UV-C C : A new technology to manage the microorganisms in musts and wines François Davaux 1, Sandra Torriani 2 1 Institut Français de la Vigne et du Vin, Pôle Sud-Ouest, V Innopole, Lisle/Tarn, France 2 Verona University, Department of Biotechnology, Italy
Principle The systems emits UV-C at the germicidal wavelength of 253.7 nm. That is of sufficient energy and duration to inactivate contaminating micro-organisms (Yeast and bacteria) The transfer of the UV-C energy is done directly, selectively and efficiently to the microbial DNA The dosage of the UV-C depends on the subject produce (turbidity, color, level of microbiological contamination), UV-C output and transient time
Source of UV Light The UV-C Low-Pressure Mercury Lamps and free ozone Centered emission at wavelength 253,7 nm Destruction of the micro-organisms: Virus, yeasts, Bacteria, Algae, moulds, protozoon Maximum germ-destroying effect between 26-265 Nm Damage on the basis pyrimidic of nucleic acid (DNA, ARN) Dimer formation especially when 2 molecules of thymine or cytosine are close on the same bit to DNA For the other bases of DNA, the effect is less Hydration of the pyrimidic bases: deterioration of the genetic code Denaturation of the DNA: consequence of the formation of dimers and hydrates
History of sterilization by UV-C radiation Highlighted by Downs and Blunt, in 1878 of bactericidal effects with solar radiation First successful attempts to sterilize water in Marseille in 196 by Henry and Cernovedeau First industrial applications of UV treatment: treatment shellfish in Japan in the 5s
Current applications of UV sterilization Used for more than 4 years for the sterilization of drinking water, wastewater, treatment of seawater for aquaculture and shellfish Used in the food industry to sterilize surfaces (pots and capsules packaging, bottle necks before closing, materials, tools,...), fruits juice, apple juice, cider Decontamination of air for clean rooms or air conditioning
The regulation USA : FDA approved to disinfect surfaces in contact with food and the surfaces of food, drinking water, fruit juices Canada : Authorized in apple juice and cider South Africa : Authorized for wine and beverages base of grape juice and fruit juice Europe : surface in contact with food, drinking water
Description of the sterilizer The «Turbulator» with UV-C Unit of sterilization SP4 Spiral Form (setting in turbulence) Low Pressure Mercury Lamp Tube quartz Treatment chamber
Must treatment 8 7 1 NTU 12 NTU 56 NTU 126 NTU 85 NTU 64 NTU 14 NTU 489 NTU Yeast - Log CFU/ml 6 5 4 3 2 1 Loin de l'œil Colombard Sauvignon Sauvignon Colombard Macabeu Sauvignon Tannat rosé 212 211 21 Control UV-C Treatment 887 J/l UV-C Treatment 1774 J/l UV-C Treatment 2662 J/l Efficiency to reduce Yeast population : CFU = -1 Log minimum for 887 J/l Turbidity has an influence Elimination of microorganisms is efficient enough to delay the start in spontaneous fermentation
