Study of varietal wines from the qualified origin denomination Rioja (Spain): analysis of wine colour, polysaccharides, polyphenols and biogenic amines and amino acides 

The interaction between mannoproteins and wine phenolic compounds is a subject of great interest as some studies show the possible impact in color stability and an improvement in the sensory characteristics namely the reduction of red wine astringency.

‘Cabernet sauvignon’ and ‘Merlot’ are among the most recognized red wine grape cultivars. This work is aimed at investigating the proanthocyanidin composition of skins and seeds to determine the grape variety and the vintage effects on the phenolic composition of Bordeaux grapes.

White wines are commonly stabilised by removing the heat unstable proteins through adsorption by bentonite, an effective but inefficient wine processing step. Alternative absorbents are thus sought and zirconium dioxide (zirconia) is recognised as a promising candidate.

Results indicated that cross-flow microfiltration removed similarly to fining treatments the most astringent tannins, but cross-flow microfiltration also removed up to 14 % more colour. RP-HPLC and spectrophotometric results showed that egg albumin is a softer fining treatment compared to gelatine and cross-flow microfiltration.

Protein stabilization is an important part of the winemaking process of white wines, and in this work we present the results of protein stabilization of different monovarietal wines (Xarel.lo, Chardonnay, and Muscat) by a continuous stabilizing filtration process using a column packed with zirconium oxide operating in a continuous regime in a closed loop at pilot scale.