Extraction of Lipids from Aqueous Protein-Rich Streams using Near-Critical Dimethylether

High Levels of Policosanols and Phytosterols from Sugar Mill Waste by Subcritical Liquefied Dimethyl Ether

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content.

Mechanism of separation and removal of water from oily sludge using liquid dimethyl ether to dissolve hydrocarbons

The effective disposal of oily sludge generated from the petroleum industry has received increasing concern. The primary difficulty for the reduction and resource utilization of oily sludge is dewatering. Therefore, finding an efficient and energy-saving dewatering technology is an urgent need for the treatment of oily sludge. In this study, an innovative developed method using liquefied dimethyl ether (L-DME) for dewatering is employed to deal with oily sludge for the first time. Oily sludge from a refinery was used to conduct experiments in sequencing dissolution-separation reactors. Changes in the dehydration rate, oil recovery, group components (hydrocarbon series of petroleum, including saturates, aromatics, resins and asphaltenes) at different extraction time, temperatures and L-DME additions were measured. The results revealed that L-DME removed 90% of the water and recovered 40% of the oil, which was an amazing dehydration effect for oily sludge. The water-binding form of oily sludge is different from sewage sludge and other biomass and the water in oily sludge is in a stable water-in-oil (W/O) suspension emulsified state. L-DME was mixed with semi-colloidal like oily sludge to break the structure of the water-in-oil emulsion, making the mixture into a solid-liquid two phase substances that were easy to separate, thus achieving a high degree of separation of water. The dissolution of saturated hydrocarbons, aromatic hydrocarbons, and small amounts of colloid by L-DME played an important auxiliary role in water removal.

Sub- and Supercritical Extraction of Slovenian Hops (Humulus lupulus L.) Aurora Variety Using Different Solvents

This work investigates the efficiency of supercritical fluid extraction of hops with a variety of solvents including carbon dioxide (CO₂), propane, sulfur hexafluoride (SF₆), and dimethyl ether (DME) at various densities (low-density and high-density). Operating parameters were 50 bar, 100 bar and 150 bar and 20 °C, 40 °C, 60 °C and 80 °C for all solvents, respectively. The influence of process parameters on the total yield of extraction and content of bitter acids in the extracts has been investigated. The mathematical model based on Fick's second law well described the experimental extraction results. Furthermore, HPLC analysis has been used to determine α- and β-acids in extracts. The yield of bitter compounds in hop extracts was largely influenced by the type of solvent, the temperature and pressure applied during extraction. The results show that CO₂ and propane were roughly equivalent to DME in solvating power, while SF₆ was a poor solvent at the same conditions. The highest yield as well as the highest concentration of bitter acids in extracts were obtained by using DME, where the optimal operating conditions were 40 °C and 100 bar for the extraction of α-acids (max. concentration 9.6%), 60 °C and 50 bar for the extraction of β-acids (4.5%) and 60 °C and 150 bar for the maximum extraction yield (25.6%).

Extraction of oil from wet Antarctic krill (Euphausia superba) using a subcritical dimethyl ether method

In this study, a novel method for obtaining high-quality krill oil from wet Antarctic krill by using subcritical dimethyl ether (SDE) was proposed. A response surface design was used to obtain the best SDE extraction parameters. The optimum extraction efficiency of 93.77 ± 0.92% was obtained at a stirring speed of 1030 rpm, temperature of 47 °C and dynamic extraction time of 90 min. Compared with n-hexane, ethanol, supercritical CO₂ and subcritical n-butane extraction, the krill oil extracted by SDE exhibited low peroxide values (1.46 ± 0.26 mmol kg⁻¹), high astaxanthin (218.06 ± 4.74 mg kg⁻¹), phosphatidylcholine (PC) (33.95 ± 0.65%), and phosphatidylethanolamine (PE) (11.67 ± 0.23%) content. Moreover, krill oil extracted by SDE has high levels of EPA (16.38 ± 0.05%) and DHA (7.91 ± 0.07%). SDE extraction proved to be an efficient and safe method for extraction of quality krill oil from wet Antarctic krill, and it could be a promising method for oil extraction in wet food in future.

In this study, a novel method for obtaining high-quality krill oil from wet Antarctic krill by using subcritical dimethyl ether (SDE) was proposed.

An Efficient Extraction Method for Fragrant Volatiles from Jasminum sambac (L.) Ait

The sweet smell of aroma of Jasminum sambac (L.) Ait. is releasing while the flowers are blooming. Although components of volatile oil have been extensively studied, there are problematic issues, such as low efficiency of yield, flavour distortion. Here, the subcritical fluid extraction (SFE) was performed to extract fragrant volatiles from activated carbon that had absorbed the aroma of jasmine flowers. This novel method could effectively obtain main aromatic compounds with quality significantly better than solvent extraction (SE). Based on the analysis data with response surface methodology (RSM), we optimized the extraction conditions which consisted of a temperature of 44°C, a solvent-to-material ratio of 3.5:1, and an extraction time of 53 min. Under these conditions, the extraction yield was 4.91%. Furthermore, the key jasmine essence oil components, benzyl acetate and linalool, increase 7 fold and 2 fold respectively which lead to strong typical smell of the jasmine oil. The new method can reduce spicy components which lead to the essential oils smelling sweeter. Thus, the quality of the jasmine essence oil was dramatically improved and yields based on the key component increased dramatically. Our results provide a new effective technique for extracting fragrant volatiles from jasmine flowers.