The Characterization by Electrophoresis of the Proteins Extracted by Dilute Alkali From Wheat Flour

The fate of oxidised glutathione (GSSG) mixed with dough has been investigated using W-fabelled GSSG. It was found that over 50 % of the fabet became bound by a disulphide bond to protein during the mixing of dough. The water-soluble proteins bound more glutathione, especially in the initial stages of mixing, than did the gluten proteins. The binding was partly reversible under normal doughing conditions.A new hypothesis is presented concerning the role of thiol-disulphide exchange reactions in afecting the rheological properties of dough. The hypothesis recognises the apparent importance of thioldisulphide exchange reactions, but does not involve the polymerisation of proteins by disulphide linkages. The change,from dry flour to wet dough will necessitate conformational re-arrangements in the proteins. The rate at which intramolecular disulphide bonds can be resorted will influence the rate of conformational re-arrangement.The hypothesis could account for the actions in dough of chemical improvers, thiol compounds, oxidising compounds, thiolblocking reagents and GSSG.Thiol groups will afect the kinetics of disulphide resorting.

Binding of oxidised glutathione to dough proteins and a new explanation, involving thiol disulphide exchange, of the physical properties of dough

Jones

Carnegie

1971

Effects of temperature, photoperiod, and light quantity on protein production in wheat grains

Kolderup

1975

Five varieties of common spring wheat were cultivated under controlled conditions at five temperatures from 12 to 24 "C. From the time of heading three day-length treatments were applied at each temperature: 10 h, 24 h, and natural day length. Nitrogen content in the grains increased by 46-124 % with increasing temperature, and also increased significantly with extension of the photoperiod. Natural days, supplying more light energy, gave lower nitrogen contents than the other treatments. Protein yields per pot were more constant. The relative amounts of lysine, valine, and threonine decreased with increasing temperature and extension of the photoperiod, while glutamic acid, proline, and phenylalanine increased. However, at the highest temperatures this trend was hardly apparent. Protein fractionation showed that the decrease in lysine was correlated with an increase in the ratio of alkali-soluble to salt-soluble proteins.

Gel formation in acidified aqueous suspensions of cereal flours

Jennings

1978

The amounts of gel formed when wheat flours are suspended in IM acetic acid or in phenol-acetic acid-water (1 : 1 : 1, w/v/v) are highly correlated with the total nitrogen contents and the Zeleny sedimentation values of the flours. It is concluded that the Zeleny sedimentation test depends on the formation of this gel. Gel formation in acidified aqueous suspensions is markedly affected by the ionic strength and pH of the suspending medium, but not by non-polar molecules or reagents that react specifically with sulphydryl groups or disulphide bonds. The gel is readily dispersed by ultrasonic treatment and gel formation is prevented completely by the amounts of sodium chloride added to dough during breadmaking.