Total Fatty Acid Methyl Esters Research Articles

Growth Performance and Biochemical Composition of Tetradesmus obliquus in Media with Different Phosphorus Concentrations

In this study, the effects of phosphorus on culture growth and biochemical composition of Tetradesmus obliquus were investigated. T. obliquus was cultivated in medium with different P concentrations. Cell number, optical density and dry weight values were measured every other day and total protein and lipid content, amino acid and fatty acids profiles were detected. The highest cell number (2905x104), optical density (1.07) and dry weight (0.04 mgL-1) were observed in 75% P+ medium. 50% P- medium has the highest (47.7% of dry weight) protein amount and the maximum of total lipid content (17.08% of dry weight) was determined in 75% P- medium. 75% P+ medium has the highest total amino acid value (64.37 mgg-1 dry weight) and 75% P- medium has the lowest (55.22 mgg-1dry weight). The highest saturated fatty acids (23.57%) and mono-unsaturated fatty acids (19.97%) were observed in 50% P- medium. The second highest percentages of polyunsaturated fatty acids values were in the 75% P- medium (48.63 %). These results show that phosphorus limitation increases the total protein, lipid and fatty acid methyl esters amounts and restricts the cell division and anabolic reaction. An excess in phosphorus has an enhancing effect on amino acid synthesis.

Evaluation of a New Cerium Oxide-Bismuth Oxide-Based Nanobiocomposite as a Biocatalyst for Biodiesel Production

Biodiesel is a promising renewable energy source that can be used together with other biofuels to help meet the growing energy needs of the rapidly increasing global population in an environmentally friendly way. In search for new and more efficient biodiesel production methods, this work reports on the synthesis and use of a novel biocatalyst that can function in a broader range of pH and temperature conditions, while producing high biodiesel yields from vegetable oils. Biodiesel was synthesized by transesterification of non-edible Eruca sativa oil using a lipase from Aspergillus niger that was immobilized on cerium oxide bismuth oxide nanoparticles. The synthesized nanoparticles were first grafted with polydopamine which facilitated the subsequent anchoring of the enzyme on the nanoparticle support. The enzyme activity, pH and temperature stability, and reusability of the immobilized lipase were superior to those of the free enzyme. Following response surface methodology optimization, the highest biodiesel yield of 90.6% was attained using 5 wt% biocatalyst, methanol to oil ratio of 6:1, reaction temperature of 40 °C, pH of 7, and reaction time of 60 h. The produced biodiesel was characterized by Fourier transform infrared spectroscopy and its fatty acid methyl ester composition was determined by gas chromatography-mass spectrometry. Erucic acid methyl ester was identified as the major component in biodiesel, with 47.7 wt% of the total fatty acid methyl esters content. The novel nanobiocatalyst (Bi2O3·CeO2@PDA@A.niger.Lipase) has the potential to produce high biodiesel yields from a variety of vegetable oils.

Improving cold flow properties of palm fatty acid distillate biodiesel through vacuum distillation

Palm fatty acid distillate (PFAD), a by-product of refining process of crude palm oil can be used as a potential feedstock for biodiesel production. However, the application of palm oil-based biodiesel is often hinder by its poor cold flow properties (CFP). Biodiesel fuel with poor CFP may crystallize and result in clogging of fuel lines, filters and injectors that cause engine operability problems. For that, a vacuum distillation method was designed and its feasibility and efficiency in improving the CFP was examined. A total of 13.60wt% of total saturated fatty acid methyl esters were successfully removed from the PFAD biodiesel, resulting in the improvement of the cloud point (CP), cold filter plugging point (CFPP) and pour point (PP) of PFAD biodiesel from 20 °C, 19 °C, and 15 °C to 13 °C, 11 °C, and 9 °C, respectively. It is remarkable that the improved CFPP satisfied the requirements for grade C summer biodiesel for temperate climates in EN 14212 standard. Additionally, Sarin (UFAME) empirical correlation was evaluated and it was found to have a good prediction of CFP for PFAD biodiesel, with lower than 2 °C deviation.

