EVOLUTION OF PHENOLIC COMPOUNDS DURING WINEMAKING AND MATURATION UNDER MODIFIED ATMOSPHERE A. Bimpilas, D. Tsimogiannis, V. Oreopoulou Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens (NTUA)

Phenolic substances of wine Phenolic acids Gallic Caffeic P-coumaric Flavan-3-ols Catechin Epicatechin Procyanidins Flavonols Quercetin Kaempferol Myricetin Anthocyanidins Malvidin Delphinidin Cyanidin Petounidin Peonidin

Anthocyanins 3-Ο-glucoside 3-Ο-(6-acylated)-glucoside

Reactions between phenolic compounds during storage Anthocyanins Flavanols Polymeric pigments Flavanol-Anthocyanin adduct Methylmethine Flavanol-Anthocyanin adduct Anthocyanin Anthocyanin-Flavanol adduct Flavanol

Use of inert gases during storage Wine is protected from oxidative spoilage The initial good quality (fruit bouquet, color and flavor) is ensured Phenolic compounds of wine are protected

Experimental

Alcoholic fermentation Vinifications Alcoholic fermentation Stabilization Packaging laminated bags [20mL] N2 CO2 N2-CO2 (1:1) Cultivars Origin of cultivation Maceration process Allagiannis winery [Markopoulo, Attica ] Merlot Syrah Markopoulo, Attika pectinolytic enzymes Avantis Estate [Chalkida, Evia] 3) Mavrokou-ntoura Kymi, Evia Cold maceration under modified atmosphere (70% N2, 30% CO2) Pilot plant of the department of oenology and beverage technology [Technological Educational Institute of Athens] 4) Agiorgitiko Nemea, Korinthos Four different red wine varieties have been vinificated and two different maceration procedures have been used, so as to study the evolution of phenolics and provide feedback to the industry to improve the process And have been packaged in laminated bags under different inert atmospheres so as to optimize the storage atmosphere of each variety.

(Folin-Ciocalteu assay) Methods Samples Total Phenols (Folin-Ciocalteu assay) Chromatography (SPE  HPLC-DAD, LC-MS/MS) Color Measurement (Spectrophotometer) Antiradical activity (DPPH assay)

Results and discussion

Identification of individual phenolic compounds with HPLC min 10 20 30 40 50 60 mAU 100 200 300 400 500 520 nm - Anthocyanins Mv-3-glc Mv-3-acglc Mv-3-coumglc Pt-3-glc Pn-3-coumglc Dp-3-glc Pn-3-glc Pn-3-acglc Pt-3-acglc Pt-3-coumglc min 10 20 30 40 50 60 mAU 25 75 100 125 150 175 360 nm - Flavonols Q-3-glcr Q M-3-glc Q-3-glc L-3-glc M M-3-glcr I-3-glc S-3-glc

Extraction of phenolic compounds during vinification Total Phenols [ppm gallic acid] Free anthocyanins [ppm Mv-3-glc] CI HUE Merlot 2143±45 599.7±12 1.126±0.033 0.788±0.002 Syrah 1954±21 527.2±9.7 1.045±0.033 0.726±0.003 Mavrokou-ntoura 2165±69 533.5±23.5 1.039±0.006 0.630±0.002 Agiorgitiko 2550±35 461.2±4.1 0.943±0.006 0.598±0.001

Total phenolic content and antiradical activity % change of antiradical activity between 360 and 600days N2 -23% CO2 -60% N2-CO2 (1:1) -38% % change of antiradical activity between 360 and 600days N2 -45% CO2 -50% N2-CO2 (1:1) -42%

The decline of free anthocyanins during storage   Variety Packaging atmosphere Mv-3-glc Mv-3-acglc Mv-3-coumglc k [mon-1] R2 Merlot N2 -0.319 0.998 -0.336 CO2 -0.201 0.990 -0.223 0.983 -0.217 0.863 N2-CO2 (1:1) -0.239 0.994 -0.262 -0.268 Syrah -0.175 0.999 -0.192 0.993 0.195 0.960 -0.150 0.995 -0.170 -0.199 0.981 -0.324 -0.333 0.315 Mavrokountoura -0.259 0.984 -0.247 -0.252 0.977 -0.164 0.911 -0.158 0.882 -0.171 0.865 -0.299 0.986 -0.286 0.992 -0.271 0.997 Agiorgitiko -0.348 0.920 -0.392 0.913 -0.460 0.901 -0.317 0.795 -0.359 0.785 -0.456 0.842 -0.366 0.937 -0.414 0.928 -0.527 0.964

Color parameters

Hydrolysis of wine flavonols during storage % increase of total flavonol aglycones during storage Merlot N2 20% CO2 11% N2-CO2 (1:1) 18% Syrah 35% 10% Mavrokountoura 4% 3%

Conclusions The extraction of individual phenolic compounds during maceration differs with time and maceration procedure and optimal conditions can be designed for each variety Packaging atmosphere can affect the total phenolic content, antiradical activity, and the rate of polymerization reactions between phenolic compounds during wine storage The use of pectinolytic enzymes during vinification may lead to hydrolysis of certain glycosylated phenolic compounds, whereas increased carbon dioxide concentration during storage may inhibit such enzymatic reactions Our results showed that industry can select the optimum inert gas consistency for each grape variety, to favor quick reduction of free anthocyanins and wine stability

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