Micro-Oxygenation and Fining Agent Treatments: Impact on Color of Moroccan Red Press Wine

Abstract

Red press wine is collected after pressing solid parts (seed and skin) of grapes pomaces. Higher pressure induces more colorful, astringent, bitter and rustic wines. This is caused by the presence of undesirable phenolic compounds. To overcome this problem, the most common practice used in wine industry is the oenological treatment which enhances the clarity, stability and the wine taste. In the present work, press wines were separately submitted to four different treatments: micro-oxygenation and the addition of three fining agents: gelatin, polyvinylpolypyrrolidone (PVPP) and pea protein. The phenolic total index decreased (8%) significantly (P<0.05) for gelatin treatment, the PVPP based formulation treatment led to the largest loss (8%) in color intensity, (12%) in redness (a*), (9%) in polymeric pigments and increasing to 9% lightness (L*). Unlike micro-oxygenation which has decreased (5%) the color intensity. For the monomeric anthocyanins, the greatest reduction of acylated and coumaroylated anthocyanins at bottling and glucoside anthocyanidins after five months of storage was observed for both basic PVPP and gelatin.

Application of soy protein isolate in the fining of red wine

“…In this context, SPI was similar to other protein agents. Aziz et al (2017b) did not find significant differences for the color intensity while fining with polyvinylpolypyrrolidone, gelatin, or pea protein isolate on 'Cabernet Sauvignon' wine. González-Neves et al (2014) found that anthocyanin content was slightly reduced by the use of albumin and egg gelatin, and was not affected by the use of vegetable proteins (gluten proteins) in most of the red wines of 'Tannat' evaluated in the study.…”