Abstract
Optimizing the bread-making quality properties of flour is currently one of the main aims of the bakery industry. Therefore, this study has investigated the effects of N fertilization and fungicide application at wheat heading on the protein content (GPC), gluten composition and rheological properties of wheat. Field experiments were carried out in North-West Italy over a 3 year period, on a high protein cultivar of soft winter wheat. Grain samples were collected for each agronomic treatment at four ripening timings, from the milk stage to the final combine harvesting, and the contents of the different gluten fractions were quantified. The late N fertilization increased the GPC (+1.2%) and dough strength (W) (+22%) as a result of a similar enhancement of all the gluten protein fractions, while the fungicide application slightly reduced the GPC (−0.3%) and W (−4%), mainly because of a dilution of the gliadin content, due to the significantly higher grain yield (+8.6%) and thousand kernel weight (+5.5%). These agronomic practices did not modify the gluten composition significantly, expressed as the relative ratio between the gliadins (glia) and the high (HMW) and low (LMW) molecular weight glutenins (gs), and confirmed by the accumulation trend of the different protein fractions during ripening. The year resulted to have the most marked effect on the gluten protein fraction ratios and alveographic parameters. The lowest W was observed in 2015, and although the highest GPC was recorded for the same year, the lowest gs/glia ratio was also observed. Instead, 2016 showed the highest gs/glia and HMW-gs/LMW-gs (H/L) ratios, and also the highest P/L value (2.2). In 2015, a slightly higher temperature during the ripening stage resulted in a greater increase in the γ-gliadin enriched fraction than the α/β gliadin ones, and marked differences were noted in the rheological traits. This field experiment has highlighted the interactive role of environmental and agronomic factors on the content and quality of gluten proteins and their bread-making ability, thus making a further contribution to the development of an integrated crop strategy for the cultivation of high protein wheat in humid Mediterranean areas.
Highlights
Wheat is the crop that is cultivated the most throughout the world and it is a staple food in many countries
This study has investigated the effects of N fertilization and fungicide application at wheat heading on the protein content (GPC), gluten composition and rheological properties of wheat
The continuous search for the optimal conditions to maximize grain yield and obtain satisfactory bread-making properties in wheat makes the study of the role of agronomic practices in a specific environment of fundamental importance
Summary
Wheat is the crop that is cultivated the most throughout the world and it is a staple food in many countries. The improvement in the GPC content after a late fertilizer application is due to a higher N availability, which, considering the mobility of this element in the soil, is limited by the source and the timing of the N supply [7] Both the N uptake in vegetative organs in the pre-anthesis period, which is remobilized during grain filling, and the amount of N absorbed during ripening and directly transported to the kernels, provide an accumulation of grain storage gluten proteins [10]. The timing of the accumulation of the different gluten protein fractions during grain development seems to be fundamental to determine the structural–thermal gluten properties and the wheat quality, and to provide useful indicators of the technological quality of dough [16]
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