Abstract
Malting is a controlled germination of the barley grain in preparation for brewing, distilling, or food manufacturer. Where exposure to moisture leads to the activation and synthesis of enzymes that in turn modifies the physical structure of the endosperm, converting stored starch into simple sugars, yielding a friable malt suitable for downstream use. Different barley varieties, defined by a distinct genotype, exhibit different malting characteristics that are attributable to both the way the grain responds to water, and the abundance of isoforms of key enzymes that are expressed. Identifying the proteins that control this response is important to barley breeders in developing varieties with desirable malting characteristics.
In this investigation, we used discovery proteomics (DDA) and compositional analysis to achieve an unbiased characterisation of the barley proteome before and after malting, in three barley varieties that differ in protein content and response to water. We focused on three InterGrain barley genotypes: (1) Flinders, an established premium variety; (2) Maximus, a high protein variety malted to unique specification, and (3) IGB1467, a trial breeding line with a unique phenotype of malting at lower water content.
High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS), and computational biology was used to define the proteins that are differentially expressed between barley grain and malt barley in the three InterGrain genotypes. The results will provide insight into how the expression of different protein isoforms or classes of proteins in the three genotypes influence key malt quality traits. Understanding the difference in protein expression and their impact on the level of modification will provide foundational knowledge for further research.