Wine and Beer Questions

Enology (wine fermentation) — Commercial alcoholic fermentation of grape must is carried out using selected strains of which microorganism?

Vinegar (acetic acid) production — In the traditional slow, surface process, a heavy, thick, slimy film of acetic acid bacteria forms. This growth primarily reduces which rate in the system?

Brewing microbiology — “Sarcina sickness” (ropey, turbid, sour beer defect) is caused by which organism historically known as a sarcina-former?

Wine spoilage ecology — Which groups of microorganisms can cause spoilage faults in wines under unfavorable conditions?

Dairy and vegetable fermentations — Gassiness caused by carbon dioxide liberated by heterofermentative lactic acid bacteria is commonly termed:

Brewing yeasts — Which organism is the classic bottom-fermenting, cold-tolerant lager beer yeast used for “low” fermentation?

Fermentation defects — When fructose is converted to mannitol by contaminating microbes, the defect is commonly termed:

Winemaking terminology — The crushed, pulped grapes (juice, skins, seeds, and sometimes stems) used at the start of wine production are called:

Beer quality faults — What defect can contamination by “S. patorianns” (intended: wild <em>Saccharomyces</em> pastorianus or related yeast) cause in finished beer?

Brewing microbiology – off-flavour identification: In beer quality control, which contaminant is classically responsible for producing a distinct “parsnip-like” odor and taste in finished beer?

Fermented beverages – origin and strength: Which beverage is of Japanese origin and typically contains about 14–17% alcohol by volume in its traditional form?

Beer spoilage – Sarcina sickness: The “Sarcina sickness” of beer caused by <em>Pediococcus cerevisiae</em> is characteristically associated with which changes?

Beer spoilers – diastatic activity: Which organism is a well-recognized potential spoilage yeast in beer due to its ability to ferment dextrins (over-attenuation)?

Vinegar production – slimy spoilage: Which species of vinegar bacteria is most commonly cited in classical texts for causing sliminess (“mother of vinegar”) in vinegar?

Brewhouse mash holding – unintended fermentations: If the mash in the brewhouse is held too long at permissive temperatures, which contaminant fermentations may occur and damage wort quality?

Beer styles – ale vs. lager: Which of the following is NOT an ale type of beer?

Wine microbiology – alcohol as a hurdle: At approximately what ethanol concentration are acetic acid bacteria that spoil musts and wines effectively inhibited in practice?

Wine spoilage nomenclature – “tourne”: In traditional enology, the spoilage most commonly occurring in wine called “tourne” refers to which process?