5 Flashcards
What is special about lambic beers?
Can’t be mimicked as uses traditional spontaneous mixed fermentation so have complex microbiota
What is unique about the mashing process for Lambic beers?
Malt is mixed with >30% unmalted wheat, supports growth of Brettanomyces.
What is the purpose of using old whole hop bells in Lambic beer production?
Provide less bitterness, generate humulinic acids which are highly inhibitory towards bacteria.
What is a coolship in brewing?
An open metal vessel where wort cools overnight and is inoculated with environmental microorganisms.
Why are wooden barrels used in Lambic beer production?
Hard to sanitize, harbor resident microbiota like Brettanomyces which are essential for flavor.
Describe the microbial succession in Lambic beer production.
Enterobacterial and wild yeast phase, alcohol fermentation phase, acidification phase, maturation phase.
What are the characteristics of enterobacteria in the initial phase of Lambic beer fermentation?
Gram-negative, facultatively anaerobic, carry out mixed-acid fermentation.
Why is enterobacteria considered undesirable in modern Lambic production?
Linked to off-flavours and potential health risks, modern breweries acidify wort to inhibit their growth.
What characterizes the second phase of yeast involvement in Lambic fermentation?
Dominated by Saccharomyces species, quick conversion of carbohydrates to ethanol.
What do lactic acid bacteria (LAB) and acetic acid bacteria (AAB) contribute to in Lambic beer?
Responsible for acidification, LAB fermentatively produces lactic acid, AAB oxidatively produces acetic acid.
What role does Brettanomyces play in the maturation phase of Lambic beer?
Further attenuation, production of unique phenolic and ester profiles, forms biofilm pellicle.
What impacts does Brettanomyces have on the aroma of Lambic beers?
Produces volatile phenolic compounds and esters, contributes to the distinctive Brett flavour.
What is the pressing process for white wine?
Pressed immediately to remove skins
for less tannic wine
What is the pressing process for rose wine?
Juice run off after a few hours.
What is the pressing process for red wine?
Fermented with skins before pressing.
What describes free run wine?
Wine that runs off the vat without pressing.
What bacteria are involved in wine production?
Acetic acid bacteria, Lactic acid bacteria.
What mold is associated with wine production and can contribute to its flavor?
Botrytis.
How is wine typically fermented?
Inoculated with dried yeast, Saccharomyces; non-Saccharomyces yeast also present on grape skins.
At what temperatures are white and red musts fermented?
White must at 10-15°C, red must at 25-30°C.
What are the by-products of wine fermentation besides ethanol?
Glycerol, acetic acid, higher alcohols, esters.
What is glycerol’s role in wine?
A viscous product but usually not enough to modify wine mouthfeel.
What are the criteria for yeast selection in winemaking?
Fermentation vigour, finishes fermentation to dryness, reproducible characteristics, ethanol and temperature tolerance, no off-flavors, sulfur dioxide tolerance.
What is malolactic fermentation?
Malic acid is broken down into lactic acid and carbon dioxide by enzymes from LAB.
