physicochemical parameters were also measured in the wine using a spectrophotometric technique. Total acidity and pH were not significantly different among the wines. Cork R wines were however significantly different in alcohol. Residual sugar for all samples was below the limit of detection. Gallic acid was significantly highest in Cork A wines, which indicates the contribution of Cork A to the concentration of this compound in the wine. Different cork types are assumed to release different concentrations of phenolic compounds. This may be due to differences in surface roughness of cork that would increase the surface area in contact with the wine. Therefore, corks from different origins (suppliers) could be used to bring about subtle differences to the wine. <![CDATA[<b>Influence of Vineyard Vegetational Borders on Western Grape Leafhopper <i>(Erythroneura elegantula </i>Osborn), its Egg Parasitoids <i>(Anagrus </i>spp.) and Generalist Insect Predators</b>]]> Studies have shown that vegetational diversity in or around cropping systems can enhance natural enemy abundance, although the impact on herbivores is less certain. We studied the influence of vineyard vegetational borders on density of the western grape leafhopper, Erythroneura elegantula, its major parasitoids, Anagrus spp., and two generalist predators, Orius spp. and Leptothrips mali. Two study vineyards had planted, perennial flowering hedgerows, one bordered a natural riparian zone, and one had a sparse border of native trees. From April to September 2007, we counted leafhopper nymphs and adults of Anagrus spp., Orius spp. and L. mali within 10 m of the border, and at additional 20 m intervals up to 90 m. At two sites with a diverse border, leafhopper density was stable nearest the border; at other distances leafhopper density decreased between the first and second generations. This effect was not seen at the sparse border site. Anagrus spp. density was enhanced at one site with a diverse border, but only late season. There was no border effect on the generalist insect predators, by site or early vs. late season. Regression analysis showed a positive relationship between leafhopper and Anagrus spp. density, suggesting that the parasitoids were responding to higher leafhopper density. We conclude that, depending on the nature of the border vegetation, there can be an effect on leafhopper nymphal density, but in this study there is no evidence that it was due to natural enemies. <![CDATA[<b>Metal Concentrations in Grape Spirits</b>]]> Metals are a necessity for human health as they play significant roles in biological systems. However, contamination of food and beverages by heavy metals such as lead (Pb), iron (Fe), chromium (Cr), cadmium (Cd), copper (Cu), cobalt (Co), Nickel (Ni) and zinc (Zn) is a major public health problem in developing countries. In this study we evaluated the levels of Li, Be, B, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sb, Ba, Hg and Pb in grape spirits, including pot still spirit, neutral wine spirit and commercial brandies. Interesting variations in the levels of metals was observed. Factors such as origin and type of spirits influenced levels of metals in spirits. These differences in some metal levels such as copper can be used to determine possible adulteration and in authenticity assessments of brandies. Surprisingly the commercial brandies had higher metal concentrations when compared to pot still spirit and neutral wine spirit. Unmatured pot still spirit had the highest copper levels. Our study shows that generally the metal levels in most of the commercial brandies were within permissible limits. <![CDATA[<b>The Effect of Cluster Position Determined by Vineyard Row Orientation on Grape Flavonoids and Aroma Profiles of <i>Vitis vinifera </i>L. cv. Cabernet Sauvignon and Italian Riesling in the North Foot of Tianshan Mountains</b>]]> Vineyard row orientation plays a critical role in determining cluster microclimate. This study aimed to figure out how cluster positions determined by vineyard row orientation affect grape flavonoids and aroma profiles of Cabernet Sauvignon and Italian Riesling grapes. Three cluster positions (two canopy sides and the inner canopy) of NS and EW oriented row Cabernet Sauvignon and NS oriented row Italian Riesling were selected for the experiment. Microclimate data was monitored around clusters from both canopy sides of different row orientations. The south canopy side had higher daytime temperatures and PAR than the north canopy side in EW row orientation. Flavonoids of grape skins and seeds were separated and determined by LC-MS, and aroma compounds of grape must were determined by GC-MS. Results showed that flavanols were affected by orientations, and EW orientation had higher berries skin flavanol concentration than NS orientation. EW-IN berries had fewer glucuronide form flavonols and 3'-hydroxylated flavonols than the other two positions in EW orientation. Inner canopy berries had lower flavonol concentration than other positions in EW orientation of CS and NS orientation of IR. To aromas, C6/C9 were the main compounds significantly affected by row orientations. EW orientation berries had higher C6 alcohols concentration such as (E)-3-Hexen-1-ol, (E)-2-Hexen-1-ol and (Z)-3-Hexen-1-ol than NS orientation, while NS orientation berries had higher C6 aldehyde concentrations such as Hexanal and (E)-2-hexenal than EW orientation. EW-IN berries had more abundant C6/C9 compounds than the other two positions. The study provided preliminary scientific evidence for vineyard viticulture practice and harvest strategy. <![CDATA[<b>Screening <i>Non-Saccharomyces </i>Yeasts as Low Ethanol Producing Starter Cultures</b>]]> Non-Saccharomyces