The addition of hops can be done all at once, but more commonly, they are added in portions throughout the boiling process, either at the beginning or near the end. Bittering hops are typically added at the start to maximize the extraction of alpha acids and remove undesirable flavors. Aroma hops are added halfway through or at the end to contribute delicate hop flavors. Some bittering hops can also enhance hop aroma when added early.
The primary method to achieve hop flavor and aroma in beer is by adding hops very late in the boil. This practice is known as “late hopping,” “late kettle hopping,” “aromatic hopping,” or “finish hopping.”
In smaller breweries, whole hops or pellets are manually added to the kettle. When adding hops, the heat should be turned off or the hops should be added slowly to avoid boiling over.
The amount of hops used is determined by factors such as alpha-acid content, desired hop flavor and aroma, hop condition, extraction efficiency, brewing process, and water composition. Bitterness hopping rates can be calculated, while rates for flavor and aroma hops are less precise.
One way to enhance the formation of flocs in beer is by adding kettle finings. Copper finings (also known as Irish moss) are derived from seaweed and primarily consist of a complex starchy polymer called K-carrageenan. K-carrageenan, like polyphenols, has a negative charge and helps precipitate positively-charged proteins from the wort solution.
The rate of copper finings usage varies among breweries but typically ranges from 10 to 80 mg/l (or ppm). The differing rates are due to variations in malt formulations, mashing systems, and wort gravities.
Choice of Material
Copper fining products come in various forms and degrees of purification, including powders, tablets, granules, refined carrageenan, and alkali-washed seaweed.
Timing the addition of copper finings is crucial because prolonged exposure to high temperatures can denature K-carrageenan and reduce its effectiveness.
Powdered products are usually mixed thoroughly with cold water to form a suspension before being added to the kettle or whirlpool. Adding powdered products directly to the kettle may result in under-dosing and decreased performance due to product loss up the chimney.
Some brewers add tannic acid to decrease hop utilization, prevent color reactions, and improve wort clarity by promoting hot break formation.
Lactic acid can be added to lower the pH of the wort. Breweries typically produce lactic acid in propagation tanks.
Calcium Sulfate or Calcium Chloride
Calcium sulfate (gypsum) or calcium chloride are often added during the boil to lower the wort’s pH by 0.1-0.2 units.
Syrups and Sugars
Syrups and sugars can be added to the kettle in either dry or liquid forms.
Ale brewers, especially those in Belgium, sometimes add fruits, spices, and herbs to the brew kettle during or after the boil for additional flavoring.