Protein Profile Characterization of Hop (Humulus lupulus L.) Varieties

The protein composition of different hop varieties (bitter and aroma cultivars) based on their molecular weights was investigated by using capillary electrophoresis. In order to carry this out, an optimized protein extraction method was developed. The results show that the majority of hop proteins were in a size range between 5 and 45 kDa, represented by three main protein peaks at 5 kDa, 15 kDa, and 25 kDa. The hop varieties could be divided into two different groups according to their percentage of protein content in certain size ranges. Only one variety had a different protein profile; its characteristic protein peaks were found at 22 kDa, 35 kDa, and 51 kDa. To be acquainted with this variety, the protein pI's and molecular weights were examined with the combination of OFFGEL electrophoresis and capillary electrophoresis. This study shows a molecular size distribution of the proteins of bitter and aroma hop cultivars.