ADDRESSING WINE QUALITY. Horticulture & Crop Science The Ohio State University/OARDC

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1 ADDRESSING WINE QUALITY THROUGH THE RECOGNITION OF WINE FLAWS Todd Steiner Horticulture & Crop Science The Ohio State University/OARDC Wooster, OH 44691

2 Wine # 2?

3 Oxidized Visual appearance: The appearance of brown tones in a white table wine, brownish-red hues in a red table wine and an orange blush / rose Aroma: Sherry-like or acetaldehyde odor

4 Oxidized Cause: Many compounds found in grapes and wine are readily oxidized These include both enzymatic and non- enzymatic reactions Juice enzymatic oxidation is caused by tyrosinase and laccase oxidizing phenols in the production of brown pigments

5 Oxidized Cause: Non-enzymatic oxidation in wine is caused by certain phenols such as catechin and epicatechin in a two-step process forming hydrogen peroxide and oxidizing ethanol to acetaldehyde

6 Oxidized Factors influencing oxidation Grapes containing rot particularly Botrytis cinerea produce higher amounts of browning enzymes Turbid juice with high solids Oxygen absorption in wine Low amounts of free sulfur dioxide id in must and wine

7 Oxidized Prevention: Harvest quality grapes with low rot Clarify the juice reducing solids for enzymatic activity and oxidation Fill tanks from bottom when racking over from tank to tank Check pump seals and hoses for leaks or loose fittings in uptake of oxygen

8 Oxidized Prevention: Avoid excessive headspace in tanks and barrels Limit uptake of oxygen at bottling line by adding an inert gas to the filling bowl Flush bottles with nitrogen to replace oxygen

9 Oxidized Prevention: The proper use of sulfur dioxide Critical times of addition are to the must, after alcoholic fermentation and bottling It is extremely important to monitor and maintain proper sulfur dioxide levels based on wine ph

10 Oxidized Remedy: Excessive oxidation is nearly pointless to remedy Fining agents such as potassium caseinate, PVPP and yeast fining can be possible solutions Lower levels of oxidation can utilize blending as tool

11 Wine # 3?

12 Volatile Acidity Aroma: A wine measuring high in volatile acidity will give off a sharp, pungent vinegar aroma Cause: Acetobacter and Gluconobacter All belong to the family Acetobacteriaceae

13 Volatile Acidity Cause: Aerobic bacteria metabolism oxidizing ethanol and glucose producing acetic acid Small amounts of ethyl acetate will contribute to a vinegary taint

14 Volatile Acidity Two ways of introduction into must and wine Grapes - damaged or rotten fruit Dirty cellar equipment such as pumps, hoses, tanks and contaminated wooden barrels

15 Volatile Acidity Factors favoring acetic acid production Optimal temperatures vary from 10 C (50 F) to 35 C (95 F) Appearance of acetic acid bacteria may form a film, haze or pellicle located mainly on the surface

16 Volatile Acidity Factors favoring acetic acid production High ph in must or wine Aeration of wine during transfer Headspace levels in tanks and barrels Warm storage temperatures t Low sulfur dioxide

17 Volatile Acidity Prevention of acetic acid spoilage Starts in the vineyard with clean fruit avoid rot, high ph or high soluble solids Grapes containing significant amounts of rot should be treated with ppm SO 2

18 Volatile Acidity Prevention of acetic acid spoilage Ferment with a commercial recommended strain for the variety yyou are vinifying Avoid natural fermentations Punch the cap down twice daily for red wine fermentations

19 Volatile Acidity Prevention of acetic acid spoilage Once fermentations are complete the proper p amount of SO 2 should be added to the wine Monitor and maintain SO 2 levels based on ph to.8 ppm molecular to bottling Keep tanks and barrels topped off Develop a sound sanitation practice

20 Volatile Acidity Remedy: reduction is difficult however, there are several possible solutions Reverse osmosis coupled with ion exchange Oxidative yeast fining utilizing acetic acid as a carbon source Blending may be an option for wines lower in volatile acidity

21 Wine # 4?

22 Higher Alcohols Aroma: Wines will express aromas of butanol, methanol and propanol (fusel oil) Cause: Higher alcohols are formed mainly during alcoholic fermentation Yeast produce small amounts of primary aliphatic alcohols having higher molecular weights then ethyl alcohol

23 Higher Alcohols Factors responsible for higher alcohol production High concentrations of amino acids such as leucine, isoleucine and valine Increased amounts and size of Juice solids Grape variety influences fusel alcohol production likely attributed to the nitrogen and amino acid composition in the fruit

