Phenolic compounds of Moroccan red press wines: Influence of fining agents and micro-oxygenation treatments

- Vegetable protein has affinity to the fraction of oligomeric apparent pranthocyanidins.
- Catechin, epicatechin, fraction of polymeric tannins decreased by gelatin and PVPP.
- Proanthocyanidin oxidation decreased by vegetable protein 36%.
- Saliva Precipitation Index and astringency decreased by PVPP and vegetable protein.

To improve the sensory quality of Moroccan red press wines, press wines were separately submitted to micro-oxygenation and three fining agents (gelatin, Polyvinylpolypyrrolidone (PVPP) based formulation and pea protein) treatments at the winery Château Roslane, Morocco. The results showed that each treatment has a distinct behavior in relation with interactions and precipitation monomeric flavan-3-ol and fractions apparent and total condensed tannins. The fining agent corresponding to the vegetable protein has a greater affinity with the fraction of oligomeric condensed tannins with apparent aDP: 3.2. However, gelatin and PVPP based fining agent have an affinity with the catechin and epicatechin as well as with the fraction of polymeric tannins (apparent aDP: 6.6). For the structural parameters of proanthocyanidins, no significant differences were found out in global aDP and percentage of prodelphinidin between the different treatments. The global percentage of galloylation appeared slightly affected, while the global percentage of oxidized proanthocyanidins increased (9%) significantly (P < 0,05) for micro-oxygenation treatment, unlike the fining agent has basic vegetable protein has decreased 36% the percentage of oxidation. For the Saliva Precipitation Index (SPI) and sensory analysis, the greatest reduction of SPI, bitterness and astringency was observed for both basic PVPP and vegetable protein fining agents.