Temperature Flashcards
(18 cards)
What is the most important factor that affects the outcome of mashing?
Temperature
Temperature affects access to starch and the effectiveness of enzymes.
What is gelatinisation in the context of starch?
It opens starch granules, allowing water and enzymes to enter for hydrolysis.
Do barley starch granules need to be gelatinised for hydrolysis by barley enzymes?
No, barley starch granules don’t need to be gelatinised for hydrolysis to be catalysed.
Why is gelatinisation necessary in mashing?
Mashing is measured in minutes, while seedling growth is measured in weeks.
What happens if mashing is performed at 20℃?
The mash would likely start fermenting/souring before achieving target extract efficiency.
What factors affect the gelatinisation of starch granules?
Cereal type, variety, and harvest.
What is meant by enzyme effectiveness?
The rate of the reactions that enzymes catalyse.
How does temperature affect enzyme reactions?
Reactions proceed faster with increased temperature up to a certain point.
What is activation energy?
The energy required for a reaction to occur.
What is the optimum temperature for enzyme activity?
The temperature at which the rate of reaction catalysed by that enzyme is fastest.
List the enzymes and their optimum temperatures for mashing.
- Pentosanases: 35-65℃
- Endo β-(1,4) glucanase: 37-45℃
- Endo β-(1,3) glucanase: 50-60℃
- Barley β-glucanase: 40℃
- β-Glucan solubilase: 60℃
- Endoproteases: 45-50℃
- Carboxypeptidases: 45-50℃
- Aminopeptidases: 50℃
- α-Glucosidase: 40-45℃
- Limit dextrinase: 60-62.5℃
- β-Amylase: 63-65℃
- α-Amylase: 70-75℃
What is a notable challenge with enzyme temperature optima in mashing?
They may not reflect actual conditions in the mashing vessel.
What factors can inhibit enzyme function during mashing?
Products of the reactions they catalyse.
What happens to enzyme activity during mashing as pH changes?
pH tends to drop, affecting enzyme function.
What is cytolysis?
The hydrolysis of cell wall components β-glucans and pentosans.
What are the common temperature stands used in mashing?
- 45℃ β-glucanase stand
- 52℃ protease stand
- 63℃ β-amylase stand
- 72℃ α-amylase stand
- 76℃ enzyme inactivation stand
True or False: Only the named enzyme works at its respective temperature stand.
False
All enzymes not at their inactivation temperature work to some extent at all temperatures.
What is the extract efficiency achieved in standard mashes compared to 20℃ mashing?
97% in standard mashes vs. 18.5% at 20℃.
