Fl Kerslake

Characterization of macromolecular complexes in red wine: Composition, molecular mass distribution and particle size.

Precipitates were prepared from two compositionally different Pinot noir wines with addition of excess ethanol, and contained primarily polysaccharide, tannin and protein. The ethanol-soluble material was further fractionated into polymeric (tannin) and monomeric phenolics. Tannin associated with precipitates was of a higher molecular mass than that remaining in ethanolic solution. Wine fractions were reconstituted at the ratios of the original wine and analyzed using nanoparticle tracking analysis. The average particle size of the tannin fraction was 75-89 nm, and increased when combined with the precipitate (≅ 200 nm). Addition of the monomeric fraction to the tannin-precipitate complex increased both the incidence and concentration of smaller particles, reducing the average particle size. The formation of aggregates occurred in all fractions and only minor differences in particle size distribution were found between wines. Differences in particle concentration between wines appear to be due to differences in the total concentration of macromolecules rather than compositional differences.

Viticulture for Sparkling Wine Production: a Review

The current understanding of the influences of climate and viticultural practices on fruit quality at harvest and on sparkling wine quality is reviewed. Factors such as variety, clone, planting density, pruning method, local climate and soils, and current and future climate warming are discussed in the context of achieving a desired harvest quality. A common observation was the relatively less intensive viticultural management applied to grapes destined for sparkling wines compared to table wines throughout the world. Few studies have focused on management of fruit specifically for sparkling wine production. Given that it is accepted that a lower pH, higher titratable acidity, and lower soluble sugars than table wine are considered desirable for sparkling wine production, the literature from viticultural studies for table wines which influence these desired fruit quality parameters has been reported. Specific findings on canopy management, leaf removal, and yield manipulation for the production of table wines indicate potential for application and development to optimize fruit for the production of sparkling wines. Fruit quality targets are remarkably uniform across international growing regions but distinct combinations of variety, clone, and management are currently used to arrive at those targets. Further, studies of viticultural management, particularly those that alter cluster temperature and exposure to incident light, yield manipulation, and fruit quality are likely to best inform production techniques that result in fruit quality ideal for the production of premium sparkling wines. New challenges include the need for increasing mechanization to maintain cost-effective production and climate warming, which affects the production of fruit for premium sparkling production in terms of flavor development and high acidity. Current trends include the diversification of growing regions to cooler regions that enable the production of high acid fruit and increased exploration of alternative varieties and clones that are better suited to a warmer climate.