Volker Schneider

Schneider-Oenologie · laboratory

Atypical aging is an off-flavor that can occur in white wines within a period of a few weeks to one year after the first addition of sulfur dioxide postfermentation. Its sensory characterization is varied and controversial, including a premature loss of varietal aroma combined with an increase in off-flavors that comprise various attributes such as...

For evaluation of flavonoid phenols in the low concentration range in white table wines, four colorimetric assays have been compared: (a) reaction with Folin-Ciocalteu reagent before and after precipitation of flavonoids in HCl-methanal (FC); (b) reaction with vanillin (VAN); (c) reaction with 4-(dimethylamino)-cinnamaldehyde (DAC); and (d) a rapid...

When white grape juice is processed without sulfur dioxide, enzymatically induced oxidation occurs and leads to a precipitation of phenolic compounds as insoluble brown pigments. Wines obtained from oxidized must are reported to display more resistance against oxidative quality degradation during aging. Hyperoxidation makes use of deliberate oxidat...

Postfermentation wine yeast lees display antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white, and red wines using fluorescence-based oxygen sensors operating in a n...

The use over many years of a fast and specific colorimetric method for the determination of flavonoid phenols in white wines and musts yielded far-reaching insights into the relationship between these phenols, perceived astringency, and premature oxidative aging. Furthermore, it provided extensive data on the impact of various vinification techniqu...

The phenolic make-up of red wines. Measurement of total phenols, anthocyanins, and tannin. Extraction of phenols in red winemaking. Tannin mouthfeel properties. Oxygen consumption by oxygen scavengers. Reactions between phenolics and oxygen. Means of oxygen supply. Barrel aging. Use and effect of oak alternatives. Preparing red wine for bottling.

Color, astringency and related in-mouth sensations of orange wines, also known as amber wines, are mainly attributable to their tannin. It is extracted in considerable but highly variable amounts and qualities during the long maceration period of such whites. This study focusses upon the assessment of tannin extraction using simple total phenol mea...

Liquid chromatography-mass spectrometry revealed that agglomerated corks from one manufacturer released more than 40 odorless compounds into the wine, which were not, or only in substantially lower amounts, released by natural corks. One of these compounds has been identified as suberic acid, a key component of the cork suberin polymer. It has also...

Screw caps differ in the oxygen barrier effect of their sealing inserts. Too much oxygen promotes oxidative ageing, too little oxygen promotes reductive ageing. Reductive ageing under hermetically sealing bottle closures is due to the formation of increased levels of volatile sulphur compounds, in particular thiols and H2S, whose odour causes reduc...

Board and Bench Publishing, 1st edition, San Francisco 2019. 239 pages. Contents: - The various kinds of white wine aging, sensory and chemical basics. - Typical and oxidative aging. - Influence of grape and juice processing. - Effect of reducing agents. - Impact of oxygen uptake and winery operations. - Impact of storage temperature and bottle cl...

Volker Schneider & Sarah Troxell: Acidity Management in Musts and Wines (126 pages). Contents: - Chemical and sensory basics. - Acidification with tartaric and other acids. - Enological differenciation and sensory impact of wine potassium levels. - Deacidification with potassium carbonates and its wine-dependent efficiency. - Deacidification with...

AT A GLANCE • An innovative screw cap liner capable of modulating the concentration of volatile sulfur compounds (VSCs) in screw capped wine has been subjected to performance trials; • The innovative liner includes a layer containing active copper capable of immobilizing VSCs, present in the bottle headspace. Essentially their scavenging by copper...

In a vineyard field experiment it was demonstrated that Saccharomyces cerevisiae yeast can be adsorbed from the soil by the roots of Vitis vinifera subs. vinifera and transported via vine to the stems and surface of the grapes. To exclude any extrinsic yeast contamination, the ripening grapes were sterilized and wrapped in plastic bags. Eleven act...

In a vineyard field experiment is was demonstrated that Saccharomyces cerevisiae yeast can be adsorbed from the soil by the roots of Vitis vinifera subs. vinifera and transported via vine to the stems and surface of the grapes. To exclude any extrinsic yeast contamination, the ripening grapes were sterilized and wrapped in plastic bags. Eleven acti...