Batch Extraction of Oil from Rice Bran with Liquefied Low Temperature Dimethyl Ether

Abstract

From a green chemical point of view, techniques for extracting organic substances employing conventional solvents must be replaced with novel environment-friendly techniques. Dimethyl ether (DME) may be one of such alternative solvents to be used. Rice bran is a co-product of rice milling, which is rich in oil content.Theoretically, around 20-25% of the total weight of rice bran must be oily components known as rice bran oil (RBO). In the present study, liquefied DME was used as a low temperature solvent for extracting RBO.From 10 g of fully dried rice bran used in a single batch extraction with DME, ca. 0.90 g of RBO were recovered (efficiency, 9.0%). Although the efficiency of total RBO extraction by batch extraction with DME was lower than the conventional solvent extraction system using acetone, lipid-pigment complexes potentially beneficial for human health such as ferulic acid-conjugated lipids were efficiently extracted.Fatty acid compositions found in RBO prepared by DME extraction and conventional solvent extraction did not differ. Lastly, improvement of the extraction efficiency was attempted by designing a column-based flow system allowing extraction of RBO with an optimized amount of liquefied DME. By this approach, the efficiency of RBO extraction attained ca. 24% (ca. 0.24 g of RBO extracted and recovered from 1 g of dried rice bran), using 10 to 20 g of liquefied DME applied to 1 g of rice bran packed in the column-type extraction chamber.

Dewatering and Extraction of Hydrophilic Solutes and Essential Oils from Cryo-preserved Lemon Peels Using Liquefied Dimethyl Ether

“…Handling of DME was basically achieved according to Hara et al [13]. With some modifications, a batch-type extraction system was employed.…”

“…Notably, cryo-liquefied DME can be used as a low-temperature extraction solvent for a variety of laboratory procedures for extraction of neutral fats from food wastes such as rice brans [13] and pigments such as chlorophylls and carotenoids from plant tissues [14].…”

Fluorometric Quantification of Ferulic Acid Concentrations Based on Deconvolution of Intrinsic Fluorescence Spectra

“…FA is naturally found in the seeds of apple, artichoke, peanut, orange, and coffee, and most commelinid cereals such as barley and rice. In commelinid seeds, FA is localized in the bran, the hard outer layer of grain, therefore FA-cojugated oils can be readily extracted from the rice bran (Hara et al, 2016). The highest range of FA concentrations in the glucosilated form has been found in seed of flax (Linum usitatissimum) reaching 0.02% of total dry weight (Beejmohun and Fliniaux, 2007).…”

“…FA measurements by such dual LIF technology may help quantifying FA content not only in the living plants in the fields, but also in the products after harvesting, such as the grains of wheat (Pussayanawin et al, 1988;Saadi et al, 1998) and rice bran oil (Hara et al, 2016). In fact, in general, monocots are rich in FA and its derivatives, so that leaves of monocots can be distinguished from those of Environ.…”

“…As discussed above, it is important to quantify the internal FA level in vegetables and fruits, thus, non-invasive methods are desired in order to allow handling of the intact fresh produces. Conventionally, FA-specific spectroscopic analysis was performed with extracts from vegetables and fruits (Yeh and Yen, 2005) and FA-conjugated lipids in edible oils such as rice bran oil (Hara et al, 2016), but this method cannot be extended to applications in non-invasive approach. In this point of view, fluorometric approach has some advantages and there have been several reports on quantification of FA based on its intrinsic fluorescence.…”