yeasts are known for their low fermentation rate in comparison to Saccharomyces cerevisiae. In this study, non-Saccharomyces yeasts were inoculated into Chenin blanc grape must and fermented under aerobic and anaerobic conditions. Saccharomycodes ludwigii displayed a strain-dependent fermentation rate, which yielded between 5.2% and 9.9% ethanol concentration under both conditions, albeit with residual sugar. Aerobic conditions favoured the production of reduced ethanol which was between 5.8% and 9.7% for non-Saccharomyces yeasts in comparison to S. cerevisiae (10%). This trend was observed for Wickerhamomyces anomalus, Stamerella bacillaris (Candida zemplinina), Metshnikowia pulcherrima, Cyberlindnera saturnus, Wickerhamomyces subpelliculosus and Cyberlindnera jadinii. The laboratory-scale wines prepared with the aforementioned yeasts yielded ripe fruit and floral aroma attributes while other non-Saccharomyces yeasts resulted in wines with spicy, acidic and solvent aroma notes. <![CDATA[<b>The Effect of Pre-Harvest Application of Pectic Oligosaccharides and Abscisic Acid on Technological Ripening and Anthocyanin Profile of 'Syrah' Must and Grapes Grown in a Warm Climate</b>]]> The progressive increase of environmental temperature as a consequence of climate change is a challenge for the wine industry. Elevated temperatures during grape ripening affect the development of grape skin color by inhibiting the synthesis of pigments and promoting their degradation, which causes an imbalance in the chromatic quality of must and red wine. The application of pectic oligosaccharides (POs) and abscisic acid (ABA) triggers the phenylpropanoid pathway and increases the color index in grapes. Since the at-harvest pigments and phenolic compounds are determinant for wine quality, this work addressed the pre-harvest application of POs and ABA as an in-field strategy for improving the quality of Syrah must and grapes grown in a warm climate. The color development, physicochemical parameters, phenolic content, and pigments in berries and must were evaluated. Results showed POs and ABA improved berry color development and anthocyanin content during ripening. Musts from POs-treated berries exhibited the highest phenols concentration and the most intense color, related to higher chroma values and anthocyanin content, particularly delphinidin, petunidin, and malvidin 3-glucosides, while ABA improved must tonality by reducing the hue angle. In summary, POs and ABA application at veráison, differentially modulated the technological ripening of Syrah grapes and can be an alternative to conventional agrochemicals to preserve the quality of musts elaborated from grapes grown in warm climates, by increasing the content of phenolic compounds and enhancing berry skin color development through the differential accumulation of anthocyanins. <![CDATA[<b>Phytochemical Characterization and Antiplatelet Activity of Mexican Red Wines and Their By-products</b>]]> Red wines and their grape pomaces are important sources of phenolic compounds. Inhibition of platelet aggregation is one of the mechanisms proposed for cardioprotective effect of phenolic compounds from wine and grape pomace; however, phenolic content is affected by region, variety and winemaking process. In the present study, antiplatelet effect of red wines and grape pomaces was related to its phenolic content (determined by spectrophotometric techniques) and profile (determined using HPLC-MS/MS). in vitro Anti-platelet aggregation was determined using human platelets. Results showed that Zinfandel wine and Cabernet Sauvignon grape pomace presented the highest phenolic content. Phenolic profiles presented differences in the presence of flavonoids and oligomeric tannins. Results from platelet aggregation showed that Merlot and Petit Verdot wines and Petit Verdot grape pomace sample presented the highest antiaggregant effect. These results indicate that antiplatelet effect could be related to phenolic profile than phenolic content in wines and grape pomaces. Cardioprotective effect of red wines and grape pomace could be related to specific compounds such as monomelic and polymeric flavan-3-ols. <![CDATA[<b>An Overview of Mites on Grapevine and the Discovery of a New Phytoseiidae Species: <i>Typhlodromus (Typhlodromus) spiceae</i></b>]]> The European grapevine (Vitis vinifera L.) is the main species used for wine making, with South Africa being one of the top wine exporting countries. Grapevine is vulnerable to a range of pests, including mites. We present an overview of phytophagous and predatory mites on grapevine in South Africa and describe a new phytoseiid species which was discovered in the winelands region of Wellington, South Africa. Grapevine shoots with leaves were collected over two growing seasons at four farms in Wellington. A nursery, mother block and a commercial vineyard were selected on each farm. The mites were removed with a mite brushing machine and slide mounted. The Phytoseiidae Database, as well the most recent relevant literature were used in confirming the new species. Illustrations of the new species were made using photographs taken by Zeiss Axioskop TM Research that included a Zen Soft Imaging System. The new Typhlodromus species, Typhlodromus (Typhlodromus) spiceae sp.n., is set apart from closely related species by setae Z4 being 0.7 times the length of Z5 and by having a short, saccular and thick-walled spermathecal. This species was found together with one phytophagous mite species (Brevipalpus lewisi) and several predatory mite species (Typhlodromus praeacutus, Typhlodromus saevus, Eusieus addoensis). A key to identify females of the South African species of Typhlodromus (Typhlodromus) is provided.