Malting Process Flashcards
What is Steeping?
The seed is soaked in water to encourage it to grow
What’s the ideal moisture content for germination?
43-46%
At what percentage does germination begin to start?
30 -35% - Germination activates the biochemical processes that synthesise key enzymes
What plant growth hormone initiates the production of crucial enzymes?
Gibberellic acid (triggered by low simple sugar concentration within the embryo)
What happens when the GA travels into the Aleurone layer?
Triggers the synthesis of enzymes that will break down the starchy endosperm
Why should water sensitive grain have a short initial steep, followed by a longer air rest?
To help the grain achieve a better and more even water uptake during the second water stand
What is the typical range of temperature at which the barley grows during steeping?
Water and air temperatures is between 9-16˚C
Air-on temperatures should not exceed 21-23˚C, to avoid damaging the grain.
β-Glucanases and xylanases (pentosanases) do what?
Break down the cell walls
What does proteases do?
Will break down the protein matrix, as well as the middle lamella.
This exposes the starch molecules, making them accessible for the α- and β-amylases to work on them
What type of steeping vessels are there?
Conical
Flat Bottom
What type of germination vessels are there?
Saladin Boxes
Circular
What is the optimum moisture content after kilning?
3-6%
Standard ale malt = 2-3% moisture
Standard pale malt = 4-6% moisture
What is green malt?
Malt at the end of germination
Why is green malt kilned for?(5)
Kill embryo but preserve enzymes Reduce moisture content Produce unique flavours and colours Drive off DMS Create a product than can be easily milled
Low temperatures during the initial stages of kilning will preserve more what?
Enzymes
What is the Maillard reaction?
The products of germination, the sugars from starch breakdown and the amino acids react, converting them into melanoidins, all react together to eventually give colour and flavour to the malt
What are the 3 stages of drying process?
Free drying - Moisture in the husk is removed by warm, dry air at lower temperatures around 50-60˚C (air off)
Forced drying - Moisture falls below 12-13%, temperature rise to 65-75˚C (air on) to force the moisture from the centre of the grain and remove it
Curing -air-on temperature is at its highest. It is > 70˚C, however most of the time it is > 85˚C. Colour and flavour are easily formed
What is germinative Energy?
The percentage of kernels that germinate and gives a measure of dormancy.
100 grains are placed on a filter paper in a petri dish in 4mls of water for 72hrs at 18˚C to see a percentage of germination.
What is water sensitivity?
The potential of the grain to grow in water - this reflects conditions during steeping
Same as GE but placed in 8ml of water for 72hrs but checking every 24 for corn counts
What moisture content can barley be stored at? (before its steeped)
12%
What is the typical temperature for steeping and how long is it steeped for?
14 - 16˚C
48hrs
What is the typical temperature and duration for germination?
14-20˚C
4-6 days
What is Nitrosamine (NDMA)
Carcinogenetic compound usually formed from direct fire in a kiln (the protein hordein react with nitroxide)
What is deculming?
Removing the rootlets from the malt after kilning
How many air rests are there when steeping and why?
3, so the grain can replenish the oxygen back into the embryo and suck up water more effectively
What are some enzymes that can effect brewing?
Lipids
Phenols
Tannins
