Determination of Free Phenolic Acids in Wort and Beer by Coulometric Array Detection

Abstract

The simultaneous determination of 19 phenolic compounds was performed directly in wort and beer by a combination of reverse-phase high-performance liquid chromatography coupled with coulometric array detection. Chromatographic separation was achieved with an appropriate gradient of flow and a binary solvent based on phosphate buffer, methanol, and acetonitrile in a 45-min run. Eight serial coulometric detectors were used for on-line generation of voltammetric data to resolve coeluting compounds. The method was reliable and sensitive, the regression coefficient of standard calibration curves is 0.972 < or = r < or = 1.000, and the standard deviation value ranges from 0.010 to 0.129 mg/L for wort and from 0.002 to 0.332 mg/L for beer. The mean concentrations of phenolic acids were 22.1 and 33.8 mg/L, respectively, in worts and beers produced in Italy. These amounts represent 5 and 10% of the non-tannic, non-flavonoid phenols in wort and beer, respectively.

Determination of polyphenols in beer by an effective method based on solid-phase extraction and high performance liquid chromatography with diode-array detection

“…Hayes et al (1987) determined the phenolic compounds commonly as benzoic acid derivatives, protocatechuic and gallic acids as cinnamic acid derivatives, caffeic acid, p-coumaric and ferulic, finally (+)-catechin and (-)-epicatechin were also quantified. Floridi et al (2003) determined 19 phenolic compounds in beer; average values of 23 different samples were 0.6 mg/l for gallic acid, 0.84 mg/l for protocatechuic acid, 0.4 mg/l for gentistic acid, 0.6 mg/l for caffeic acid, 1.4 mg/l for p-coumaric acid, 2.4 mg/l for ferulic acid, and 2.9 mg/l for salicylic acid, respectively. García et al (2004) compared the contents of ten polyphenols in nine alcohol-free beer samples produced in different Spanish breweries.…”

Total contents of phenolics, flavonoids, tannins and antioxidant capacity of selected traditional Ethiopian alcoholic beverages

“…Phenolic compounds are important components of beverages, to which they contribute flavor, color, and sensory properties such as bitterness and astringency [9,11,[13][14][15], aroma and haze formation during storage [9]. Moreover, phenolic compounds are known to play an important role in alcoholic beverages making processes, since they participate in clarification, and present an inhibiting effect on spoilage micro-organisms, as well as, on clarification enzymes [9,11].…”

“…Total phenolic compounds in liqueurs made from red fruits [17], wine [18][19][20][21], worts and beer [13,22,23], traditional fermented sorghum beers "dolo" [16], alcoholic beverages made from purple rice [24], ciders [25] and spirit drinks [26]; anthocyanins in liqueurs made from red fruits [17], dolo [16] and wine [21]; total flavonoids in wines [21]; and antioxidants capacity in wine [12,18,20,21], beer [23], liqueurs made from red fruit [17], alcoholic beverages made from purple rice [24] were determined.…”

Comparison of Antioxidant Activity of Barley (Hordeum vulgare L.) and Malt Extracts with the Content of Free Phenolic Compounds Measured by High Performance Liquid Chromatography Coupled with CoulArray Detector

“…Various techniques have been used for the determination of polyphenolic compounds, including high performance liquid chromatography (HPLC) with electrochemical 8,16 , mass spectrometry detection 4,5,23 , UV spectrophotometric 5,6,7,10 or fluorimetric detection 17 .…”