Pressurized Liquid Extraction Extracts Research Articles

Sequential high-pressure extraction using green solvents to recover bioactive compounds from sesame cake

Sesame cake was submitted to pressurized liquid extraction (PLE) for process optimization. Then, supercritical fluid extraction (SFE), followed by optimized PLE were applied to recover the oily fraction and the polar extract, respectively. PLE samples, at optimized condition and from SFE deffated cake, showed high levels of TPC (33.15 and 31.86mg GAE/g), DPPH (97.64 and 94.38 µmol TE/g), FRAP (46.12 and 46.69mg TE\\g), flavonoids (2.26 and 2.31mgQE/g extract), yield (13.76 and 16.25%) and protein (56.52 and 54.08mg BSA/g), respectively. The oily fraction presented high levels of carotenoids and essential fatty acids, while PLE extracts presented higher concentration of ferulic acid, 4-aminobenzoic acid, and quercetin compared to Soxhlet extract. Total Reduced Sugar (TRS) content suggests sesame cake as good biomass for bioethanol production. The sequential process (SFE + PLE) was efficient to recover two bioactive fractions from sesame cake, contributing to improve the value of this co-product.

Pressurized liquid extraction followed by high-performance liquid chromatography for determination of beta-ecdysone extracted from Pfaffia glomerata (Spreng.) Pedersen

Pfaffia glomerata (Spreng.) Pedersen has among its main bioactive compounds saponins, with the phytoestroid β-ecdysone as its chemical marker. In this study, pressurized liquid extraction (PLE), a green extraction technique used to obtain bioactive compounds from plants, was employed to extract beta-ecdysone from P. glomerata leaves, stems, and roots. The 22 factorial design was used with the variables temperature (333 K and 353 K) and flow rate (1.5 and 2 mL min−1), pressure (300 Bar), time (60 min), and solvent [ethanol and distilled water (70:30 (v/v)] were kept constant for all parts of the plant. The results of experimental responses demonstrated that the factors temperature and flow rate significantly interfere with the yields of leaf (0.499%), root (0.65%) and stem (0.764%) extracts. The latter presented presents the highest yield compared to the other parts of the plant. HPLC results showed the presence of beta-ecdysone in all parts of the plant with concentrations of β-ecdysone 86.82, 76.53 and 195.86 mg L−1 to leaf, root and stem, respectively. FT Raman results exhibited typical peaks of beta-ecdysone, such as 3310 cm−1, 1654 cm−1, and 1073 cm−1 for all plant parts. Another interesting result was the presence of the peak at 1460 cm−1 in the PLE root extract can be associated with selenium. This foundational knowledge confirms that the PLE extraction process was efficient in obtaining the chemical marker of Pfaffia glomerata in all plant parts.

Tetraselmis chuii Edible Microalga as a New Source of Neuroprotective Compounds Obtained Using Fast Biosolvent Extraction.

Tetraselmis chuii is an EFSA-approved novel food and dietary supplement with increasing use in nutraceutical production worldwide. This study investigated the neuroprotective potential of bioactive compounds extracted from T. chuii using green biobased solvents (ethyl acetate, AcOEt, and cyclopentyl methyl ether, CPME) under pressurized liquid extraction (PLE) conditions and supercritical fluid extraction (SFE). Response surface optimization was used to study the effect of temperature and solvent composition on the neuroprotective properties of the PLE extracts, including anticholinergic activity, reactive oxygen/nitrogen species (ROS/RNS) scavenging capacity, and anti-inflammatory activity. Optimized extraction conditions of 40 °C and 34.9% AcOEt in CPME resulted in extracts with high anticholinergic and ROS/RNS scavenging capacity, while operation at 180 °C and 54.1% AcOEt in CPME yielded extracts with potent anti-inflammatory properties using only 20 min. Chemical characterization revealed the presence of carotenoids (neoxanthin, violaxanthin, zeaxanthin, α- and β-carotene) known for their anti-cholinesterase, antioxidant, and anti-inflammatory potential. The extracts also exhibited high levels of omega-3 polyunsaturated fatty acids (PUFAs) with a favorable ω-3/ω-6 ratio (>7), contributing to their neuroprotective and anti-inflammatory effects. Furthermore, the extracts were found to be safe to use, as cytotoxicity assays showed no observed toxicity in HK-2 and THP-1 cell lines at or below a concentration of 40 μg mL-1. These results highlight the neuroprotective potential of Tetraselmis chuii extracts, making them valuable in the field of nutraceutical production and emphasize the interest of studying new green solvents as alternatives to conventional toxic solvents.

