Rheological and emulsifying properties of arabinoxylans from various cereal brans

Authors: YAN, JINXIN - China Agricultural University; DENG, CHANGNING - China Agricultural University; ZHU, QIAOMEI - China Agricultural University; QIU, SHUANG - China Agricultural University; Yadav, Madhav; YIN, LIJUN - China Agricultural University

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2019
Publication Date: 9/18/2019
Citation: Yan, J., Deng, C., Zhu, Q., Qiu, S., Yadav, M.P., Yin, L. 2019. Rheological and emulsifying properties of arabinoxylans from various cereal brans. Journal of Cereal Science. 90:1-10. https://doi.org/10.1016/j.jcs.2019.102844.
DOI: https://doi.org/10.1016/j.jcs.2019.102844

Interpretive Summary: Cereal brans are abundant low-value resources that can be utilized to make functional products for food and industrial purposes. They are rich in cell wall material, and contain carbohydrates such as cellulose and hemicellulose (mainly composed of arabinoxylans,AXs). In addition to their major carbohydrate components, AXs usually also contain small amounts of other components such as lignin, phenolic acids, and proteins. Several studies have reported that AXs are bound to each other through phenolic groups to form gels. The importance of the functional phenolic groups and protein prompted us to develop conditions for making functional AXs from corn bran, wheat bran and sorghum bran with high protein and phenolic acids. In the current study we have found that AXs isolated at a lower temperature had more phenolic compounds and protein than the AXs extracted at a higher temperature. Also AXs obtained from red sorghum bran had a relatively higher content of ferulic acid and protein compared to the AXs from corn bran and wheat bran. The higher phenolic content in AXs from red sorghum bran gave it a better gel strength. These AXs can form strong gels, so they have potential to be used in drug delivery matrices. These findings improve our understanding of AX gels, and will help to increase utilization of these polymers in food and pharmaceutical applications. Due to the higher levels of protein and phenolic compounds in the AX from sorghum bran, it had a better emulsifying ability than the AXs from corn bran and wheat bran. Food industries will benefit by using such AXs from sorghum bran, which will help to reduce the amount of emulsifier needed to stabilize beverages and significantly decrease the cost of soft drink production. In this way it will increase the value of grain milling by-products benefiting U.S. grain processors and farmers. In addition, if these compounds are commercialized, revenue from their sale will help to reduce the cost of fuel ethanol prepared from corn, wheat and sorghum grains. These results may benefit farmers because utilization of these products will ultimately improve the markets for agricultural by-products.

Technical Abstract: The aim of this research is to investigate the molecular characteristics, rheological performance and emulsifying properties of arabinoxylans (AX) obtained from corn bran, wheat bran and red/white sorghum bran using two different extraction temperatures (25 degrees C & 85 degrees C). All AXs isolates had notable differences in molecular weight (MW), ranging from 13,400 Da (white sorghum bran AX extracted at 85 degrees C) to 545,000 Da (wheat bran AX extracted at 25 degrees C) and had a typical arabinoxylan structure. Both the glucose content and the arabinose/xylose (A/X) ratio in AXs from sorghum bran were higher than the AXs obtained from wheat bran and corn bran. Extraction at high temperature led to an increase in the yield of AXs and there was a significant difference in their compositions and functionalities. Rheological studies showed that the apparent viscosity of AX solutions was greatly influenced by pH (the highest viscosity was found at pH=4), and viscosity increased with concentration but decreased at higher temperature. Most of AX solutions displayed Newtonian behavior at a low concentration but shear-thinning behavior at a high concentration except corn bran AXs. Laccase oxidation promoted the crosslinking of cereal bran AXs, and the rheological results exhibited that a gel point appeared in red sorghum bran AX extracted at 25 degrees C. The AXs from sorghum bran had a better emulsifying ability and the O/W emulsions stabilized by these AXs possessed a smaller particle size, followed by corn bran AXs and wheat bran AXs.