Determination of Phenolic Content in Different Barley Varieties and Corresponding Malts by Liquid Chromatography-diode Array Detection-Electrospray Ionization Tandem Mass Spectrometry

Abstract

A simple and reliable method for the simultaneous determination of nine phenolic compounds in barley and malted barley was established, using liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS/MS). The phenolic compounds can be easily detected with both systems, despite significant differences in sensitivity. Concentrations approximately 180-fold lower could be achieved by mass spectrometry analysis compared to diode array detection, especially for the flavan-3-ols (+)-catechin and (−)-epicatechin, which have poor absorptivity in the UV region. Malt samples were characterized by higher phenolic content comparing to corresponding barley varieties, revealing a significant increase of the levels of (+)-catechin and (−)-epicatechin during the malting process. Moreover, the industrial malting is responsible for modification on the phenolic profile from barley to malt, namely on the synthesis or release of sinapinic acid and epicatechin. Accordingly, the selection of the malting parameters, as well as the barley variety plays an important role when considering the quality and antioxidant stability of beer.

Phenolic composition as measured by liquid chromatography/mass spectrometry and biological properties of Tunisian barley

“…[6,15,18,19] The alcoholic mixtures, such as ethanol/water and methanol/water, allowed higher extraction yields of free phenols, mainly in terms of total phenolic compounds. [8,11] Therefore, in this work, ethanol was used as solvent to extract free phenolics that will be largely present in the beer during the malting process.…”

“…[27] Also, Carvalho et al [6] reported that flavanols were the major phenolic fraction in barley and malt from Portugal. In this work, PB3 (a dimeric flavanol) was found to be the most abundant phenolic compound identified in the four barley varieties with 72.63%, 72.46%, 68.19%, and 61.63% of the TPC for Swihli, Faiz, Rihane, and Manel, respectively (Fig.…”

“…Procyanidins and catechin were reported to be the major phenolics in numerous barley genotypes native to Japan. [3] Carvalho et al [6] described that catechin was the major free phenolic compound for both barley and malt from Portugal.…”

“…[1][2][3] Recently, barley (Hordeum vulgare L.) has gained renewed interest as an ingredient for the production of functional foods and beverages. [4][5][6] Barley is a widely consumed cereal over the world, mainly as animal feed and malt, which is a raw material for the beer and spirit industry. [3,4,7] Both barley grain and malt contain high levels of antioxidative phenolic compounds.…”

“…Therefore, the presence of natural antioxidants in malting barley and screening for malting barley varieties with elevated levels of antioxidants is of great interest to produce beers with high levels of reactive oxygen scavengers. [5,6,9,13,16] Several reports are available on the phenolic composition of barley varieties from different countries in the world, [4,[11][12][13] while there is not any scientific information on the phenolic composition of Tunisian barley varieties. Consequently, the purpose of this study is to determine genotypic differences among four Tunisian barely varieties (TBV) in in vitro antioxidant and antibacterial activities and phenolic composition based on high-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS) for the first time.…”