Bottle Fermented Sparkling Wine: Cork or Crown Closures During the Second Fermentation?

Bottle-fermented sparkling wine producers are continuously striving to increase quality and produceniche products. One production tool that could be used is a cork closure instead of a crown cap closureduring the second fermentation and maturation on yeast lees. Anecdotal evidence suggests that thisleads to stylistic differences in the wine. Six pairs of South African bottle-fermented sparkling wines(Méthode Cap Classique), closed by either a cork or crown cap, were investigated. Analyses includedbottle pressure, infrared spectroscopy, phenolic acids, sensory attributes and CO2 kinetics. Generally,there were differences between the cork-closed and crown-capped wines. Cork-closed wines tended tohave lower pressure compared to crown-capped wines, albeit still well within legal requirements. Otherdifferences were evident in the infrared spectral data and in the polyphenol profile of the analysed wines.Levels of gallic, caftaric, caffeic and p-coumaric acids could be used collectively as marker compounds todifferentiate between cork-closed and crown-capped wines. The effect of the cork was also evident in thesensory attributes and CO2 kinetics. Cork-closed wines were judged to have smaller bubbles and a longeraftertaste. It was also shown that the cork-closed wines tended to lose CO2 from the glass slower after beingpoured than their crown-capped counterparts. The data tentatively support the anecdotal evidence thatcork can be used during the second fermentation and maturation on the yeast lees to change the style ofbottle-fermented sparkling wine.

Effect of Oxygen and Nitrogen Sparging during Grape Fermentation on Volatile Sulphur Compounds

Elemental sulphur is a common fungicide applied in vineyards before harvest, and has been found toincrease the production of desirable polyfunctional mercaptans, but also H2S and unwanted reductivesulphur aroma compounds. This paper investigates the effectiveness of oxygen and nitrogen sparging,applied during fermentation, on the removal of volatile sulphur compounds in Sauvignon blanc wines.Increasing the amount of elemental sulphur added to grapes after pressing, from nil to 10 to 100 mg/L,led to an increase in the formation of 3-mercaptohexanol (3MH), of 3-mercaptohexyl acetate (3MHA) forthe 10 mg/L additions only, and of some unwanted reductive compounds. Few changes were observed inthe concentrations of aroma compounds when the juices were sparged with nitrogen during fermentation.Additions of oxygen during fermentation led to some decrease in the concentration of polyfunctionalmercaptans for the 10 mg/L sulphur additions, but did not significantly remove reductive aroma compounds.Few differences were observed in the concentration of wine phenolics or of further wine aroma familieswith any of the treatments.

Formulation of Entomopathogenic Nematodes for the Control of Key Pests of Grapevine: A Review

Entomopathogenic nematodes (EPNs) are insect parasites that are used successfully as biological controlagents against key pest insects of grapevine. To achieve low chemical residues and the sustainableproduction of grapes, it is important that biological control agents such as entomopathogenic nematodesfor the control of grapevine insect pests be incorporated in an integrated pest management system forgrape production. However, the commercialisation and large-scale use of EPNs is limited by their shortshelf life in formulations and in storage, thus leading to poor quality and reduced efficacy against insectsin the field. In South Africa, interest in the use of EPNs within an integrated pest management system hasgrown over the past two decades, therefore developing a formulation technique with an acceptable storagesurvival period, while maintaining infectivity, is essential. Moreover, the successful control of insects usingEPNs is only achievable when the formulated product reaches the end user in good condition. This reviewis focused on the different types of formulations required for storage and ease of transport, together withthe application formulation for above-ground pests and the factors affecting them. The quality assessment,storage and handling of formulated EPNs are also discussed.

Biological Deacidification Strategies for White Wines

Traditionally, the use of malolactic fermentation gives rise to microbiologically stable wines. However, malolactic fermentation is not free from possible collateral effects that can take place under specific scenarios. The present work tests the influence of different biological deacidification strategies on the volatile and non-volatile components of white must from Germany. The study compared mixed cultures of Lachancea thermotolerans and Schizosaccharomyces pombe and a pure culture of Sc. pombe to the classical biological deacidification process performed by lactic acid bacteria. Strains of Oenococcus oeni and Lactiplantibacillus plantarum were co- or sequentially inoculated with S. cerevisiae to carry out malolactic fermentation. Different fermentation treatments took place at a laboratory scale of 0.6 L in vessels of 0.75 L. The instrumental techniques Fourier-transform mid-infrared spectroscopy (FT-MIR), high performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS) were used to evaluate different chemical parameters in the final wines. The results showed the ability of Sc. pombe to consume malic acid in combination with L. thermotolerans without using S. cerevisiae or lactic acid bacteria. Fermentations involving Sc. pombe consumed all the malic acid, although they reduced the concentrations of higher alcohols, fatty acids and acetic acid. Simultaneous alcoholic and malolactic fermentations reduced malic acid by about 80%, while classical malolactic fermentation reduced it by 100%. Fermentations involving L. thermotolerans produced the highest lactic acid, ester and glycerol concentrations.

Influence of Grapevine Leafroll-associated Virus-3 in Mature Plants of Vitis vinifera L. cv Albariño on 110R and 196.17C Rootstocks

The detrimental effects of grapevine leafroll disease (GLD) have been documented mainly in young plantsand little data is available on infected grapevines when they reach maturity. This study examined theinfluence of the rootstock on the effect of GLRaV-3 in a 20-year-old Vitis vinifera cv Albariño vineyard inwhich the virus has been spread by Planococcus ficus. Plants grafted on Richter 110 or Castell 196.17 withsimilar development were analysed for grapevine leafroll-associated viruses. In particular, 25 GLRaV-3-infected and 25 leafroll-free and asymptomatic vines were selected and monitored during a period of threeyears to determine grape yield and must components. Although the virus infection affected plants on bothrootstocks, it caused a greater effect on plants grafted onto 110R, with average accumulated yield losses ofup to 33%, relative to losses of 16% for plants on 196.17C. The sugar content was lower in the must frominfected plants on 110R (-2.1ºBrix) than in the must from plants on 196.17C (-1.5ºBrix). The presence ofthe virus was associated with decreased concentrations of primary amino nitrogen (PAN) and ammonium(NH4+), with the greatest effect for 110R (-35%). As 110R is the most used rootstock in Spain, particularcare must be taken to prevent the transmission of GLRaV-3 to certified virus-free plants on 110R in newvineyards. In sensitive varieties such as Albariño, particularly in areas with an active spread of the virusby mealybugs, grafting on 196.17C seems to minimise the effect that GLD has in a medium to long term.