Mash Agitation Flashcards
(18 cards)
What is the purpose of effective mash agitation?
To ensure a uniform mash, prevent overheating, minimise fouling, minimise oxygen pick-up, provide access to substrates, minimise shear forces, and assist in mash transfer.
True or False: Excessive agitation always improves extract recovery in mashing.
False
What is the main role of the agitator in mash agitation?
To assist in effective and even heat transfer to the mash.
Fill in the blank: Proper mash agitation should create localised ________ to help transfer heat.
turbulence
What happens when the mash is subjected to excessive shear forces?
It increases viscosity, reduces particle size, and hampers wort separation.
What are the characteristics of modern agitators compared to the first ones?
They are wider, have perforations, angled blades, optimised height, and central mixing features.
What are the recommended agitator tip speeds for hammer milled grist?
< 3.0 m/s
What does VSD stand for in the context of agitator operation?
Variable Speed Drive
True or False: Agitators should operate at high speeds during temperature stands.
False
What is the function of perforations in agitator blades?
To allow mash flow through, preventing solids build-up and aiding mixing.
What is the effect of shear forces on β-glucans during mashing?
They encourage cross-linking, increase viscosity, and form gels, reducing filterability.
Fill in the blank: Agitators should be designed to ensure the central zone of the vessel is ________.
mixed
What is the design feature of the Ziemann Holvrieka Colibri agitator?
A flat-faced perforated blade that moves mash over the base heating plates.
How do higher agitator speeds affect mash mixing?
They increase shear, oxygen pick-up, and can reduce mixing effectiveness.
What is the recommended maximum agitator tip speed for coarse grits?
4.3 m/s
What can ultrasonic vibrators do in conjunction with agitators?
Help mixing, drive off entrained air, and reduce total mashing time.
What is the primary function of baffles in mashing vessels?
To prevent the mash from rotating and ensure effective mixing.
Fill in the blank: The first agitators were also called ________.
propellors
