Lesson 5 - Hop Chemistry SAQ
This lesson allows you to test yourself on the material covered in Lesson 4 on ‘Hop Chemistry’ and determine the level to which you have attained the outcomes.
Suggested Response - Q2
*Indicate whether the following statements are true or false. If false, provide a reason why you think this.
a) There is one type of α-acid and iso-α-acid.
b) The hop essential oils provide the aroma and flavour in hops.
c) Hard resins are oxygenated α-acids and β-acids; they are found in the bracts of the hop cone.
d) Since the polyphenols in beer come mainly from malt, those contributed by the hops have no brewing value.
e) The levels of β-myrcene increase during the hop ripening period and α-humulene levels decrease.
Response:
a) False. There are three α-acids (humulone, cohumulone and adhumulone), which are isomerised into six iso-α-acids – namely cis-isohumulone, trans-isohumulone, cis-isocohumulone, trans-isocohumulone, cis-isoadhumulone and trans-isoadhumulone.
b) True.
c) False. The hard resins are oxygenated α-acids and β-acids, but also include other components such as prenylflavanoids, multifodal-glucosides (which are intermediate products of the alpha acids biosynthesis) and other glycoside bound polyphenols. Also, they are mainly found in the lupulin glands and not the bracts.
d) False. Polyphenols from hops reduce colloidal stability and improve flavour stability. They also increase perceived bitterness and some believe astringency.
e) True.