Comparison of Physicochemical Properties and Metabolite Profiling Using 1H NMR Spectroscopy of Korean Wheat Malt

Abstract

The objective of this study was to compare the physicochemical, enzymatic, and metabolic properties of two control wheat malts imported from Germany and the US to those of malts made from three Korean wheat varieties: Triticumaestivum L., var. Anzunbaengi, Jokyung, and Keumkang. The qualities and enzyme activities of the Korean wheat malts were generally similar to those of the control wheat malts. The Korean wheat malts had slightly lower diastatic power and enzyme activities related to saccharification. The analysis of metabolites in the wheat malt samples was performed using 1H nuclear magnetic resonance (NMR) metabolomics, which identified 32 metabolites that differed significantly among the samples. Most amino acids and lipids were more abundant in the Korean wheat malts than in the control wheat malts. These differences among malts could influence the quality and flavor of wheat beers. Further brewing studies are necessary to identify the association between beer quality and individual malt metabolites.

Quality Characteristics of Wheat Malts with Different Country of Origin and Their Effect on Beer Brewing

“…For the TN, the Korean wheat malts, KM (2.5%) and AM (2.2%), had significantly (p < 0.05) higher values than the control wheat malts, GB (1.9%) and UB (1.7%). Recently, similar results for Korean wheat malt were reported by Byeon et al [19]. Briefly, the parameters related to nitrogen, such as FAN, SN, TN, and KI, differed between the control wheat malts and the Korean wheat malts.…”

“…is is probably because KB was made from KM, which had a high methionine concentration. is was confirmed in a previous Korean wheat malt study described by Byeon et al [19], which showed that Keumkang malt had a high methionine content.…”

“…Isobutanol and isoamyl alcohol are produced by the decarboxylation and reduction of α-keto acids derived as amino acid metabolism by yeast action, and their presence depends on the nutrient composition of the wort [34,35]. High concentrations of isobutanol and isoamyl alcohol in the Korean wheat beers might be influenced by the high content of branched amino acids derived from the AM and KM, considering the high concentration of branched amino acids in Korean malts, as Byeon et al [19] reported. Isobutanol and isoamyl alcohol are associated with the beer sensory descriptions of bitterness and alcohol flavour.…”

“…e authors of these studies reported that the physicochemical properties and consumer acceptability of Makgeolli were similar regardless of whether domestic or imported wheat was used. Byeon et al [19] compared the characteristics of wheat malts made of three major Korean wheat varieties and commercial wheat malts imported from the USA and Germany. ey focused on the malt quality and composition of their metabolites, indirectly suggesting the effect of wheat malt on beer quality.…”

Exploring the genic resources underlying metabolites through mGWAS and mQTL in wheat: From large-scale gene identification and pathway elucidation to crop improvement

“…In addition, it can be coupled to either gas chromatography (GC) or liquid chromatography (LC), adding another dimension to differentiating the metabolite signals ( Alseekh and Fernie, 2018 ). By employing the above-mentioned technological platforms, one could acquire hundreds of metabolic analytes from wheat samples using the NMR-based ( Byeon et al., 2020 ) or MS-based techniques ( Ameye et al., 2020 ; Wang et al., 2020 ). Although this number is far from covering the whole metabolome of a given species (hundreds detected versus thousands predicted), this is likely reflective of what can be currently achieved in wheat.…”