Pressurized Liquid Research Articles

Automated Pressurized Liquid Extraction of Microbial Lipids from Oleaginous Yeasts

The lipids produced by oleaginous microbes are considered sustainable resources for biofuels. To facilitate controlled lipid production and lipid analysis, more efficient lipid extraction methods are required. This study describes the automated pressurized liquid extraction (APLE) method for lipid extraction from dried cells of the oleaginous yeast species Rhodosporidium toruloides and Cryptococcus curvatus. Cells were mixed with diatomite in a mortar, added to the sample chamber, and treated with a mixture of chloroform and methanol at 105°C. More than 95% lipids were extracted. Analysis by using high-performance thin-layer chromatography showed that the neutral lipid contents in the obtained samples by APLE method were similar to those by the ball milling-assisted extraction method. The lipids had an essentially identical fatty acid composition compared with lipids extracted with the acid-heating extraction (AHE) method. This demonstrated that lipids can be efficiently extracted from oleaginous yeasts in less time and without harsh pretreatment procedures.

Comparison between Pressurized Liquid Extraction and Conventional Soxhlet Extraction for Rosemary Antioxidants, Yield, Composition, and Environmental Footprint.

Nowadays, “green analytical chemistry” challenges are to develop techniques which reduce the environmental impact not only in term of analysis but also in the sample preparation step. Within this objective, pressurized liquid extraction (PLE) was investigated to determine the initial composition of key antioxidants contained in rosemary leaves: Rosmarinic acid (RA), carnosic acid (CA), and carnosol (CO). An experimental design was applied to identify an optimized PLE set of extraction parameters: A temperature of 183 °C, a pressure of 130 bar, and an extraction duration of 3 min enabled recovering rosemary antioxidants. PLE was further compared to conventional Soxhlet extraction (CSE) in term of global processing time, energy used, solvent recovery, raw material used, accuracy, reproducibility, and robustness to extract quantitatively RA, CA, and CO from rosemary leaves. A statistical comparison of the two extraction procedure (PLE and CSE) was achieved and showed no significant difference between the two procedures in terms of RA, CA, and CO extraction. To complete the study showing that the use of PLE is an advantageous alternative to CSE, the eco-footprint of the PLE process was evaluated. Results demonstrate that it is a rapid, clean, and environmentally friendly extraction technique.

Prenatal exposure to organic pollutants in northwestern Spain using non-invasive matrices (placenta and meconium)

Human exposure to environmental organic pollutants (OPs) begins in the uterine life period by trans-placental transfer. Epidemiological studies have consistently demonstrated the vulnerability of human fetuses and infants to the effects of OPs because of their rapid growth and organ development, cell differentiation, and immaturity of metabolism. The aim of the present study was to evaluate the prenatal exposure to OPs characterized by different physicochemical properties using non-invasive biological samples (meconium and placenta). A total of 88 placenta and 53 meconium samples were collected in Ourense, a city located in northwestern Spain, at the delivery and after birth from mothers and their infants from the University Hospital of Ourense, respectively. Selective pressurized liquid extraction (SPLE) methodologies were used to determine the targeted OPs in the selected biological samples. Cleanup of extracts was performed by solid-phase extraction (SPE) using EZ-POP cartridges and detection by gas chromatography (GC) coupled to tandem mass spectrometry (QqQ-MS/MS). The targeted OPs were detected with the following mean level total concentration order polycyclic aromatic hydrocarbons (PAHs) > organophosphorus pesticides (OPPs) > non-dioxin like polychlorinated biphenyls (NDLPCBs) > pyrethroids (PYRs) > polybrominated diphenyl ethers (PBDEs) > dioxin like polychlorinated biphenyls (DLPCBs) > organochlorine pesticides (OCPs) for placenta and ΣNDLPCBs > ΣPAHs > ΣOCPs > ΣPYRs > ΣOPPs > ΣDLPCBs > ΣPBDEs for meconium, respectively. Significant correlations (p < .050) between the socio-demographic characteristics of the selected population (mother's parity, age, weight increase during pregnancy, place of living and smoking habits) and log transformed concentration of some of the targeted OPs (OCPs, PBDEs, PYRs, OPPs and PAHs) were detected. The results obtained shown the complementary information given by both biological samples selected. Nevertheless, additional research will be needed to gain an understanding of the trans-placental transfer of OPs, to choose the best biological matrix to evaluate the prenatal exposure to OPs in a correct way and to know their health implications.

