Lipid Extraction Efficiency Research Articles

Lipids source and degradation as revealed by molecular biomarkers in soils after acid-pretreatment: A case of a plantain soil under long-term cultivation

The extractable lipids are important components in soil organic matter (SOM) which were used to trace the sources and degradation of SOM. The protection of lipids by soil mineral have been suggested through organic solvents. But, the extraction efficiency of some lipid compounds was low. This study applied a mild acid treatment to firstly remove most of the reactive mineral particles, and without altering SOM chemical structures in 10% HF/1M HCl (1:4 w: v). Based on the obtained lipid biomarker information, we observed that the lipid extraction efficiency significantly increased by organic solvents on after removal of active minerals. The acid treatment increased the scientific to quantitative the amount of lipids. The minerals showed significant differences in the selective protection to different components of lipids. In this study, the amount range of protected n-alkanoic acids is 73~85%, n-alkanol 41~62% and n-alkanes 26~46%. After the vegetation was replaced, the increased alkenoate and alkane in soil input by the plant tissues of plantain directly, and the alkanols probably input by the hydrolysis of wax esters. Under the interference of man-made tillage activities, the C content in 0-20 cm decreased, suggesting that cultivated activities may enhance SOM degradation and accelerate SOM turnover. Understanding SOM behaviour in this area will provide important information for soil management and to evaluate carbon cycling in human-affected ecological systems.

Lipid extraction from Nannochloropsis oceanica biomass after extrusion pretreatment with twin-screw extruder: optimization of processing parameters and comparison of lipid quality.

The objective of this work was to evaluate the effects of extrusion pretreatment on the efficiency of lipid extraction and the quality of lipid extracted from the microalga Nannochloropsis oceanica. Five processing parameters of extrusion pretreatment using a twin-screw extruder were studied: die configuration, distance from the internal surface of the die to the end of the screw (δ), temperature, screw rotation speed, and the water content of biomass. The results showed that die configuration, δ, and the water content of the biomass were vital factors affecting lipid extraction efficiency. After the pretreatment of extrusion, the extraction time was shortened from 10h to 20min, and the amount of solvent used was reduced to one-third of that without pretreatment. The content of polyunsaturated fatty acid (PUFA) in crude lipid increased by over 30 percent of those components without pretreatment, especially for eicosapentaenoic acid (EPA), which increased by 37.45%. In addition, the unsaponifiable content and acid value of the crude lipid extracted from the extruded microalga decreased significantly, which would facilitate further refining processes.

Evaluation of CO2-induced azole-based switchable ionic liquid with hydrophobic/hydrophilic reversible transition as single solvent system for coupling lipid extraction and separation from wet microalgae

The utilization of microalgae as bioenergy source was limited by the excessive cost and energy consumption during the process of lipid extraction and separation. CO2-induced switchable ionic liquids (S-ILs) with reversible hydrophobic-hydrophilic conversion were synthesized and applied for lipid extraction and separation. The reversible transition mechanism of switchable IL is due to the formation of carbamate. The novel approach based on S-ILs was developed for lipid extraction from wet microalgae, which coupled microalgae cell disruption, lipid extraction, separation, and solvent recovery process without additional solvents. The highest lipid extraction efficiencies from wet microalgae were obtained by C6DIPA-Im, and the lipids were recovered from the extraction phase by simply bubbling CO2. Furthermore, C6DIPA-Im maintained more than 83.6 ± 3.6% of its initial lipid extraction efficiency after recycling five times. The S-IL based extraction and separation method provides a new strategy for sustainable bioenergy production.