Effects of Modified Atmospheric Packaging on Ground Chicken Color and Lipid Oxidation

The objective of the current study was to evaluate the color changes and lipid oxidation of ground chicken patties packaged in polyvinyl chloride (PVC) film, high-oxygen (HiOx)–modified atmospheric packaging (MAP; 80% oxygen + 20% carbon dioxide [CO2]), and carbon monoxide (CO)-MAP (0.4% CO + 19.6% CO2 + 80% nitrogen) and stored at 2°C. Surface color was measured using a HunterLab MiniScan spectrophotometer on days 0, 1, 2, and 4. Lipid oxidation, pH, and aerobic plate count were determined on days 0 and 4 of storage. Fatty acid profiles were determined on day 0 to characterize saturated and unsaturated fatty acids. Patties packaged in PVC had greater (P < 0.05) pH than HiOx-MAP and CO-MAP. Gas chromatography analysis indicated that ground chicken has 72.8% unsaturated fatty acids and 27.2% saturated fatty acids (based on total lipids and fatty acid methyl ester). The formation of carboxymyoglobin on ground chicken patty surface was confirmed by peaks at 420 and 570 nm, whereas oxymyoglobin had peaks at 410 and 580 nm. Instrumental color analysis indicated both HiOx-MAP and CO-MAP had greater (P < 0.05) redness (a* values) than PVC on day 4 of storage. Patties packaged in HiOx-MAP had greater (P < 0.05) chroma values than CO-MAP and PVC on day 4 of storage. Visual panelists noted less (P < 0.05) surface discoloration in CO-MAP than PVC and HiOx-MAP on day 4 of storage. Lipid oxidation was greater (P < 0.05) in PVC and HiOx-MAP than CO-MAP. CO inclusion at 0.4% level effectively inhibited lipid oxidation and stabilized surface redness during refrigerated storage of ground chicken.

Variability of Omega-3/6 Fatty Acid Obtained Through Extraction-Transesterification Processes from Phaeodactylum tricornutum

The effect of direct transesterification methods on the omega-3/6 composition of extracts from Phaeodactylum tricornutum was studied. The aim of this work was to identify an extraction method which allowed to obtain the most suitable profile of fatty acids in terms of its potential benefits to health, particularly if further used in the food industry. Seven methods using acids, alkalis, and heterogeneous-catalysts, (namely methods from 1 to 7, abbreviated as M1-M7) were performed to determine α-linolenic (ALA), linoleic (LA), docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids. The composition of fatty acids was in all cases characterized by the major abundance of palmitic (23.95-34.08%), palmitoleic (30.94-35.56%), oleic acids (3.00-7.41%), and EPA (0.5-6.45%). Unsaturated fatty acids extraction yield was higher with a two-step transesterification process (M6, 63.65%). The total fatty acid methyl ester content (FAME) obtained with acid-transesterification (M1) reached about 21% wt, and 60% w/w total lipids. ALA higher relative content (ALA/LA ratio) was obtained when a lipid pre-extraction step was performed prior to acid-catalysis (M4). The transesterification method based on alkali-catalyst (M3, KOH catalyst) led to obtain higher DHA relative contents (DHA/EPA ratio up to 0.11), although its FAME content was 3.75-fold lower than that obtained with acid-transesterification (M1). Overall, this study shows that direct transesterification with alkali-catalyst (M3) improves the determination of PUFA content from the diatom through a more efficient transesterification-based extraction process, and thus allow to assess the value of the biomass more accurately for application in the food industry.

Catalytic behavior of La[formula omitted]O[formula omitted]-promoted SO[formula omitted] /ZrO[formula omitted] in the simultaneous esterification and transesterification of palm oil

Catalytic behavior of La2O3 promoted SO42−/ZrO 2 (SZ) in the simultaneous esterification and transesterification of palm oil with 10 wt% myristic acid was studied. La2O3 (90 wt% purity) derived from domestic monazite ore was introduced into SZ by impregnation method. Effects of La2O3 loading and reaction parameters on the reaction behavior and the conversion were also investigated. The 20 wt%La2O3-SZ catalyst possessed dual strong basic and acid sites which could efficiently promote both esterification and transesterification reactions. Using the 20 wt%La2O3-SZ catalyst, the initial reaction rate of esterification and transesterification reactions was faster, and equilibrium was reached faster. The equilibrium of total fatty acid methyl ester (FAME) content of 74.51 wt% and myristic acid methyl ester (MAME) content of 8.41 wt% were achieved. The 20 wt%La2O3-SZ catalyst maintained a relatively stable catalytic behavior during three reaction cycles. No significant loss in catalyst activity for esterification reaction was observed after reusing the catalyst five times without regeneration.

