Scielo RSS <![CDATA[South African Journal of Enology and Viticulture]]> vol. 40 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Foliar application of <i>Steinernema yirgalemense </i>to control <i>Planococcus ficus: </i>Assessing adjuvants to improve efficacy</b>]]> The vine mealybug (Planococcusficus) is regarded as a key mealybug pest of grapevines in South Africa, with entomopathogenic nematodes (EPNs) being touted as a potential alternative to chemical control, although their vulnerability to above-ground environmental conditions has limited their use. In this study, tests were conducted to assess the ability of adjuvants to increase the deposition of S. yirgalemense on grapevine leaves. The combination of Nu-Film-P® and Zeba® resulted in significantly more infective juveniles (30) being deposited per 4 cm² leaf disc than with either the control (14.8), or with Nu-Film-P® (23.3), although not significantly more than with Zeba® alone (29.2). The ability of S. yirgalemense, in conjunction with the two adjuvants, to control P. ficus on grapevine foliage was then assessed under controlled conditions. The application of S. yirgalemense with both Zeba® and Nu-Film-P® to P. ficus on leaf discs in a growth chamber resulted in 84% mortality, significantly greater than that attained by the application of S. yirgalemense with either Zeba® (47%), or water alone (26%). Similar results were observed in a glasshouse trial, in which the combination of S. yirgalemense, Zeba® and Nu-Film-P® offered 88% control of P. ficus on leaf discs hung on potted vines, compared with the control that was achieved with S. yirgalemense with either Zeba® (56%) or water alone (30%). This study demonstrates the potential of a combination of S. yirgalemense with adjuvants to give significant control of P. ficus on grapevine foliage, compared with using EPNs alone. <![CDATA[<b>Free radical-scavenging activity and anthocyanin profiles of Cabernet Sauvignon and Merlot wines from four wine grape-growing regions in China</b>]]> The present study focused on the free radical-scavenging activity and anthocyanin profiles of Cabernet Sauvignon and Merlot wines produced from four different regions in China. The anthocyanin profiles in all wine samples were analysed by HPLC-MS/MS, while the free radical-scavenging activity was estimated by the DPPH assay. The results show that the contents of phenolic subclasses and the levels of antioxidant activity in all wine samples varied greatly among cultivars and environmental factors of vine growth, and these values were the most prominent in Yuquanling regional wines. As the main components in anthocyanins, the percentages of malvidin-3-O-glucoside and its derivatives showed differences within grape cultivars in the different regional wines; these monomeric anthocyanins (not present simultaneously in the four regional wines studied within grape cultivars) had concentrations below 10 mg Mv/L. The significant correlation was obtained between DPPH-scavenging ability and the total phenolic, flavonoid and anthocyanin content. It can be concluded that this information could be used as a biochemical marker for the authenticity of the single-cultivar red wines that were produced from the four regions above. <![CDATA[<b>Diversity and identification of yeasts isolated from tumultuous stage of spontaneous table grape fermentations in central China</b>]]> Table grapes are of increasing interest for wine production in China. In this study, 480 yeast isolates were isolated from the tumultuous stage during the spontaneous fermentation of six table grape varieties, which were cultivated in an ecological environment that was not industry-influenced, in Central China. The 26S rDNA D1/D2 domain sequence analysis was more efficient for yeast species identification than the 5.8S-ITS region RFLP analysis in the present study. All the tested strains belonged to nine species from six genera: Hanseniaspora guilliermondii, H. opuntiae, H. uvarum, Pichia terrícola, Kazachstania hellenica, K. zonata, P. occidentalis, Saccharomyces cerevisiae and Zygosaccharomyces bailii. The yeast species and populations differed notably among the grape varieties. S. cerevisiae was found in the samples of four grape varieties (Vitis amurensis, Iona, Moldova and V. davidii), but not detected in Cuihong and Alimandeng Rose. Interdelta sequence fingerprinting analysis was used to discriminate between 128 S. cerevisiae isolates. Eight S. cerevisiae genotypes (G1 to G8) were distinguished. Genotypes Gl, G2, and G3 were the most dominant strains, accounting for 32.03%, 24.22% and 28.13% of the isolates respectively. This study shows the diversity of yeast species associated with spontaneous fermentations of different table grape varieties grown in an ecological environment without any wine industry effect or footprint. <![CDATA[<b>Effect of Gibberellic acid (GA<sub>3</sub>) inflorescence application on content of bioactive compounds and antioxidant potential of grape <i>(Vitis </i>L.) 