Reduction of yeast population with UV treatment on white musts : Sauvignon 21 7,E+7 175 6,E+7 17 Yeast - CFU/mL 5,E+7 4,E+7 3,E+7 2,E+7 1,E+7 Start in AF Start in AF Start in AF Start in AF Density 165 16 155 15 Start in AF Start in AF Start in AF Start in AF,E+ 1 2 3 4 5 6 7 Nb of hours after treatment 145 1 2 3 4 5 6 7 8 Nb of hours after treatment Control 887 J/l 1774 J/l 2661 J/l 4435 J/l Control 887 J/l 1774 J/l 2661 J/l 4435 J/l Control : spontaneous start of the AF, 24 h after the test UV-C 887 J/L : spontaneous start of the AF, 43 h after the treatment UV-C 1774 J/L : spontaneous start of the AF, 5 h after the treatment UV-C 2661 and 4435 J/L : spontaneous start of the AF, 78 h after the test
Stop the Alcoholic fermentation of a sweet white wine 8 7 Colombard 211 6 Yeast - Log CFU/ml 5 4 3 2 1 Control UV-C treatment - 887 J/l UV-C treatment - 1775 J/l UV-C treatment - 2662 J/l Good effectiveness for to help stopping AF on sweet wines Reduces the yeast population between 2,3 and 4,2 Log Associated with cold treatment, this technique would allow to limit SO2 doses
UV-C treatment of white and rosé wine Test on 2,5 hl 5 Pinot gris 6 Yeast - Log CFU/ml 4 3 2 1 Sauvignon Sauvignon /5 ml Sauvignon Log CFU/mL 5 4 3 2 1 Yeasts Lactic Bacteria Acetic Bacteria 21 211 Control UV-C treatment - 887 J/l UV-C treatment - 1775 J/l UV-C treatment - 5915 J/l Control 125 25 5 612 75 1 Joules/Liter Good effectiveness in white and rosé wine More efficiency eon bacteria More effective on the clarified wine
UV-C treatment of red wine Barbera 211 Montepulciano 211 6 4 Log CFU/mL 5 4 3 2 Control UV-C - 1 J/l CFU/mL 35 3 25 2 15 1 Control UV-C - 1 J/l 1 5 Yeast Lactic bacteria Acetic barteria Yeast Lactic bacteria Acetic barteria Cabernet Sauvignon 211 16 14 Brettanomyces - CFU/ml 12 1 8 6 4 2 Less efficient than red wine Good efficiency on Brettanomyces Better efficiency on bacteria Control UV-C treatment - 887 J/l UV-C treatment - 1775 J/l
Influence of UV-C on physico-chemical analysis Treatment on wine 211 Pink Wine Red Wine Pinot Grigio Rosato Montepulciano Barbera Control Treated Treated Treated Treated Control Control Control 1 J/L 1 J/L 1 J/L 1 J/L Alchool % v/v 12,78 12,79 11,64 11,64 13,12 13,1 13,33 13,33 Sugar g/l 1,5 1,4 1,5 1,5 4,1 4,12 3,1 3,1 Alcoholic strength by volume corrected % v/v 12,87 12,86 11,73 11,73 13,37 13,38 13,52 13,52 sugar Total extract g/l 18,1 18,1 19,3 19,28 33,3 33 34,9 34,8 Total acidity g/l 6,7 6,68 5,52 5,5 5,87 5,85 8,39 8,37 Acetic acid g/l,24,24,19,18,5,52,31,3 ph 3,25 3,24 3,52 3,5 3,78 3,76 3,57 3,57 Malic acid g/l 2,5 2,52 1,53 1,52 <,2 <,2 1,21 1,2 Lactic acid g/l <,2 <,2,57,58 1,17 1,17 1,24 1,22 Tartaric acid g/l 3,13 3,1 2,41 2,41 3,51 3,5 4,59 4,59 Glycerol g/l 5,68 5,66 6,19 6,18 8,15 8,17 11,16 11,15 Total SO2 mg/l 23, 2, 6, 6, 1, 1 2 2 Free SO2 mg/l 1, 1, < 1 < 1 <,5 <,5 1 1 Total anthocyan mg/l - - 16 16 48 46 372 366 Total flavonoids mg/l - - 197 211 212 1999 1924 194 dtat % - - - - 3,3 31,2 24,1 22,6 Abs 42 nm abs,19,111,253,255 4,592 4,598 5,2 5, Color intensity abs - - - - 13,495 13,5 1754 175 Tone - - - -,642,644,462,463 Treatments with UV-C showed no analyticals differences in comparison with the control
Impact of UV-C treatment in must on the content of esters and acetates in red wine Sauvignon Blanc Test on 2,5 hl mg/l 2, 1,8 1,6 1,4 1,2 1,,8,6,4,2, hexyl acetate [mg/l] isoamyl acetate [mg/l] phenylethyl acetate [mg/l] ethyl decanoate [mg/l] ethyl hexanoate [mg/l] ethyl octanoate [mg/l] Control 1183 J/l 3552 J/l 2-phenylethanol 2 18 Low impact of UV-C treatment on esters and acetates Dose effect on ethyl hexanoate Low sensory impact mg/l 16 14 12 1 8 6 4 2 Control 1183 J/l 3552 J/l