Green Approach to Enhance the Recovery of Polyphenols from Blackcurrant and Bilberry Leaves: Evaluation of Microwave-Assisted and Pressurized Liquid Extraction.

The aim of the present study was to evaluate microwave-assisted (MAE) and pressurized liquid extraction (PLE) for the recovery of polyphenols from blackcurrant and bilberry leaves and the preservation of their antioxidant activity. The extractions were carried out varying the solvent/solid (SS) ratio, temperature and time. During MAE, increasing the SS ratio increased the polyphenol concentration in the extracts from blackcurrant and bilberry leaves, while increasing the temperature had a positive effect only on bilberry polyphenols. During PLE, only a temperature increase was a determining factor for the isolation of blackcurrant leave polyphenols. Based on polyphenol recovery, optimal extraction parameters were established resulting in a yield of 62.10 and 56.06 mg/g dw in the blackcurrant and bilberry MAE extracts and 78.90 and 70.55 mg/g dw in the PLE extracts. The optimized extracts were profiled by UPLC ESI MS2, and their antioxidant capacity was evaluated through FRAP, DPPH, ABTS and ORAC assays. The characterization of the extracts by UPLC ESI MS2 confirmed flavonols as the predominant compounds in both blackcurrant and bilberry leaves, while flavan-3-ols and procyanidins were the main compounds responsible for high antioxidant capacity as confirmed by the ABTS and ORAC assays. Due to the extract composition and antioxidant capacity, PLE proved to be a technique of choice for the production of blackcurrant and bilberry leave extracts with high potential for use as value-added ingredients in the food and nutraceutical industry.

Pressurized liquid extraction of bioactive extracts with antioxidant and antibacterial activity from green, red and brown Algerian algae

In this work, the protein, sugar, phenolic and phlorotannin contents, as well as the antioxidant and antibacterial activity of hydroethanolic extracts of six algae species from the west cost of Algeria (Padina pavonica, Halopteris scoparia, Cystoseira mediterranea, Ulva lactuca, Ulva intestinalis, and Ceramium virgatum), obtained by pressurized liquid extraction (PLE) were investigated. Ceramium virgatum PLE extracts showed the highest content of protein (4.36 ± 0.13 %), while the total sugar content was maximum in U. lactuca extract (23.89 ± 0.21 %). Likewise, P. pavonica PLE extract presented a relevant total phenolic content (49.82 ± 1.40 mg GAE/g extract). On the other hand, phlorotannins were only found in brown algae in a range of 1.84–2.93 mg PGE/g. Furthermore, P. Pavonica extract presented considerably higher antioxidant capacity of inhibiting ABTS radical (1.16 ± 0.023 mmol TE/g) and 50 % of DPPH (1,1-diphenyl-2-picryl hydrazyl) (IC50 = 57.03 ± 1.28 μg/mL) in comparison with the other studied algae. Regarding to the potential antimicrobial activity, the results showed that Cystoseira Mediterranea produced the lowest minimal inhibitory concentration on Salmonella typhi (0.83 ± 0.14 mg/mL), Escherichia coli (4.66 ± 0.57 mg/mL), Vibrio cholera (1.08 ± 0.14 mg/mL), and Candida albicans (2.16 ± 0.28 mg/mL). Besides, different carotenoids and phenolic compounds were tentatively identified by LC-DAD in the algae extracts which could be the responsible of the tested bioactivities. These findings show the potential of using PLE as green solvent extraction technique and the prolific bioactivities of Algerian seaweeds.

