Malt Handling Flashcards
Name some components of malt handling
The components of a malt handling and storage system are:
An intake pit or hopper
Magnets
Bucket elevators
Conveying systems (pneumatic, drag chain, pipe chain and disc, belt, screw)
A dust aspiration system
Silos
A destoner
Malt screening
Malt weigher(s)
Manual dust cleaning and collection systems
What factors must be controlled during malt storage?
Moisture, Temperature, Mould, Pests
These factors are critical for maintaining the quality of malt.
What is the best temperature for grain in storage?
Below 15°C
This temperature prevents insect and mite activity and limits fungal growth.
What two factors work together to cause grain spoilage?
Moisture and Heat
These factors also reduce enzyme levels in the malt.
What types of damage can insects cause to grain?
Burrowing into them, chewing at kernels, excreting unpleasant smelling materials
Insect damage can lead to spoilage and contamination.
Which mould species is particularly harmful to grain?
Aspergillus species
This mould can produce dangerous mycotoxins and unpleasant flavours.
What can the activity of insects and fungus in grain lead to?
Raised temperature in the grain, accelerating spoilage
This heating can also affect enzymes in the grain.
What is a roller mill?
A roller mill is a type of mill where grain is passed between two or more pairs of rollers, using compression and shear to comminute the grain.
What role does the feed or distribution roller play in a roller mill?
It helps distribute and orientate the grain correctly for milling.
How should grains ideally enter the rollers in a roller mill?
Tip first, to allow them to be split longitudinally.
What does a low roller diameter imply for the nip zone and throughput?
A smaller nip zone and a lower rate of throughput.
What factors determine the throughput of a pair of rollers?
Speed of rotation, size of the mill gap, and length of the rollers.
What is the purpose of fluting on roller mills?
To increase the coefficient of friction and shear on the grain.
How does the particle size profile requirement for a mash filter compare to that of a mash tun and lauter tun?
The particle size profile requirement for a mash filter is simpler and much finer.
This results in a less complex design for hammer mills.
What is the role of the comminution chamber in a hammer mill?
It is an enclosure where grain is fractured by beaters and screens to achieve desired particle size.
The upper part is a hard solid surface, while the lower part features a screen with holes.
What is the size range of the holes in the screen of a hammer mill?
The hole size typically ranges from 1-4 mm, with most in the range of 1.5 mm to 3 mm.
The screen size determines the maximum grist particle size.
What factors can be adjusted to influence grist particle size in a hammer mill?
- Rotor speed
- Number and length of beaters
- Beater profile
These adjustments have a less significant effect compared to screen size.
What is the purpose of blowing air or CO2 through the hammer mill?
To prevent grist heating up and to keep the screen clear.
It also maintains a negative pressure in the mill.
What are the three technologies used for malt conditioning?
- Malt conditioning screw (Buhler Condimat)
- Steep conditioned wet mill
- Full steep wet mill
What is the purpose of malt conditioning screws?
To hydrate malt by spraying with water or flushing with steam
What is the typical hydration time and temperature for modern malt conditioning screws?
One minute at 35°C
How much does water conditioning increase total malt moisture?
2.0-2.5%
What is one advantage of conditioning malt?
Increased husk elasticity allows for more thorough milling
What is the effect of malt conditioning on extract efficiency?
It improves extract efficiency