OPTIMASI PANJANG HYDRAULIC FRACTURE PADA RESERVOIR NON-KONVENSIONAL DENGAN METODE UNIFORM CONDUCTIVITY RECTANGULAR FRACTURE

Energy needs in the future will continue to grow along with the growth of the population. Renewable and non-renewable energy sources continue to develop with various innovations. However, energy consumption from non-renewable energy such as coal, oil, and natural gas still dominates. Therefore, one of the potential non-renewable energy sources that can be optimized at present is unconventional oil and gas reserves. Unconventional oil and gas are oil and gas that comes from sourcerock, low permeability reservoirs, such as shale oil, shale gas, tight sand gas, coal bed methane, and methane-hydrate. To produce oil and gas from the tight sand gas reservoir, the hydraulic fracture method is a commonly used method. A hydraulic fracture is a well stimulation technique in which rock is fractured by a pressurized liquid. The process involves the high-pressure injection of fracking fluid into the wellbore to create crack in the deep rock formation through which natural gas, petroleum and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants hold the fracture open. Well log data such as gamma ray log, SP log, density log, resistivity log and so on will be processed and produce shale volume, porosity, permeability, and water saturation. Procced data from well log will be validated by core data. These data will be input into a reservoir model. A hydraulic fracture design will be made in the reservoir model with a certain length, width, and permeability using the uniform conductivity rectangular fracture method. The simulation will continue by using different length fracture design so that the optimum fracture length value is obtained.&#x0D; Keywords: Hydraulic Fracture, Reservoir Modelling, Reservoir Simulation

Pressurized liquid extraction followed by liquid chromatography coupled to a fluorescence detector and atmospheric pressure chemical ionization mass spectrometry for the determination of benzo(a)pyrene metabolites in liver tissue of an animal model of colon cancer

Since metabolism is implicated in the carcinogenesis of toxicants, an efficient extraction method together with an analytical method is warranted to quantify tissue burdens of a carcinogen and/or its metabolites. Therefore, the aim of this study was to validate a pressurized liquid extraction (PLE) method for measuring metabolites of benzo(a)pyrene [B(a)P; a food-borne carcinogen] from tissue samples. The sample extraction was performed separately by PLE and liquid–liquid extraction (LLE). PLE followed by high-performance liquid chromatography coupled to online fluorescence detector (HPLC-FLD) was used to quantify separated analytes; and by ultra-high-performance liquid chromatography (UHPLC) coupled to atmospheric pressure chemical ionization tandem mass spectrometry (UHPLC-APCI-MS/MS) were used for confirmation purposes. The UHPLC-MS/MS was set-up in the atmospheric pressure chemical ionization (APCI) positive interface with selective reaction monitoring (SRM). The analytical performance characteristics of the PLE technique was assessed at different temperatures, pressure, number of cycles and solvent types. A methanol + chloroform + water mixture (30:15:10, v/v/v) yielded greater recoveries at an extraction temperature range of 60–80°C, pressure of 10 MPa and an extraction time of 10 min. The PLE method was validated by the analysis of spiked tissue samples and measuring recoveries and limits of quantitation for the analytes of interest using HPLC-FLD equipment. The optimized PLE-HPLC-FLD method was used to quantify the concentrations of B(a)P metabolites in liver samples obtained from a colon cancer animal model. Overall, PLE performed better in terms of extraction efficiency, recovery of B(a)P metabolites and shortened sample preparation time when compared with the classic LLE method.