A facile and mild one-pot process for direct extraction of lipids from wet energy insects of black soldier fly larvae

The insect lipids were recovered using one-pot manner via a high speed homogeniser from the wet black soldier fly larvae as the novelty lipid feedstocks at room temperature and pressure in this study. The comparison of the influences of different conditions (solvent types, solute-solvent ratios, water contents, and homogenization intensities) on the lipid extraction efficiency and lipid compositions were studied and evaluated. The results indicated that all the binary solvents tested in this work present a higher extraction capacity (70–74%) than the monophasic solvent increasing two-fold the lipid extraction yield. There was a significant difference between the 30.96% and 86.67% in saponifiable lipids purity for different extraction solvent systems. The effects of water contents on the lipid extraction process for relatively low contents of non-polar solvent in the binary extraction solvents system were greater than that of high contents of non-polar solvent. However, fatty acid methyl esters profiles from the energy biomass indicate that relevant fatty acids were present in all solvent extracts, with no significant variation in the FAME composition provided for different investigated conditions. Key characteristics of the recovered lipids indicate that the pretreatment process-cell disruption was a critical step in the recovery of intracellular lipids from the wet biomass, which significantly enhancing the lipid extraction process. In combination with SEM images of the damaged cells, the precise mechanism of cell disruption via the high speed homogeniser was comprehensively described. At last, the kinetic model (r2 ≥ 0.9937) of lipid extraction from the ruptured cell at various homogenization intensities (6000–14000 rpm) was explored in preliminary. The extraction constants were determined for the lipid extraction process, ranging from 0.0531 to 0.0681 s−1. Considering its energy-efficiency and potential for scale-up, the one-pot manner may be a promising method to achieve industrial-scale lipid extraction from wet biomass.

Pressurized liquid extraction with ethanol as a green and efficient technology to lipid extraction of Isochrysis biomass

This work was the first time to establish a green pressurized liquid extraction (PLE) process to extract microalgal lipids from Isochrysis biomass. PLE with ethanol exhibited superior lipid extraction performance in comparison to Soxhlet and Folch methods and PLE with n-hexane. To reduce the cost in ethanol utilization, ethanol concentration was optimized and found that PLE with 90% ethanol concentration obtained the highest lipid extraction efficiency (41.5 wt%) and total fatty acids (TFAs) recovery value (92.17 wt%) using Isochrysis sp. biomass. Results about lipid class detected by TLC-FID technique showed that ethanol concentration distinctly affected the content of lipidic class during lipid extraction by PLE. Similarly, the process with 90% ethanol concentration achieved over 90 wt% of TFAs recovery values with three different Isochrysis species. Overall, PLE process mediated with ethanol was a promising approach to extract Isochrysis-derived lipids from sustainable microalgal biomass for food application.

Outdoor cultivation of the green microalga Chlorella vulgaris under stress conditions as a feedstock for biofuel.

The present work investigated the potential of the green alga Chlorella vulgaris to produce high-quality biofuel under culture stress conditions. The cultivation was carried out in a 1000 lopen plate tank system, which provides biomass yields comparable to open pond systems, but with less area needed. Algal biomass and lipid content were measured repeatedly. We compared the two solvent systems n-hexane and hexane/isopropanol (HIP) for extraction efficiency of lipids and applied three different extraction methods Soxhlet, soaking, and soaking followed by Soxhlet (soak-Sox). The combination of the HIP solvent and the soak-Sox provided the highest lipid yield (15.8 ± 0.174). Volumetric biomass and lipid productivity were 0.201gl-1day-1 and 31.71mgl-1day-1, respectively, whereas areal biomass and lipid productivity were 25.73gm-2day-1 and 4.066gm-2day-1, respectively. The fatty acid profile by means of gas chromatography resulted in seven fatty acids from C12 to C18. The most abundant fatty acid methyl esters (FAMES) were palmitic (C16:0), oleic (C18:1), and stearic (C18:0) acids. Lipid synthesis enhanced by optimizing the Kuhl growth medium with replacing nitrate by urea (50% N compared to the original recipe) increased salt content (10g/l NaCl), ferrous sulfate (0.5g/l), and sodium acetate addition (1g/l). With regard to density, kinematic viscosity, gravity, pour point, flash point, and cetane number, the Chlorella-biodiesel comply with ASTM and EN standards thus pointing at the high potential of lipids synthesized by Chlorella as a feedstock for biodiesel production.

