Monitoring of barley starch amylolysis by gravitational field flow fractionation and MALDI-TOF MS.

BACKGROUND

In barley, starch occurs in the form of granules with bimodal size distribution. Enzymatic hydrolysis of the starch granule is one of the most important reactions occurring during malting and mashing. Previous studies revealed the discrepancies in the assumption that barley varieties with better malting qualities should have a higher A/B (large/small starch granules) ratio. This led us to focus our attention on detailed analysis of two barley varieties, Jersey and Tolar, both with high malting quality but significantly differing in A/B (1.28 and 0.66, respectively), were chosen for more detailed analysis in the actual work. In this study, the capacity of gravitational field flow fractionation (GFFF) to monitor amylolysis of the starch granules was investigated.

RESULTS

Isolated starch granules from these two barley cultivars were treated with amylases. The changes in starch granule size and bimodal distribution were studied by GFFF. Simultaneously, free sugars released during enzymatic digestion were observed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The changes in the fractogram and in the mass spectra reflect a correlation with the progress of enzymatic hydrolysis.

CONCLUSION

The results show the interest in utilization of GFFF as a simple and cheap method for monitoring changes in the distribution of the starch granule size during amylolysis.