iTRAQ-based quantitative proteomic analysis of key barley proteins reveals changes after malting

Abstract

Since the choice of malting varieties, as well as the impact of malting on protein composition and other malt quality parameters, are fundamental for beer production, there was a need to focus on this study. The present work was undertaken to evaluate the effect of malting processing on the barley proteins. The relationship between the protein pattern of barley grains and malt was investigated by combination of HPLC SEC separation with MS. We have found that the biggest difference between grain and malt protein profiles was observed in the fraction, where these proteins were identified: β-amylase, β-glucosidase and two various isoforms of protein Z (Z4, Z7). This peak was significantly increased after the malting. In addition, iTRAQ was applied for investigation of the relative quantitative changes of selected proteins after food technological processing. Our results indicate that the content of β-amylase is increased more rapidly in comparison to β-glucosidase. On the other hand, protein Z7 seems to have the opposite trend. The quantitative analysis reveals the increasing tendency of protein Z4 and decreasing tendency of Z7 protein after malting.

GRAPHICAL ABSTRACT

KEYWORDS:

• Barley
• HPLC SEC separation
• iTRAQ
• malting process
• protein
• mass spectrometry

Additional information

Funding

This work was supported by institutional support RVO:68081715 of the Institute of Analytical Chemistry of the CAS.