Evaluation, comparison of different solvent extraction, cell disruption methods and hydrothermal liquefaction of Oedogonium macroalgae for biofuel production

Cell disruption and lipid extraction methods for macroalgae are not well reported. Therefore, we compared various lipid extraction methods and extraction efficiency of various solvents to improve lipid yields from Oedogonium fresh water macroalgae. Lipid extraction was done by 2 methods viz., modified Bligh and Dyer method and soxhlet extraction using either single solvents or mixtures. In soxhlet extraction method five solvents were used (1) Hexane commonly used solvent for lipid extractions, (2) chloroform: methanol (2:1), (3) Chloroform: hexane (1:1), (4) Chloroform: hexane (1:2), (5) Dichloromethane + methanol (2:1). To improve lipid extraction yields, various cell disruption methods were also compared during the present study. Impurities of chlorophyll and protein were also detected in the extracted lipids. Hydrothermal liquefaction of algal biomass with TiO2 was also conducted at 300 °C. HTL was more effective by which 23.3 wt% of bio-crude oil was obtained.

Lipid extraction from wet Nannochloropsis biomass via enzyme-assisted three phase partitioning

A green and efficient enzyme assisted three phase partitioning (EA-TPP) process was firstly developed to extract microalgal lipids using wet Nannochloropsis sp. biomass. In the pretreatment of microalgal biomass by four hydrolytic enzymes, TPP obtained a higher TFAs lipid extraction efficiency by cellulase compared with the resting enzymes. After optimization by EA-TPP of the wet disrupted Nannochloropsis biomass (3 g), the maximum TFAs extraction yield (90.40%) was attained at 20% ammonium sulphate, 6–7 pH, 1:2 slurry/tert-butanol ratio and 70 °C for 2 h incubation time and two extraction cycles. Moreover, results also revealed that the lipidic species compositions of Nannochloropsis sp. biomass were greatly related with the EA-TPP parameters. In the laboratory scale for wet disrupted microalgae biomass, EA-TPP process achieved 88.70% TFAs extraction yield under the optimized conditions. In all, EA-TPP process could be a promising approach to extract microalgae lipids for food application using wet microalgae biomass.

Process design and economics for production of advanced biofuels from genetically modified lipid-producing sorghum

This study evaluates the potential for making advanced biofuels from genetically modified (GM) lipid–producing sorghum. A biodiesel coproduction process is developed to extract, purify, and upgrade lipids to diesel fuel while carbohydrates are utilized for making ethanol through acid thermal pretreatment, enzymatic hydrolysis, and fermentation. To assess the advantages of coproducing biodiesel from GM–sorghum, process economics are compared to a cellulosic ethanol biorefinery receiving non-GM sorghum. Minimum ethanol selling prices (MESP) that reach a breakeven point after 30 years of service life are calculated as an economic index to compare the two processes. Results indicate that biodiesel coproduction improves the economics by lowering the MESP from $3.08/gal for the ethanol-only process to $2.46/gal. Sensitivity analyses reveal that increasing sorghum’s lipid content, increasing the lipid extraction efficiency, and reducing the solvent-to-solids ratio in lipid extraction columns are the most important process parameters to further enhance technoeconomics. Analyses indicate that a lipid content above 13 wt% (dry basis) or a biomass price less than $65/Mg (dry basis) will result in a 2014 ethanol wholesale price of $2.25/gal for the coproduction process.

Repeated Utilization of Ionic Liquid to Extract Lipid from Algal Biomass

In this work, different kinds of ionic liquids and reaction conditions for the extraction of lipid from microalgae biomass were optimized and repeated use of ionic liquids for microalgal lipid extraction was evaluated. Morphological changes of microalgae cells were compared in terms of pre- and post-treatment to understand the mechanisms of ionic liquid treatment. Ionic liquid [BMIM][MeSO4] showed the best lipid extraction efficiency at 70°C and with reaction time of 2 hours. The ratios (ILs : methanol) of 1 : 7 and 1 : 3 were the optimum ratios to complete the extraction of the lipids from microalgae. The initial 50% volume fraction of [BMIM][MeSO4] was 16.04% of dry weight, which showed the highest five average extraction rates. The loss of ionic liquid in the reaction system and the increase in water content of ionic liquids were considered as the main reasons for the decrease in the extraction rate. It is suggested that the potential of lipid extraction in this IL-methanol co-solvent system is promising due to the high efficiency, low cost, safety, environmental protection, and other characteristics.

