Free asparagine concentrations in Canadian hard red spring wheat cultivars
Malunga, L.N., Ames, N.P., Masatcioglu, M.T., Khorshidi, A.S., Thandapilly, S.J., Cuthbert, R.D., Sopiwnyk, E., Scanlon, M.G. (2019). Free asparagine concentrations in Canadian hard red spring wheat cultivars. Canadian Journal of Plant Science, [online] 99(3), 338-347. http://dx.doi.org/10.1139/cjps-2018-0134
Plain language summary
Food authorities have identified a health risk associated with the consumption of acrylamide, a compound that can be formed during heat processing (e.g. deep frying and baking) of some foods. This reaction requires the presence of free asparagine, which is an amino acid found in many staple foods in our diet such as wheat. In order to ensure the safety of products made with Canadian wheat, it is important to develop strategies to reduce the amount of free asparagine, which is a precursor to acrylamide. The objective of this research was to generate information about the levels of free asparagine found in Canadian wheat varieties and examine if relationships exist between free asparagine content and standard dough and bread making quality indices. The experiment involved analysing free asparagine content of both wholemeal and white flour milled from 30 Canadian Western Red Spring wheat varieties grown in the Prairie Provinces. Results showed that the free asparagine content of the wheat varieties ranged from 305 to 986 µg/ g for wholemeal, values which were similar to those reported for wheat grown in other parts of the world. The amounts of free asparagine in the white flour were lower 40 – 60 % lower, indicating that much of the wheat’s asparagine is accumulated in the kernel’s outer layers. Statistical analysis of the data showed that free asparagine content was significantly affected by wheat variety, suggesting that breeding strategies could be investigated to produce wheat with lower levels of free asparagine. A number of tests to predict dough and bread baking quality were performed, but few were found to correlate significantly with asparagine content, suggesting that a class of wheat that has a reputation for good dough strength might not be prone to higher asparagine content. Overall, this study gives a first look at asparagine content in Canadian wheat and provides information to support the development of strategies for ensuring the safety of wheat-based food products and the marketability of Canadian wheat.
The amino acid asparagine is considered the rate limiting precursor in the formation of acrylamide in cereal-based baked foods. However, there are no data on the quantity of this precursor in Canadian wheat. Wholemeal and white flour samples obtained from 30 Canadian hard red spring wheat grown in the Prairie provinces were analysed for asparagine content by liquid chromatography. The asparagine content varied from 302 to 965 and 116 to 336 μg g−1 for wholemeal and white flour, respectively. Therefore, wheat grown in Canada has similar asparagine levels to wheat grown in other parts of the world. Analysis of variance suggested that asparagine content is significantly affected by genotype (p < 0.001), suggesting that breeding strategies could be investigated to produce cultivars with lower levels of this amino acid. Few significant correlations were observed between wheat and flour quality parameters and asparagine content, although there was a tendency towards weaker dough strength indices with increasing asparagine content.