Adiabatic Absorption by Absorbent Atomization for Improving Absorption Heat Transformer Performance

Abstract Absorption heat transformers (AHTs) are a type of absorption heat pumps that are primarily driven by low-grade (typically waste) heat and produce higher temperature (high-grade) heat. Under the Indus3Es project, a 10 kW LiBr-H2O “Lab Scale” absorption heat transformer was built as a first experimental step toward larger scales. The focus was on the high-pressure vessel (HPV) (absorber and evaporator) design. To enhance performance, the aim was to obtain complete adiabatic absorption prior to the main absorption process accompanied by heat transfer. This maximizes the temperature within the absorber. This is particularly beneficial for absorption heat transformers, compared to chillers, because obtaining an elevated temperature is the objective. To obtain adiabatic absorption, atomizing spray nozzles were used as the liquid absorbent distribution system. This method proved successful; complete adiabatic absorption was obtained before the droplets contacted the absorber heat exchange surfaces. However, the spray nozzles must be supplied with pressurized liquid and are potentially more delicate than alternative liquid distribution systems. Therefore, future work may focus on determining the required atomization level to avoid excessive pressures and nozzle requirements.

Content of phenolic compounds and mannitol in olive leaves extracts from six Spanish cultivars: Extraction with the Soxhlet method and pressurized liquids

Olive leaves are considered a promising source of bioactives such as phenolic compounds and mannitol. The extraction of high added value products is an issue of great interest and importance from the point of view of their exploitation. However, the content of these compounds can differ between cultivars and extraction methods. In this work, six olive leaves cultivars, including three wild cultivars, and two extraction processes (an innovative and alternative technique, pressurized liquid extraction, and a conventional Soxhlet extraction) were evaluated and compared towards the selective recovery of bioactive compounds. The wild cultivars showed the highest content of phenolic and flavonoid compounds, being oleuropein the compound present in higher amount. Findings also revealed that the highest mannitol content in the extracts was observed with the commercial cultivars, specifically in Arbequina. It is thus possible to decide which cultivars to use in order to obtain the highest yield of each bioproduct.

Glycerol as Alternative Co-Solvent for Water Extraction of Polyphenols from Carménère Pomace: Hot Pressurized Liquid Extraction and Computational Chemistry Calculations.

Glycerol is a co-solvent for water extraction that has been shown to be highly effective for obtaining polyphenol extracts under atmospheric conditions. However, its efficacy under subcritical conditions has not yet been studied. We assessed different water-glycerol mixtures (15%, 32.5%, and 50%) in a hot pressurized liquid extraction system (HPLE: 10 MPa) at 90 °C, 120 °C, and 150 °C to obtain extracts of low molecular weight polyphenols from Carménère grape pomace. Under the same extraction conditions, glycerol as a co-solvent achieved significantly higher yields in polyphenols than ethanol. Optimal extraction conditions were 150 °C, with 32.5% glycerol for flavonols and 50% for flavanols, stilbenes, and phenolic acids. Considering gallic acid as a model molecule, computational chemistry calculations were applied to explain some unusual extraction outcomes. Furthermore, glycerol, methanol, ethanol, and ethylene glycol were studied to establish an incipient structure–property relationship. The high extraction yields of gallic acid obtained with water and glycerol solvent mixtures can be explained not only by the additional hydrogen bonds between glycerol and gallic acid as compared with the other alcohols, but also because the third hydroxyl group allows the formation of a three-centered hydrogen bond, which intensifies the strongest glycerol and gallic acid hydrogen bond. The above occurs both in neutral and deprotonated gallic acid. Consequently, glycerol confers to the extraction solvent a higher solvation energy of polyphenols than ethanol.

