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(1) Hops contain 0.5% ~ 2% hop oil, which is very volatile. About 97% hop oil evaporates during wort boiling, and some of them will be lost during the separation of thermosetting and condensing solids and fermentation process. However, the flavor threshold of these substances is very low (5g / L). Trace amount of hop oil can give strong and unique flavor to beer.
(2) The bitter taste of beer is mainly from isohumulone, the isomerization product of A-acid in hop resin. Isomerization of A-acid is of great significance for beer brewing, because the solubility of A-acid is very low (150 ~ 300mg / L), and isomerization of A-acid through wort boiling has strong refreshing and bitter taste, and the solubility is high (2000mg / L).
The isomerization of a acid is related to temperature and time. With the increase of temperature and time, the isomerization rate increases. However, if the boiling time is too long, part of the iso-a-acid will be further converted into other non bitter isomers, such as derivative iso-a-acid, which will reduce the bitter value of wort, so the boiling time of wort should not be too long.
Relatively speaking, hop B-Acid has almost no isomerization during wort boiling, and most of them are oxidized to form oxidation products of B-Acid. Some oxidation products have bitterness, while others have only fragrance but no bitterness.
The isomerization rate of A-acid is usually about 50%. After the loss of A-acid in fermentation and post-treatment, it enters into the finished beer about 30%.
(3) To increase the antiseptic ability of beer, hops soft resin can inhibit and kill some bacteria, which can increase the antiseptic ability of beer.
(4) In the process of wort boiling, some proteins in wort and polyphenols (tannins, anthocyanins, etc.) dissolved in hops condense to form some complex compounds, which will be removed in the later process, so as to improve the abiotic stability of beer.
Thank you for your reading.
Edited by Helen
Email: [email protected]
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