Partial removal of protein associated with arabinoxylans: impact on the viscoelasticity, crosslinking content and microstructure of the gels formed

Authors: MENDEZ-ENCINAS, MAYRA - Center For Research In Food And Development (CIAD); CARVAJAL-MILLAN, ELIZABETH - Center For Research In Food And Development (CIAD); Yadav, Madhav; KALE, MADHUVANTI - Z-Trim Holdings, Inc; LÓPEZ-FRANCO, YOLANDA - Center For Research In Food And Development (CIAD); RASCON-CHU, AGUSTÍN - Center For Research In Food And Development (CIAD); LIZARDI-MENDOZA, JAIME - Center For Research In Food And Development (CIAD); BROWN-BOJORQUEZ, FRANCISCO - Universidad De Sonora; SILVA-CAMPA, ERIKA - Universidad De Sonora; PEDROZA-MONTERO, MARTÍN - Universidad De Sonora

Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2018
Publication Date: 3/1/2019
Publication URL: https://handle.nal.usda.gov/10113/6479674
Citation: Mendez-Encinas, M.A., Carvajal-Millan, E., Yadav, M.P., Kale, M., López-Franco, Y., Rascon-Chu, A., Lizardi-Mendoza, J., Brown-Bojorquez, F., Silva-Campa, E., Pedroza-Montero, M. 2019. Partial removal of protein associated with arabinoxylans: impact on the viscoelasticity, crosslinking content and microstructure of the gels formed. Journal of Applied Polymer Science. 47300:1-10.

Interpretive Summary: Arabinoxylans (AXs) are plant cell wall carbohydrate polymers. They can be extracted from low value agricultural and industrial by-products such as cereal brans, crop residues and distiller’s dried grains with solubles (DDGS). The DDGS is a byproduct of fuel ethanol production from corn and other grains. Some AXs can form strong gels, which have potential applications as drug delivery matrices. In addition to sugars, AXs usually also contain small amounts of other components such as lignin, phenolic acids, and proteins. As reported by many researchers, AXs polymers may be linked with each other through phenolic groups to form gels. However, the role of the protein present on AXs on gel formation has not been studied. This prompted us to isolate AXs from corn DDGS and partially remove their protein by treating them with protease. The reduction in the amount of protein in AX was found to cause an increase in its gel strength and gel homogeneity. Protease treatment did not have any negative effect on its molecular structure. Thus, this technique of partial removal of protein can be useful in preparing gels with greater strength and more uniform structure. These findings improve our understanding of AX gels, and will help to increase utilization of these polymers in food and pharmaceutical applications. Thus these results may benefit US farmers as utilization of these products will ultimately improve the markets for agricultural by-products. It will also benefit the U.S. food and pharmaceutical industries and ultimately the U.S. economy.

Technical Abstract: Arabinoxylans (AX) treated with protease and dialysed (AXP) or only dialysed (AXD) formed gels showing a significant increase in the elastic modulus G’ (1291 and 1419 Pa respectively) and the ferulic acid dimers (3.34 and 3.10 ug/mg polysaccharide respectively) and trimers (0.57 and 0.53 ug/mg polysaccharide respectively) in comparison to untreated and non-dialyzed AX gels (767 Pa, 0.56 and 0.12 ug/mg polysaccharide respectively). Nevertheless, the G’ values and cross-linking contents were not statistically different among the AXP and AXD gels, suggesting that the amount of protein removed (54%) does not affect the gelling capability of the molecule. Confocal laser scanning microscopy analysis showed that AXP treatment promotes the continuity and homogeneity of the gel formed. In addition, scanning electron microscopy observations indicated that AXD and particularly AXP sample had a more homogeneous and compact gel microstructure. Thus, it is clear that the partial removal of the protein fraction associated with AX does not impact the viscoelasticity and cross-linking content of the gels formed but could improve their microstructural characteristics.