Extraction of High-Value Lipids and Phenolic Compounds from Sorghum Bran via a Sequential Supercritical Carbon Dioxide Approach

Abstract

Sorghum bran, containing high-value lipids and phenolic compounds, is an underutilized food processing byproduct. This study developed and optimized a green method based on a sequential pure supercritical carbon dioxide (SC−CO 2 ) and ethanol/water-modified SC−CO 2 extraction to extract wax-rich lipids and phenolic compounds from sorghum bran in a single step. The extraction conditions, namely, temperature (20−100 °C), pressure (20−40 MPa), extraction time (0.5−5 h), and cosolvent type (ethanol or ethanol−water), were optimized for the highest wax-rich lipids and phenolics extraction yields. In the first part, neat SC−CO 2 at 40 MPa and 60 °C resulted in the highest lipid yield (6.2%, w/w dry basis), which contained ∼5% (w/w) high-melting point waxes. The purified wax fractions containing phytosterols showed high melting points of 57−87 °C. In the second part, the highest total phenolics and flavonoids yields were achieved at 40 MPa and 40 °C via 15% (w/w) ethanol−water (1:1, v/v) modified SC−CO 2 by 150 ± 3 mg of gallic acid equivalent (GAE)/100 g of bran (dry basis) and 99.6 ± 4 mg of catechin equivalent (CAE)/ 100 g of bran (dry basis), respectively. Overall, this study provides a novel single-step extraction approach based on SC−CO 2 to extract and fractionate lipids and phenolic compounds from sorghum bran.

Advances in the novel and green-assisted techniques for extraction of bioactive compounds from millets: A comprehensive review

“…The black sorghum bran was subjected to supercritical CO 2 extraction, followed by a subsequent extraction using a mixture of 50 % (v/v) ethanol and water. SFE yielded the highest phenol yields (13.9 mg GAE/g bran) [ 25 ]. The SFE extract revealed the presence of four primary phenolic acids: cinnamic acid, caffeic acid, p-coumaric acid, and ferulic acid.…”

“… -SCE (3 h at 40 MPa and 40 °C) + 1:1 ethanol-water extraction resulted in a yield of 13.9 mg GAE/g bran. [ 25 ] SCE Sorghum (whole kernel, bran, and dried distillers' grains with soluble [DDGS]) Pressure: 30 and 40 MPa Temperature: 50 and 70 °C Time: 0.5–5 h -SCE at 40 MPa and 70 °C produced a higher wax yield of 4.9 % from DDGS compared to the whole kernel (0.6 %) and bran (3.3 %) fractions. -Whole kernel extracts had the highest wax (89 %)in SCE, while DDGS and bran had 53.3 % and 26.8 % wax, respectively, after SCE at 40 MPa and 70 °C.…”

“…Currently, there exists a substantial literature addressing innovative extraction methods for extracting bioactive compounds from millets and their by-products. For example, recently the novel and green-assisted extraction techniques including DES assisted technique for phenolic [ 20 ] and flavonoid compounds in sorghum [ 21 ], foxtail millet [ 20 , 22 ], Supercritical fluid extraction of phenolic compounds in Foxtail millet [ 23 , 24 ] and sorghum [ [25] , [26] , [27] , [28] ], US assisted technique for phenolic and flavonoid compounds in sorghum [ [29] , [30] , [31] , [32] ] and proso millet [ 33 ], Microwave-assisted technique for 3-DXA (3-deoxyanthocyanidins) flavonoid [ 34 ]and phenolic compounds in sorghum [ [34] , [35] , [36] , [37] ] and kodo millet [ 38 ], enzyme assisted technique for polyphenol and flavonoid compounds in pearl millet [ 39 , 40 ], finger [ 39 , 41 , 42 ], sorghum [ 39 , 43 ], foxtail [ 44 ]and proso millet [ 45 ] and accelerated assisted technique for phenols compounds in sorghum millet [ 46 ], have been employed for the extraction of millet bioactive components. However, after an extensive review of the literature, and to the author's best knowledge, no comprehensive review articles have been identified that offer an in-depth analysis of novel extraction techniques and their potential applications in the context of millet grains.…”

Vapor–Liquid Equilibrium Phase Behavior of Binary Systems of Carbon Dioxide with Eugenol or Guaiacol

“…Several authors have studied the physical chemical characteristics of phenols from a bio-oil complex mixture. , Montesantos et al studied the extraction on a hydrothermal biocrude obtained from lignocellulosic biomass, and up to ∼42% of PCs were recovered from the extracts. Tuhanioglu and Ubeyitogullari investigated the extraction of sorghum bran via a sequential sc-CO 2 and obtained high-value lipids and PCs. Piantino studied the extraction of Baccharis dracunculifolia leaves using sc-CO 2 , and the results obtained the global yield extraction higher than ethanolic extraction.…”

“…19,20 Montesantos et al 19 studied the extraction on a hydrothermal biocrude obtained from lignocellulosic biomass, and up to ∼42% of PCs were recovered from the extracts. Tuhanioglu and Ubeyitogullari 21 investigated the extraction of sorghum bran via a sequential sc-CO 2 and obtained high-value lipids and PCs. Piantino 22 25 and the Peng−Robinson (PR) 26 equations of state using the van der Waals one-fluid mixing rule (vdW-2).…”