|YAZAR, GAMZE - University Of Idaho|
|KOKINI, JOZEF - Purdue University|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2021
Publication Date: 7/29/2021
Citation: Yazar, G., Kokini, J.L. and Smith, B., 2022. Effect of endogenous wheat gluten lipids on the non-linear rheological properties of the gluten network. Food Chemistry, 367, p.130729. https://doi.org/10.1016/j.foodchem.2021.130729
Interpretive Summary: Commercial vital wheat gluten was used to study the impact of endogenous wheat gluten lipids on mixing behavior, thermal properties, and non-linear rheological properties of gluten networks. Mixing properties revealed striking differences in hydration dynamics and consistencies of gluten and lipid-removed gluten, meaning endogenous wheat lipids having critical functional role at very low levels. Removal of lipids also affected thermal properties of gluten proteins by increasing denaturation temperatures. Endogenous lipids allowed for greater extensibility and lower elasticity of wheat gluten. Endogenous wheat lipids in vital wheat gluten were found to control the affinity of gluten proteins to water and thus affect thermal characteristics and rheological behavior of the gluten network, which both contribute to baked product quality.
Technical Abstract: Commercial vital wheat gluten was used to study the impact of endogenous wheat gluten lipids on mixing behavior, thermal properties, and non-linear rheological properties of gluten network. For this purpose, endogenous lipids were extracted from vital wheat gluten (VWG) with 95% ethanol. Farinograms revealed striking differences in hydration dynamics and consistencies of VWG and lipid-removed vital wheat gluten (LRVWG) due to endogenous wheat lipids having strong functionality at very low levels. The development time (reaching 500 BU consistency) was reached 4 minutes earlier and consistency increased constantly as mixing proceeded indicating a higher affinity to water for gluten proteins in the absence of endogenous lipids. DSC results supported Farinograph data and suggested higher denaturation temperature for VWG (69.2±1.23 °C) due to reduced water affinity as a result of protein-lipid interactions when compared with LRVWG (63.6±0.25 °C). Large Amplitude Oscillatory Shear (LAOS) tests suggested a mixture of type III (weak strain overshoot) and type IV (strong strain overshoot) non-linear behavior for gluten with a higher tendency to type III behavior for VWG indicating more extensibility in the presence of lipids. Narrower elliptical trajectories of the normalized elastic Lissajous-Bowditch curves, higher intracycle stress magnitude and reduced clockwise rotation of the un-normalized stress-strain loops, higher difference between the magnitudes of G'L and G'M (G'L > G'M), lower phase angle values obtained for LRVWG under large deformations pointed out a more elastic network with a higher degree of strain stiffening when compared to VWG.