Sorghum Oleoresins: Effect of Extraction on Compositional and Structural
Characteristics
Abstract
Oleoresins are resin-like viscous materials obtained from plants,
oilseed, or spices with functional properties. The extraction process
determines their stability, composition, and physicochemical properties.
Oleoresins were obtained from ground waxy burgundy whole grain sorghum
with and without ball milling by using the following solvents: two types
of novel ionic liquids (IL1: 1-n-Hexyl-3-methylimidazoliumchloride, IL2:
1-Ethyl-3-methylimidazoliumchloride), ethanol and dichloromethane. The
effects of processing were evaluated for the extraction yield, protein,
fat and total phenolic content, fatty acid composition, particle size
and zeta potential, and FTIR spectra. The use of ILs and ball mill
process significantly (P < 0.05) affected the extraction yield
and physicochemical properties. The highest extraction yields increased
(31.35% ± 0.58) when ball milling used with IL2 in comparison to the
lowest (18.37% ± 0.77) obtained by traditional ethanol extraction. In a
similar way, protein concentration and phenolic content were the highest
(1.37% ± 0.05 and 0.57% ± 0.01, respectively) with ball milling
extraction and IL1. The FTIR spectra indicated higher phospholipids (at
1200 cm-1) and protein-phospholipid bonding (at 1700 cm-1) by ILs, and
ball milling as compared to traditional extraction. Overall, wet
milling-assisted extraction by using ball mill and ILs can provide
control for the composition of the oleoresins important for their
functional properties with higher extraction efficiencies as compared to
traditional techniques.