In vitro digestibility and molecular weight distribution of proteins from historical and modern wheat cultivars

Authors: GULATI, PARIDHI - University Of Nebraska; BRAHMA, SANDRAYEE - University Of Nebraska; Graybosch, Robert; Chen, Yuanhong - Richard; ROSE, DEVIN - University Of Nebraska

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2020
Publication Date: 4/1/2020
Citation: Gulati, P., Brahma, S., Graybosch, R.A., Chen, Y., Rose, D.J. 2020. In vitro digestibility and molecular weight distribution of proteins from historical and modern wheat cultivars. Journal of the Science of Food and Agriculture. 100(6):2579-2584. https://doi.org/10.1002/jsfa.10283.
DOI: https://doi.org/10.1002/jsfa.10283

Interpretive Summary: Celiac disease and real or imagined non-celiac intolerance may be more prevalent than even in our recent ancestors. One hypothesis for this apparent trend suggests wheat breeding has led to a change in the digestibility of the gluten proteins found in wheat grain and all wheat-based food products. In the United States, wheat breeding, per se, did not commence until the mid-1940’s. Cultivars produced before that time all were selections from plant introductions or land-races. To investigate whether wheat breeding has in fact changed gluten digestibility, a study was designed to evaluate properties of flour samples derived from a collection of wheat cultivars. Cultivars included land-races introduced before the advent of wheat breeding, and various products of wheat breeding released from the 1940s until 2013. All cultivars were grown in uniform field trials near Mead, in eastern Nebraska. After harvest, samples were milled, and baked to bread. Breads were subjected to an in vitro (laboratory) digestibility assay. The protein digestibility of the breads was generally consistent for all cultivars, except for that of three older lines. These entries all had significantly lower digestibility. All post-1940 cultivars had similar digestibility, and these values exceeded those of the older wheat entries. Modern wheat breeding, therefore, seems to have had a positive and unifying effect on gluten digestibility.

Technical Abstract: BACKGROUND Previous research has suggested that proteins and other quality parameters of wheats may have changed over a century of wheat breeding. These changes may affect protein digestibility. The in vitro protein digestibility of breads made with 21 cultivars of wheat introduced or released in the USA between 1870 and 2013 was therefore evaluated. RESULTS Protein digestibility increased with release year, but was not normally distributed; three older cultivars had significantly lower digestibility than the other cultivars: 42.0 ±'0.3 mol% (primary amino N/total N) versus 34.7 ±'0.7 mol%; P <'0.001. High molecular weight (MW) protein fractions increased and low MW protein fractions decreased with release year, but these changes were not related to protein digestibility. Thus, other differences in protein composition or other flour components may contribute to diminished digestibility of the three older cultivars. CONCLUSIONS This study identified differences in protein digestibility among wheat cultivars that may have important implications for human nutrition. Further investigation is required to determine the specific characteristics that differentiate high- and low-digestibility wheat cultivars. © 2020 Society of Chemical Industry