Harnessing Biology Flashcards
What is yeast used for in making wine
Ferment sugars in grape juice
Why are vats used in making wine
Prevent air from reaching wine, ensuring conditions are anaerobic
How are the yeast cells killed in making wine
Alcohol conc. increases until it killls yeast cells, fermentation stops
What is beer made of
Barley
What are small scale fermenters fitted with?
What does this allow?
(Wine)
Airlock
- allows CO2 to escape
- prevents entry of oxygen
What does the fungus penicillium produce?
The antibiotic penicillin
What is the function of the cooling jacket in an industrial fermenter
Removes heat energy
-> stopping the fermenter overheating and enzymes denaturing
What is the function of air filter in an industrial fermenter
Filters air coming in
-> maintaining sterile conditions
What is the function of stirrers in an industrial fermenter
Keep broth well stirred
-> oxygenate all parts of the fermenter
-> prevent micro organisms settling
Function of the growth medium in an industrial fermenter
Contains all necessary glucose and amino acids
-> micro organism growth
Function of super heated steam in industrial fermenter
Applied before fermenter is used
-> kills unwanted micro organisms
> leaves only water + no other residue
What bacteria is yogurt made with
Lactobacillus bulgaricus
What happens to milk to kill bacteria (yoghurt)
Pasteurised (heated)
What is added to the milk after it cools?
What temp is it maintained at, at this stage?
(Yoghurt)
Lactobacillus
46 degrees C
What does maintaining the mixture at 46 degrees C ensure?
(Yoghurt)
The bacteria’s enzyme aren’t denatured
Process of making yoghurt?
- equipment is sterilised
- milk is pasteurised (heating)
- lactobacillus is to cooled milk + left at 46 degrees C for 4 hours
- lactobacillus anaerobically respires -> lactic acid
- further cooled to 5 degrees C
What does lactobacillus produce when anaerobically respiring?
Lactic acid
lactobacillus respires anaerobically to produce lactic acid. What does this do
- Lowers the pH, acting as a preservative
- acid coagulates the milk protein
-> as the acidic conditions change the shape of the proteins - giving yoghurt flavour and texture)
What is anaerobic respiration in yeast used for making?
Beer brewing
Bread making
Anaerobic equation in yeast?
Glucose -> ethanol + carbon dioxide
C6 H12 O6 -> 2C2 H5 OH + 2CO2
What is ethanol and where is it found
Alcohol found in alcoholic drinks (beer and wine)
How does bread rise
Bubbles of carbon dioxide gas expand the dough
Does ethanol remain after the bread has been cooked
No
It has evaporated due to the high temps
2 ways to detect the presence of carbon dioxide
Limewater - turns cloudy white
Hydrogen carbonate - orange -> yellow