Recovery and determination of cholesterol-lowering compounds from Olea europaea seeds employing pressurized liquid extraction and gas chromatography-mass spectrometry

Our previous work demonstrated the presence of compounds with hypocholesterolemic capacity in olive seeds. These compounds were extracted using CO2-expanded ethyl acetate and identified as tyrosol, hydroxytyrosol, and β-sitosterol using GC–MS. This work describes the extraction of these compounds from different olive seeds using pressurized ethyl acetate. Their solubility in ethyl acetate at temperatures ranging from 40–200 °C was theoretically predicted by Hansen solubility parameters. The content of these compounds was estimated by GC–MS, as well as, the reduction of the micellar cholesterol solubility (RMCS) capacity of extracts enabling to establish the optimum extraction temperature at 100 °C. A GC–MS method was developed and validated in terms of its analytical characteristics for a sensitive determination and quantification of tyrosol, hydroxytyrosol, and β-sitosterol in different olive seeds. Within varieties, Manzanilla seeds presented the highest concentration of tyrosol, hydroxytyrosol, and the lowest concentration of β-sitosterol, as well as the highest RMCS capacity.

Adélie penguin colonies as indicators of brominated flame retardants (BFRs) in East Antarctica

While persistent organic pollutant (POP) contamination within Antarctica is largely caused by long-range atmospheric transport (LRAT), Antarctic research bases have been shown to be local sources of POPs such as brominated flame retardants (BFRs). This study compared concentrations of seven polybrominated diphenyl ethers (PBDE) congeners and five novel flame retardants (NBFRs) found in Adélie penguin (Pygoscelis adeliae) colony soils near the Australian research stations, Mawson and Davis, to assess the stations as local sources of these contaminants and provide a much needed baseline for contamination of BFRs in East Antarctica. Soil samples (n = 46) were collected from Adélie colonies at close proximity to the research stations as well as further afield during the 2016-17 austral summer. Samples were analysed using selective pressurised liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). PBDEs (BDE-28, -47, -99, -100, -153, -154 and -183) were detected in 45/46 samples with ∑7PBDE concentrations ranging from <0.01 to 1.63 ng/g dry weight (dw) and NBFRs (2,3,4,5,6-pentabromotoluene (PBT), 2,3,4,5,6-pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2,4,6-tribromophenoxy) ethane (BTBPE)) detected in 20/46 samples, with a range of ∑5NBFR from not detected (ND) to 0.16 ng/g dw. Soils taken from around the Davis and Mawson research stations were more highly contaminated (n = 10) than penguin colonies (n = 27) and control areas not affiliated with breeding seabirds (n = 8). The most common congener detected was BDE-99, reflecting inputs from LRAT. However, the congener profiles of station soils supported the hypothesis that research stations are a local source of PBDEs to the Antarctic environment. In addition, the NBFR pentabromoethylbenzene (PBEB) was quantified for the first time in Antarctic soils, providing essential information for baseline contamination within the region and highlighting the need for ongoing monitoring as global regulations for the use of BFRs continuously change.

Selective pressurized liquid extraction of plant secondary metabolites: Convallaria majalis L. as a case

A fast and efficient selective pressurized liquid extraction (sPLE) method was developed to extract secondary metabolites from complex plant matrix. Convallaria majalis L., a plant producing toxic steroids, was used as proof-of-concept. The method was optimized in the aspects of preheating, dispersant, extraction temperature and solvent, and the use of C18 as in-cell cleanup sorbent. Eight authentic natural steroids with diverse sugar moieties and hydrophobicities were selected as reference analytes and spiked to 0.1 g dried leaves. The extraction performance was evaluated based on the analytes’ stability, recovery, matrix effect in the electrospray interface and the level of co-extractives. With the optimal method, the extraction was finished in 10 min. A colorless extract was obtained with recoveries ranging from 63% to 107% and absolute matrix effects ranging from 3% to 27%. The optimized method was validated by extracting 0.1 g, 0.2 g and 0.4 g spiked plant samples; method accuracy and precision were assessed by recoveries and relative standard deviations of the combined extraction-analysis workflow. The method was also tested on soil samples and indicated its suitability for measuring secondary metabolites in multiple environmental matrices. To our knowledge, this is the first time sPLE has been reported to extract plant secondary metabolites from a complex plant matrix, with satisfactory recoveries and low matrix effects. This is also the first time (s)PLE has been reported to extract plant secondary metabolites from soil. We envision the method be coupled with liquid chromatography-electrospray ionization-high resolution mass spectrometry in a standard metabolomics workflow to facilitate plant metabolomics studies.

