Ferulic acid: Difference between revisions

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rapid increases of bound ferulic acid concentration in the early stages of wort production were observed. The free ferulic acid concentration in wort without any preparations increased until the heating at 75°C step. After boiling the wort with hops, the stabilization of free ferulic acid content was observed, and after 14 days of main fermentation only a slight (3%) decrease of free ferulic acid was observed. During the 28 days of beer maturation the free ferulic acid concentration decreased about 14% in comparison to the same beer after the main fermentation. A further decrease in free ferulic concentration of 30 mg/hL after beer storage (1 month) was also observed compared to the fresh beer levels. The percent decrease of free ferulic acid content in beer after storage, in comparison to the maximal concentration which was obtained in wort heated at 75°C, was about 35%.<ref name=szwpie/>
rapid increases of bound ferulic acid concentration in the early stages of wort production were observed. The free ferulic acid concentration in wort without any preparations increased until the heating at 75°C step. After boiling the wort with hops, the stabilization of free ferulic acid content was observed, and after 14 days of main fermentation only a slight (3%) decrease of free ferulic acid was observed. During the 28 days of beer maturation the free ferulic acid concentration decreased about 14% in comparison to the same beer after the main fermentation. A further decrease in free ferulic concentration of 30 mg/hL after beer storage (1 month) was also observed compared to the fresh beer levels. The percent decrease of free ferulic acid content in beer after storage, in comparison to the maximal concentration which was obtained in wort heated at 75°C, was about 35%.<ref name=szwpie/>
During wort boiling, the free wort Ferulic acid (FA) concentration increased by 10%. This net increase was the result of several factors. During wort boiling, thermal decarboxylation of FA will lead to the formation of 4VG. At the end of the boiling process, 0.14 ppm 4VG was found in the wort. This thermal decarboxylation caused the wort FA concentration to diminish by 9%. However, during wort boiling, the wort volume will decrease by 7–8% due to evaporation. This will cause an apparent increase in FA content. Finally, the addition of hop pellets will cause a real increase in wort FA content by 7–11% (based on results obtained in laboratory hop addition experiments). Taking into account these three factors, a net increase of the wort FA content during wort boiling will occur. The reassociation or coprecipitation of free FA with AX, polyphenols or proteins was negligible. Otherwise, no net increase in free FA content would occur during pilot-scale wort boiling. This was confirmed during laboratory-scale wort boiling experiments under reflux (no evaporation) without hop addition. During these experiments, the increase in 4VG corresponded with the decrease in FA.<ref name=vanvan/>




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Ferulic acid, the main phenolic acid in barley and wheat malts, is ester-bound to arabinoxylans (in a constant arabinose : FA ratio). Feruloylated arabinoxylans are present in all parts of the grain, mainly in the aleurone layer (75%) and the endosperm. Only a minor part of ferulic acid (shown to be an effective antioxidant) is present in malts in free forms. Malting and mashing result in a limited release of free ferulic acid from arabinoxylans (by the enzyme deferuloylase).[1][2]

Ferulic acid is the main phenolic acid found in beers, representing between 48 and 58% of the total phenolic acids. It is present in barley, and approximately 10% in free form and the rest connected in the ester form with arabinoxylated polymers.[3]

Walters et al. showed that ferulic acid has greater antioxidant activity than catechin in the presence hydroxyl radical, in addition to being more effective in preventing of lipid oxidation. However, catechin showed greater sequestering activity of superoxide radicals.[3]

The ferulic acid (4.131) liberated is a potential anti-oxidant and if decarboxylated during boiling or by bacteria or pof+ yeast strains, gives rise to 4-vinyl guaiacol, a strongly flavored substance that is undesirable in most beers.[2]

The maximal release of FA occurs in the range of 45-50°C. Within the range of 25 to 60°C, a longer mashing-in time leads to a higher detachment of ferulic acid. Above 65°C, the mashing-in time has no more influence on the release. In this temperature range, most of the FA degrading enzymes are denatured. Consequently, the released amount of ferulic acid corresponds with the unbound water-soluble fraction in malt.[4]

The maximal release of free FA occurs at 40°C and pH of 5.8, and the level reaches a plateau after around 2 hours, although the mash reaches a maximal level only after temp is increased to 65°C or higher in order to extract the remaining water-soluble portion.[5] Even at optimal enzyme activity, no more than ~23% of the total wort FA is extracted. Within the optimal ranges of cinnamoyl esterase, stirring the mash significantly increases the extraction of ferulic acid because stirring increases the amount of arabinoxylan extraction.

The flavor threshold of 4VG in blond specialty beers is 370 ppb.[5]

Rye appears to have much higher levels of ferulic acid compared to barley and other grains.[4] Contrary to popular belief, wheat malt has a lower amount than barley malt.

Results of McMurrough et al. (88) suggested the release of ferulic acid through enzymatic hydrolysis of arabinoxylan during both malting and mashing. Levels of ferulic acid in barley have been reported to vary from 365 to 605 µg/g (130). Humberstone and Briggs (65,66) showed that the ferulic acid esterase activity level increased during the first 3 days of germination and remained high.[6]

ferulic acid (FA) is generally a flavor-inactive phenolic acid, having a flavor threshold in beer as high as 600 ppm.[5]

the content of each phenolic acid increases during kilning up to 80°C. Above 80°C, the content of hydroxycinnamic acids decreases. The phenolic acid content increases during kilning up to 80°C, which was partly attributed to the enhanced extractability of the drying tissue and partly to enzymatic release. During malting, phenolic acids are partly released due to the degradation of complex barley components.[7] However, cinnamoyl esterases, which are able to release hydroxycinnamic acids from cinnamoylated saccharides, have also been found in barley and barley malt.

