Measurement of catechin-7-O -glucoside from barley to malt

Abstract

The content of catechin‐7‐O‐glucoside throughout the malting process was evaluated by high‐performance liquid chromatography with diode‐array detection coupled to electrospray ionisation tandem mass spectrometry (HPLC‐DAD‐ESI/MS) in 10 Czech varieties of barley and corresponding malts. Glycosylation confers catechin better water solubility and resistance to oxidative and alkaline degradation, with a significant impact on beer quality. However, the sugar moiety also affects catechin bioavailability and may hinder its health effects. The results show that the total catechin‐7‐O‐glucoside content is higher in malt [ranging from 22.3 ± 0.7 to 84 ± 6 mg catechin equivalents (CE)/kg] compared with barley (from 6.3 ± 0.4 to 36 ± 1 mg CE/kg). The catechin‐7‐O‐glucoside content ratio between malt and barley varied from ~1.5‐ to 7‐fold for varieties Pioner and Sunshine, respectively. The study of the glycosylation rate during individual stages of the malting process using a barley variety Tipple revealed that the content of catechin‐7‐O‐glucoside gradually increases (0.26 mg CE/kg/h) during the germination stage (~3‐fold higher after 120 h of germination). In addition, the glycosylation rate is 5 times faster during kilning steps (1.36 mg CE/kg/h) and its content almost doubles after kilning. The first steps of the kilning stage encompass optimal moisture and temperature for enzyme activity (~45% moisture and 55°C) which may explain the higher catechin‐7‐O‐glucoside formation rate. © 2018 The Institute of Brewing & Distilling

Time-Course Comparative Metabolome Analysis of Different Barley Varieties during Malting

“…Pihlava counted and compared the total hardatine content in different types of beer . Carvalho found a significant effect of kilning on the synthesis of catechin-7- O -glucoside, which may contribute to antioxidant properties of malt and affect haze formation . However, little research has been done on the time-dependent changes of the secondary metabolites during malting.…”