Dr. Christian E. BUTZKE Associate Professor of Enology Department of Food Science. (765) FS Room 1261

Transcription

1 Dr. Christian E. BUTZKE Associate Professor of Enology Department of Food Science (765) FS Room 1261

2 Sulfur in Wine Reduced H 2 S hydrogen sulfide S 2- sulfides Oxidized electron-rich neutral electron-poor S elemental sulfur SO 2 sulfur dioxide HSO - 3 bisulfite SO 2-4 sulfate

3 ... CONTAINS SULFITES 1. Microbial stability 2. Inhibition of browning enzymes 3. Binding of acetaldehyde 4. Antioxidant

4 History of SO 2 in Winemaking Regulated in Europe since 1400s US labeling since 1988

5 Health Aspects of SO 2 Problem population: Steroid-dependent asthmatics = 20% of asthmatics = 200,000 in US Can be fatal! Does it cause headaches? No!

6 Regulation of SO 2 In Winemaking Total SO 2 allowed: 350 mg/l Labeling required*: 10 mg/l Naturally produced by yeast: 1-14 mg/l *even if naturally produced

7 Total SO 2 in Commercial Wine BATF analysis of 4,676 wines (mg/l) Legal limit: 350 Average US: 74 Average CA: 74 OR: 61 WA: 71 NY: % less than % less than % more than 350 Maximum: 686!

8 Forms of SO 2 SO 2 + H 2 O SO 2 aq Molecular SO 2 pk 1.8 SO 2aq H + + HSO 3 - Bisulfite ion pk 7.2 HSO 3 - H + + SO 3 2- Sulfite ion

9 Forms of SO 2 in Wine % 50 - SO molecular 2 HSO 3 - SO

10 Forms of SO 2 in Wine HSO 3 - % SO 2 molecular

11 SO 2 Binding Free bisulfite ion binds with: Acetaldehyde Pyruvate 2-Ketoglutarate Malvidin-3-glucoside Glucose => Bound SO 2 vs. Free SO 2

12 Forms of SO 2 "Total SO 2 " = Bound bisulfite ions + Free bisulfite ions + Molecular SO 2 (+ Sulfite ions)

13 Molecular SO 2 O O S => Antimicrobial activity

14 Mousecular SO2

15 Temperature and Molecular SO 2 => Wine Serving Temperature pk1 32 F (0 C) 60% F (10 C) 78% F (20 C) 100% F (25 C) 115% F (50 C) 195% 2.12

16 Microbial Stability and SO2 SO 2 sensitivity: Malolactic bacteria? YES! Saccharomyces? NO! Kloeckera? YES? Brettanomyces? YES?

17 ph and Molecular SO 2 % % Free SO Free SO 2 required SO 2 - HSO 3 molecular SO (mg/l) 2- SO ph

18 Microbial Stability, ph and SO 2 % Free (mg/l) SO SO SO2 2 molecular Free SO 2 required ph

19 ph and Molecular SO 2 % SO 2 molecular = present pH Free SO 2 = 0.85 ( ph ) required Decrease ph by 0.1 => use 20% less Free SO 2 Decrease ph by 0.3 => use 50% less Free SO 2

20 ph and Molecular SO 2 pk 1 in water = 1.77 pk 1 in wine = 1.83

21 SO 2 Chart

22 SO 2 and Fermentation Lag Phase Alcohol mg/l Days

23 SO 2, EtOH and MLF Oenococcus oeni suppression: free SO 2 to 0.8 molecular at 12% EtOH free SO 2 to 0.5 molecular at 14% EtOH

24 SO 2, Thiamin and Brett Rate Thiamin cleavage by HSO 3 - ph

25 Inhibition of Browning Enzymes Polyphenol oxidases Tyrosinase (from grape)? YES! Laccase (from Botrytis rot)? NO!

26 Binding of Acetaldehyde Acetaldehyde = "oxidized", "Sherry" "bruised apple" aroma CH 3 CHO + HSO 3 - CH 3 CHOHSO 3 - Acetaldehyde Bisulfite Hydroxyethane sulfonic acid

27 SO 2 and Oxygen SO 2 = a weak antioxidant Phenol + O 2 = Quinone + H 2 O 2 H 2 O 2 + Ethanol = Acetaldehyde H 2 O 2 + Phenol = Quinone H 2 O 2 + SO 2 = Sulfate SO 2-4 O 2 + SO 2-3 = Sulfate 1 / 2 : 30 days O 2 + Ascorbate = DehydroA 1 / 2 : 35 min Note: Sulfate (oxidized sulfite) doesn t show in Total SO 2!

