Scielo RSS <![CDATA[South African Journal of Enology and Viticulture]]> vol. 41 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>A Review of the Potential Use of Entomopathogenic Nematodes to Control Above-Ground Insect Pests in South Africa</b>]]> Entomopathogenic nematodes (EPNs), of the families Steinernema and Heterorhabditis, are insect parasites that have been successfully used as biological control agents of soil-based insect pests on the North American and European continents. The success of nematodes as biological control agents of the soil stages of pest insects has led to research into their use for control of above-ground insect pests. Laboratory-based studies have shown exceptionally good control, in most cases, against such pests as mealybugs, codling moth and leaf miners. As the life stages of the above-ground insect pests have not co-evolved together with those of EPNs, they are, generally, more susceptible than the soil-based life stages. However, EPNs are susceptible to desiccation and vulnerable to UV radiation, so that ensuring their survival beyond soil environments is problematic. The impetus to avoid environmental stressors can cause EPNs to seek sheltered, cryptic habitats on foliage, where their target insect pest (such as mealybugs) may be found. The current paper provides an overview of information on the application of EPNs as a biocontrol agent for the control of insect pests above ground and on foliage, with particular reference to research done in South Africa. <![CDATA[<b>Phenolic and Sensorial Evolution during Bottle Ageing of South African Shiraz Wines with Different Initial Phenolic Profiles</b>]]> The aim of this research was to evaluate the colour and phenolic evolution of Shiraz red wines made from the same vineyard, but with different initial phenolic profiles. Several vineyard-related variables were initially evaluated in a first vintage (2014), but grape ripeness was shown to be the most determining factor on most of the phenolics and the taste and mouthfeel of the wines. In the second vintage (2015), wines made from four different ripeness levels were aged up to 18 months and periodically analysed during this period. The results show how Shiraz wines with different initial phenolic profiles might develop differently over time during bottle ageing. In the second vintage, some of the colour and phenolic parameters of the wines were similar after completing the alcoholic fermentation (AF). However, these small differences between the wines became more noticeable over time, especially when comparing the wines made from the highest sugar level with the rest. These differences were especially noticeable in the polymeric fraction (polymeric phenols and polymeric pigments), with a larger number of polymeric forms found in the wines made from the ripest berries, and subsequently a larger formation of polymeric pigments. Differences in the wines' phenolic composition, and the differences in the alcohol content of the wines, also influenced the taste and mouthfeel evaluation of the wines, and these were maintained over time. <![CDATA[<b>Effect of Calcium Carbonate Residues from Cement Industries on the Phenolic Composition and Yield of Shiraz Grapes</b>]]> Phenolic compounds are secondary metabolites synthesised in response to biotic or abiotic stress in plants. This stress-induced increase in phenolic compound concentrations is generally activated by internal levels of abscisic acid (ABA). The exogenous application of ABA or calcium chloride on grapevines is also known to increase grape yield and alter the phenolic composition of grapes. Residues of cement industries such as calcium carbonates (CaCO3) are a safe environmental source of calcium that could be used to induce the synthesis of phenolic compounds and act as a yield promoter in grapes and other crops. Consequently, the objective of this study was to evaluate the effect of cement industries' CaCO3 residues (CaCO3R) on the yield and concentration of phenolic compounds in Shiraz grapes. Thirteen phenolic compounds were identified and quantified by HPLC-DAD. Malvidin-3-O-glucoside was the major anthocyanin found in Shiraz grapes, and its concentration increased by more than 200% in CaCO3R-treated vines. Similarly, the concentration of cinnamic acid, the main precursor of phenolic compounds, increased by more than 900% in grapes treated with CaCO3 residues at harvest time. Finally, catechin, epicatechin and procyanidin B1 and B2 increased significantly at harvest time in CaCO3R-treated grapes relative to the controls. In general, it was found that foliar application of CaCO3 residues from the cement industry at véraison induced an increase in yield, and in the concentration and composition of phenolic compounds in grapes. <![CDATA[<b>Effect of Grapevine Canopy Side on Selected Sensory Attributes of Pinotage and Cabernet Sauvignon Wines</b>]]> Grapevine row direction, canopy exposure and grape maturity can define the sensory attributes of wine. From this perspective, canopy exposure that favours colour intensity, astringency, aroma intensity and balanced acidity could result in improved wine quality. The aim of this study was to examine the effect of canopy exposure on selected sensory attributes of Pinotage and Cabernet Sauvignon wines from Paarl, Durbanville and Darling in South Africa. Pinotage and Cabernet Sauvignon grapes were harvested from both sides of the canopy of vines planted to E-W and N-S directions. Wines were made from the harvested grapes. Grapes and wines underwent physicochemical and sensory analysis. Durbanville Cabernet Sauvignon from the south side had decreased alcohol content. Total acidity, residual sugar (RS) and pH were not different between sides. Wines from the east side had increased colour, aroma, mouthfeel and overall quality. Paarl Cabernet Sauvignon was not different between sides for any physicochemical