Genome-wide association study of lipase and esterase in wholegrain wheat flour (Triticum aestivum L.)

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.

Exploring genetic dependence of lipase activity to improve the quality of whole-grain wheat

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.

Effect of alkaline extraction pH on structure properties, solubility, and beany flavor of yellow pea protein isolate

In the current study, the impact of alkaline extraction pH (8.5, 9.0, and 9.5) on chemical composition, molecular structure, solubility and aromatic profile of PPI was investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the quantification of free sulfhydryl group and disulfide bond contents, size exclusion chromatography with multi-angle static light scattering and refractive index (SEC-MALS-RI), circular dichroism (CD) spectroscopy, and headspace solid phase micro extraction gas chromatography-mass spectroscopy (HS-SPME-GC-MS). We found that protein recovery yield increased from 49.20% to 57.56% as the alkaline extraction pH increased from 8.5 to 9.5. However, increasing the extraction pH promoted the formation of protein aggregates which decreased the percent protein solubility although there was no influence on protein secondary structure. PPI extracted at pH 9.0 possessed the lowest beany flavor as revealed by the selected six beany flavor markers including alcohols, aldehydes, ketones and pyrazine. The lowest lipoxygenase activity at pH 9.0 may contribute to the least beany flavor in PPI. Therefore, pH 9.0 was found to be the optimal condition for preparing premium PPI in terms of yield, functionality, and aromatic profile using alkaline extraction-isoelectric precipitation process. The findings could have fundamental implications for the preparation and utilization of pea proteins in food applications.

Effect of germination on the chemical composition, thermal, pasting, and moisture sorption properties of flours from chickpea, lentil, and yellow pea

Chemical composition, thermal, pasting, and moisture adsorption properties of flours from chickpea (Cicer aretinium L.), lentil (Lens culinaris Merr.), and yellow pea (Pisum sativum L.) were investigated over a 6-day germination. Protein content increased for pulses over germination while lentil had the highest protein content that increased from 30.65 to 33.60 g/100 g dry basis (d.b.). Lipid content in pulse flours decreased over germination with chickpea having the greatest decline, i.e. from 8.00 to 5.90 g/100 g (d.b.). Total starch decreased in lentil and yellow pea flours during germination, while there was no significant change (p > 0.05) in germinated chickpea flours. Thermal properties of pulse flours changed slightly, while pasting properties varied among pulses. The highest final viscosities for chickpea, lentil, and yellow pea flours were 1061, 981, and 1052 cP and were observed after 2, 1, and 0 days of germination, respectively. Moisture adsorption isotherms showed improved water adsorption capability after germination.

Genotype, environment, seeding rate, and top-dressed nitrogen effects on end-use quality of modern Nebraska winter wheat

BACKGROUND

Fine-tuning production inputs such as seeding rate, nitrogen (N), and genotype may improve end-use quality of hard red winter wheat (Triticum aestivium L.) when growing conditions are unpredictable. Studies were conducted at the Agronomy Research Farm (ARF; Lincoln, NE, USA) and the High Plains Agricultural Laboratory (HPAL; Sidney, NE, USA) in 2014 and 2015 in Nebraska, USA, to determine the effects of genotype (6), environment (4), seeding rate (3), and flag leaf top-dressed N (0 and 34 kg N ha^-1 ) on the end-use quality of winter wheat.

RESULTS

End-use quality traits were influenced by environment, genotype, seeding rate, top-dressed N, and their interactions. Mixograph parameters had a strong correlation with grain volume weight and flour yield. Doubling the recommended seeding rate and N at the flag leaf stage increased grain protein content by 8.1% in 2014 and 1.5% in 2015 at ARF and 4.2% in 2014 and 8.4% in 2015 at HPAL.

CONCLUSION

The key finding of this research is that increasing seeding rates up to double the current recommendations with N at the flag leaf stage improved most of the end-use quality traits. This will have a significant effect on the premium for protein a farmer could receive when marketing wheat. © 2017 Society of Chemical Industry.