Impact of UV-C treatment in wine on the volatils compounds Pink Wine Red Wine Pinot Gris Rosé Montepulciano Barbera Control Treated Treated Treated Treated Control Control Control 1 J/L 1 J/L 1 J/L 1 J/L isoamyl acetate µg/l 133 136 447 465 494 469 718 74 ethyl hexanoate µg/l 75 74 679 66 191 177 197 163 Isoamilic alcohol mg/l 18,8 19,2 19,8 17,32 2,4 21,6 2,6 28,2 hexyl acetate µg/l 84 84 13 13 4 3 4 3 1-hexanol µg/l 1339 1292 97 994 773 735 442 461 cis-3-hexenol µg/l 44 44 54 59 6 57 2 22 ethyl octanoate µg/l 1266 1292 1195 1163 333 311 251 253 free linalool µg/l 4 5 21 19 9 8 17 17 ethyl decanoate µg/l 33 336 373 376 153 148 163 156 alpha-terpineol µg/l 5 4 9 11 6 6 14 13 diethyl succinate µg/l 5455 5218 966 984 964 88 853 9158 citronellol µg/l 8 7 11 12 18 17 26 25 ac. Hexanoic µg/l 3923 3875 378 3626 1174 1173 973 12 2 phenyl ethanol mg/l 1,48 1,9 12,62 12,45 24 25,1 19,5 23,2 ac. Octanoic µg/l 7648 1131 6994 6823 2113 2197 1795 178 4-ethylphenol µg/l 5 6 2 1 5 5 8 7 4-vinilguaiacol µg/l 29 3 12 21 5 5 19 15 ac. Decanoic µg/l 2376 2231 222 2354 69 726 571 451 4-vinylphenol µg/l 9 9 7 11 2 2 13 13 ac monoethyl succinic mg/l 5,57 5,29 8,43 8,23 7,86 7,75 1,7 12,6 tyrosol µg/l 45 423 572 635 683 772 795 843 At low doses, the use of UV-C does note cause significant differences
Impact of UV-C treatment in must on the content of varietal thiols in wine Sauvignon Test on 2,5 hl 3-mercaptohexan-1-ol 3-mercaptohexan-1-ol acetate 18 1 16 14 8 3MH [ng/l] 12 1 8 6 ac 3MH [ng/l] 6 4 4 2 2 Control 1183 J/l 3552 J/l Control 1183 J/l 3552 J/l No impact on 3MH No significant impact on ac 3MH The organoleptic impact will be negligible
Effect of UV-C treatment on free radicals in wine 14 ORAC value - µmol TE/1ml 12 1 8 6 4 2 Cabernet Sauvignon Red Wine 1 Red Wine 2 Merlot Control UV-C Treatment - 1 J/L No significant impact
Effect of UV-C treatment in white and rosé wine oxidation,3,25 OD 42 nm,2,15,1,5 Macabeu - 2,5 hl Sauvignon -2,5 hl Sauvignon -2,5 hl Sauvignon -2,5 hl Colombard -2,5 hl Pinot Grigio -22 hl Rosé -17 hl Sauvignon -2,5 hl Loin de l'œil -2,5 hl 21 211 212 Control UV-C treatment - 887 J/l UV-C treatment - 1 J/l UV-C treatment - 1775 J/l UV-C treatment - 2662 J/l UV-C treatment has no effect on the white and rosé wines oxidation
Effect of UV-C treatment in red wine oxidation Tone - OD42 / OD52,9,8,7,6,5,4,3,2,1 Gamay -2,5 hl Montepulciano -3 hl Barbera -15 hl Malbec -2,5 hl Malbec -2,5 hl Cabernet Sauvignon -2,5 hl 21 211 212 Control UV-C treatment - 887 J/l UV-C treatment - 1 J/l UV-C treatment - 1775 J/l UV-C treatment - 2662 J/l Gamay -2,5 hl UV-C treatment has no effect on the red wines oxidation
Inactivation of microorganism is as temporary or permanent? Réplication of nucleic acid becomes very difficult once the pyrimidique molecules are bonded together UV-C can cause other lesions such as DNA cuts and thymine-glycols. If the replication do not occur, mutant cells that are unable to replication (permanent inactivation) In certain conditions, the enzymatic mechanisms are able to repair cellular damage (temporary inactivation) The dose of UV-C must be strong enough to cause irreversible damage to microorganisms
