Beer : Health and Nutrition

114 Chapter Five
Table 5.14 Phenolic compounds in beer.
Fraction Examples Levels (mg/L)
Phenolic alcohols Tyrosol 3–40
Phenolic acids Ferulic acid, p-coumaric acid, vanillic acid, caffeic
acid, gallic acid
10–30
Phenolic amines and amino acids Hordenine, tyramine, tyrosine 10–20
Flavan-3-ols Catechin 0.5–13
Epicatechin 1–10
Flavan-3,4-diols Leucocyanidin 4–80
Flavonols Quercetin, myrecetin, rutin < 10
Condensed polyphenols Dimeric catechins 5–8
Polymeric catechins < 1
Proanthocyanidins 20–60
Prodelphinidins 3–10
lipoproteins (see Chapter 6) than are ascorbic acid, alpha-tocopherol and beta-carotene
(Vinson et al. 1995). However, in studies looking at lipoprotein-bound activity, they
were not as good as polyphenols from tea and wine (Vinson et al. 1999).
Walker et al. (2001a) emphasise that the quality of antioxidants is more relevant
than their absolute quantity. In other words, measuring the total polyphenol level in
a foodstuff is probably of less value than measuring the type of polyphenol. In their
work they have measured (using a luminescence-based system) the antioxidant activity
of individual fractions emerging from high-performance liquid chromatography.
They divided the antioxidants into ascorbic acid and related compounds, polyphenolic
avonoids, catechin and related compounds and epicatechin and related compounds.
Such a test revealed cider to perform best from among the beverages tested (Fig. 5.1).
The correlation between total polyphenol content and antioxidant activity is weak. It
seems that there is a greater diversity of phenolic compounds in beer than in red wine
or cider. Walker et al. (2001a) compared a range of foodstuffs for their relative antioxidant
value as determined in a standard laboratory assay (Table 5.15). Clearly beer
measures up well; however, I stress again that this is very much an in vitro assay – it is
one thing having antioxidants at high levels, but are they taken up into the body and do
they reach the parts where they need to exert an effect? This will be in uenced by the
food matrix itself, the type of antioxidants and the presence of other factors, including
alcohol. Smaller molecules tend to be more readily assimilated, and so are those which
are more water-soluble.
Gorinstein et al. (2000), using laboratory animals and clinical investigations, showed
that the content of total polyphenols is higher in white wine than in beer. However, beer
possessed a higher antioxidant activity. The authors ascribed this to the fact that levels
of procyanidins, epicatechin and ferulic acid were signi cantly higher, statistically, in
beer than in white wine.