Lipid Extraction From Oleaginous Microorganism with Electrochemical Method

In this study, electro‐treatment is used to disrupt the microbe cells for facilitating the lipid extraction from oleaginous yeast. Two types of the electrochemical assisted lipid extraction are performed. One is that an electrochemical method is used as pre‐treatment to break cells, and thereafter solvents (hexane, methanol, and mixture of chloroform:methanol) are used to dissolve the lipid, defined as electrochemical pre‐treatment followed extraction. The extraction efficiency reaches 43 and 92% in the electrochemical involved treatment with hexane and chloroform:methanol, respectively. In addition, simultaneous electrochemical treatment and lipid extraction is also conducted. In the process, the biomass dispersed in the solvents is subjected to the electrochemical treatment for extraction, defined as simultaneous electrochemical treatment and lipid extraction. The highest lipid extraction efficiency is 92.17% w/w dry biomass obtained at 48 h extraction time with chloroform:methanol:water as solvents. Electrochemical treatment shows great potential in lipid extraction as it somewhat reduces the toxic chloroform utilization. Increase of current of electro‐treatment leads to the increase of saturation degree of the biodiesel converted from lipid extracted with electro‐treatment. It is found that the current of electro‐treatment should be kept below 0.4 A in order to avoid the impact on biodiesel property. Practical applications: The study provides a way of lipid extraction from oleaginous microorganism with an electrochemical method. It has great potential to be utilized in lipid extraction from microorganisms.

Techno-economic and environmental assessment of conceptually designed in situ lipid extraction process from microalgae

An in situ lipid extraction process from two microalgae strains, Chlorella vulgaris and Botryococcous braunii, was conceptually designed and simulated in Aspen Plus. The techno-economic and a “pond-to-pump” life cycle carbon emission analysis were then conducted in an optimization framework consisting of two decision variables, volumetric fraction (VF) and lipid percentages (LP) of the organic phase in the extraction column. The VF significantly affected the lipid extraction efficiency and consequently both minimum lipid selling price (MLSP) and carbon emissions, while the LP was only significant at low extraction yields. The MLSP from B. braunii was about $2.34 L−1, while the cost of lipid production from C. vulgaris was not economically viable. A sensitivity analysis was then conducted to assess the impact of perturbations in key process and financial parameters on the MLSP and emissions from B. braunii. The potential efficiency of wastewater as a source of nutrients for algal cultivation was considered as well. The greatest sensitivity was attributed to lipid content and algal productivity so that a 30% deviation from the base values changed the MLSP and emissions about 44% and 70%, respectively. The results suggested the potential use of wastewater nutrients as a way to reduce both the MLSP and emissions to respectively about $1.8 L−1 and 4.2 kg CO2 kg−1.

Comparison of lipid extraction methods for the microalgae Acutodesmus obliquus

Microalgae are widely used in the pharmaceutical and energy industries, therefore the conditions for their cultivation and extraction methods play an important role in the profiling and acquisition of lipids. The efficiency of lipid extraction from microalgae has attracted great interest from industry because of the wide variety of lipids and amounts that can be obtained. Acutodesmus obliquus (Scenedesmus obliquus UTEX 393) was used in this study. It was cultivated in Bold 3N medium modified with 75% nitrogen at 25°C, pH 6.8, 125 r/min and a photoperiod of 18/6 h and illuminated with white light provided by a Light-Emitting Diode Surface Mount Device extensions (LED SMD) with an intensity of 1200 µE/(m2•s). The cells were stained with the Red Nile (RN) technique to indicate lipid production. Four extraction methods were compared, classical, microwave (MW), Soxhlet, and ultrasound (US), using the same solvent proportions (hexane: chloroform: methanol=1:2:3). All samples were analyzed with Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography coupled to Mass Spectrometry (GC-MS). The results showed: 1) lipid production detected by RN was consistent with microalgal growth; 2) the MW technique was the best extraction method, according to the statistical analysis through Randomized Complete Block (RCB) design and performance of 4.6%; and 3) the presence of saturated and unsaturated acids was indicated by FTIR spectra. GC-MS was able to identify palmitic and linoleic acids as the likely major constituents of the sample. Keywords: Acutodesmus obliquus, lipid extraction, trans-esterification, Red Nile (RN) DOI: 10.25165/j.ijabe.20181105.3748 Citation: Hurtado D X, Garzon-Castro C L, Cortes-Romero J, Tello E. Comparison of lipid extraction methods for the microalgae Acutodesmus obliquus. Int J Agric & Biol Eng, 2018; 11(5): 211–217.