UV-C generates mutants cells? Studies have shown (Sipicski, 211) that the natural wine yeasts have a high capacity to reorganize their genomes The UV-C is used for decades for the water treatment without any problems According to scientific literature, the release of any mutant induced by UV-C treatment in the environment has never been reported for potable water or fruit juice Even if there is change, it can in no way lead to the emergence of new cellular characteristics dangerous to humans
Influence of UV-C on Result of triangulare test the tasting 211 Barbera UV-C 1 J/L Nb of good 6/12 Significant NS Treatment 3 J/l response 6/12 difference at 5% NS Montelulciano 1 J/L 7/12 NS Pinot grigio 1 J/L 6/12 NS Schiava rosé 1 J/L 7/12 NS 211 UV-C Treatment Nb of good response Significant difference at 5% Sauvignon Colombard Colombard 887 J/l 6/1 NS 1775 J/l 4/1 NS 2661 J/l 4/1 NS 887 J/l 4/7 NS 1775 J/l 3/7 NS 2661 J/l 5/7 S 887 J/l 5/8 NS 1775 J/l 5/8 NS 2661 J/l 5/8 NS UV-C treatment of wines does not show significant differences compared to control
Influence of UV-C on the tasting White wine Variety : Sauvignon 2,5 hl UV-C treatment : 887 and 1775 J/l 211 PAI aromatic intensity 3, 2,5 redox Intensely aromatic nose 2, 1,5 vegetable thiols 1, heat in the mouth,5, fruity thiols bitter terpene fruity acid fermentation sweetness fat Control UV-C treatment - 887 J/l UV-C treatment - 1775 J/l UV-C treatment of wines does not show significant differences compared to control
Influence of UV-C on the tasting Rosé wine Variety : Pinot Grigio UV-C treatment : 1 J/l 211 duration of taste / odor pale yellow 7 6 greenish 5 structure sweetness 4 3 2 1 acacia flowers citrus bitter honey acidity fresh herbaceous herbs Control UV-C treatment - 1 J/l UV-C treatment of wines does not show significant differences compared to control
Influence of UV-C on the tasting Red wine Variety : Barbera UV-C treatment : 1 and 3 J/l 211 duration of taste / odor 8 7 ruby violet astringency bitter structure 6 5 4 3 2 1 flower (pink, purple) spicy (pepper, clove) more acidity cherry clippings dried plum straw / hay jam / marmallata Barbera Control Barbera UV-C treatment - 1 J/l Barbera UV-C treatment - 3 J/l UV-C treatment of wines does not show significant differences compared to control
Conclusions Real effectiveness of UV rays on the destruction of micro-organisms No generation of pathogenic mutant, very low risk of reactivation of microorganisms treated with UV-C The must treatment by UV-C can delay the start of spontaneous AF by 1 to 3 days Facilitates the stop of AF in sweet wines Color and turbidity limit the effectiveness of UV-C treatment More effective on white and pink than red wines More effective on bacterias than yeasts No or low impact on aromatic compounds (esters, acétate and thiols) No sensory impact at usual doses but with high doses, UV treatment can cause of reduction notes With this technology it is possible to manage the micro-organism in must or wine This technology can also be used to disinfect grape juice slightly altered and degrade the PPO A promising technology for bottling wine and eliminate microorganisms with using a soft technology