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In a two-year field trial, the effect of nitrogen (N) and sulfur (S) fertilization was investigated on grain yield, grain quality parameters, formation of acrylamide (AA), and the precursor free asparagine (Asn) in organically and conventionally produced winter wheat cultivars. In both production systems, different types, amounts, and temporal distributions of N were tested. The the effect of S fertilizer types and amounts on free Asn was only tested in the conventional farming system. Within both cropping systems, grain yield and baking quality were significantly influenced by N treatment while the effect on free Asn was only minor. Especially within the organic farming system, increasing N fertilization levels did not increase free Asn significantly. A slight trend of increasing free Asn levels with an intensified N supply was observed, especially in the presence of crude protein contents of 14% or higher. However, only N amounts of 180 kg N ha−1 or higher increased the probability of high free Asn contents considerably, while N supply below that amount led to free Asn values similar to the unfertilized controls. The results indicated that good baking quality can be achieved without significantly increasing free Asn levels. In addition, cultivars affected the levels of free Asn significantly. Compared to cv. Bussard and Naturastar, cv. Capo exhibited the lowest AA formation potential at an N supply of 180 kg N ha−1 while simultaneously reaching a crude protein content > 15% (conventional) and > 12% (organic). Thus, it seems that cultivars differ in their ability to store and incorporate free Asn into proteins. Over all trials, a relation of free Asn and AA was shown by R2 = 0.77, while a relation of free Asn and protein was only R2 = 0.36. Thus, lowering free Asn by adjusting N treatments should not necessarily affect baking quality. S fertilization within conventional farming did not change the free Asn amount or crude protein significantly, probably due to the fact that soil was not sulfate-deficient. In summary, it was evident that free Asn amounts in wheat varied widely both within cultivars and between cropping systems. In order to clearly unravel genotypic differences and their interaction with environmental factors and especially N fertilization, further research is needed.

This study investigated the impact of organically grown cereals on the level of free asparagine (Asn) with simultaneous consideration of grain yields and flour qualities over three growing seasons in Germany. Additionally, the relation of free Asn and acrylamide (AA) was investigated. By including free Asn results of a second trial site, heritability of the trait free Asn was calculated. Free Asn was significantly influenced by species and within species by cultivars. Rye showed the highest free Asn amount, followed by einkorn, emmer, wheat, and spelt. Replacing rye with spelt would reduce free Asn by 85%. Cultivars differed in free Asn by up to 67% (wheat), 55% (spelt), and 33% (rye). Year significantly influenced free Asn levels. Heritability was high for wheat and spelt concerning locations, but regarding years, heritability was low for wheat but high for spelt and rye. For organically grown cereals, the relation between free Asn and AA formation has never been investigated. Across species and years, a correlation of R2 = 0.69 *** was found. Thus, free Asn can serve as an indicator for AA formation. In conclusion, the level of free Asn can be highly influenced by proper selection of species and cultivars.

The amino acid asparagine (Asn) plays a key role in acrylamide (AA) formation in strongly heated cereal foodstuffs. The influence of different nitrogen (N) fertilizers (calcium ammonium nitrate, CAN; urea ammonium sulfate solution, UAS, applied according to the CULTAN method; urea; urea ammonium nitrate, UAN; ammonium nitrate sulfate containing the nitrification inhibitor 3,4‐dimethyl pyrazole phosphate, Entec 26®; and a combination of liquid manure and CAN) at a nitrogen level of 180 kg N ha–1 and an additional sulfur (S) supply on grain yield, quality, Asn concentration, and the potential of AA formation of winter wheat were studied in a 2‐year field experiment. Grain yields varied between 61 und 104 dt ha–1 dry matter depending on cultivar (cv), fertilization, and year. Quality demands concerning crude protein concentration and sedimentation value were reached when CAN, CAN+S, urea, or a combination of liquid manure and CAN were applied. Asparagine concentrations in flours varied from 2.6 to 13.6 mg per 100 g flour dry matter depending on cultivar, fertilization, and year. In both years, a close nonlinear correlation between crude protein concentration and the concentration of free Asn with r²2004 = 0.93 and r²2005 = 0.94 was observed. Nitrogen fertilizers leading to high crude protein concentrations caused significantly increased Asn concentrations. In both years, a correlation between the concentration of free Asn and the potential of AA formation with r²2004 = 0.72 and r²2005 = 0.84 was found. The application of S (CAN compared to CAN+S) had no beneficial effect on the Asn concentration and the potential of AA formation, most likely because S concentration in grains was sufficient even without additional S supply.