Gluten-like proteins, a common feature of pod bearing leguminous tree seed germs

Authors: MOSTAFA, TAGHVAEI - University Of Idaho; SMITH, BRENNAN - University Of Idaho; GAMZE, YAZAR - University Of Idaho; Bean, Scott; Tilley, Michael - Mike; Ioerger, Brian

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2021
Publication Date: 4/5/2021
Citation: Mostafa, T., Smith, B., Gamze, Y., Bean, S.R., Tilley, M., Ioerger, B.P. 2021. Gluten-like proteins, a common feature of pod bearing leguminous tree seed germs. PLoS ONE. https://doi.org/10.1371/journal.pone.0249427.
DOI: https://doi.org/10.1371/journal.pone.0249427

Interpretive Summary: The gluten proteins of wheat are unique in their ability to form viscoelastic dough and it is the dough forming ability of gluten that allows wheat to be made into a wide range of baked products such as breads, pasta, cookies, etc. The lack of proteins able to form dough is a major limitation in the production of baked products using non-wheat grains such as sorghum, rice, etc. However, isolated corn proteins and carob germ proteins have been found to be able to form weak wheat-like dough. Interesting carob germ flour proteins may form a dough through similar ways as wheat gluten. To determine if germ proteins in species related to carob may also have dough forming abilities, this research characterized protein and rheological properties from honey locust, mesquite, Kentucky coffee tree, and carob and compared the results to wheat gluten. This research will help identify novel sources of proteins for food use, provide additional information for how wheat gluten proteins function and provide information on how other non-wheat proteins can be modified to improve their functionality in baked foods.

Technical Abstract: The protein composition, molecular weight distribution, and rheological properties of honey locust, mesquite, Kentucky coffee tree, and carob seeds were compared against wheat gluten. Polymeric and Osborne fractionation protocols were used to assess biochemical properties. Dynamic oscillatory shear tests were performed to evaluate protein functionality. All samples had similar ratios of protein fractions as well as high molecular weight disulphide linked proteins except for the Kentucky coffee tree germ proteins, which were found to have lower molecular weight proteins with little disulfide polymerization. Samples were rich in acidic and polar amino acids (glutamic acid, arginine, and proline). Rheological analyses showed that vital wheat gluten had the most stable network, while Kentucky coffee seed proteins had the weakest. High molecular weight disulphide linked glutenous proteins are a common, but not universal feature of pod bearing leguminous trees.