Beer Phenolic Composition of Simple Phenols, Prenylated Flavonoids and Alkylresorcinols

Abstract

Beer is a fermented beverage with beneficial phenolic compounds and is widely consumed worldwide. The current study aimed to describe the content of three families of phenolic compounds with relevant biological activities: prenylated flavonoids (from hops), simple phenolic alcohols (from fermentation) and alkylresorcinols (from cereals) in a large sample of beers (n = 45). The prenylated flavonoids analyzed were xanthohumol, isoxanthohumol, 6- and 8-prenylnaringenin. The total prenylated flavonoids present in beer ranged from 0.0 to 9.5 mg/L. The simple phenolic alcohols analyzed were tyrosol and hydroxytyrosol, ranging from 0.2 to 44.4 and 0.0 to 0.1 mg/L, respectively. Our study describes, for the first time, the presence of low amounts of alkylresorcinols in beer, in concentrations ranging from 0.02 to 11.0 µg/L. The results in non-alcoholic beer and the differences observed in the phenolic composition among different beer types and styles highlight the importance of the starting materials and the brewing process (especially fermentation) on the final phenolic composition of beer. In conclusion, beer represents a source of phenolic compounds in the diet that could act synergistically, triggering beneficial health effects in the context of its moderate consumption.

Effects of the Non-Alcoholic Fraction of Beer on Abdominal Fat, Osteoporosis, and Body Hydration in Women

“…Polyphenols are also critical to the flavor, astringency, bitterness, haze, and body of beer [21,22], and their concentration varies according to the ingredients and processing [23,24]. Regular beer, both ale and lager beers, is richer in polyphenol content compared to alcohol-free beers [25]. [27], silicon from Jugdaohsingh (2007) [28] and sodium and potassium derived from the Food composition data of 16 European countries via www.EuroFIR.org.…”

Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops

“…Here we report comparable results between 723 and 2456 µg/L (see Table 3). A more recent analysis of beer polyphenols revealed a range of prenylated flavonoids of 0 and 9500 µg/L and highest containing beers were stouts and IPAs with an average range between 1.900 and of 2190 µg/L (40). The values of the stouts in general are comparable to FIGURE 3 | Fragmentation patterns of the prenylated flavonoids in hops adapted from Stevens et al (35).…”

The Role of Bioactive Phenolic Compounds on the Impact of Beer on Health

“…Because of its high concentration, also thanks to high producing yeasts (see Section 5 , “The role of barley, yeast and hop genetics on beer phenols”), the simple phenolic alcohol tyrosol is one of the main phenols looked at in beer, present also in alcohol-free beers [ 10 ]. Concentration is so high in certain beers, reaching that of red wine [ 11 ], that authors have hypothesized that tyrosol could represent an indirect source, through biotransformation, of the more biologically active hydroxytyrosol [ 12 ] (see Section 6 , “Phenols-related health effects of beer consumption”). In alcoholic beers, both phenols possibly protect yeast from the stress generated by high levels of ethanol, a phenomenon that has been demonstrated for wine’s resveratrol [ 13 ], indicating that phenols not only undergo changes during brewing, but they also direct it.…”

“…Among minor phenols, those derived from barley, for example alkylresorcinols, are a group of phenolic lipids for which in vitro antioxidant and antigenotoxic [ 15 ] and in vivo diet-induced obesity-suppressing [ 16 ] activities have been reported. Even if contribution to alkylresorcinols dietary intake appears not significant, higher amounts were reported in stout beer [ 11 ]. Other quantitatively minor phenols derived from hop, for example, xanthohumol and other prenylated flavonoids, contribute significantly to beer flavor and aromas and have antibacterial, anti-inflammatory and antioxidant properties, and phytoestrogen activity [ 17 , 18 ].…”

“…Other quantitatively minor phenols derived from hop, for example, xanthohumol and other prenylated flavonoids, contribute significantly to beer flavor and aromas and have antibacterial, anti-inflammatory and antioxidant properties, and phytoestrogen activity [ 17 , 18 ]. Prenylflavonoids are of particular interest for beer as, on the one hand, no other food sources other than hop are known and, on the other hand, they are present regardless of the fermentation method, ale or lager, even if higher concentrations were found in stout and India Pale Ale styles [ 11 ].…”