Comparative studies of the Osborne protein fraction of wheat varieties with different dough and baking properties

Abstract

The proteins of flours from the wheat varieties Clement (CLE) and Disponent (DIS), which are characterized by substitution of the wheat chromosome 1B by the rye chromosome 1R (CLE) and by 1BL/1RS-translocation of chromosome segments (DIS), respectively, and which yield sticky doughs, were extracted by the Osborne procedure and compared with the good variety Kolibri (KOL). CLE and DIS delivered significantly higher amounts of water-soluble proteins (31.2 and 23.2% of the total protein) than KOL (15.5%). The proportions of ethanol-soluble proteins were approximately constant for the three varieties (31.5-33.9%) while the amounts of residual proteins after extraction with ethanol were significantly different (CLE, 16.8%; DIS, 21.6%; KOL, 26.4%). Water extracts as well as residues exhibited also marked differences in their amino acid compositions. Investigation of the water extract from DIS by gel permeation chromatography and by RP-HPLC showed the presence of prolamins: omega 1,2-gliadins and/or omega-secalins could be detected on the basis of amino acid composition and N-terminal amino acid sequence. In the case of good varieties such as KOL, these prolamins seem to remain partially in the residue of the ethanol extract under the conditions of the classical Osborne procedure, whereas they are found in the water extract in the case of such varieties as CLE and DIS. On the other hand, a modified Osborne procedure (salt/ethanol/acetic acid) delivered the prolamins, which correspond to 39-40% of the total protein, completely within the ethanol fraction in the case of all three varieties.(ABSTRACT TRUNCATED AT 250 WORDS)