'Einset Seedless' berries</b>]]> Gibberellic acid (GA3) is a plant growth regulator widely used in the cultivation of seedless grape varieties to increase their yield. Hormonisation treatment has beneficial effects on yield size and quality, yet its influence on the level of biologically active compounds and grape antioxidant activity has not yet been studied extensively yet. Clusters of 11-year-old 'Einset Seedless' grapevines trained according to the single Guyot pruning style were sprayed with GA3 at 100, 200 or 300 mg/L dose once, twice or three times. Fruit harvested on 25 September were immediately examined for acidity, extract content, biologically active substances and antioxidant capacity using the DPPH test. In addition, correlations occurring between some parameters measured were calculated. Hormonisation had a negative effect on the content of extract, flavonoids and ascorbic acid, while it had no effect on the anthocyanin level. The antioxidant activity determined by the DPPH assay depended on dose and the number of treatments, and the analysed parameters were shown to decrease significantly with increasing application number. Gibberellic acid at 100 and 300 mg/L application rates had a significantly increased DPPH level compared to the control and 200 mg/L dose. The single GA3 treatment, and when applied three times, and application rates at 100 and 200 mg/L were shown to have a significant influence on phenolic acid content. The level of tannins after a single GA3 treatment and a 300 mg/L dose increased significantly. <![CDATA[<b>Gentisic acid, salicylic acid, total phenolic content and cholinesterase inhibitory activities of red wines made from various grape varieties</b>]]> Alzheimer's disease is characterised by a decrease in acetylcholine (ACh) levels in the brain due to the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). As a result, disorders in cholinergic transmission are observed, leading to cognitive impairment. In this work, the inhibition of AChE and BChE activities by red wines made of various grape varieties was determined for the first time. There was no significant difference in the polyphenol content between the grape varieties; nevertheless, there were significant differences in the content of gentisic acid and salicylic acid, and in the inhibition of AChE and BChE between the wine samples. A statistically significant correlation between AChE inhibitory activity and salicylic acid, as well as between BChE inhibitory activity and total phenolic content, was recorded. In model solution studies, it was shown that salicylic acid effectively inhibited BChE activity at concentrations similar to the maximum concentrations found in the test wines. Hierarchical cluster analysis (HCA) revealed that the wines could be divided into three groups. Cabernet Sauvignon and Syrah wines had the highest content of salicylic acid and AChE inhibitory activity, as well as low BChE inhibitory activity. Pinot noir, Tempranillo, Regent and Rondo wines showed the lowest content of salicylic acid and low AChE inhibitory activity. Garnacha tinta, Merlot, Montepulciano and Negroamaro wines had a medium content of salicylic acid, and the highest or medium BChE inhibitory activity. This work is important for both the wine industry and for health protection. <![CDATA[<b>Effects on Berry Shrinkage in <i>Vitis vinifera. </i>L cv. 