Eight purposes and reasons of wort boiling
In the brewing, saccharification, filtration, boiling, cooling and fermentation processes, boiling process is the most easily overlooked. Cast hops, looks like other times can only watch wort tumbling in the boiling pot.
But in fact, boiling is a very critical part of the brewing process. It plays an important role in connecting with others. At this stage, the high temperature will deactivate the enzyme, add hops to a-acid isomerization, remove heat coagulation material and volatile flavor substances, and so on. Why do we have to carry out the boiling operation of wort? On the surface, we must achieve the following eight main purposes. See the figure below.
In fact, these eight goals serve only one final goal, namely, optimization of the wort boiling process to prevent excessive heat load, reduce heat consumption, shorten the wort boiling time, and accelerate equipment turnover.Therefore, in boiling operation, it is not only simple to put hops, but also need to pay attention to wort boiling time, boiling method, control of evaporation strength and boiling strength and other aspects.
1.Evaporation and concentration of wort
During saccharification and filtration, the addition of additional water maximizes extract recovery. The boiling process fully evaporates this part of the water to achieve the desired (target) wort weight (OG).
The main factors that determine the final weight are the initial weight and the boiling time.
The longer the boiling time, the higher the final specific gravity.
2.Stop enzyme reaction
Boil can stop the saccharification process that converts starch into sugars. Perhaps it can be said that the most important role of boiled wort is to inhibit the activity of residual enzymes after the saccharification process.
Inhibiting enzyme activity can maintain the desired sugar/dextrin ratio.
If any enzyme catalyzed process continues, it will produce "thin" beers with poor taste characteristics.
Wort is essentially a nutrient-rich liquid.
Close to an ideal environment for the growth of (harmful) bacteria; in short, all bacteria in wort grow wildly;
These bacteria will cause the beer to spoil and affect the taste.
The boiling time of 15 minutes is enough to kill almost all types of bacteria.
At the same time, hops have a natural bactericidal property that can inhibit the growth of bacteria to a minimum.
4.Remove hot coagulum - protein condensation
Wort contains many protein compounds of different molecular weights. Some of the polymer fraction (coagulable nitrogen), if not removed, will affect the taste and stability of the beer and is therefore an undesirable ingredient.
In boiling, the protein will undergo two different but connected stages of change.
Protein degradation, boiling, removes water from the protein molecule, making it unstable and insoluble in water. Protein Coagulation: After degradation, protein molecules will become part of a colloidal system with a special "isoelectric point" (IP). Due to the different IP of different protein compounds, the protein will precipitate out of solution.
If the effect of protein coagulation is not good, thermal coagulum will not precipitate. Unremoved proteins then cause turbidity issues and make the beer exceptionally bitter.
However, in the boiling phase, it does not remove all the protein. Wort without protein is also not good. Some proteins help maintain good foam and form the desired taste characteristics.
Strong tumbling boiling can help achieve this goal. Most of the protein will precipitate as a hot coagulum in the gyratory sedimentation tank, and other proteins will be removed as cold coagulates after the wort has cooled. Prior to the production of sake, compounds that did not precipitate in the form of hot coagulum or cold settling may result in the formation of cold turbidity.