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BACKGROUND Whole‐grain wheat flour is facing the quality challenge of lipid rancidity, which decreases its nutritional, sensory, and technological properties. One of the major causes of lipid rancidity is endogenous esterases and lipases. This study evaluated 66 European wheat varieties grown at a single site over three years (2014, 2015, and 2016). RESULTS The 66 wheat varieties showed up to threefold variance on esterase and lipase activities. Wheat varieties that are suitable for lipid‐stable whole‐grain products (‘Julius’, ‘Lona’, and ‘Banquet’) were selected according to their consistently low esterase and lipase activities. The 3‐year mean‐based broad‐sense heritability of esterase and lipase was 0.75 and 0.44 respectively. CONCLUSIONS The findings indicate great genetic dependence of both esterase and lipase activities in wheat. The moderate to high heritability brings a new prospect of breeding selection of low‐lipase‐activity wheat for stable whole‐grain products. This result will improve the use of wheat as raw material, benefit cultivation selection, and provide consumers with better quality products. © 2020 Society of Chemical Industry

Lipid stability is one of the major determinants of the quality of wholegrain wheat flours. Wheat grains contain a wide range of metabolites, many of which have antioxidant activities and can inhibit lipid oxidation. Metabolomics offers an opportunity for a broad understanding of the metabolite profiles of wheat germplasm resources. In this study, untargeted liquid chromatography mass spectrometry was used to investigate the metabolite diversity of 65 European wheat varieties. The wheat varieties showed various metabolite profiles. Well-known antioxidants in wheat, such as ferulic acid, α-tocopherol, secoisolariciresinol, and apigenin-diglucoside, were tentatively detected and showed variance among the wheat varieties. Partial least-squares discriminant analysis was used to identify metabolite features associated with the differential oxidative stability of 20 wheat varieties. Tentative markers suggest that, besides the known antioxidants, other compounds may be relevant in predicting the stability of the wholegrain flour, though further study is necessary. The findings build a preliminary foundation of wheat variety selection for stable wholegrain use.

Lipase activity is one of the main causes of the lipid rancidity in wholegrain wheat flour, leading to its short shelf life. Genetically diverse wheat germplasm offers potential for the selection of wheat cultivars with low lipase activity for stable wholegrain end use. This study evaluated 300 European wheat cultivars harvested in 2015 and 2016 on the genetic association of lipase and esterase activities in wholegrain wheat flour. Esterase and lipase activities in wholegrain flour were measured photometrically with p-nitrophenyl butyrate and p-nitrophenyl palmitate as substrates, respectively. Both enzyme activities showed wide ranges among all cultivars within each year, with differences up to 2.5-fold. The two years showed low correlations between each other, indicating a large environmental impact on the enzyme activities. Cultivars ‘Julius’ and ‘Bueno’ were suggested to be better suited for stable wholegrain products, as they had consistently low esterase and lipase activities compared to the other cultivars. A genome-wide association study revealed associations with single nucleotide polymorphisms in genes located on the high-quality wheat genome sequence of the International Wheat Genome Sequencing Consortium. Eight and four candidate genes were tentatively proposed to be associated to esterase and lipase activity, respectively, in wholegrain flour. Our work shows esterase and lipase activities from a new perspective, that combines reverse genetics to understand the underlying causes. This study outlines the possibilities and limitations to improve lipid stability of wholegrain wheat by genomics-assisted breeding methods, thereby offering new opportunities to optimize the quality of wholegrain wheat flour and wholegrain products.