NEW METHOD FOR THE QUANTIFICATION OF CONDENSED TANNINS AND OTHER WINE PHENOLIC COMPOUNDS USING THE AUTOMATED BIOSYSTEMS SPICA ANALIZER

The recovery of bioactive compounds from grape and wine by-products is currently an important and necessary objective for sustainability. Grape pomace is one of the main by-products and is a rich source of some bioactive compounds such as polyphenols, polysaccharides, fatty acids, minerals and seed oil. Polysaccharides contained in the grape cell wall can be rhamnogalacturonans type II (RG-II), polysaccharides rich in arabinose and galactose (PRAG), mannoproteins (MP), homogalacturonans (HG) and non pectic polysaccharides (NPP).

It is a well-established fact that premature oxidation is noxious for wine aromatic quality and longevity. Although some oxidation-related aroma molecules have been previously identified, there are not works carrying out systematic research about the changes in the profiles of odour-active volatiles during wine oxidation.

The quality of wines has often been associated with their geographical area of production. The aim of this work was to characterize Protected Designation of Origin (PDO) Xinomavro red wines from different geographical areas of Amyndeon and Naoussa in Northern Greece, elaborated with variables that contribute to their differentiation, such as soil characteristics, altitude, monthly average temperature and rainfall.
Xinomavro fruit parcels from different vineyards within the two PDO zones (5 PDO Naoussa and 6 PDO Amyndeon) were vinified following a standard winemaking process. A total of 25 aroma compounds were quantified using gas chromatography-mass spectrometry (GC-MS) with simultaneous full scan and selected ion monitoring for data recording, and odor activity values (OAVs) were determined.

Laccases from lactic acid bacteria (LAB) are described as multicopper oxidase enzymes with copper union sites. Among their applications, phenolic compounds’ oxidation and biogenic amines’ degradation, have been described. Besides, the role of LAB in the toxicity reduction of ochratoxin A (OTA) has been reported (Fuchs et al., 2008; Luz et al., 2018). Fungal laccases, but not bacterial laccases, have been screened for OTA and mycotoxins’ degradation (Loi et al., 2018). OTA is a mycotoxin produced by some fungal species, such as Penicillium and Aspergillus sp., which infect grape bunches used for winemaking.

Climate change is a great challenge for the environment and affects the wine industry as well. Sunburn damage of sensitive grapes increase with severe heat periods. Besides significant loss of yield sunburn, modifies sensory properties of the wines and may cause climate-related off-flavours. To initiate sunburn in a controlled way, in 2021 sunburn was directly induced in the vineyard with the GrapeBurner device, exposing grapes of the varieties Riesling and Pinot Blanc with UV and IR radiation. This device was first assembled by Kai Müller of the university in Geisenheim and consists of a carriage with 6 UV/IR lamps. A 15 min irradiation was applied in early September at 60°Oe. Due to the colder season in 2021 the grapes were not harmed by previous sunburn damage.