Pressurized Liquid Extraction (PLE) in an Intermittent Process as an Alternative for Obtaining Passion Fruit (Passiflora edulis) Leaf Hydroalcoholic Extract (Tincture)

Tinctures are medicinal plant extracts obtained by extraction with a hydroalcoholic solution (70%) by percolation (PER). This process takes about 26 h to prepare, in addition to using a large amount of solvent. In our research, passion fruit leaf tinctures were obtained using extract with the same pressurized hydroalcoholic solution as in an intermittent process. The objective was to demonstrate that this emerging technology can be economical and profitable. An optimization using Central Composite Rotatable Design (CCRD) was performed to evaluate the influence of process variables on the yields and compositions of the extracts. The temperature (T) was the factor that most influenced the responses. Extraction with pressurized liquid (PLE) provided total yields and total phenolic and flavonoid contents in greater amounts than PER. The optimized conditions of the process variables studied in the CCRD for the highest content of total phenolics (43.2 mg GAE/g) and flavonoids (58.8 mg QE/g) were at 100 °C with a rinse volume of 120% of the divided extractor volume in four cycles of the intermittent process. When adjusting the PLE in an intermittent process, and according to the one-dimensional mass transfer by the continuous diffusion of the Fick model, the effective diffusion coefficient (1.28 × 10−12 m2/s) was not affected by T. The kinetic curve of PLE extraction indicates that the adjusted intermittent process occurred in the period of the constant extraction rate when compared to the kinetics of the semi-continuous process. The yielded extracts were rich in isovitexin, and the highest levels were identified in the extracts obtained via PLE, indicating that this intermittent process can bring a product to market with the same quality but with a much shorter production time and the use of fewer solvents. Antioxidant activity, determined by DPPH, FRAP and ORAC, was also higher in extracts obtained via PLE.

Evaluation of Eugenia uniflora L. leaf extracts obtained by pressurized liquid extraction: Identification of chemical composition, antioxidant, antibacterial, and allelopathic activity

Pitangueira (Eugenia uniflora L.) leaves are rich in phenolic compounds. To evaluate these compounds, pitangueira leaves were submitted to extraction by aqueous infusion (AI) and by pressurized liquid extraction (PLE). PLE extracts were obtained with water (PLE-W), water:ethanol (PLE-W:E), and ethanol (PLE-E). Fifty-four extracted compounds were tentatively identified by LC-MS. The PLE-W:E extraction resulted in a higher concentration of phenolic acids and tannin compounds, while PLE-E showed a higher concentration of flavonoids. All extracts tested in vitro showed good antioxidant activity, as evaluated by thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) assays in rat brain homogenates model systems and in protecting yeasts under oxidation. Among the eight bacterial strains tested with the pitangueira leaf extracts, antibacterial activity was observed mainly against Staphylococcus aureus with the extracts of AI, PLE-W, and PLE-W:E. And for Pseudomonas aeruginosa, only the AI extract showed antibacterial activity. The other strains were not affected by the extracts. All extracts exhibit an allelopathic effect against lettuce seeds. Even though 72.2% of the putatively identified compounds were common to all extracts, PLE extracts provide more regular antioxidant, antibacterial, and allelopathic activities.

Development of a Pressurized Green Liquid Extraction Procedure to Recover Antioxidant Bioactive Compounds from Strawberry Tree Fruit (Arbutus unedo L.).

Strawberry tree fruits (Arbutus unedo L.) are a natural source of valuable biologically active compounds. Therefore, the aim of this work was to develop a green extraction approach using pressurized liquid extraction (PLE) to provide the highest yield of bioactive compounds. Different extraction solvents (distilled water, 50% and 96% ethanol) and different PLE parameters were investigated: temperature (40, 80, and 120 °C), static extraction time (5 and 10 min), and number of cycles (1 and 2). Total phenolic contents (TPC), hydroxycinnamic acids (HCA), flavonols (FL), total flavonoids (TF), condensed tannins (CT), and antioxidant capacity (DPPH and FRAP) were determined in PLE extracts. Solvent type, temperature, static extraction time, and number of cycles had a statistically significant effect on all bioactive compounds and antioxidant capacity (p ≤ 0.05). All bioactive compounds were positively correlated with temperature, except for TPC and DPPH. For all polyphenols studied, the optimal PLE parameters were a temperature of 120 °C, a static extraction time of 10 min and 2 cycles. The best solvent for most bioactive compounds was 96% ethanol, except for TPC, for which 50% ethanol was better. This study suggests that PLE is a promising tool to intensify the extraction of bioactive compounds from strawberry tree fruits.