Assessing the effects of Salicornia brachiata Roxb. growth on coastal saline soil quality over temporal and spatial scales

Global climate change and human interference gradually increase the salt-affected land; hence the availability of agricultural land is decreasing day by day. Higher salinity severely affects the physical, chemical and biological characteristics of the soil. Various studies investigated the effects of growing crop plants on soil quality but such investigations on halophytic plants in their natural habitat are limited. Salicornia brachiata was selected to assess its effects on the soil quality over temporal and spatial scales because of its highest importance value index among the naturally growing coastal halophytes at the studied sites. The root zone soil of S. brachiata was sampled (six times in one growing period) from six different coastal sites in Gujarat, India. Soil characteristics, microbial community composition (ester linked-fatty acid methyl ester profiling) and genes (16S rRNA, nifH and cbbL) abundance in comparison with control soil (without vegetation) were studied. The root zone soil of S. brachiata had significantly higher pH, K+ and P, and lower EC, NO3–-N, NH4+-N and Na+ contents than control soil. The contents of total, GM+ve, GM−ve, total bacterial, fungal and actinomycetes FAMEs (fatty acid methyl esters) were higher in the S. brachiata covered soils (37.98, 6.44, 10.38, 16.35, 1.74 and 2.12 nmol g−1, respectively) than control soils (22.22, 3.81, 5.47, 9.30, 0.77 and 1.23 nmol g−1, respectively). Among the studied sites, root zone soil from Diu possessed the highest total, bacterial (GM+ve and GM−ve), fungal and actinomycetes FAMEs, whereas the Vivaniya site exhibited the lowest. Among the sampling periods, S. brachiata soil exhibited significantly elevated contents of total FAME and FAME biomarkers of microbial taxonomic groups in the initial two sampling months (August and October), followed by December and the least in June. Compared with control soil, S. brachiata covered soil possessed the microbial community shift related to the enhanced abundance of total bacterial, GM−ve and fungal FAMEs. The abundance of 16S rRNA, cbbL and nifH genes was higher in S. brachiata covered soils (1.64 × 109, 5.06 × 106 and 2.53 × 107, respectively) compared with control soil (6.78 × 108, 1.55 × 106 and 6.99 × 106, respectively). In the August and October months, the abundance of all three genes was highest in S. brachiata and control soils. The findings of this study confirm the significant effects of S. brachiata on saline soil properties (soil characteristics, microbial activities and genes abundance) over temporal and spatial scales. The results strongly suggest the potentials of S. brachiata for the restoration of salt-affected degraded lands for healthy ecosystem functioning.

Hydrothermal Liquefaction of Food Waste: Effect of Process Parameters on Product Yields and Chemistry

Increasing food waste generation (1.6 billion tons per year globally) due to urban and industrial development has prompted researchers to pursue alternative waste management methods. Energy valorization of food waste is a method that can reduce the environmental impacts of landfills and the global reliance on crude oil for liquid fuels. In this study, food waste was converted to bio-crude oilviahydrothermal liquefaction (HTL) in a batch reactor at moderate temperatures (240–295°C), reaction times (0–60 min), and 15 wt.% solids loading. The maximum HTL bio-crude oil yield (27.5 wt.%), and energy recovery (49%) were obtained at 240°C and 30 min, while the highest bio-crude oil energy content (40.2 MJ/kg) was observed at 295°C. The properties of the bio-crude oil were determined using thermogravimetric analysis, fatty acid methyl ester (FAME) analysis by gas chromatography with flame ionization detection, CHNS elemental analysis, and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). FT-ICR MS results indicated that the majority of the detected compounds in the bio-crude oil were oxygen-containing species. The O4class was the most abundant class of heteroatom-containing compounds in all HTL bio-crude oil samples produced at 240°C; the O2class was the most abundant class obtained at 265 and 295°C. The total FAME content of the bio-crude oil was 15–37 wt.%, of which the most abundant were palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0), and polyunsaturated fatty acids (C18:3N:3, C18:3N:6).

