Changes in the phenolic acid content during wort boiling and whirlpool

Phenolic acids were repeatedly pointed out as powerful antioxidants. The studies in the past prove the differences in the phenolic acids content in malts and worts. In this work, the influence of wort boiling and whirlpool separation on the phenolic acid content was studied.

Worts were produced in the local brewery by the infusion method using pale pilsner-type barley malt. Samples were analysed at the beginning of the boil, after the boil and after whirlpool separation (5 and 30 min). Free and total alkali extractable phenolic acids contents were analysed using HPLC-DAD.

The main phenolic acid in all worts was ferulic acid in the free (35.47 ±3.28-117.51 ±4.40 mg·dm(-3)) as well as total alkali extractable form (193.49 ±4.84-294.72 ±2.65 mg·dm(-3)). With both forms no decrease was seen after boiling of wort (80 min at 100-100.5°C) followed by wort separation in the whirlpool. Similarly, no significant changes in the free and total form of p-coumaric acid content were seen.

It can be concluded that an elevated temperature during wort boiling and separation in whirlpool had no significant influence on the content of phenolic acids (at least in the case of the specific mashing program applied in this brewery: equipment, enzyme preparations, mashing, time-temperature parameters etc.). The differences in the phenolic acids levels could be rather attributed to different supplies of malt used for the production.