Observations on the quality characteristics of waxy (amylose-free) winter wheats

Authors: Graybosch, Robert; Ohm, Jae-Bom; Dykes, Linda

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2016
Publication Date: 11/7/2016
Publication URL: http://handle.nal.usda.gov/10113/5581431
Citation: Graybosch, R.A., Ohm, J., Dykes, L. 2016. Observations on the quality characteristics of waxy (amylose-free) winter wheats. Cereal Chemistry. 93(6):599-604.

Interpretive Summary: Previous investigations have suggested waxy (amylose-free) wheats (Triticum aestivum L.) possess weak gluten properties, and may not be suitable for commercial gluten extraction. This would limit the use of waxy wheat as a source of unique starch, as gluten is a by-product of the wheat starch purification process. Fifty waxy wheat lines were used to determine to what extent gluten protein and other grain quality related traits might vary, and consequently, allow the development of waxy wheat with acceptable gluten properties. Among the waxy lines, significant variation was observed for all measured quality traits with the exception of flour protein concentration. No waxy entries statistically equaled the highest ranking non-waxy entry for grain volume weight, falling number, flour yield or mixograph mix time. No waxy lines numerically exceeded or equaled the non-waxy mean for falling number, flour yield or mixograph mix time. For grain and flour protein related variables, however, many waxy lines were identified well within the range of acceptability, relative to the non-waxy controls used in this study. Approximately 50% of the waxy lines did not differ from the highest ranking non-waxy cultivar for grain and flour protein concentrations. Forty-three (86%) of the tested waxy lines were not significantly different from the non-waxy line with the highest mixograph mixing tolerance, and 22/50 (44%) of the waxy wheat lines did not differ from the highest ranking non-waxy line in gluten index scores. All waxy experimental lines tested produced gluten via Glutomatic washing. The quality of the gluten, as measured both by mixograph and gluten index, varied widely among the waxy lines tested, and waxy lines not statistically different from the highest ranking control non-waxy cultivars were identified. These observations suggest that weak gluten is not a natural consequence of the waxy trait, and waxy cultivars with acceptable gluten properties can be developed.

Technical Abstract: Previous investigations have suggested waxy (amylose-free) wheats (Triticum aestivum L.) possess weak gluten properties and may not be suitable for commercial gluten extraction. This limitation could prevent the use of waxy wheat as a source of unique starch, because gluten is a by-product of the wheat starch purification process. Fifty waxy wheat lines were used to determine the extent to which gluten protein and other grain quality related traits might vary and, consequently, allow the development of waxy wheat with acceptable gluten properties. Among the waxy lines, significant variation was observed for all measured quality traits with the exception of flour protein concentration. No waxy entries statistically equaled the highest ranking nonwaxy entry for grain volume weight, falling number, flour yield, or mixograph mix time. No waxy lines numerically exceeded or equaled the mean of the nonwaxy controls for falling number, flour yield, or mixograph mix time. For grain and flour protein related variables, however, many waxy lines were identified well within the range of acceptability, relative to the nonwaxy controls used in this study. Approximately 50% of the waxy lines did not differ from the highest ranking nonwaxy cultivar for grain and flour protein concentrations. Forty-three (86%) of the tested waxy lines were not significantly different from the nonwaxy line with the highest mixograph mixing tolerance, 22/50 (44%) of the waxy wheat lines did not differ from the highest ranking nonwaxy line in gluten index scores, and 17/50 (34%) did not differ from the highest ranking nonwaxy line in extracted wet gluten. All waxy experimental lines produced gluten via Glutomatic washing. The quality of the gluten, as measured both by mixograph and gluten index, varied widely among the waxy lines tested. These observations suggest that weak gluten is not a natural consequence of the waxy trait, and waxy cultivars with acceptable gluten properties can be developed.