Method of selecting barley variety, barley β-amylase gene and process for producing malt alcoholic drink

A method of selecting a barley variety, which comprises:

• heating a crude enzyme solution extracted from a seed of a barley;
• determining the enzyme activity of a β-amylase in the crude enzyme solution heat-treated;
• and
• selecting a barley variety comprising a β-amylase having a residual activity of from 85 to 90% as a result of the activity determination compared to an unheated control,
• determining a nucleotide sequence of a gene encoding the β-amylase of the selected barley variety, and
• selecting the barley variety comprising a structural gene of the β-amylase comprising the sequence set forth in SEQ ID NO:1,
• wherein said heating of the crude enzyme solution occurs at a predetermined temperature of 55 to 58° C. and for a time of 10 to 60 minutes.