Vol.:(0123456789) 1 3 Chemical Papers https://doi.org/10.1007/s11696-020-01276-1 ORIGINAL PAPER Analysis of phenolic compounds in beer: from raw materials to the final product Darijo Šibalić 1  · Mirela Planinić 1  · Anita Jurić 2  · Ana Bucić‑Kojić 1  · Marina Tišma 1 Received: 24 January 2020 / Accepted: 1 July 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020 Abstract Two types of lager pale beers were produced at industrial scale according to German Beer Purity Law using the same brewing procedure, but different hop varieties. Beer phenols issued from malt and hop can contribute directly to several characteristics of beer, mainly flavor, astringency, haze, body, and fullness. The aim of this paper was to analyze simple phenolic compounds, total polyphenols and total flavonoids contents, antioxidant activity in raw materials (malt and hops) and in samples taken out from several production stages (after wort production, boiling, fermentation, filtering and pasteurisation). Eighteen dif- ferent phenolic compounds which belong to the groups of hydroxybenzoic and hydroxycinnamic acid derivates, flavan-3-ols, flavonols and procyanidins dimers were analysed. Among all tested phenolic compounds, 9 compounds were identified in malt, 13 in hops, while 10 in samples taken from the brewing process. Based on the obtained results, it is suggested that the choice of hops is very important for obtaining the desired beer quality and to establish its shelf life. Keywords Beer · Malt · Hop varieties · Wort · Polyphenols Introduction Knowledge on the characterisation of phenolic compounds in raw materials as well as in all brewing stages is important in brewing since polyphenols have an influence on the for- mation of beer haze, colour, bitterness and astringency, foam stability and redox state (Siebert 2006; Ilmure et al. 2008; Dixon et al. 2005). Additionally, polyphenols have an influ- ence on the filtration process and stability of the beer dur- ing aging (Friedrich and Galensa 2002; Vanderhaegen et al. 2003). Solubilisation of phenolics from the raw materials occurs in the early stage of the brewing process. Barley malt is still the most important starch source used in brewing. Some authors reported that the total polyphenols content and antioxidant potential of malt extracts are higher than those of the corresponding barley samples (Fogarasi et al. 2015). General chemical composition of malt wort depends on the applied temperature profile during mashing (Brandam et al. 2003; Zhao and Zhao 2012). The polymerisation of pheno- lics into polyphenols occurs during boiling and fermentation (Wannenmacher et al. 2018). Furthermore, dimeric proan- thocyanidins, as well as their monomers, can polymerize during storage by oxidative and acid-catalysed mechanisms (Asano et al. 1984). Complex phenolic profile of the beer includes catechins and proanthocyanidins, prenylchalcones, and derived flavanones, flavonols, hydroxybenzoic acids, hydroxycinnamic acids and stilbenes (Collin et al. 2013). Low molecular polyphenols increase the reduction power of beer, while when simple phenols or polyphenols monomers react with proteins, no haze is formed (Siebert 1999). Haze is composed of complexes between condensed polyphenols and water-soluble proteins. Besides having a negative effect on haze, water-soluble proteins have a positive role in the formation and stabilization of the head foam (Perrocheau et al. 2005). They contribute to the beer flavour stability and have a role in beer aging (Wu et al. 2011).The flavoursome components of beer include bitter iso-α-acids and aromatic essential oils from hops, while esters, volatile fatty acids, sulphur-containing compounds, aldehydes and vicinal dik- etones originate from yeast (Leça et al. 2015; Bravi et al. 2017). Some phenolic acids are precursors of beer aromas, e.g. decarboxylation of ferulic acid during brewing leads to * Anita Jurić anita.juric@aptf.sum.ba 1 Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, F. Kuhača 18, 31000 Osijek, Croatia 2 Faculty of Agriculture and Food Technology, University of Mostar, Biskupa Čule bb, 88000 Mostar, Bosnia and Herzegovina