Bugs 'n Stuff Flashcards
What 3 compounds might you add to a sluggish ferment to get it going again?
Diammonium Phosphate / DAP
Thiamine / Vitamin B
Ammonium Sulphate
What is Gelatin used for in the fining process?
Reduces astringency and off-tastes.
Can reduce harsh tannins in red wines
What is the Oxidative Enzyme found in healthy grapes?
Tyrosinase
What is Calcium Carbonate used for?
Reducing levels of Tartaric acid
What are Kloeckera, Hanseniaspora, Candida and Metschinikowia?
Native yeasts found in grape musts from yeasts on the grape’s bloom
What are Halo-anisoles responsible for?
Compounds that can cause negative musty smells in wine incl. Cork Taint
What is Geraniol?
How can be prevented?
Compound resulting from Lactic Acid metabolising Sorbic Acid giving aromas of Geraniums.
Add SO2 in combination with Sorbic Acid
What use is Carbon in the fining process?
What is a disadvantage of using?
Removes off-odours and colour
Fairly non selective
What are the volatile compounds that give floral aromas to aromatic grape varieties?
Terpenes
What is the ester caused by struggling yeasts usually caused by very cold ferments?
What is the aroma effect?
Ethyl acetate
Smells of pear drop / banana
What does a vine convert Sucrose into?
Glucose and Fructose
What are the aromatic compounds that give herbaceous / vegetal aromas to some grape varieties such as Cab Sav and Sauv Blanc?
Pyrazines
What is the VA responsible for wines smelling of vinegar, nail polish remover?
Acetic acid
What are Leuconostoc Oenos, Lactobacillus and Pediococcus and what is their purpose?
Bacteria that cause Malolactic fermentation
What is Potassium Bitartrate?
Tartrate crystals; easier to remove than Calcium Tartrate
What is Oidium Tuckeri / Unicular Necator?
The fungi responsible for Powdery mildew
What is sometimes used in addition to Sulphur Dioxide?
Why can’t it be used on its own?
Ascorbic acid / Vitamin C
Is an antioxidant but has no antiseptic properties
What are Benzoic and Cinnamic acids?
Non flavonoid phenolic compounds
What are Mannoproteins?
What are they thought to do?
By-product of yeast autolysis
Thought to prevent tartrate crystallisation and soften tannins
What are the oxidising enzymes found in i) grey Rot affected fruit and ii) Healthy fruit?
i) Laccase
ii) Tyrosinase
Which bacteria causes Pierce’s disease?
Xylella Fastidiosa
What is Xylella Fastidiosa?
Vineyard bacteria that causes Pierce’s Disease
What is Casein and where it used?
Principle milk protein
Used in fining, mainly white wines, to remove excess colours or oxidative taints.
Usually used with Tannin
What is the compound that is a by-product of oxidation that smells of browning cut apples?
Acetaldehyde
What is Potassium Bicarbonate used for?
Used before fermentation to reduce Tartaric Acid
The yeast genus primarily responsible for alcoholic fermentation?
Saccharomyces Cervisiae
What is the ‘green apple’ acid is found naturally in grapes and sometimes used for acidification?
Malic acid
What is Resveratrol?
Good or bad?
A non flavonoid phenolic compound
Considered to contribute to health benefits of moderate consumption of red wine
What is the by-product of alcoholic fermentation that gives wine mouthfeel, texture and smoothness?
Glycerol / Glycerine
Which is the sugar produced by the grapevine by inverting Sucrose that is preferred by yeasts?
Glucose
What is the preferred fining agent to remove astringent ‘green’ tannins particularly in fine wines?
Egg albumen
What does the fungus Botrytis Cinerea cause?
Noble Rot or Grey Rot if not managed
Which is the sugar produced by the grapevine by inverting Sucrose that is LESS preferred by yeasts?
Fructose
Which acid is found naturally in grapes and commonly used for acidification?
Tartaric acid
What is the acid created by MLF?
Lactic acid
Once Indigenous yeasts die out what takes over fermentation?
Saccharomyces Cervisiae
What spreads Xylella Fastidiosa?
The vector Glassy-winged sharpshooters
At what abv to indigenous yeasts mostly die out?
~4% abv
What is the lactone that smells of cumin, maple, walnut and often found in oxidative and mature wines?
Sotolon
What are the flavonoid phenolic compounds responsible for giving colour to wine?
Anthocyanins
What is the compound responsible for the smell of rotten eggs / drains and what process usually causes it?
Hydrogen Sulphide
Reductive winemaking
Which is the sugar produced by photosynthesis?
Sucrose
What are the flavonoid phenolic compounds that are the building block for tannins?
Catechins
What fungus causes Powdery Mildew?
Oidium (tuckeri) / (Unicula necator)
What is Bentonite, why is it used in the fining process and what are two potential drawbacks of using?
Montmorillonite Clay
Used for removing proteins
Non selective and throws large qty of lees
Which 4 fining agents MUST be avoided for a wine to be labelled Vegan?
Isinglass, Casein, Albumen and Gelatin
What are the acronyms for the 3 Halo-anisoles responsible for Cork Taint?
TCA, TBA, TeCA
Why might Tannin be added to wine?
Prevents and treats over fining
Also aids precipitation of excess proteins
What is Plasmopara Viticola?
The fungus responsible for Downy Mildew
What is Calcium Tartrate?
Tartrate crystals, harder to remove than Potassium Bitartrate
What is the Oxidative Enzyme found in Grey Rot affected fruit?
Laccase
What is the terpene responsible for giving Syrah its aroma like Black pepper?
Rotundone
What are the encompassing terms for the pungent sulphur compounds caused by reduction that give aromas of onion, cabbage?
Thiols, mercaptans
What is the ‘fault’ that causes a wine to smell of sweaty horse or sticking plaster?
Brettanomyces
What is PVPP used for?
Synthetic polymer, reduces bitterness and browning in wines esp. white wines.
Can be used to soften excessively tannic red wines
What is Acidex?
A double salt
A mix of Calcium Carbonate and Calcium tertrate-malate used to reduce levels of both Tartaric and Malic acid
What is Phomopsis Viticola?
The fungus that causes Phomopsis, sometimes called Excoriose
Why is Isinglass used in the fining process?
Removes phenolics and can improve clarity of white wines.
What are 4-ethyl-phenol (4-EP) and 4-ethylguaiacol (4-EG)?
Volatile phenols caused by spoilage yeast Brettanomyces
Why might Silica Sol be used in fining?
Used in association with Isinglass or Gelatin to remove proteins, Silica Sol aids flocculation
What is the umbrella term for flavonoid and non flavonoid compounds?
Polyphenols also Phenolic compounds, Polyphenolics
What is TDN (1, 1, 6-trimethyl-1, 2, dihydronathalene) responsible for?
Giving petrol, kerosene like aromas in wines such as old Riesling
What is the alcohol created by the anaerobic metabolism of yeast?
Ethyl alcohol / Ethanol
What is the compound, normally resulting from MLF that gives buttery aromas?
Diacetyl
What is Eutypa Lata?
The fungal disease called Eutypa Dieback