Growth enhancement in marine copepod, Pseudodiaptomus annandalei fed with the sodium acetate containing N/P starved medium grown, Tetraselmis suecica

Algal lipids are considered to be good raw materials towards aqua feed formulation and biofuels production, and hence, they have been investigated for decades. Using external carbon source, microalgal cultivation has been getting attention due to high biomass productivity and lipid content with flexible cultivation of algae. In this present study, a marine microalga, Tetraselmis suecica was cultivated by combined method with sodium acetate as carbon source and reciprocal nutrients concentration. The reciprocal concentration of nitrogen and phosphorus with sodium acetate supply towards lipid and fatty acid methyl esters (FAME) synthesis in terms of live feed efficiency was attempted. The highest FAME content (78.44 ± 1.18% of DW) of alga was obtained in nil nitrogen condition with limited phosphate concentration (N0-PL) followed by N0-P (77.31 ± 2.5% of DW) combination. Limitation of phosphate with combination of nil nitrogen (N0-PL) showed slight increment of total FAME accumulation and its higher increments resulted in mono-unsaturated fatty acids (MUFA) accumulation, indicating nitrogen starvation was a real FAME trigger under heterotrophic cultivation. Effect of heterotrophic cultivated T. suecica feeding on marine copepod Pseudodiaptomus annandalei produced higher population density (119 ± 15 ind. L−1) in N0-P combination and high rate (71.98%) of nauplii production was obtained in N0-PL combination. These findings suggested that the heterotrophic microalgae cultivation can be practiced for aqua feed (especially for copepod cultivations) formulation as well as to phosphorous removal from wastewaters.

Microbial biomass and phospholipid fatty acid (PLFA) profile changes in bioconversion of wheat straw

Serpula lacrymans was shown to grow rapidly on wheat straw solid state fermentation (SSF). This study aimed to determine the pattern of ergosterol and the relative composition of phospholipid fatty acid (PLFA) produced during fungal growth. The PLFA analysis was carried out on the upper layer of the solvent extraction and was performed on the incubation from 0 up to 35 days. Relative abundant (%) of each fatty acid methyl ester (FAME) produced during the fungal growth was measured by comparing the amount of an individual FAME with the total FAME detected. The dominant PLFA released by the fungi were: 18:2n6c (linoleic acid) 24:1n9 (nervonic acid), 18:1n9c (oleic acid), and 16:0 (palmitic acid). The highest amount of fatty acid produced during the fungal growth is linoleic acid ranged from 186.92-345.78 μg g-1.

Data‐Driven Modeling of Biodiesel Production Using Artificial Neural Networks

AbstractData‐driven modeling of biodiesel production was developed by simultaneous transesterification and esterification of rapeseed oil and myristic acid with methanol, without catalyst or with different amounts of sulfated zirconia catalyst. An artificial neural network (ANN)‐based model was created with experimental literature data. The input data, i.e., reaction time, catalyst, temperature, and methanol‐to‐oil ratio, and output data, i.e., total fatty acid methyl ester and oleic acid methyl ester, were considered to develop the model. Multiple input single output (MISO) ANN architecture was taken to predict the above targeted two output parameters. The proposed ANN model is computationally efficient and works reasonably well when tested on biodiesel production for solving the MISO model.

Early Effect of Pine Biochar on Peach-Tree Planting on Microbial Community Composition and Enzymatic Activity

Biochar offers several benefits as a soil amendment, including increased soil fertility, carbon sequestration, and water-holding capacity in nutrient-poor soils. In this study, soil samples with and without biochar additives were collected for two consecutive years from an experimental field plot to examine its effect on the microbial community structure and functions in sandy soils under peach-trees (Prunus persica). The four treatments evaluated consisted of two different rates of biochar incorporated into the soil (5%, and 10%, v/v), one “dynamic” surface application of biochar, and a 0% biochar control. Fatty acid methyl ester (FAME) analysis was used to assess the microbial community structure, and enzyme activities involved in C, N, P, and S nutrient cycling were used as a means of assessing soil functionality. Total FAME and bacterial indicators increased by 18% and 12%, respectively, in the 10% incorporated and 5% surface applied treatments. Biochar applications increased β-glucosaminidase and arylsulfatase activities, 5–30% and 12–46%, respectively. β-glucosidase and acid phosphatase activities decreased by approximately 18–35% and 5–22% in the 0–15 cm soils. The overall results suggest that biochar’s addition to the sandy soils stimulated microbial activity, contributing to the increased mean weight diameter (MWD), C sequestration, and consequential soil health. The changes in microbial community structure and functions may be useful predictors of modifications in soil organic matter (SOM) dynamics due to the long-term application of pine biochar in these systems.