Application of a low-voltage direct-current electric field for lipid extraction from squid viscera

Squid viscera are one of the predominant by-products of squid and its lipids and proteins are of high nutritional quality and economic value. The objective of this work was to evaluate an electrical treatment for efficient extraction of lipids from squid viscera. Electrical treatments were carried out with various electric field strengths (5 V/cm, 10 V/cm, and 15 V/cm) for different time durations. By using this electrical method, the lipid extraction efficiencies reached 71.2 ± 1.0%, 72.1 ± 1.2%, and 71.7 ± 1.5% at electric field strengths of 5 V/cm for 12 h, 10 V/cm for 2.5 h, and 15 V/cm for 50 min, respectively. The electrical method exhibited a powerful ability to disrupt the cell membrane, which was observed by scanning electron microscopy and confocal microscopy. In the meantime, crude proteins were also recovered from squid viscera. Altogether, this work clearly demonstrated that this electrical method is an efficient technique for lipid extraction from squid viscera. This study developed a new approach as an alternative to the traditional method to extract lipids from squid viscera. The application of a low-voltage direct-current electric field for lipid extraction from squid viscera is of great importance both from the view of environmental interests and economic interests, and provides new ideas for lipid extraction from other food wastes.

Overcoming the cell wall recalcitrance of heterotrophic Chlorella to promote the efficiency of lipid extraction

Abstract One of the major challenges associated with algal fuels production from heterotrophic Chlorella (H. Chr.) is the rigid and complex structure of the cell wall. The cell wall of H. Chr. consists mainly of hydrophilic carbohydrates that prevent contact between the extraction solvent and the microalgal cells. Moreover, the cross-link ether structure on the thick cell wall, which causes part of the lipid to bind to the biopolymers by means of a glycosidic bond, also prevents lipid extraction. Chemical pretreatment is necessary to overcome cell wall recalcitrance of H. Chr. and promote lipid extraction efficiency. Among the different pretreatment methods, acid could disrupt the cell wall more efficiently and make lipid extraction available without drying. The best result was obtained with H2SO4 at a concentration of 0.5 M, 120 °C for 1 h and the solid load was 10% (wt.). Under these conditions, the lipid yield was 41.41% (based on raw material) and the solid residue yield was 11.88%.

Wet in situ transesterification of spent coffee grounds with supercritical methanol for the production of biodiesel

This work introduces biodiesel production from wet spent coffee grounds (SCGs) with supercritical methanol without any pre-drying process. Supercritical methanol and subcritical water effectively produced biodiesel via in situ transesterification by inducing more porous SCG and enhancing the efficiency of lipid extraction and conversion. It was also found that space loading was one of the critical factors for biodiesel production. An optimal biodiesel yield of 10.17 wt% of dry SCG mass (86.33 w/w% of esterifiable lipids in SCG) was obtained at reaction conditions of 270 °C, 90 bars, methanol to wet SCG ratio 5:1, space loading 58.4 ml/g and reaction time 20 min. Direct use of wet SCG waste as feedstock for supercritical biodiesel production eliminates the conventional dying process and the need of catalyst and also reduces environmental problems caused by landfill accumulation.

Influence of High Pressure Homogenization on Free Fatty Acid Formation in Nannochloropsis sp.

