Improved solvent economy and rate of rice bran lipid extraction using hydrolyzed rice bran with hexane as solvent

In-situ (trans)esterification of lipid-dense post-hydrolysis rice bran at ambient pressures with low acid loading

“…Table 2 is a summary of the characteristics and lipid composition of the collected RB and generated PHRB. Similar to previous reports [8,21], the lipid content of PHRB (~31 wt%) is higher than the native RB (~16 wt%). The observed increase in lipid content could be attributed to the dissolution of the solid fraction [26].…”

“…Thus, the addition of more methanol or an increase in SSR improves the overall mass transfer of the system. In a related work where lipids from PHRB were extracted with hexane as the solvent, the increase in SSR from 4 to 12 mL/g resulted in better diffusivity of the lipids [8].…”

“…Despite the significant content of lipids in RB, mechanical extraction of RB lipids (RBL) only allows recovery of no more than 55% even with an optimized die configuration of a screw press for the continuous extraction and recovery of the lipids [7]. This is probably owing to its relatively lower lipid content and smaller particle size compared to oil-bearing seeds, thus, favoring the use of solvents for lipid recovery from RB [8].…”

“…Owing to RBL having high FFA and other non-triglyceride components, refining yield to produce refined rice bran oil, only ranges from 50 to 70% [3], which makes it relatively more expensive to produce when compared to other edible oils. But like other edible oils, RBL has fatty acid distribution, which could be adopted for use as fuel in the form of fatty acid methyl ester (FAME) [8,12]. Although the presence of FFAs is also a concern in FAME production, these could still be converted to FAME with the use of appropriate catalysts, typically H 2 SO 4 [9][10][11], or carrying out the (trans) esterification reaction under sub-or supercritical conditions of methanol [13][14][15].…”

“…However, the catalytic activity was not entirely ruled out since the reaction was carried out under subcritical conditions, which has been previously reported to enable (trans)esterifictaion to proceed even without a catalyst for lipids with high FFA [22]. In a separate work by Go et al [8], the proposed direct DAH approach for non-delipidated RB was revisited, but this time around the focus was on the extraction of lipids using hexane, which the authors found that lipids in PHRB were more easily extracted as compared to RB and requires 30 to 80% less solvent.…”