Effective lipid extraction from undewatered microalgae liquid using subcritical dimethyl ether

BackgroundRecent studies of lipid extraction from microalgae have focused primarily on dewatered or dried samples, and the processes are simple with high lipid yield. Yet, the dewatering with drying step is energy intensive, which makes the energy input during the lipid production more than energy output from obtained lipid. Thus, exploring an extraction technique for just a thickened sample without the dewatering, drying and auxiliary operation (such as cell disruption) is very significant. Whereas lipid extraction from the thickened microalgae is complicated by the high water content involved, and traditional solvent, hence, cannot work well. Dimethyl ether (DME), a green solvent, featuring a high affinity for both water and organic compounds with an ability to penetrate the cell walls has the potential to achieve this goal.ResultsThis study investigated an energy-saving method for lipid extraction using DME as the solvent with an entrainer solution (ethanol and acetone) for flocculation-thickened microalgae. Extraction efficiency was evaluated in terms of extraction time, DME dosage, entrainer dosage, and ethanol:acetone ratio. Optimal extraction occurred after 30 min using 4.2 mL DME per 1 mL microalgae, with an entrainer dosage of 8% at 1:2 ethanol:acetone. Raw lipid yields and its lipid component (represented by fatty acid methyl ester) contents were compared against those of common extraction methods (Bligh and Dryer, and Soxhlet). Thermal gravimetry/differential thermal analysis, Fourier-transform infrared spectroscopy, and C/H/N elemental analyses were used to examine differences in lipids extracted using each of the evaluated methods. Considering influence of trace metals on biodiesel utilization, inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy analyses were used to quantify trace metals in the extracted raw lipids, which revealed relatively high concentrations of Mg, Na, K, and Fe.ConclusionsOur DME-based method recovered 26.4% of total raw lipids and 54.4% of total fatty acid methyl esters at first extraction with remnants being recovered by a 2nd extraction. In additional, the DME-based approach was more economical than other methods, because it enabled simultaneous dewatering with lipid extraction and no cell disruption was required. The trace metals of raw lipids indicated a purification demand in subsequent refining process.

Reusable Heterogeneous SnO2/ZnO Catalyst for Biodiesel Production from Acidified/Acid Oils

A catalyst comprised of SnO2 impregnated on ZnO nanowires, which presented remarkable ability to catalyze fatty acid esterification/transesterification reactions, is reported. For optimization of reaction conditions, artificially acidified soybean oil with 10 wt.% oleic acid was used as a model feed. The optimized conditions were: 150 °C, 6 h, 5 g of oil, catalyst concentration of 5%, and methanol:oil molar ratio of 15:1. The catalyst achieved 92% of total fatty acid methyl esters (FAME) content and was used five times without the necessity of catalyst washing from one reaction to the other. Then, such conditions were applied to produce biodiesel from the oil extracted from Scenedesmus sp. microalgae; the system reached 72% of FAME content, without any previous refining or degumming process of the oil. Rietveld refinement, X-ray diffraction, elemental mapping in scanning transmission electron microscopy, X-ray photoelectron spectroscopy, and pyridine-desorption Fourier-transform infrared spectroscopy were used to characterize the material.

Catalytic Behavior of La2O3-Promoted SO42-/ZrO2 in the Simultaneous Esterification and Transesterification of Palm Oil

Catalytic behavior of La 2 O 3 promoted SO 4 2- /ZrO 2 (SZ) in the simultaneous esterification and transesterification of palm oil with 10wt% myristic acid was studied. La 2 O 3 (90% purity) derived from domestic monazite ore was introduced into SZ by impregnation method. Effects of La 2 O 3 loading and reaction parameters on the reaction behavior and the conversion were also investigated. The 20%La 2 O 3 -SZ catalyst possessed dual strong basic and acid sites which could efficiently promote both esterification and transesterification reactions. Using the 20%La 2 O 3 -SZ catalyst, the initial reaction rate of esterification and transesterification reactions was faster, and equilibrium was reached faster. The equilibrium of total fatty acid methyl ester (FAME) content of 74.51% and myristic acid methyl ester (MAME) content of 8.41% were achieved. The 20%La 2 O 3 -SZ catalyst maintained a relatively stable catalytic behavior during three reaction cycles. No significant loss in catalyst activity for esterification reaction was observed after reusing the catalyst five times without regeneration.

