Lecture 14 Brewing Microbiology Flashcards
Which are the main species of yeast and bacteria used in the brewing process?
The main yeast species in brewing include Saccharomyces cerevisiae, while bacteria like Lactobacillus and Pediococcus may be used. Each has specific metabolic pathways, substrates, and products.
What are the key metabolic processes involved in ale production?
involves several metabolic processes;
malting, mashing, lautering, boiling, fermenting, conditioning, and packaging.
Each step contributes to the flavor, aroma, and quality of the final product
What are the characteristics of domesticated yeast used in brewing?
Domesticated yeast possesses traits like high fermentation efficiency, tolerance to alcohol, desirable flavor profile, and adaptability to brewing conditions. These characteristics are developed through selective breeding.
-less off-flavours
-less sexual production
How does Saccharomyces cerevisiae contribute to beer brewing?
Its ability to ferment various sugars and withstand the brewing environment.
What methods are employed for controlling microbial growth in industrial beer production?
-the use of antimicrobial agents like hops and low pH<4.5
-closed system
-sanitization (chemical and heat)
-screenings (agar plating, hemocytometer, sensory)
- ATP bioluminescence = instant detection of microbial activity.
What properties make beer resistant to spoilage?
factors like low pH, the antimicrobial properties of hops, and aseptic brewing conditions. These properties inhibit the growth of unwanted microorganisms.
What is the role of malting in beer production, and what enzymes are developed?
Malting involves germination and kilning of grains, leading to the development of malt enzymes, including 𝛼-amylase and 𝛽-amylase, which break down starches into fermentable sugars.
How does yeast contribute to beer making?
Yeast, specifically Saccharomyces cerevisiae for warm fermenting (ale) and Saccharomyces pastorianus for cold fermenting (lager), produces alcohol and contributes to flavor, carbonation, and overall beer characteristics.
Each yeast strain has different flavours.
Beer Brewing Process
- Malting
- Mashing/Lautering
- Kettle
- Wort cooling and oxygenation
- Pitching yeast
- Fermentation
- Conditioning
- Packaging
What is Malting
Malting:
What: Germinating and kilning grains.
Why: Develops enzymes (𝛼-amylase, 𝛽-amylase) for starch breakdown.
What is Mashing/Lautering:
What: Steeping grains in hot water.
Why: Activates enzymes, converts starches to sugars.
What is Kettle/Boiling?
What: Wort (sugar-rich liquid) is boiled with hops.
Why: Sterilizes, extracts flavors from hops, and removes undesired compounds.
Wort Cooling and Oxygenation
What: Cooled wort is oxygenated.
Why: Prepares wort for yeast fermentation.
Pitching Yeast:
What: Adding yeast to wort.
Why: Initiates fermentation - yeast consumes sugars, produces alcohol and CO2.
Fermentation
What: Yeast converts sugars to alcohol and CO2.
Why: Creates beer and contributes to flavor and carbonation.
