Protein composition and agglomeration tendency of gluten isolated from European wheats (Triticum aestivum L.) in a batter system

Pilot scale isolation of gluten (with recovery of gluten on 400, 250, and 125 mu sieves) from flour prepared from six European wheat varieties (Apollo, Slejpner, Sperber, Camp Remy, Minaret, and Soissons) resulted in, on average, gluten yields of 9.6% (4.7-13.2% range). Gluten protein recoveries averaged 63.0% (34.5-85.7% range). Gluten yields and gluten protein recoveries were linearly related and increased when mixing times and baking absorptions required for optimal dough development of the parent flours increased, indicating that there is a relationship between the agglomeration properties of gluten proteins in a batter system and the optimal technological conditions necessary for processing the flours in breadmaking. The Osborne protein fractions in the gluten fractions were determined. The 0.05 M acetic acid soluble (glutenin) fraction was quantitatively the most important fraction (40-46% of gluten Kjeldahl nitrogen) while comparable levels of 70% ethanol soluble (gliadins) and 0.05 M acetic acid insoluble (residue protein) were found (17.9-22.3% of gluten Kjeldahl nitrogen and 22.0-29.0% of gluten Kjeldahl nitrogen for gliadins and residue protein, respectively). With decreasing pore size of the sieves, the level of glutenin in the gluten decreased while the level of gliadins increased. This indicates that, in gluten with good agglomeration properties, the level of glutenins is high and that the agglomeration properties of such proteins (i.e. their tendency to aggregate) strongly determines the agglomeration behavior of the gluten as a whole.