Dietary Fiber Complex in Beer

Most reports on carbohydrates in beer deal with sensory and technological properties. A nutritional approach requires a distinction between digestible carbohydrates, which provide the caloric value of a beer, and nondigestible carbohydrates or dietary fiber (DF) - a substrate for gut microflora. The aim of this work was to determine the DF and compounds associated with the fiber matrix in lager, dark, and alcohol-free beers. A specific procedure that included treatment with digestive enzymes, dialysis, acidic hydrolysis, and cellulase hydrolysis was used. Results showed that the beer contained a quantitatively important DF complex (1.3-3.8 g/L) made up of indigestible polysaccharides, polyphenolic compounds, and a minor amount of protein. Analysis of polyphenols and antioxidant activity using 2,2′-azinobis(3-azinobis(3- ethylbenzthiazoline-6-sulfonate)) (ABTS) and ferric-reducing antioxidant power (FRAP) assays in beer and dialysis retentates revealed that a significant portion of the total polyphenols in the beer (17-44%) was associated with DF, which might affect their bioavailability and metabolism.