28 SO 2 and Oxygen at Bottling vs.

29 SO 2 and Oxygen at Bottling Normal bottle headspace, ullage, is commercially between 4 and 7 ml. Example: 7 ml of 20% oxygen = 2 mg O 2 2 mg O mg SO 2 => Sulfate 4 mg SO 2 /750 ml bottle 6 mg/l Free SO 2 Loss

30 SO 2 and Oxygen at Bottling If bottling without N 2 sparging, wine receives ca. 1 saturation with air during filling: Example: 750 ml of 69 F = 1.4 mg O mg O mg SO 2 => Sulfate 2.9 mg SO 2 /750 ml bottle 4 mg/l Free SO 2 Loss

31 SO 2 and Oxygen at Bottling Combined Free SO 2 loss at bottling: mg/l 10 mg/l + additional losses => Add mg/l SO 2 EXTRA before bottling

32 SO 2 Application Burning Sulfur Wicks

33 SO 2 Application Weighing out Potassium Metabisulfite Watch cold stability! RadioShack USB Scale

34 SO 2 Application Dosing SO 2 Gas Caution!

35 Sorbic Acid Yeast growth inhibitor: Legal limit: Sensory threshold: 200 mg/l 300 mg/l 135 mg/l Some yeasts are resistant! NO effect against bacteria Added as potassium salt (Sorbate) => Watch cold stability!

36 Geranium Off-Odor Cause Sorbic acid + Malolactic bacteria Prevention Avoid sorbate as preservative Use sorbate only with proper SO 2 Add no earlier than day before bottling Always bubble test/sterile filter NO removal option from wine

37 Barrel Maintenance Physical Cleaning Chemical Cleaning Sanitation Storage

38 Barrel Maintenance Physical Cleaning Low/high water pressure sprayers Steam cleaners (to ca. 7 oz condensate) Dry ice (CO 2 ) blasting Shaving/re-toasting

39 Barrel Maintenance Cleaning/Sanitizing w/water/steam Note: No chlorine residues in water + soften Solubility of K-bitartrate is 10x higher in hot water than in cold Cell kill at 180 F = 10x more effective than at 170 F

40 Sanitizers Chlorine

41 Heat Conductivity of Wood Conductivity of wood is 1/1000 that of copper Conductivity of the wood along the grain is about 3x better than across the grain.

42 Relative Thermal Conductivity Cu 32 Alu 17 Iron 4 SS 1 Water 0.04 Wood 0.03 Air 0.002

43 Barrel Cleaning Systems Sellers FR1 Chemdet Turbodisc Tom Beard

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45 BBL Nooks & Crannies!

46 Barrel Maintenance Chemical Cleaning Rinse solutions (averages) Hot" ( F) water optional 3-5 min Soda ash Na 2 CO 3 optional 2 g/l Cold water Percarbonate optional 2 g/l Citric acid = BOD to neutralize 1.6 g/l

47 Barrel Preparation Sanitation Sanitizing agents? Steam/hot & cold water Soda ash Percarbonate Surfactants SO 2 DMDC UV light Accelerated electron beam Chlorine Ozone

48 Barrel Maintenance Chemical Sanitation Experimental/historic rinse solutions: Vinegar / Peracidic acid CuSO 4 High-proof alcohol Salt water

49 Sanitizers Soda Ash Na 2 CO 3 Strong alkaline (ph 11.3 at 1%) Dissolves proteins, fats, oils carbohydrates, tartrates Neutralizes acidic odors (V.A.) Neutral ph best for bacteria Sanitizing effect?

50 Sanitizers Percarbonates Per(oxy)carbonate NaO-O-COONa Release of oxygen radicals via H 2 O 2 Application at room temperature Effective over wide ph range (1-8) Alkaline Degradation to soda ash, water, O 2 Sanitation effect via H 2 O 2?

51 Sanitizers Percarbonates Common uses: Chlorine-free laundry and wood bleach

52 Dry: g S/bbl Every 3-4 weeks! Wet: 225 g Citric/bbl 45 g KMBS/bbl

53 Stop and smell the Barrel!

54 Brett?

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