24 Higher Alcohols Factors responsible for higher alcohol production Vigorous yeast strains such as Montrachet produce higher amounts then champagne strains Increased fermentation temperatures

25 Prevention: Higher Alcohols Avoid excess addition of nutrients to the must ( base on analysis of FAN) Clarify juice lowering the amount of solids Select a low vigorous commercial yeast strain Control fermentation ti temperatures t

26 Higher Alcohols Remedy: Low amounts can add to a wines complexity while higher amounts are tough to remedy Blending can be used as an option if fusel oil concentration is not to high

27 Wine # 5?

28 Cork Taint Aroma: cork taint gives off aromas described as a damp wet basement, musty, moldy or even mushroom Cause: The primary compound associated with cork taint is TCA (2,4,6,-trichloroanisole)

29 Cork Taint Cause: The microflora of unprocessed cork consist primarily of molds including penicillium of several species In cases of wines exhibiting cork taint, Penicillium is frequently identified Microbial methylation of chlorophenols

30 Cork Taint Always associated with 3 circumstances Phenolic material: wood Chlorination: Chlorine based compounds Methylation: Mold Source:

31 Cork Taint Cause: Contamination of the cork is usually related to the cork batch Contaminant molecules infiltrate the cell structure and become trapped in the cell walls In the U.S. the incidence of cork taint is reported to range from 1 8%

32 Cork Taint Prevention: It is vital to develop an inspection plan to carry out quality control procedures of purchased cork The use of the Military-Standard ( Mil- spec ) system for cork quality control

33 Cork Taint Inspection involves: Physical characteristics, aroma analysis and visual analysis

34 Cork Taint Sensory Analysis Involves Sample size Et Extraction ti media Contact time Number of analysis Distinction of normal wood and cork taint Sensory variations due to different washing mediums

35 Cork Taint Cork taint rejection criteria: 1) Acceptable-good, sweet, oaky cork wood, 2) Acceptable-samples with slight earthy or mushroom aromas not considered a defect 3) Unacceptable-samples with obvious TCA or other cork taint compounds

36 Wine # 7?

37 Brettanomyces/Dekkera Aroma: Aromas associated with Brettanomyces/Dekkera are described as barnyard, horse blanket, smoky, burnt plastic and band aid Can also produce high amounts of acetic acid

38 Brettanomyces/Dekkera Cause: Brettanomyces/Dekkera are yeast that enzymaticaly y convert vinyl phenols derived from cinnamic acids to produce the compounds associated with these aromas being 4-ethylphenol and 4-ethylguaiacol

39 Brettanomyces/Dekkera Sensory thresholds 4-ethylphenol typically found in concentrations being eight times higher then 4-ethylguaiacol 4-ethylphenol threshold 300 to 600 ng/ml 4-ethylguaiacol threshold 50 ng/ml

40 Brettanomyces/Dekkera Clausen (1904) reported Brettanomyces being responsible for secondary fermentation in English stock beers Therefore people who prefer this style may accept some Brett aromas and flavors in wine

41 Brettanomyces/Dekkera Can be viewed as a Dr. Jekyl and Mr. Hyde scenario According to Fugelsang(1997) lower concentrations of these compounds may add positive character or complexity Bordeaux wines may have this associated with them

42 Brettanomyces/Dekkera Cause: Typically growth occurs after alcoholic fermentation during storing of wine in tank, barrel or bottle A majority of populations seen as oxidative growth in barrel aging of reds Occur in imperfections of the wood and between the staves

43 Brettanomyces/Dekkera Brettanomyces is in the environment Studies have shown it to be in the vineyards, water, soil, grape must, fermentation tanks and in barrels

44 Brettanomyces/Dekkera Prevention: Brettanomyces becomes established when winery sanitation becomes lacksed Henick-Kling (2001) reports Brettanomyces sensitive to SO 2, ozone, dimethyl dicarbamate and filtered at < 1 micron Grapes with rot present add at ppm SO 2

45 Brettanomyces/Dekkera Prevention: Early detection for 4-ethylphenol and 4- ethylguiacal yg can help further contamination Maintain SO 2 levels at.8ppm molecular accordingtophinwine Keep barrels topped properly

46 Brettanomyces/Dekkera Prevention: Recommended no cross blending with infected barrels into new or unknown barrels Sanitize all pumps, hoses and lines that have been in contact with Bretty wine Keep traffic down in winery from outside environments or sanitize footwear