Enhancement of Lipid Productivity of Chlorella sp. Using Light-Converting Red Fluorescent Films Based on Aggregation-Induced Emission

The conversion of light wavelength from green (500–600 nm) to red (600–700 nm) in the solar spectrum can significantly enhance the biodiesel productivity of microalgae because microalgal photosynthetic pigments utilize the red light more efficiently. Herein, we applied light-converting fluorescent films to enhance the biomass and lipid productivity of oleaginous Chlorella sp. Although the fluorescent dyes have been reported to exhibit excellent fluorescence quantum yields in the solution state, the solid film state is more preferred to overcome limitations such as low stability and potential leakage issues. However, conventional fluorescent dyes exhibit poor emission in the solid film state due to aggregation-caused quenching (ACQ). Therefore, this study utilized aggregation-induced emission (AIE)-type diketopyrrolopyrrole (DPP) fluorescent dyes to overcome the ACQ problems and to fabricate highly efficient light-converting red fluorescent films. The fabricated light-converting film showed excellent photosynthetic photon flux density increase in the red wavelength range by AIE. A maximum total fatty acid methyl ester increase of Chlorella sp. was 28.8% using a light-converting film containing a deep-red (650–700 nm) emitting dye M2. In conclusion, we confirmed that the use of solar energy with light-converting films could boost microalgal productivity efficiently, even without using light-emitting diodes that require electricity.

Influences of Water Content in Feedstock Oil on Burning Characteristics of Fatty Acid Methyl Esters

Strong alkaline-catalyst transesterification with short-chain alcohol is generally used for biodiesel production due to its dominant advantages of shorter reaction time and higher conversion rate over other reactions. The existence of excess water content in the feedstock oil might retard the transesterification rate and in turn deteriorate the fuel characteristics of the fatty acid methyl esters. Hence, optimum water content in the raw oil, aimed towards both lower production cost and superior fuel properties, becomes significant for biodiesel research and industrial practices. Previous studies only concerned the influences of water contents on the yield or conversion rate of fatty acid methyl esters through transesterification of triglycerides. The effects of added water in the reactant mixture on burning characteristics of fatty acid methyl esters are thus first investigated in this study. Raw palm oil was added with preset water content before being transesterified. The experimental results show that the biodiesel produced from the raw palm oil containing a 0.05 wt.% added water content had the highest content of saturated fatty acids and total fatty acid methyl esters (FAME), while that containing 0.11 wt.% water content had the lowest content of total FAME and fatty acids of longer carbon chains than C16 among the biodiesel products. Regarding burning characteristics, palm-oil biodiesel made from raw oil with a 0.05 wt.% added water content among those biodiesels was found to have the highest distillation temperatures, flash point, and ignition point, which implies higher safety extents during handling and storage of the fuel. The added water content 0.05 wt.% in raw oil was considered the optimum to produce palm-oil biodiesel with superior fuel structure of fatty acids and burning characteristics. Higher or lower water content than 0.05 wt.% would cause slower nucleophilic substitution reaction and thus a lower conversion rate from raw oil and deteriorated burning characteristics in turn.

Dispersive Liquid-Liquid Microextraction Combined with Microwave Demulsification for Determination of FAME Residuals in Biodiesel Wastewater.

