Hydrogen sulfide and methanethiol are recognised as two of the most significant contributors to reductive off-flavours in wine.
Polysaccharides (PS) are one of the main compounds found in wines, and they come mainly from the grape cell walls or from the yeasts, and they play an important role in the technological and sensory characteristics of wines. Polysaccharides obtained from yeasts have been more studied, especially mannoproteins, since there are commercial products.
High temperatures typical of warm climates cause the colour of red wines to become increasingly unstable over time.
Stems may bring various benefits to the wine such as alcoholic reduction, color protection or improvement of the tannic intensity.
Light-induced reactions can be responsible for detrimental changes of white and rosé wines. This is associated to the photo-degradation of riboflavin (RF) and of methionine (Met) causing the appearance of light-struck taste (LST).