Determination of 19 anthelmintics in environmental water and sediment using an optimized PLE and SPE method coupled with UHPLC-MS/MS

A sensitive quantification method using pressurized liquid extraction (PLE) and solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for determination of 19 anthelmintic drugs (ADs) belonging to seven structural groups (Benzimidazoles, Diphenylsulfides, Imidazothiazoles, Hexahydropyrazines, Macrocylic lactones, Salicylanilides, Tetrahydropyrimidines) in environmental water and sediment samples. Eleven SPE cartridges, sample pH, elution solvents were tested to determine the optimal conditions for extraction. Among these investigated SPE types, the best recoveries for 19 target ADs were obtained from Oasis HLB cartridge with 37–102%, 45–103%, 37–88%, 28–82% and 31–90% for spiked river water, tap water, rainwater, wastewater, and sediment respectively (with RSD < 15%), except for closantel. The 19 ADs were separated within 10 min by a BEH C18 column and monitored in both positive and negative ions modes with switching electrospray ionization source. The cross-talk interferences were solved by identification of secondary mass spectrum of substances through MRM-IDA-EPI scanning using Qtrap. These interference peaks could be efficiently eliminated by setting MRM segments or using Qtrap to obtain tertiary fragmented information. The developed methods were satisfactory in terms of linearity, accuracy, and precision, and used eight isotopically labeled compounds as internal standards to correct matrix effects. Method quantification limit (MQL) for 19 ADs was below 1.1 ng/L, 0.4 ng/L, 5.4 ng/L and 2.3 ng/g for river water, tap water, wastewater, and sediment, respectively. The validated method was successfully used to investigate the occurrence of anthelmintics in water and sediment samples from Chengdu, China. All ADs were detected in environment with the concentrations at ng/L level.

Simultaneous extraction and separation of bioactive compounds from apple pomace using pressurized liquids coupled on-line with solid-phase extraction

The objective of this work was the development of an on-line extraction/fractionation method based on the coupling of pressurized liquid extraction and solid-phase extraction for the separation of phenolic compounds from apple pomace. Several variables of the process were evaluated, including the amount of water of the first stage (0–120 mL), temperature (60–80 °C), solid-phase extraction adsorbent (Sepra, Isolute, Strata X and Oasis) and activation/elution solvent (methanol and ethanol). The best results were observed with the adsorbent Sepra. The temperature had a small effect on recovery, but significant differences were observed for phlorizin and a quercetin derivative. Results indicate that ethanol can be used to replace methanol as an activation, extraction/elution solvent. While using mostly green solvents (water, ethanol, and a small amount of methanol that could be reused), the developed method produced higher or similar yields of acids (2.85 ± 0.19 mg/g) and flavonoids (0.97 ± 0.11 mg/g) than conventional methods.

Selective pressurized extraction as single-step extraction and clean-up for the determination of organophosphate ester flame retardant in Citrus aurantium leaves by gas chromatography-tandem mass spectrometry.

In this work, an analytical method has been developed and validated for the determination of organophosphate esters (OPEs) in urban ornamental tree leaves. OPEs are flame retardants and plasticizers which are classified as health and environmental hazards substances. Their presence in urban air has been previously described. The method proposed in this work would allow the use of urban tree leaves as simple, cheap, and widely distributed in urban areas alternative to the existing active and passive sampler for sample collection. The method was based on sample treatment by selective pressurized liquid extraction (SPLE) and determination by gas chromatography with triple quadrupole mass spectrometry detector. After the optimization of the extraction solvent, the key parameters applied to SPLE (clean sorbent and sorbent amount applied for the sample clean-up, temperature, extraction cycles, and time) were optimized using a Box-Behnken response surface design. The method achieves high recoveries (higher than 60% for most of the target compounds), accuracies between 70 and 109%, and method detection and quantification limits ranged 0.05-4.96ng/g dw (dry weight) and 0.15-14.4ng/g dw, respectively. The method allowed the proper biomonitoring of OPE in tree leaves. Concentrations measured in analyzed samples were from 47.5 to 5477ng/g dw (TEP). The most frequently detected compounds were triethyl phosphate tri-n-butyl phosphate, triphenyl phosphate, and tris(1-chloro-2-propyl)phosphate, while tris(2-ethylhexyl)phosphate was not detected in the analyzed samples. The proposed analytical method constitutes a starting point for the use of ornamental urban trees as passive sampler for the evaluation of OPE as air pollutants. Graphical Abstract.

