Attractiveness and sweetness of red wines: Synergies between American oak barrels and mannoproteins

The type of soil management, tillage versus cover crops, can modify the soil microbial activity, which causes the mineralization of organic N to NO3–N and, therefore, may change the soil NO3–N availability in vineyard. The soil NO3–N availability could influence the grapevine nutritional status and the grape amino acid composition. Amino acids are precursors of biogenic amines, compounds mainly formed during the malolactic fermentation. Biogenic amines have negative effects on consumer health and on the wine organoleptic quality. The objective was to study if the effect of conventional tillage and two different cover crops (leguminous versus gramineous) on grapevine N status, could relate to the wine biogenic amines composition.

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (furaneol) is an important aroma compound in fruits, such as pineapple and strawberry, and is reported to contribute to the strawberry-like note in some wines. Several grapevine species are used in winemaking, and furaneol is one of the characteristic aroma compounds in wines made from American grape (Vitis labrusca) and its hybrid grape, similar to methyl anthranilate. Muscat Bailey A is a hybrid grape variety [V. labrusca (Bailey) x V. vinifera (Muscat Hamburg)], and its wine is one of the most popular in Japan. The inclusion of Muscat Bailey A in the ‘International List of Vine and Varieties and their Synonyms’ managed by the ‘International Organisation of Vine and Wine (OIV)’ in 2013 has further fueled its popularity among winemakers and researchers worldwide.

During wine aging, several complex phenomena of gas transfer take place in barrels due to the wine/oak contact. The efficiency of this gas transfer varies according to oak wood’s intrinsic physical properties. This research aims to better understand oxygen transfer phenomena through dry oak staves and especially through stave gaps, in order to reevaluate the importance of barrel-making on a barrel’s supply of oxygen. Experimentation was based on the development of an innovative permeameter of laboratory scale, for which the principal operating conditions concerning applied pressure, the choice of liquid phase/gas phase, and the grain type of oak are taken into account and investigated. With a specially developed tightening system, the existing pressure at stave gaps in a barrel could be reproduced on a laboratory scale in order to estimate its influence on oxygen transfer efficiency.

The use of next-generation sequencing (NGS) has helped understand microbial genetics in oenology. Current studies mainly focus on barcoded amplicon NGS but not shotgun sequencing, which is useful for functional analyses. Since the high percentage of grapevine DNA conceals the microbial DNA in must, the majority of sequencing data is wasted in bioinformatic analyses. Here we present capture depletion of grapevine whole genome DNA.

Sessile oak and pedunculate oak have shown several differences of interest for enological purposes. Tannic and aromatic composition among sessile oak or pedonculate oak has been well studied. Sessile oak is generally more aromatic than pedunculated, while the later is more tannic. This scientific point of view is rarely applied to classify oak in cooperages. Most coopers use the type of grain to distinguish wide and thin grain.