'Merlot' From Changes in Canopy/Root Ratio: A Preliminary Approach</b>]]> A trial was conducted to find a possible relationship between the canopy/root ratio and the incidence and severity of premature berry shrinkage, and to propose an alternative to avoid this phenomenon in 'Merlot' grapevines. The ratio was changed by cutting foliage at a certain height 15 days before véraison, and by delaying the removal of trunk shoots. Treatments were the control (T1), 50% foliage area of control (T2), 75% foliage area of control (T3), and delayed trunk shoot removal (T4). Foliage area and the canopy/ root ratio were lower in the T2 and T3 treatments. T4 was ineffective in changing the parameters. The incidence of berry shrinkage was lower for the T2 and T3 treatments, with the percentage of affected plants dropping from the 52% of the control to 22.9% and 31.3% for T2 and T3 respectively, and from 52.4% of the affected bunches to 16.6% and 21.2% for the same treatments respectively. The percentage of affected bunches falling into the range of moderate to severe damage fell from the 24% of the control to 5.2% and 3.9% for T2 and T3 respectively. Therefore, it is possible to avoid the incidence and severity of berry shrinkage by decreasing the canopy/root ratio in 'Merlot' grapevines. <![CDATA[<b>Application of Heated Water to Reduce Populations of <i>Brettano-myces bruxellensis </i>Present in Oak Barrel Staves</b>]]> New 16 L and three-year-old commercial 225 L barrels representing French and American oaks of different toasting levels, contaminated with Brettanomyces bruxellensis, were obtained. Center sections of individual staves were sawn into 3 x 3 cm cubes and submerged 2 mm into heated water at 50°C, 60°C, 70°C, or 80°C. Following heat treatment, cross sections and/or shavings were collected and transferred into a yeast recovery medium for incubation for &gt;60 days. Culturable cells were not recovered from cubes heated in water at 70°C for 20 minutes, or 80°C for 15 minutes, when the yeast was present in oak at depths of <4 mm. However, longer heating times (70°C for 30 min or 80°C for 20 min) were required if B. bruxellensis was present at depths of 5 to 9 mm within cubes made from staves. Based on these results, heating water to at least 70°C for a minimum of 30 minutes is recommended to reduce risk of wine spoilage by barrels contaminated with B. bruxellensis. <![CDATA[<b>Physiological Response of Three Grapevine Cultivars Grown in North-Western Poland to Mycorrhizal Fungi</b>]]> West Pomerania (Poland) is located near the northern boundary of the range of viticulture (the coldest zone A). Unfavourable weather conditions can pose a serious threat to the cultivated vines. One of the treatments used to increase the tolerance of plants to abiotic and biotic stresses is inoculation with symbiotic soil microorganisms. This paper focuses on the influence of mycorrhization on the changes in soil microbiology, the degree of colonization of roots by mycorrhizal fungi, and on selected physiological parameters of three grapevine cultivars ('Pinot Noir' on SO4 rootstock, 'Regent' on 5BB rootstock, and 'Rondo' on 125AA rootstock). The applied inoculation had a stimulating effect on the colonization of roots by arbuscular mycorrhizal (AM) fungi, as evidenced by higher mycorrhizal frequency and intensity in the mycorrhized plants. The mycorrhizal treatment increased the intensity of CO2 assimilation and transpiration. Mycorrhization reduced the efficiency of photosynthetic water use and increased stomatal conductance for water in the grapevines tested. The mycorrhizal treatment did not affect the concentration of assimilation pigments in vine leaves. The mycorrhization of grapevines had no effect on the values of initial fluorescence, maximum fluorescence, the maximum potential efficiency of photochemical reaction in PS II, the size of the pool of reduced electron acceptors in PS II, nor on the value of the PS II vitality index. <![CDATA[<b>Grapevine Leaf Application of <i>Steinernemayirgalemense </i>to Control <i>Planococcus ficus </i>in Semi-field Conditions</b>]]> The vine mealybug, Planococcus ficus Signoret (Hemiptera: Pseudococcidae), is a key insect pest of South African grapevine. The ability of mealybugs to avoid or resist the action of chemical pesticides has led to the investigation of alternative control methods, such as the application of entomopathogenic nematodes (EPNs). However, EPN application faces challenges, due to the maladaptation of EPN species to above-ground conditions. In this study, the ability of adjuvants to improve the control of P. ficus in grapevine using an indigenous nematode species, Steinernema yirgalemense, was investigated. A trial