MALDI-TOF mass spectrometry provides an efficient approach to monitoring protein modification in the malting process

Proteins in barley grains are determinants of beer quality, which are modified during malting to provide nutrition for yeast during brewing. Different malting barley varieties behave differently during malting. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to characterize storage proteins including albumin, globulin, hordein and glutelin in grains and malt of parental varieties and a doubled haploid (DH) population. Each parental variety produces malt with particular quality profiles. The protein profiles of analyzed extracts in seed and malt were compared to find the most influenced proteins during the malting process. Our results revealed that malting procedure dramatically affected the composition and amounts of albumin, then hordein, glutelin and globulin in barley. Moreover, hordein and glutelin profiles in the DH population exhibited high levels of polymorphism. The genetic information represented by individual hordein and glutelin profiles was successfully mapped as molecular markers in a genetic linkage map. Twelve and 8 (hordein in seed and malt, respectively) or 10 and 8 (glutelin in seed and malt, respectively) segregating peaks were scored as polymorphic across the population, and all peaks were located to the chromosome 1H. The MALDI-TOF MS provides a method with high resolution and throughput to characterize mass patterns of extracted storage proteins in barley and malt.