Pressurized Liquid Extraction: A Powerful Tool to Implement Extraction and Purification of Food Contaminants.

Pressurized liquid extraction (PLE) is considered an advanced extraction technique developed in the mid-1990s with the aim of saving time and reducing solvent with respect to traditional extraction processes. It is commonly used with solid and semi-solid samples and employs solvent extraction at elevated temperatures and pressures, always below the respective critical points, to maintain the solvent in a liquid state throughout the extraction procedure. The use of these particular pressure and temperature conditions changes the physicochemical properties of the extraction solvent, allowing easier and deeper penetration into the matrix to be extracted. Furthermore, the possibility to combine the extraction and clean-up steps by including a layer of an adsorbent retaining interfering compounds directly in the PLE extraction cells makes this technique extremely versatile and selective. After providing a background on the PLE technique and parameters to be optimized, the present review focuses on recent applications (published in the past 10 years) in the field of food contaminants. In particular, applications related to the extraction of environmental and processing contaminants, pesticides, residues of veterinary drugs, mycotoxins, parabens, ethyl carbamate, and fatty acid esters of 3-monochloro-1,2-propanediol and 2-monochloro-1,3-propanediol from different food matrices were considered.

Application of pressurized liquid extraction to grape by-products as a circular economy model to provide phenolic compounds enriched ingredient

The aim of this study was to valorise wine-making by-products optimizing the recovery of phenolic compounds from Cannonau grape pomaces using Pressurized Liquid Extraction (PLE). To achieve these goals, PLE experiments were performed by a Response Surface Methodology (RSM) based on a Central Composite Design 23 model to address the polar compound extraction. The selected independent variables were: temperature, composition of extractant solvent (% ethanol) and extraction time. The response variables were extraction yield and recovery of phenolic compounds. Phytochemical profile of PLE extracts was analysed by high-performance liquid chromatography coupled to a time-of-flight mass analyser (HPLC-ESI-TOF-MS) in order to address the individual phenolic extraction effectiveness. Hence, the optimum values to maximize phenolics extraction were 130 °C, 55% ethanol and 22 min. Extraction results obtained by using PLE system was compared with that obtained with conventional solid-liquid extraction. The proposed experimental model has proven to be a valuable alternative method to optimize extraction of bioactive compounds from wine-making by-products.

Comparison of Green Technologies for Valorizing Sugar Beet Leaves (Beta vulgaris L.)

This study is focused on the valorization of sugar beet leaves (Beta vulgaris L.), a prominent by-product wasted during the process of sugar. For doing so, Ultrasound-Assisted Extraction (UAE), Pressurized Liquid Extraction (PLE), and Maceration Extraction (ME) methods were compared by evaluating the extraction yield, Total Phenolic Compounds (TPC), Total Flavonoid Content (TFC), individual phenolic profile, and antioxidant activity (e.g., DPPH, FRAP, and ABTS). Ethanol and water (70% V/V) were employed as extracting solvents. The TPC for UAE and PLE methods was 4.90±0.083 and 6.46±0.33 (mg GAE/mL), respectively, differing significantly (P<0.05) from each other. Moreover, the TFC in the PLE method was the highest with 1.45±0.06 mg QE/mL (P<0.05). The antioxidant activity of extracts was significantly different as the PLE method yielded the highest quantities. Benzoic acid was present only in the PLE extracts, while PLE and ME methods recovered the highest quantity of syringic acid (0.35±0.00 mg/L) and pyrogallol (74.80±0.01 mg/L), respectively. However, the extraction yield obtained by the UAE method (19.58±0.33%) had a significant statistical difference from other methods. Therefore, despite the higher TPC and antioxidant activity reached by the PLE method, it was proved that UAE yields higher polyphenolic compounds with a lower quantity of beet leaves.

