Wort Clarification, Cooling And Oxygenation. Flashcards
Hot break
Is produced during the boil. It contains proteins, polyphenols, lipids, and hop residues.
Cold break
Is composed of finer particles. Whilst it’s composition may vary quite a lot, depending on the brewing recipe, cold break contains approximately 55% proteins, 25% carbohydrates and 20% polyphenols. It is formed when wort is cooled. The colder the wort, the greater the volume of cold break. Cold break is not removed in the brewhouse, but instead sediments out in the fermentation vessel.
Trub
Is the name given to the hot and cold break (often as sediment) as it is removed from the wort or beer.
Reasons for removing hot break
- proteins in the break can lead to blocked filters and hazes in the finished beer
- polyphenols can be astringent in taste. If left in the wort, they can give the beer an astringent taste. Polyphenols can also combine with proteins to form hazes as the beer ages.
- lipids can reduce the stability of beer foam. The also give a stale, cardboard flavour to the beer as it ages.
- spent hops and trub, left in suspension, can smother the yeast cells (cover their surface), preventing them from absorbing wort nutrients. This leads to poor fermentation. Leaving the spent hood in the solution also risks their polyphenols leaching out, which would lead to problems explained above.
Hot wort clarification systems
Whirlpool, hop back, hop strainer, centrifuge, sedimentation, coolship,
Hop strainers
We can also remove while hope using a hop strainer. The sort is run through a strainer, while the whole hood are removed using a screw conveyor. The hop strainer does not allow a bed if whole hood to form, so it does not remove trub.
Sedimentation
As hops and trub are denser then wort, they tend to sink once the wort has stopped boiling. You can leave the wort in the kettle and allow the trub and hops to settle out into the bottom, before running the sort off from the vessel. The same process occurs in a sedimentation tank, where wort is moved from the kettle after boiling. But both methods take a long time and comparatively ineffective and inefficient.
Coolship
The oldest method of work clarification is the coolship. The coolship is a large, shallow, and open vessel. As there is only a short distance for them to fall, the trub and hood settle out quickly. The coolship also forms cold break, which will not go forward to the fermentation vessel. Furthermore, the coolship cools the wort, due to its large surface area. However, cool shops can contaminate wort with airborn yeast and bacteria. They are therefore only suitable for producing sour and spontaneously fermented beers.
Kettle finings
We use kettle finings to improve wort clarification. react with proteins, which aids their removal after the wort is cooled, as cold break
Process aids
Are materials that we add to our beer to enhance our brewing process, by either speeding it up, increasing its yield, or improving the quality of our final product.
How do kettle finings work
-negatively charges granulated seaweed carrageenan, binds with positively charged proteins, stick together and floc out.
- dissolves at >69*. Added early enough to dissolve, but not so early that they are destroyed
What are kettle finings
Are made of pure seaweed that has been purified and granulated. Carrageenan, which is a carbohydrate, is the active part of the seaweed.
Purpose of wort cooling.
WE DO NOT WANT TO COOK OUR YEAST
- achieve the correct temperature at the start of fermentation for healthy yeast growth
- cool without contamination the wort
-cool the wort in the required time frame
- recover heat from the hot wort as it is cooled
-precipitate cold break
-minimise wort losses
- minimise energy usage
Factors that help oxygen dissolve easily in wort
- low temperature- gasses are more soluble in liquids at lower temperatures
- high pressure- higher pressures increase the gases solubility.
- high surface area- where small bubbles or oxygen are used, the area of oxygen exposed to wort, and vice versa, is higher.
- high levels of turbulence- turbulence breaks up bubbles, giving a greater surface area between the gas and the liquid, this in turn dissolves more oxygen.
In line oxygenation
With a Venturi, the pressure in a flow of liquid drops as the diameter of pipe decreases, which allows the oxygen or air to be drawn into the pipe. When the pressure increases beyond the constriction, this helps oxygen dissolve.