Biodiesel consists of various fatty acid methyl esters (FAMEs) that are mainly produced through transesterification of plant oil or animal fat. It is essential for biodiesel to be purified utmostly to meet its product standard before being traded, while the universal purification method has been water washing. However, water washing inevitably causes the residual of FAMEs in wastewater, which represents a loss of industrial profits. For the purpose of determination and monitoring of the FAME profile in wastewater, there is a necessity to develop a fast and reliable approach with small volume of sample in need. Hence, in this study, a combination of dispersive liquid-liquid microextraction (DLLME) and microwave demulsification is applied for the enrichment of residual FAMEs in water, followed by qualitative and quantitative analyses using gas chromatography-mass spectrometry. The results indicate that the optimal extractant in DLLME approach is toluene. And the optimal parameters are 20mL of water sample, 80μL of toluene as the extractant, 60s of ultrasonic irradiation duration, 200W of microwave power and 2min of microwave irradiation duration. The standard curves and linear equations obtained with these conditions are used for the quantitative analysis of biodiesel wastewater, which reveals that there was 50.35mg·L-1 of the total FAME residuals in wastewater. To the best of our knowledge, it is for the first time that the combined technique of DLLME and microwave demulsification is applied in determination of residual FAMEs in water samples. The proposed method corresponds to small volumes of sample and extractant and short analytical period. It also has the potential to be extended to the analysis of other water pollutants.

Immobilised Chlorella vulgaris as An Alternative for The Enhancement of Microalgae Oil and Biodiesel Production

Microalgae are a promising alternative for biodiesel production and a valuable source of fatty acid methyl ester (FAME). In this research, Chlorella vulgaris has been chosen as the suitable microalgae because this species was able to produce highest oils for biodiesel processing. Previously, sodium alginate (SA) was used to entrap the microalgae in the culturing process due to its low toxicity and high transparency. However, SA have some disadvantages such as bead disruption which leading to the loss of microalgae cell. Therefore, this research has been conducted to evaluate the oil production of immobilised Chlorella vulgaris using different matric systems at different ratios which are 0.3:1, 1:1 and 2:1. Currently, six matric systems have been developed, they are SA as a control, a combination of SA and chitosan (SA+CT), SA and carrageenan (SA+CR), SA and gelatin (SA+GT), SA and calcium alginate (SA+CA), and SA and sodium carboxymethylcellulose (SA+CMC). The microalgae was first cultivated, harvested and extracted to produce oil, prior to use in the transesterification process. The SA+GT showed the highest oil yield with 59.14% and a total FAME of 0.56 mg/g. The FAME profile of oil extracted microalgae showed high potential for biodiesel production as it consisted of palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The results proved that the combination of SA+GT had improved the oil yield and fatty acid composition as compared to the other matric systems, which may have useful application for the biodiesel industry. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Dietary inclusion of full-fat Hermetia illucens prepupae meal in practical diets for rainbow trout (Oncorhynchus mykiss): Lipid metabolism and fillet quality investigations

Insects are able to bio-convert organic by-products into a sustainable biomass for aquafeed formulation. Specifically, among several insect species, Hermetia illucens (H) is particularly interesting for its nutritious traits but, unfortunately, the lipidic fraction is poorly represented by polyunsaturated fatty acids n-3 and poses some limits in its application in aquafeed formulation.The present study undertook an interdisciplinary approach to explore the effects of three experimental diets containing increasing levels of full-fat H meal (H0 diet based on fishmeal and purified protein-rich vegetable ingredients; H25 and H50 diets containing 25% or 50% of full-fat H meal replacing fishmeal, respectively), on rainbow trout (Oncorhynchus mykiss) fed over a 98 days experimental period. The expression of genes related to lipid metabolism by RT-qPCR, liver histology, as well as the qualitative traits of fillets and fatty acid (FA) composition were investigated. Interestingly, fads2 gene expression in pyloric caeca increased in fish fed diets containing the highest full-fat H meal inclusion (H50 > H0; p < .05). Liver histological examinations showed normal morphological aspect even though hepatic FA profiles seemed to resemble those of the diets. However, liver docosahexaenoic acid did not significantly differ between the dietary groups and showed a mean value of 11.07 g FA methyl esters/100 g total FA methyl esters. Despite the FA profile of the three diets differed depending on the H meal inclusion level, biometrics, fillet physical traits, total lipids and the overall FA profile were not jeopardised, not even eicosapentaenoic and docosahexaenoic acids.The overall results showed that the dietary full-fat H meal inclusion under study did not impair fish fillet quality, guaranteeing its nutritional value. Some effects on lipid metabolism were observed, as suggested by liver, pyloric caeca and mid intestine gene expression and liver FA profile. Future studies on the biological mechanisms behind the macroscopic traits of fish fed unprocessed insects are warmly encouraged.