was performed to assess EPN survival on grapevine foliage, when applied in the morning (high humidity / low temperature) compared with in the afternoon (high temperature / low humidity). In a semi-field trial, the combination of adjuvants Zeba® and Nu-Film-P® resulted in 66% control of P. ficus after 48 h, compared to the use of Zeba® alone (43%), and EPNs alone (28%). Additionally, lower concentrations of EPNs showed predictably lower mortality rates of P. ficus. Significantly, higher EPN survival was recorded at each time interval in the morning, compared with the corresponding interval in the afternoon. This study demonstrates the ability of S. yirgalemense, when applied with adjuvants and at an appropriate time of day, to control P. ficus on grapevine, under semi-field conditions. <![CDATA[<b>Influence of Must Supplementation on Growth of <i>Pediococcus </i>spp. after Alcoholic Fermentation</b>]]> One factor potentially affecting growth of wine spoilage microbes (e.g., Pediococcus spp.) is the presence of nutrients not consumed during alcoholic fermentation by Saccharomyces cerevisiae. To assess the impact of must nutrient supplementation on Pediococcus spp., synthetic grape musts containing low (55.2 mg N/L), medium (250 mg N/L), or high (530 mg N/L) concentrations of yeast assimilable nitrogen (YAN) were fermented by S. cerevisiae. Upon cessation of fermentative activity P. damnosus OW-2, P. inopinatus OW-8, P. parvulus WS-7C, WS-29A, OW-1, or P. pentosaceus ATCC 33316 were inoculated at 10(4) to 10(5) cfu/mL. With the exceptions of OW-1 and OW-2, none of the other species or strains grew in the synthetic wines unless yeast extract or peptone was added, suggesting the absence of an essential nutrient. Experiments were replicated using Cabernet Sauvignon musts containing low (66.9 mg N/L), medium (219 mg N/L), and high (438 mg N/L) YAN. In general, wines containing the greatest residual amino acid concentrations (high YAN) supported better growth of the aforementioned Pediococcus spp. However, low YAN wines containing negligible residual nitrogen achieved similar populations after a short period of initial inhibition, suggesting that 'excessive' nitrogen supplementation to musts does not have a large impact on growth of pediococci post alcoholic fermentation. <![CDATA[<b>Effects of different harvest times on the maturity of polyphenols in two red wine grape cultivars <i>(Vitis vinifera </i>L.) in Qingtongxia (China)</b>]]> 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>Effects of abiotic factors on phenolic compounds in the Grape Nerry - a review</b>]]> Grape berry phenolic compounds are widely described in literature. Phenolics can be divided into two main groups: flavonoids and non-flavonoids, of which the flavonoids are the most important. The two best-known groups of flavonoids are the anthocyanins and condensed tannins (also called proanthocyanidins). Anthocyanins are responsible for the red colour in grapes. The condensed tannins (proanthocyanidins) are responsible for some major wine sensorial properties (astringency, browning, and turbidity) and are involved in the wine ageing processes. This review summarises flavonoid synthesis in the grape berry and the impact of environmental factors on the accumulation rate during ripening of each of the flavonoids. The impact of the accumulated flavonoids in grapes and the resulting impact on the sensorial aspects of the wine are also discussed. <![CDATA[<b>Impact of time, oxygen and different anthocyanin to tannin ratios on the precipitate and extract composition using liquid chromatography-high resolution mass spectrometry</b>]]> Wine colour and phenolic stability over time are influenced by the amount and nature of phenolics in young wines. The ratio between different phenolic compounds can also be determinant in the colour and phenolic development of red wines. Three different anthocyanin to tannin ratios extracted in a wine-like system were saturated with oxygen several times during sample storage. A LC-HRMS method was used to evaluate the impact of a forced oxidation and of the different extracts on the wine-like composition and on the precipitate formed over time. The extract composition was found to be the most determinant factor for the precipitate formed. Time was also found to be a relevant factor according to the precipitate composition.