Abstract:

The functions of high molecular weight glutenin subunit (HMW-GS) can be analyzed by determining the parameters subject to wheat (Triticum aestivum L.) quality. However, so far, only several glutenin subunits have verified in their functions despite a lot of subunits designated. Therefore, a simple and rapid method is highly needed to detect the functions of wheat glutenin subunits. The 2 g and 10 g Mixograph have been applied in related studies in Australia and other countries. To determine the function of wheat single HMW-GS, 6 subunits, 1Ax1, 1Dx5, 1Dy10, 1Bx7, 1By8, and 1By9, were separated and purified by SDS-PAGE, and then mixed into flour of Jing 411 individually. Their effects on flour mixing properties were investigated by 10 g Mixograph testing. The tested mixing parameters were mixing time, stability time, peak resistance, peak width, right slop, and width at 8 min. Four kinds of solution were applied to obtain an appropriate control, and the solutions consisted of different combinations of 0.2% acetic acid, 50 μg mL^-1 DTT, 200 μg mL^-1 KIO₃, and 0.1% SDS. When signal subunit was added into dough, 6 mixing parameters changed to a different degree. The effects of the 6 subunits on flour quality were ranked as 1Dy10 > 1Ax1 > 1Dx5 > 1By8 > 1Bx7 > 1By9 according to mixing time, and 1Ax1 and 1Dy10 > 1Dx5 > 1By9 > 1Bx7 > 1By8 according to stability time. The peak resistance of 1By8 was the biggest among that of all subunits. The right slop varied little among that of the 6 subunits. The width at 8 min of 1Bx7 was the smallest among that of all subunits. The 1By8 was primarily considered as a good quality subunit in this study. In addition, it is suggest that in vitro small-scale testing used in this study is an effective method to study the function of single HMW subunit.

Key words: Mixograph, HMW-GS, Mixing time, Stability time, Mixing tolerance