characteristics, except TA. Wines from the south side had increased colour, aroma, mouthfeel and overall quality. Darling Pinotage was not different between sides for any physicochemical characteristics. Wines from the west side had increased intensity of aroma and acidity, whereas Durbanville Pinotage from the east side had increased alcohol, pH, TA, colour and aroma intensity, as well as overall quality. The results confirm that canopy exposure has an effect on the wine sensory attributes. This investigation illustrates the variation in sensory attribute scores of Pinotage and Cabernet Sauvignon wines from different canopy sides. Canopy exposure in a vineyard of a specific region, orientated to an E-W or N-S direction, which favours colour intensity, aroma intensity and/or mouthfeel, could result in improved wine quality. Future investigations should focus on samples collected over at least three consecutive vintages, as well as the monitoring of temperature and photosynthetic active radiation. <![CDATA[<b>The Effect of Hot Water Treatment of Rooted Grapevine Nursery Stock on the Survival of the Root-knot Nematode, <i>Meloidogyne javanica </i>(Nematoda: Heteroderidae)</b>]]> Root-knot nematodes (Meloidogyne spp.) are endoparasites which cause severe losses in grapevine. To ensure economically viable grape production, it is important that nurseries produce rooted nursery material free of plant-parasitic nematodes. Hot water treatment (HWT) at 50°C for 45 min to eliminate root-knot nematode (RKN) from rooted nursery material was investigated as a method to ensure nematode free plant material. Rooted grapevine rootstocks known to be susceptible (US 8-7 and 110 Richter), moderately resistant (1103 Paulsen and 143 B) and resistant (Ramsey) to Meloidogyne javanica were artificially infested by inoculating them with RKN eggs and larvae. After one growing season, the vines were lifted, shoots and root systems trimmed and subjected to different HWT regimes viz. 50°C for 45 min and 55°C for 20 min, while some were left as untreated controls. To evaluate plant response, each vine was planted in a pot, together with a three-week old tomato seedling as an indicator of root-knot nematode infestation. The tomato plants were removed after 12 weeks and their roots examined for the presence of M. javanica galls and egg masses. At the end of the growing season, the effects of the treatments on plant growth were assessed by determining total shoot and root mass. The results demonstrated that HWT at 55°C for 20 min significantly reduced the nematode populations in the rooted stocks, but did not eliminate the nematodes from the roots since indicator plants from HWT vines still supported a small number of galls. HWT at 55°C for 20 min also reduced the level of infestation of RKN in grapevine planting material, but resulted in a significant reduction in growth. <![CDATA[<b>Factors Influencing Olfactory Perception of Selected Off-flavour-causing Compounds in Red Wine - A Review</b>]]> Extensive work on the chemical aspects of off-flavour in wine has been carried out by international researchers, but not as many studies focus on the organoleptic effects. This literature review therefore has a focus on the status of the sensory aspects of compounds associated with specific off-flavours in red wine, viz. three volatile phenols, as well as 2-isobutyl-3-methoxypyrazine and 2,4,6-trichloranisole. The review discusses sources and effects of the selected compounds in red wine, and what previous workers have found pertaining to the mechanisms of the odour perception of aroma compounds, odour detection thresholds, and issues relating to the effects of the matrix. It also considers the factors that have been found to cause differences in olfactory perceptions between panellists/judges, and covers some of the work that has been carried out in characterising perceptual interactions between compounds in wine. Gaps that exist in the current literature are highlighted. <![CDATA[<b>Evolution of Phenolic Content, Antioxidant Capacity and Phenolic Profile during Cold Pre-fermentative Maceration and Subsequent Fermentation of Cabernet Sauvignon Red Wine</b>]]> The phenolic compound profile and content of red wines are modified during the maceration-fermentation process by several factors that alter the extractability of the compounds and by reactions that phenolic compounds undergo, and can be directly related to the quality of the final wine and its beneficial effects on the consumer. The aim of this study was to determine the change in phenolic content and profile during cold pre-fermentative maceration and fermentation without the removal of grape pomace. Total phenolics, flavonoids, anthocyanins, tannins and antioxidant capacity were determined by spectrophotometric methods, and the phenolic profile was determined by HPLC-MS on each day of the maceration-fermentation process. The results showed a variation in the content of phenolic compounds and antioxidant activity over time, but the final phenolic content showed no significative difference compared with the initial content (1 268 mg GAE/L and 1 115 mg GAE/L respectively). The phenolic profile showed that flavonoids were the principal compounds in wine and that they increased at the end of the winemaking. Condensed tannins also increased during fermentation, while anthocyanins and some phenolic acids decreased at the end of the process. The final content of phenolic compounds was similar to the initial one, but there was a change in the different fractions of phenolic compounds at the end of fermentation. <![CDATA[<b>Diversity of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Solaris and Regent Grapevine Plants Treated with Bioproducts</b>]]> The aim of this study was to identify the spores of arbuscular mycorrhizal fungi (AMF) in the rhizosphere of Solaris and Regent grapevine plants grafted onto SO4 rootstock and treated