|Park, Seok ho|
Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/5/2006
Publication Date: 7/1/2006
Citation: Park, S., Bean, S., Chung, O.K., Seib, P.A. 2006. Levels of protein and protein composition in hard winter wheat flours and the relationship to breadmaking. Cereal Chemistry. 83(4):418-423. Interpretive Summary: We investigated the relationships between protein content and composition, and studied the effects of variations of protein content and composition on the breadmaking qualities such as absorption, mixing time, loaf volume, and crumb grain. We found that protein composition is varied with changes of protein content. As protein content was increased, gliadin fraction was increased, whereas insoluble polymeric protein (IPP) and albumin and globulin fractions were relatively decreased. When total flour protein content, and soluble protein (SP), and gliadins were increased, loaf volume was increased. Bake water absorption was increased when IPP content in flour was increased. Bake mix time was not correlated with total protein content probably because IPP in total protein was positively related with mixing time, whereas SPP in total protein was negatively related with bake mix time. Bread crumb grain scores showed weak positive relations with both SP and gliadins in flour.
Technical Abstract: Protein and protein fractions were measured in 49 hard winter wheat flours to investigate their relationship to breadmaking properties, particularly loaf volume which varied from 760 to 1055 cm3/100 g flour, and crumb grain score of 1.0-5.0. Total soluble protein (SP) in 50% 1-propanol was separated into albumins and globulins (AG), gliadins, and soluble polymeric proteins (SPP) using size exclusion high-performance liquid chromatography (SE-HPLC). Insoluble polymeric protein (IPP) was determined by combustion assay of the residue. Protein composition varied with flour protein content because SP and gliadin levels increased proportionally to increased protein content, but AG, SPP, and IPP levels did not. Flour protein content was positively correlated with loaf volume and bake water absorption (r = 0.80, P<0.0001 and r = 0.45, P<0.01, respectively). The percent SP based on flour showed the highest correlation with loaf volume (r = 0.85) and low but significant correlation with crumb grain score (r = 0.35, P<0.05). Percent gliadins based on flour and on protein content were positively correlated to loaf volume (r = 0.73, P<0.0001 and r = 0.46, P <0.001, respectively). The percent IPP based on flour was the only protein fraction that was highly correlated (r = 0.62, P<0.0001) with bake water absorption followed by AG in flour (r = 0.30, P<0.05). Bake mix time was correlated positively with percent IPP based on protein (r = 0.86) but negatively with percent SPP based on protein (r = -0.56, P<0.0001).