Sustainable extraction of proteins and bioactive substances from pomegranate peel (Punica granatum L.) using pressurized liquids and deep eutectic solvents

Pomegranate peel is a source of proteins, bioactive peptides, and phenolic compounds. The simultaneous extraction of these compounds required the use of polluting solvents and reagents that are non-suitable. This work targets the development of green methodologies based on pressurized liquids (PLE) or deep eutectic solvents (DES) for the extraction of these compounds. Extracts were digested with different proteolytic enzymes and different functionalities (antioxidant, hypocholesterolemia, and antihypertensive capacities) were evaluated. Highly antioxidant and hypocholesterolemic extracts and hydrolysates were obtained using PLE while high antihypertensive capacity was observed in the hydrolysates from proteins extracted using DES. Peptides and polyphenols were identified by HPLC-ESI-Q-TOF/MS. Higher amounts of peptides were shown in hydrolysates from DES extracts while hydrolysates from PLE extracts presented higher amounts of phenolic compounds. Some peptides were assigned to proteins from Punica granatum. Both green methods improved the extraction of bioactive compounds from pomegranate peel compared to the non-sustainable method. Industrial relevanceThe development of green methodologies which employ sustainable solvents such as pressurized liquids (PLE) and deep eutectic solvents (DES) allows extracting proteins and bioactive compounds from pomegranate peel. In addition, these solvents improve the extraction of health beneficial compounds compared to the non-sustainable and polluting solvents. Therefore, they could be used for the development of nutraceuticals and functional foods or even in medicinal, cosmetic, and pharmaceutical preparations.

Screening of bioactive compounds in truffles and evaluation of pressurized liquid extractions (PLE) to obtain fractions with biological activities

Truffles, besides the appreciated aromatic compounds, contain other molecules with interesting bioactive properties. A screening of fungal sterols and β-glucans within different truffle species and locations was carried out. These compounds were extracted with pressurized liquids (PLE) generating enriched fractions. Extraction efficiency was studied with a full-factorial experimental design (Response surface methodology, RSM), using water and ethanol as extraction solvents. Polysaccharides from truffle powder (TP) and the optimal PLE extract (EP) obtained were precipitated and analysed by NMR and GC–MS. THP-1 cell cultures were utilized to test immunomodulatory properties. With the optimal PLE conditions (16.7 MPa, 180 °C, 30 min) 64 and 22.5% yields were obtained respect, with water and ethanol, generating fractions containing respect, 9.1% β-glucan and 4.5% ergosterol. NMR analyses detected (1 → 3)-β-glucan structures in truffle. The EP induced a reduction of 40% IL-1β and 60% IL-6 pro-inflammatory cytokines secretion suggesting potential immunomodulatory activity.

Extraction of bioactive compounds from defatted passion fruit bagasse (Passiflora edulis sp.) applying pressurized liquids assisted by ultrasound.