with bioproducts. The bioproducts Ausuma, Bioilsa, manure and BF Ekomix were tested and applied on their own, or combined with standard mineral fertilisation (NPK). The applied bioproducts contributed to an increase in the number of species of mycorrhizal fungi in the rhizosphere soil of the grapevines. The most frequently occurring AMF species was Claroideoglomus claroideum. Biopreparation BF Ekomix was a promising agent for increasing the number of AMF spores in the rhizosphere of Regent grapevines. In the rhizosphere of Solaris, a positive influence on the number of spores occurred after the application of Bioilsa. <![CDATA[<b>No Plunging and Cold Maceration followed by No Plunging as Alternative Winemaking Techniques: Tannin Extraction and Pigment Composition of Syrah and Pinot Noir Wines</b>]]> Three different cap management maceration techniques were compared using Syrah (2015) and Pinot Noir (2016). The control, Traditional maceration (TM), of two plunges per day for 15 days total maceration was compared with a No Plunge (NP) trial and a Cold Maceration followed by No Plunge (CM) trial. Total phenolic, tannin and colour extractions were compared during and post maceration using the AWRI WineCloudTM. Differences were noted for both varieties. The Pinot Noir wine CM trial developed higher extractions and more stable colour over time compared with the NP and TM trials. Whereas with the Syrah wine, both the CM and NP trials displayed higher total phenolic, tannin and colour extractions with more stable colour over time compared with the TM trial. <![CDATA[<b>Vulnerability of Selected Soils in the Different Rainfall Areas to Degradation and Excessive Leaching after Winery Wastewater Application</b>]]> A pot trial was conducted to assess the effect of simulated rainfall on six soils with different textures, irrigated with winery wastewater diluted to a chemical oxygen demand (COD) level of 3000 mg/L over one simulated irrigation season. Thereafter, simulated winter rainfall was applied to the pots. The rainfall was simulated according to the long term averages of the regions where the soils originated. Leaching of cations, particularly K+ and Na+ occurred only from four of the six soils when winter rainfall was simulated. In one of the sandy soils, the simulated rainfall was too low to allow leaching. In another soil, high clay content of 35% in combination with low rainfall prevented leaching. In three soils that received the same amount of rainfall, more cations leached from the duplex sandy soil compared to the two other soils. These trends indicated that leaching of cations was a function of soil texture and rainfall. The study showed that in regions with low rainfall, irrigation with winery wastewater would lead to the accumulation of cations thereby increasing soil salinity. The study confirmed that for sustainable use of winery wastewater irrigation in agriculture, different soil types will require individual management in order to avoid or minimize the negative environmental impact on natural resources by wastewater irrigation. <![CDATA[<b>Effect of Bentonite Fining on Proteins and Phenolic Composition of Chardonnay and Sauvignon Blanc Wines</b>]]> Bentonite fining is widely used to remove excess proteins in white wine prior to bottling in order to prevent protein haze formation. However, bentonite fining could also remove beneficial compounds in wine, e.g. phenolic compounds that contribute to sensory properties of wine. In this study, impact of bentonite fining on the phenolic composition of Chardonnay and Sauvignon Blanc wines has been investigated using four different bentonites: pluxcompact (PCT, Ca bentonite); bentolit (BTL, Na-Ca bentonite); pluxbenton (PBN, Na bentonite); and sperimentale (SPM, Ca-Na bentonite). Different bentonites showed similar efficiencies in removing haze-related proteins and resulted in significant decrease in total phenolic concentration. Impact on phenolic composition varied depending on the type of bentonite. In this study, fining with Ca-Na bentonite (SPM) resulted in the lowest concentrations of caftaric acid and flavanols, particularly epicatechin gallate, gallocatechin, catechin and epicatechin, which could lead to reduced mouthfeel of the resultant wine. Results presented in this study provided additional information for winemakers to choose appropriate bentonite to remove proteins with a minimal effect on reduction of phenolic compounds. <![CDATA[<b>Quantification of Resveratrol in Different Parts of Solid Pinotage Winery Waste: Investigating the Variance Between Consecutive Harvests</b>]]> Resveratrol is phenolic compound that is produced by several plant species as a protection mechanism against biotic and abiotic stress. Resveratrol is currently being investigated as nutraceutical supplement, and there is a market value for the compound. The aim of this work was to investigate, through consecutive harvests the variability of solid winery waste as a source of resveratrol as an antioxidant supplement. In this study the different parts of Pinotage solid winery waste from a 2018 and 2019 harvests were investigated as a possible resveratrol source. From the comparison of the different sources over time it was found that the 2019 Pinotage stems contained a maximum of 73 ± 4.3 μg/g resveratrol. Variable resveratrol concentrations were noted between consecutive harvests, indicating a variability in productivity. Furthermore, resveratrol distribution throughout the plant was variable, with the canes and stems having the highest concentrations. Nonetheless, it was concluded that Pinotage solid winery waste can be used as a possible source of resveratrol. The findings in this paper provide information about the extractable resveratrol and total phenolic content of different parts of Pinotage solid winery waste and the variability of resveratrol content both within the plant, and between harvests.