47 Brettanomyces/Dekkera Remedy: Once aroma and flavor characteristics have established, working with blends may be the only way to lessen the aroma However wines should not be transferred into new or uncontaminated barrels or tanks

48 Wine # 8?

49 Geranium Taint Aroma: Resembles geranium plants Cause: Caused by the presence of certain strains of lactic acid bacteria and their metabolism of sorbic acid present in wine Formation of 2-Ethoxyhexa-3,5-Diene

50 Geranium Taint Factors contributing to Geranium taint Wines with some residual sugar may have sorbic acid added to prevent refermentation by yeast

51 Geranium Taint Prevention: Keep free sulfur dioxide levels at sufficient concentrations to prevent lactic acid bacteria growth (grapes and wine) Addition of sorbic acid should be accomplished just prior to bottling

52 Geranium Taint Remedy: Wines infected with geranium taint are nearly ypointless to remedy The blending ratio of sound to defective wine is high at 11:1 making it not very cost effective Therefore prevention is the obvious cure

53 Wine # 9?

54 Hydrogen Sulfide Aroma: Higher levels resemble rotten eggs while lower levels impart a yeasty y aroma Cause: Yeast metabolic activity of organic, inorganic and elemental sulfur can lead to the production of hydrogen sulfide

55 Hydrogen Sulfide Factors responsible for H 2 S production Elemental sulfur as a grape fungicide or sulfur candles used in barrel sanitation Musts that are deficient in assimilable nitrogen Individual yeast strains

56 Hydrogen Sulfide Factors responsible for H 2 S production High concentrations of insoluble solids Increased must ph Higher fermentation temperatures

57 Hydrogen Sulfide Prevention: Avoid harvesting grapes prior to 6 weeks of the last sulfur application Use drip less sulfur sticks, sulfur dioxide gas or potassium metabisulfite for sterilization of tanks and barrels Addition of a yeast nutrient such as (DAP)

58 Hydrogen Sulfide Prevention: Add appropriate amount of SO 2 at crush Select a commercial strain shown to produce low amounts of hydrogen sulfide Clarify juice lowering the amount of solids Control fermentation temperatures Aerate fermenting must / juice Rack of lees when detected

59 Hydrogen Sulfide Remedy: If detected shortly after alcoholic fermentation try racking or sparging g with carbon dioxide or nitrogen Try racking combined with the addition of sulfur dioxide (25 ppm) settle for one week and filtrate

60 Hydrogen Sulfide Remedy: The addition of copper sulfate as a fining agent Bench trials should be performed BATF limits of.5 ppm residual copper in wine

61 Further Reduction of H 2 S Further reduction of H2S can form: Mercaptan: (Ethyl and Methyl) Can be remedied with copper sulfate and or ascorbic acid followed by copper sulfate Disulfide: Copper sulfate fining not possible Bench trials should be performed!

62 Wine # 10?

63 Film Yeast Aroma: May perceive sensory aromas of acetaldehyde, acetic acid or ethyl acetate Can also be attributed to loss of varietal character

64 Film Yeast Cause: Candida mycoderma Candida - is the primary genus of yeast that causes film yeast in our wines mycoderma general term for a mixed population of several different yeasts, molds, and bacteria contributing to film yeast

65 Film Yeast Cause: Otherwise known as Wine Flowers, describes this aerobic yeast in forming a chalky white film or pellicle on the surface They are strongly oxidative and lead to a decrease in ethanol content along with an increase in acetaldehyde concentration

66 Film Yeast Prevention: Since Candida is highly aerobic it is critical to keep oxygen from attacking your wine Keep head space to a minimum in tanks and barrels, purge transfer lines, pumps, and receiving tanks with an inert gas such as nitrogen

67 Film Yeast Prevention: Film yeast are susceptible to sulfur dioxide Maintaining free SO 2 levels under most conditions from 25 to 40 ppm will protect wines during storage

68 Film Yeast Prevention: Cellar temperatures during wine storage below 54 F will help pprevent the formation of film yeast

69 Film Yeast Remedy: Caught in early stages wine can be racked leaving film pellicle behind, filtered and sulfited Monitor and maintain free SO 2 levels to.8ppm molecular based on ph and store at lower temperatures

70 Film Yeast Remedy: Wines with a strong film yeast odor and acetaldehyde flavor may be hard to remedy

71 THANK YOU! Todd Steiner Enology Program Manager and Outreach Specialist OARDC Dept. Of Horticulture & Crop Science Phone: (330)