Location: Grain Quality and Structure ResearchTitle: Interaction mechanisms of condensed tannins (proanthocyanidins) with wheat gluten proteins Author
|Girard, Audrey - Texas A&M University|
|Tilley, Michael - Mike|
|Awika, Joseph - Texas A&M University|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2017
Publication Date: N/A
Interpretive Summary: Sorghum tannins have been shown to crosslink wheat gluten in previous research. However, the mechanism behind tannin-gluten crosslinking is not known. This study used isolated tannins that varied in their size to investigate the interaction between tannin and gluten proteins. Larger tannins had greater interaction with gluten proteins. Within the gluten proteins, a specific subset of proteins was found to preferentially bind to the tannins. Overall it appears that tannins preferentially interact with and cross-link specific gluten proteins through non-covalent interactions. This information can be used to help tailor tannin-gluten interactions to alter functionality of wheat flour.
Technical Abstract: Proanthocyanidins (PA) crosslink wheat gluten, increasing its polymer size and strength. However, precise mechanisms behind these interactions are unknown. This study used PA of different MW profiles (mDP 8.3 and 19.5) to investigate the interactions involved in PA polymerization of gluten. The higher MW PA had greater binding affinity for both glutenins and gliadins than lower MW PA, whereas both PA had higher affinity for glutenins over gliadins. The PA preferentially bound the largest of the protein fractions available: high MW glutenin subunits (HMW-GS) over low MW-GS, and '-gliadins over a- and '-gliadins. Furthermore, within the HMW-GS, PA bound more of the larger x-type than the smaller y-type. PA significantly decreased surface hydrophobicity in gluten and glutenin fractions, but not gliadins. Overall data suggests that PA preferentially crosslinks HMW-GS via hydrophobic interactions and hydrogen bonding, whereas the PA interaction with gliadins is dominated by hydrogen bonding and is relatively weaker.