Extraction and characterization of lipids and phenolic compounds from the brans of different wheat varieties

Authors: Yadav, Madhav; KAUR, AMRITPAL - Guru Nanak Dev University; SINGH, BALWINDER - Khalsa College; Simon, Stefanie; KAUR, NANCYDEEP - Guru Nanak Dev University; Powell, Michael; Sarker, Majher

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2021
Publication Date: 3/6/2021
Citation: Yadav, M.P., Kaur, A., Singh, B., Simon, S., Kaur, N., Powell, M.J., Sarker, M.I. 2021. Extraction and characterization of lipids and phenolic compounds from the brans of different wheat varieties. Food Hydrocolloids. https://doi.org/10.1016/j.foodhyd.2021.106734.
DOI: https://doi.org/10.1016/j.foodhyd.2021.106734

Interpretive Summary: Wheat bran, a by-product of the wheat dry milling process, is a good source of functional products with numerous health benefits. It contains water soluble carbohydrate polymer called arabinoxylan, which contains functional phenolic compounds and lipids. It has been well studied and reported that arabinoxylans are good flavor stabilizer. In this work the lipids and phenolic compounds from the brans of four wheat varieties and also from the arabinoxylans isolated from them are characterized. The phenolic compounds give an antioxidant capability to the bran and the arabinoxylan fraction isolated from them. Thus, the arabinoxylans, if added in beverage and other food products for stabilizing flavor, can provide an antioxidant capacity in the food products, where it will be added. The wheat brans are good dietary fiber. So, this dietary fiber with an antioxidant property will be a nutraceutical ingredient in the food products. This study can be of great value to the US and Indian agricultural industries and farmers by knowing the valuable properties of wheat brans and the arabinoxylans fraction isolated from them. It will also increase the value of wheat milling by-products benefiting U.S. and Indians wheat processors.

Technical Abstract: The lipids and phenolic compounds of wheat bran (WB) and hemicellulose B (water-extractable Hemi. B and alkali-extractable Hemi. B) fractions from four wheat varieties were investigated. The X-ray diffraction pattern and NMR spectra of those Hemi. B were also studied. The predominant lipid components identified in WB include triacylglycerols (41.58–53.24 wt. %) and free fatty acids (7.62–13.85 wt. %) with the highest content in HD-2967 and C-306 varieties (9.13 and 13.85 wt. %, respectively). The WE-Hemi. B had more lipids than the AE-Hemi. B fractions. The HD-3086 variety had the highest lipid content in its both its WE-Hemi. B and AE-Hemi. B fractions (6.60 and 3.19 wt. %, respectively). The bound phenolic content in WB was higher (1160 to 2848.88 µg GAE/g) than free phenolic content (564.17 to 724.72 µg GAE/g). The total antioxidant activity (TAA) of WB varied from 11.76 to 13.01 µmol TE/g. The bound protocatechuic and ferulic acids were the major phenolic acids with the highest content in WB of HS-490 and HD-2967 variety, respectively. The major flavonoid identified in WB was bound catechin (70.98 - 198.58 µg/g) with the highest content in HD-2967. The ferulic acid was quantified as major phenolic acid in Hemi. B fractions with a significantly higher level in WE-Hem-B (439.0 to 627.0 µg/g) compared to AE-Hemi. B (5.7 to 13.0 µg/g) fractions. The level of syringaldehyde varied from 0.8 to 1.4 µg/g in AE-Hemi. B while p-coumaric acid content in AE-Hemi. B and WE-Hemi. B varied from 0.2 to 0.3 and 5.8 to 9.7 µg/g, respectively. Sinapic acid and syringaldehyde were detected only in WE-Hemi. B fractions of HD-2967 and C-306 varieties. The X-ray diffractograms of WE-Hemi. B and AE-Hemi. B showed an amorphous profile with a broad peak in the region of 2' 15–23 deg. The structural elucidation of Hemi. B by proton NMR analysis indicated the xylose backbone with substitution mainly at C(O)-3 and/or C(O)-2 positions by arabinose residues and presence of esterified ferulic acid residues attached to arabinose side chains.