The release of ferulic acid by feruloyl esterase was found to be enhanced in the presence of other cell wall degrading enzymes.[7]

ferulic acid esterase enzyme is active (during kilning) at temperatures between 45 and 65 °C and it releases bound phenolic acids.[7] At higher temperatures (up to 75°C), the further increase in ferulic acid content was attributed to better extractability followed by a decrease due to thermal degradation. Specifically, ferulic acid reacts with proline-glucose Maillard reaction intermediates upon heating.

The relatively flavor-inactive phenolic acids can be decarboxylated to the highly flavor-active volatile phenols 4VP and 4VG in two ways (9): (1) by thermal impact during high-temperature treatments in beer production processes such as wort boiling, whirlpool holding, and pasteurization or (2) by enzymatic decarboxylation during fermentation by phenylacrylic acid decarboxylase activity of top-fermenting yeasts strains (Pad1-enzyme) (10) or by phenolic acid decarboxylase activity of contaminating micro-organisms (9, 11).[8]

rapid increases of bound ferulic acid concentration in the early stages of wort production were observed. The free ferulic acid concentration in wort without any preparations increased until the heating at 75°C step. After boiling the wort with hops, the stabilization of free ferulic acid content was observed, and after 14 days of main fermentation only a slight (3%) decrease of free ferulic acid was observed. During the 28 days of beer maturation the free ferulic acid concentration decreased about 14% in comparison to the same beer after the main fermentation. A further decrease in free ferulic concentration of 30 mg/hL after beer storage (1 month) was also observed compared to the fresh beer levels. The percent decrease of free ferulic acid content in beer after storage, in comparison to the maximal concentration which was obtained in wort heated at 75°C, was about 35%.[9]

During wort boiling, the free wort Ferulic acid (FA) concentration increased by 10%. This net increase was the result of several factors. During wort boiling, thermal decarboxylation of FA will lead to the formation of 4VG. At the end of the boiling process, 0.14 ppm 4VG was found in the wort. This thermal decarboxylation caused the wort FA concentration to diminish by 9%. However, during wort boiling, the wort volume will decrease by 7–8% due to evaporation. This will cause an apparent increase in FA content. Finally, the addition of hop pellets will cause a real increase in wort FA content by 7–11% (based on results obtained in laboratory hop addition experiments). Taking into account these three factors, a net increase of the wort FA content during wort boiling will occur. The reassociation or coprecipitation of free FA with AX, polyphenols or proteins was negligible. Otherwise, no net increase in free FA content would occur during pilot-scale wort boiling. This was confirmed during laboratory-scale wort boiling experiments under reflux (no evaporation) without hop addition. During these experiments, the increase in 4VG corresponded with the decrease in FA.[5]


  • Graf, E. Antioxidant potential of ferulic acid. Free Radic. Biol. Med. 13:435-448, 1992.
  • Kikuzaki, H., Hisamoto, M., Hirose, K., Akiyama, K., and Taniguchi, H. Antioxidant properties of ferulic acid and its related compounds. J. Agric. Food Chem. 50:2161-2168, 2002.

See also

References

  1. ↑ Szwajgier D. Dry and wet milling of malt. A preliminary study comparing fermentable sugar, total protein, total phenolics and the ferulic acid content in non-hopped worts. J Inst Brew. 2011;117(4):569–577.
  2. ↑ a b Briggs DE, Boulton CA, Brookes PA, Stevens R. Brewing Science and Practice. Woodhead Publishing Limited and CRC Press LLC; 2004.
  3. ↑ a b Siqueira PB, Bolini H, Macedo GA. O processo de fabricação da cerveja e seus efeitos na presença de polifenóis. (The beer manufacturing process and its effects on the presence of polyphenols.) Alimentos e nutrição. 2008;19(4):491–498.
  4. ↑ a b Schwarz KJ, Boitz LI, Methner FJ. Release of phenolic acids and amino acids during mashing dependent on temperature, pH, time, and raw materials. J Am Soc Brew Chem. 2012;70(4):290–295.
  5. ↑ a b c d Vanbeneden N, Van Roey T, Willems F, Delvaux F, Delvaux FR. Release of phenolic flavour precursors during wort production: Influence of process parameters and grist composition on ferulic acid release during brewing. Food Chem. 2008;111(1):83–91.
  6. ↑ Egi A, Speers RA, Schwarz PB. Arabinoxylans and their behavior during malting and brewing. Tech Q Master Brew Assoc Am. 2004;41(3):248–267.
  7. ↑ a b c Wannenmacher J, Gastl M, Becker T. Phenolic substances in beer: Structural diversity, reactive potential and relevance for brewing process and beer quality. Compr Rev Food Sci Food Saf. 2018;17(4):953–988.
  8. ↑ Vanbeneden N, Saison D, Delvaux F, Delvaux FR. Decrease of 4-vinylguaiacol during beer aging and formation of apocynol and vanillin in beer. J Agric Food Chem. 2008;56(24):11983–11988.
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named szwpie
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