Journal of Cereal Science 30 (1999) 19–31 Article No. jcrs.1998.0244, available online at http://www.idealibrary.com on Variation in the Breadmaking Quality and Rheological Properties of Wheat in Relation to Sulphur Nutrition under Field Conditions F. J. Zhao*, S. E. Salmon†, P. J. A. Withers‡, J. M. Monaghan§, E. J. Evans§, P. R. Shewry¶ and S. P. McGrath* * IACR-Rothamsted, Soil Science Department, Harpenden, Herts, AL5 2JQ, U.K.; † Campden & Chorleywood Food Research Association, Chipping Campden, Gloucestershire, GL55 6LD, U.K.; ‡ ADAS Bridgets, Martyr Worthy, Winchester, Hants, SO21 1AP, U.K.; § University of Newcastle-upon- Tyne, Department of Agriculture, NE1 7RU, U.K.; ¶ IACR-Long Ashton, Department of Agricultural Sciences, University of Bristol, Long Ashton, Bristol, BS18 9AF, U.K. Received 18 March 1998 ABSTRACT Seven field experiments were conducted at four sites in England in the 1994/95 and 1995/96 cropping seasons to investigate the effects of S application on the breadmaking quality of the premium hard winter wheat variety Hereward. Two N levels (180 and 230 kg/ha) were combined with three S levels (0, 20 and 100 kg/ha) in all experiments. Loaf volume was increased significantly by S in four out of the seven experiments, whereas increasing the N rate significantly increased loaf volume in only one experiment. Responses of breadmaking quality to S were more common than responses in terms of grain yield. Sulphur application did not affect grain protein concentration directly, but tended to increase gel protein weight in flour and the proportion of polymeric proteins. The elastic modulus of gel protein and dough resistance were decreased consistently by S, whereas dough extensibility was increased by S. Correlation and regression analyses showed that grain protein concentration was a poor indicator of loaf volume, whereas grain S status (S concentration and N: S ratio) was more influential. These results indicate that there is a current need to apply S fertiliser to wheat in many areas of England in order to maintain breadmaking quality.  1999 Academic Press Keywords: sulphur, nitrogen, wheat, breadmaking quality. molecule (intra-chain) or linking two protein sub- INTRODUCTION units (inter-chain). Viscosity (extensibility) of It has been established that the sulphur (S) nu- dough is mainly attributed to the monomeric gli- trition of wheat has an important influence on the adins, which form only intra-chain or no disulphide breadmaking quality of flour 1 . This is due to the bonds, whereas dough elasticity is primarily as- essential role of disulphide bonds in maintaining sociated with the polymeric glutenins, which form gluten functionality 2 . Disulphide bonds are formed both intra- and inter-chain disulphide bonds 2 . It from cysteine residues, either within the same is the balance between viscosity and elasticity that determines the suitability and quality of wheat flour for different end uses. Several studies have shown that S deficiency Corresponding author: Dr F. J. Zhao. Tel: 01582 763133 Ext 2667; Fax: 01582 760981; E-mail: Fangjie.Zhao@bbsrc.ac.uk favours the synthesis of S-poor proteins, such as 0733–5210/99/040019+13 $30.00/0  1999 Academic Press