Although Nannochloropsis lipids have many potential applications in biofuels and high value products, their extraction is limited by the tough cell wall of this species. High pressure homogenization (HPH) can be used to improve the extraction efficiency. However, this can possibly induce free fatty acid (FFA) formation, which has a negative impact on oil quality. In this study, the HPH pressure and number of passes are varied in a full factorial design to study the impact of these factors on FFA formation, lipid extraction efficiency, and fatty acid profile. It is found that substantial amounts of FFA are formed during HPH treatments when compared to the non‐disrupted biomass. The FFA formation is mostly influenced by the number of passes applied, which can explained by a combined effect of the longer time residing as a wet paste and the temperature increase during the treatment. The large amount of FFA formed during the least intensive HPH treatment is in contrast with only a slight increase of the lipid extraction efficiency, which indicates that minor damage to the cell is sufficient to induce lipolytic reactions. The relative fatty acid profile after HI extraction is not influenced by the HPH treatment.Practical Applications: These results have important implications for the application of HPH treatments on microalgae with the aim to improve the extraction efficiency. It is demonstrated that more intensive HPH treatments with several passes are necessary to improve the extraction efficiency of Nannochloropsis lipids. However, the least intensive HPH treatments (1 pass at 400 bar) already induced the formation of substantial amounts of FFA. Consequently, to produce a biomass with a low FFA content and a high lipid extraction efficiency, a compromise should thus be made.High pressure homogenization (HPH) can efficiently be used to improve the extraction effiency of interesting compounds from Nannochloropsis cells. However, this treatment also induces the formation of free fatty acids (FFA), which have a negative influence on oil quality.

Understanding the mechanisms of lipid extraction from microalga Chlamydomonas reinhardtii after electrical field solicitations and mechanical stress within a microfluidic device

One way envisioned to overcome part of the issues biodiesel production encounters today is to develop a simple, economically viable and eco-friendly process for the extraction of lipids from microalgae. This study investigates the lipid extraction efficiency from the microalga Chlamydomonas reinhardtii as well as the underlying mechanisms. We propose a new methodology combining a pulsed electric field (PEF) application and mechanical stresses as a pretreatment to improve lipid extraction with solvents. Cells enriched in lipids are therefore submitted to electric field pulses creating pores on the cell membrane and then subjected to a mechanical stress by applying cyclic pressures on the cell wall (using a microfluidic device). Results showed an increase in lipid extraction when cells were pretreated by the combination of both methods. Microscopic observations showed that both pretreatments affect the cell structure. Finally, the dependency of solvent lipid extraction efficiency with the cell wall structure is discussed.

AN INSIGHT ON ALGAL CELL DISRUPTION FOR BIODIESEL PRODUCTION

Objective: This review article deals with the effect that various cell disruption techniques have on the efficiency of lipid extraction. We have reviewed existing algal cell disruption techniques that aid the biodiesel production process.Methods: Current rise in demand for energy has led the researcher to focus on the production of sustainable fuels, among which biodiesel has received greater attention. This is due to its larger lipid content, higher growth rate, larger biomass production, and lower land use. Extraction of lipid from algae (micro and macro) for the production of biodiesel involves numerous downstream processing steps, of which cell wall disruption is a crucial step. Bead milling, high-pressure homogenization, ultra-sonication, freeze-drying, acid treatment, and enzymatic lysis are some methods of cell disruption. The cell disruption technique needs to be optimized based on the structure and biochemical composition of algae.Result: The lipid extraction efficiency varies depending on the algal species and the cell disruption technique used.Conclusion: In-depth research and development of new techniques are required to further enhance the cell disruption of the algal cell wall for the enhanced recovery of lipids. In addition, the operating costs and energy consumption should also be optimized for the cost-effective recovery.

Optimization of enzymatic hydrolysis for effective lipid extraction from microalgae Scenedesmus sp.

Abstract Cell wall disruption is an essential downstream processing step for improving the efficiency of lipid extraction from microalgae. Enzyme-assisted extraction of lipid from microalga Scenedesmus sp. with cellulase, xylanase and pectinase, using various parameters, such as enzyme concentration, temperature, pH and incubation time, was optimized by central composite design (CCD) coupled with response surface methodology (RSM). Both the lipid extraction from microalgae and the fatty acid methyl esters (FAMEs) production under optimal conditions showed a ∼twofold in the yields compared to the control group with no enzymatic treatment. SEM images, FTIR measurement, XPS and HPLC analysis showed that the enzymatic pretreatment caused significant alterations in the cell wall structure of microalgae. And the disruption of microalgal cell walls was primarily attributed to the breakage of β-glucosidic linkages in cellulose and hemicellulose. The study showed a promising approach can lead to an improvement in the lipid extraction yield from microalgae and further provide valuable information for the use of enzymes in microalgal processes.