Passion fruit bagasse is a rich source of phenolic compounds, including piceatannol, a stilbene to which several biological activities are conferred. This work reports the application of pressurized liquid extraction (PLE) assisted by ultrasound (US) to intensify the extraction of phenolic compounds from defatted passion fruit bagasse (DPFB). PLE at different temperatures (65-75°C) without and with different US powers (240-640W) was performed to investigate the mechanism of the assisted process. The extracts were evaluated in terms of global, total phenolic (TP), piceatannol and total reducing sugar yields. The antioxidant capacity of the extracts was determined by FRAP and ORAC assays. PLE assisted by US increased the yields, resulting in 60% more TP and piceatannol. The observed yields suggest that the main mechanism driving PLE assisted by US from DPFB was the rise in temperature caused by the ultrasonic waves. Pearson coefficient revealed a strong correlation between antioxidant capacity and total phenolics and piceatannol yield. The three-line spline model was adequately fitted to the experimental curves, showing three extraction periods in which the recovery of TP and piceatannol was higher than 70% at the end of the falling extraction rate period. PLE assisted or not by US showed to be clean, efficient and green alternatives for the recovery of phenolic compounds. The findings of this work indicate that PLE assisted by US has a great potential to improve the extraction of bioactive compounds from natural products.

Crambe seed oil: Extraction and reaction with dimethyl carbonate under pressurized conditions

In this study, the efficiency of dimethyl carbonate as a solvent in the pressurized liquid extraction (PLE) of crambe seed oil and also as the acyl acceptor in the transesterification reaction using the mixture obtained, simulating a sequential process, was investigated. In the PLE process, the effect of temperature (140–180 °C) on the yield and quality of the oil was evaluated, and the results were compared to data obtained applying Soxhlet extraction. The reaction of the PLE mixture was conducted from 250 to 350 °C. The results showed greater oil removal from the seeds under pressurized conditions, reaching a yield of ∼45%, which was higher than the yield obtained with Soxhlet extraction. The fatty acids and acylglycerols composition of the extracts obtained with the two methods were similar. However, the phytosterols and tocopherols contents of the oil obtained by PLE were around ∼62% and ∼574% higher, respectively, compared with the oil from the Soxhlet extraction. The best results in the reaction step for ester yield (66.5%) and triglyceride conversion (98.5%) were obtained at 300 °C.

Green Compressed Fluid Technologies To Extract Antioxidants and Lipids from Galdieria phlegrea in a Biorefinery Approach.

A green cascade approach was used to recover phycocyanins, carotenoids and lipids from Galdiera phlegrea. Phycocyanin extraction was performed by high pressure homogenization and purified by ultrafiltration, whereas carotenoids were obtained by a pressurized liquid extraction and lipids by supercritical fluid extraction. The second step of this innovative, green, and cost-effective procedure is able to improve the recovery of zeaxanthin and β-carotene up to 40%, without affecting the quality of compounds and avoiding the use of organic solvents and the drying processes. The isolated carotenoids were active as antioxidants, as clearly shown by their protective activity on a cell-based model. The lipid yield was increased by 12% with respect to conventional methods.

Authentication of the geographical origin and the botanical variety of avocados using liquid chromatography fingerprinting and deep learning methods

The lipid chromatographic fingerprint of different avocado fruits have been acquired and two classification multivariate methods, partial least squares-discriminant analysis (PLS-DA) and support vector machine (SVM), have been successfully tested in order to discriminate and classify a higher variability of avocado samples. Two authentication goals have been achieved attending to: (i) the geographical origin, and (ii) the botanical variety or cultivar. However, to our knowledge, there are no antecedents aimed at comparing and classifying avocado fruits. The pulp oil fraction of the avocado fruit was first extracted using pressurised liquid extraction from the previously lyophilised pulp. Then the 190–400 ​nm UV-absorption fingerprints were obtained from the avocado oils using normal phase high performance liquid chromatography coupled to an absorption diode-array detector ((NP)HPLC-DAD) and the 220 ​nm spectra were then selected for classification model building. Several input-class classification strategies were applied and the classification models were externally validated from the specific success/error contingencies. In addition, some quality metrics, i.e. sensitivity (or recall), specificity, precision, negative predictive values, efficiency (or accuracy), AUC (area under the receiver operating curve), Mathews correlation coefficient and Kappa coefficient, were determined to evaluate the performance of each classification model (PLS-DA and SVM) and the results clearly show that SVM method is the most proficient.