Determination of proanthocyanidins and catechins in beer and barley by high-performance liquid chromatography with dual-electrode electrochemical detection

Abstract

A method was developed to determine the flavanols prodelphinidin B3, procyanidin B3, (+)-catechin, and (-)-epicatechin by high-performance liquid chromatography, using dual-channel electrochemical detection. This method was especially suited to the direct analysis of beer samples and to analysis of acetone extracts of barley samples, and was capable of determining proanthocyanidins and catechins at levels of 0.1-5.0 mg l-1. The use of dual-channel electrochemical detection also enabled unambiguous peak identification by measurement of collection efficiencies. This method offered improved sensitivity and selectivity compared with ultraviolet detection, and sample preparation procedures were greatly simplified. The method was applied to the comparison of stabilized and unstabilized lagers, and to the analysis of different barley varieties grown in Ireland.

A New Laccase Biosensor For Polyphenols Determination

“…Initially a potential of -200mV was applied, because it is often referred in the literature as the potential of choice for biosensor phenolics determination [6,[12][13][14][15], though -400mV has been used [6] for the detection of rutin. Our laccase containing biosensor was sensitive to catechol, at pH 4.5 at the referred applied potential: -200mV.…”

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

“…Polyphenols and phenolic acids present in malt are natural antioxidants, capable of delaying, retarding or preventing oxidation processes, and therefore thought to have a significant effect in malting and brewing as inhibitors of oxidative damage 15 . About 80% of beer polyphenols originate from malt and the remaining 20% come from hop 9,18 . The phenolic compounds in barley include phenolic acids (benzoic and cinnamic acid derivatives), flavonoids, proanthocyanidins, tannins, and amino phenolic compounds 3 .…”

European Journal of Cancer

“…In contrast, 8-PN was shown to possess antiandrogenic activity in an androgen inducible yeast receptor assay and by androgen receptor binding studies [67]. 8, as well as of the mitochondrial pathway via caspase 9 activation. Consequently, also the executioner caspases 3 and 7 were activated and led to cleavage of poly (ADP-ribose) polymerase (unpublished data).…”

“…Barley polyphenols undergo changes during the malting and brewing process and are less well characterised than phenolic compounds from hop. However, specific proanthocyanidins from barley and malt have been separated and quantified [8][9][10].…”