Response of Wheat Storage Proteins and Breadmaking Quality to Dimethylpyrazole-Based Nitrification Inhibitors under Different Nitrogen Fertilization Splitting Strategies

Improving fertilizer nitrogen (N) use efficiency is essential to increase crop productivity and avoid environmental damage. This study was conducted during four crop cycles of winter wheat under humid Mediterranean conditions (Araba, northern Spain). The effects of N-fertilization splitting and the application of the nitrification inhibitors (NIs) 3,4-dimethylpyrazole phosphate (DMPP) and 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) as strategies to improve grain quality were examined. The hypothesis of this study was to test if the partial ammonium nutrition and the reduction of fertilizer losses presumably induced by the application of NIs can modify the grain gliadin and glutenin protein contents and the breadmaking quality (dough rheological properties). Among both NIs assayed, only DMPP showed a slight effect of decreasing the omega gliadin fraction, following splitting either two or three times, although this effect was dependent on the year and was not reflected in terms of dough extensibility. The slight decreases observed in grain quality in terms of dough strength and glutenin content induced by DMPP suggest that DMPSA is more promising in terms of maintaining grain quality. Nonetheless, these poor effects exerted by NI application on grain quality parameters did not lead to changes in the quality parameters defining the flour aptitudes for breadmaking.

Differences in Processing Quality Traits, Protein Content and Composition between Spelt and Bread Wheat Genotypes Grown under Conventional and Organic Production

The unique rheological properties of bread wheat dough and the breadmaking quality of its flour are the main factors responsible for the global distribution and utilization of wheat. Recently, interest in the production and expansion of spelt wheat has been boosted due to its significance in the production of healthy food, mostly originated from organic production. The aim of this study was to examine and compare quality parameters (gluten content, Zeleny sedimentation volume, farinograph dough properties), protein content and composition (by the Dumas method, Size Exclusion (SE) and Reversed Phase (RP) High Performance Liquid Chromatography (HPLC) analyses) of five bread and five spelt wheat varieties grown under conventional and organic production in Hungary and under conventional production in Serbia. Most of the analyzed traits showed significant differences between varieties, wheat species and growing sites. Total protein content was significantly higher in spelt than in bread wheat and under conventional than under organic production. In comparison to spelt, bread wheat showed better breadmaking quality, characterized by a higher amount of glutenins (in particular high molecular weight glutenin subunits) and unextractable polymeric proteins. The proportion of the gliadins was also found to be different under conventional and organic systems. Spelt Ostro and Oberkulmer-Rotkorn and bread wheat varieties Balkan, Estevan and Pobeda proved suitable for low input and organic systems.

IMPROVING THE BREAD QUALITY OF SUNI-BUG DAMAGED WHEAT FLOURS BY SOURDOUGH BREADMAKING AND LIQUID RYE SOUR

The breadmaking quality of bug-damaged wheat flours with high protease activity (HPAWF) and low protease activity (LPAWF) was attempted to be improved by using sourdough (prepared by L. plantarum (SD1) and L. sanfrancissensis (SD2)) and liquid rye sour (LRS) in this study. The effects of sourdoughs (20 and 40%) and LRS (1 and 2%) on the protease activity of the HPAWF were determined by SDS-PAGE. Protease activity of HPAWF decreased with the addition of 40% SD1, 20% SD2, and both levels of LRS (1 and 2%) compared to a control sample. The HPAWF bread samples produced with LRS (1 and 2%) had higher volume (P<0.05) and bread quality as compared to sourdough applications. LPAWF bread sample was comparable with those of 40% SD2 added sample in terms of volume and hardness (N) values (P>0.05), while SD1 addition caused quality losses. The overall results suggested that addition of 2% LRS had promising results for improving bread quality flours that were damaged by suni-bug at low levels.

High-Molecular-Weight Glutenin 1Bx17 and 1By18 Subunits Encoded by Glu-B1i Enhance Rheological Properties and Breadmaking Quality of Wheat Dough

The elasticity of wheat dough is mainly determined by high-molecular-weight glutenin subunits (HMW-GSs) encoded by Glu-1 loci. In this study, we performed the first comprehensive study on the effects of Glu-B1i-encoded 1Bx17 and 1By18 subunits on dough rheological properties and breadmaking quality by using a pair of Glu-B1 near-isogenic lines (NILs) ZM-NIL1 and ZM-NIL2. Comparative analysis of basic quality parameters, rapid visco analyzer (RVA) and farinograph parameters, and C-cell and loaf parameters showed that ZM-NIL2 containing Glu-B1i-encoded 1Bx17 and 1By18 subunits had better dough rheological properties and breadmaking quality than ZM-NIL1 carrying Glu-B1c-encoded 1Bx7 and 1By9 subunits, including significantly increased protein and gluten content, development time and stability, and loaf volume and score. Particularly, 1Bx17 and 1By18 subunits could significantly enhance bread texture, including significant increase in slice brightness, slice area, circumference, cell contrast, cell extension, and cell quantity. These results demonstrate that 1Bx17 and 1By18 subunits have a significant contribution to dough rheological properties and breadmaking quality.