Effects of growing environment, genotype, and commercial fertilization levels on free asparagine concentration in Western Canadian wheat

Abstract

Background and objectives Free asparagine (ASN) is the precursor to the formation of acrylamide, which is a probable neurotoxic and carcinogenic compound formed during high‐temperature (>120°C) processing of starchy foods, such as cereal‐based products. Controlling the acrylamide concentration of cereal‐based products, for example, bread, within the allowable levels established by the European Commission, is necessary for food safety purposes. One effective measure recommended by the European Commission to mitigate acrylamide in cereal‐based products is to reduce free ASN levels in raw ingredients, for example, wheat. Therefore, knowledge of free ASN levels in Canadian commercial wheat and the strategies to reduce its formation is necessary for the Canadian wheat industry to secure global market access for Canadian wheat. The objective of this study was to understand the effects of genotype, growing environment, and fertilization on free ASN concentration of whole‐wheat flour from Western Canadian wheat varieties. Findings The free ASN concentration of whole‐wheat flours in this study ranged from 281 to 1,014 µg/g (dry basis). The variation in free ASN levels in wheat was mainly influenced by the growing environment (44%), followed by genotype (31%) and the interaction between genotype and environment (18%). Although being significant, the effects of fertilization and interactions involving fertilization on free ASN concentration in whole‐wheat flour were minimal (0.7%–2.2%). Conclusion Growing wheat genotypes in suitable environments, along with the selection of wheat genotypes with lower potential for free ASN formation, are the most effective strategies to control free ASN levels in Canadian wheat. Significance and novelty Limited knowledge in regard to free ASN concentration and the strategies to reduce its formation in Canadian wheat may have a serious impact on Canadian wheat access to global markets, especially the European market. This study provides an understanding of the effects of growing environment, genotype, and fertilization on free ASN concentration of select Western Canadian commercial wheat varieties.

Understanding the Relationships between Free Asparagine in Grain and Other Traits to Breed Low-Asparagine Wheat

“…Positive correlations between free asparagine and yield have indeed been found ( Table 3 ) but, perhaps surprisingly, these correlations have not been consistent across studies. Xie et al [ 44 ], for example, found that free asparagine (measured in milligrams per gram of protein) was negatively correlated with grain yield in one year when the yield was low (between two and four tonnes per hectare), but positively associated in another year, when the yield was higher (between four and eight tonnes per hectare), suggesting a non-linear relationship. A reduction in plant stress could explain the negative correlation observed over lower yield values, whilst the positive correlation could be due to greater nitrogen availability in the soil.…”

Asparagine and dough quality: Gluten strength relationships in hard red spring wheat

“…For the same wheat samples used in this study, Xie et al (2021) reported that free asparagine was significantly ( p < .0001) affected by E, G, F, and their interactions (G × E, G × F, E × F, and G × E × F). Among these factors, E, G, and G × E had the largest effects on free asparagine content with percent total variances of 44, 31, and 18%, respectively (Xie et al, 2021).…”

“…For the same wheat samples used in this study, Xie et al (2021) reported that free asparagine was significantly ( p < .0001) affected by E, G, F, and their interactions (G × E, G × F, E × F, and G × E × F). Among these factors, E, G, and G × E had the largest effects on free asparagine content with percent total variances of 44, 31, and 18%, respectively (Xie et al, 2021). Previous studies in Europe and North America have also shown significant effects of growing conditions, genotype, and fertilization treatments on wheat free asparagine concentration (Corol et al, 2016; Curtis et al, 2009; Ohm et al, 2017).…”

“…All varieties were grown at four location-years in Manitoba, Canada: Carberry and Lilyfield were the locations for 2018, and Grosse Isle and Lilyfield the growing locations for 2019. Complete information on growing conditions for these four location-years is provided by Xie et al (2021). For all genotypes and location-years, four fertilization treatments were applied, two nitrogen levels (100 or 135 kg ha −1 ) and two sulfur levels (0 or 17 kg ha −1 ).…”

“…However, factors that affect free asparagine concentration, that is, environment (Corol et al, 2016; Xie et al, 2021), genotype (Curtis et al, 2009; Xie et al, 2021), and availability of sulfur and nitrogen to the wheat plant (Corol et al, 2016; Lea et al, 2007) also affect protein content and composition in the wheat grains. Thus, it is essential to investigate whether approaches to reduce free asparagine concentration in wheat, through judicious selection of wheat varieties for growth in specific environments as well as fertilization treatments, pose detrimental effects to gluten strength and, consequently, to bread quality.…”