Production of ethyl esters from forage radish seed: An integrated sequential route using pressurized ethanol and ethyl acetate

This work investigated the production of fatty acid ethyl esters (FAEE) from forage radish seeds using a sequential process with pressurized ethanol and ethyl acetate as solvents and acyl acceptors. First, the effect of the solvent on the extraction was determined and subsequently, the sequential reaction was carried out with the material from the pressurized liquid extraction (PLE) where the effects of temperature, residence time and water concentration were investigated. Conventional extraction was carried out for comparative purposes with regards to the oil quality of the PLE and its efficiency in the reaction. The use of ethanol resulted in a high mass yield, which was attributed to the high non-lipid fraction in the extracted material, and ethyl acetate retained proteins, phenolic compounds and sugars in the defatted meal. The main fatty acids in the oil were oleic and erucic acids and high levels of minority compounds were observed in the PLE oil. In the sequential reaction, supercritical ethyl acetate at 300 °C provided the highest FAEE content (42 wt% in 25 min). The addition of water in the acyl acceptor increased the production of FAEE, reduced the thermal degradation of the esters and provided a product with low levels of acylglycerols. Oils from PLE and conventional extraction showed similar performance in the synthesis of esters. Ethyl linolenate and ethyl linoleate were the esters that showed the highest level of degradation. The highest content of FAEE (53 wt%) was reached at 300 °C with 20% (v/v) of water, resulting in a triacetin content of 0.92 wt%.

Neuroprotective Potential of Thinned Peaches Extracts Obtained by Pressurized Liquid Extraction after Different Drying Processes.

Genetic, environmental and nutritional factors are suggested as primary factors of Alzheimer’s disease (AD), and secondary metabolites such as polyphenols present in thinned peaches are considered as good candidates for AD prevention. Thinned peaches are usually dried to avoid putrefaction, but the effects of the drying method and the extraction process on the polyphenol composition and the neuroprotective potential have never been addressed. In this work, a pressurized liquid extraction (PLE) method was optimized and applied to thinned peaches dried under different conditions, and their neuroprotective potential was evaluated in vitro. In addition, the PLE extracts were characterized via HPLC-Q-TOF-MS/MS, and a permeability assay was performed to evaluate the ability of the identified metabolites to cross the blood–brain barrier (BBB). The PLE extracts obtained from freeze-dried (FD) samples with 50% ethanol in water at 180 °C showed the best neuroprotective potential. Finally, among the 81 metabolites identified, isoferulic acid, 4-methyldaphnetin, coniferyl aldehyde and 3,4-dihydroxyacetophenone were found at higher concentrations in FD extracts. These metabolites are able to cross the BBB and are positively correlated with the neuroprotective potential, suggesting FD together with PLE extraction as the best combination to exploit the neuroprotective capacity of thinned peaches.

Pressurized green liquid extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii whole fruit: Process optimization and biological activities of green extracts

The Opuntia Stricta var. Dillenii's prickly pears are an underutilized fruits, which provide a great source of betalains (mainly, betacyanins) and phenolic compounds (phenolic acids and flavonoids) that could play an important role in health-promotion. This study focuses on the optimization of process for the green extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii's whole fruits by Pressurized liquid extraction (PLE), using a response surface methodology (RSM) by a central composite design (CCD) in order to obtain rich extracts in betalains and phenolic compounds with the similar profile of the original one found in O. dillenii fruits (avoiding any degradation of these compounds during the extraction process) with proven biological activities. For PLE optimization, the ethanol volume in water (0–100%, v/v) and the temperature (25–65°C) were selected as independent variables. The identification and quantification of the individual bioactive compounds of the obtained green extracts were done by HPLC-DAD-ESI/MS and HPLC-DAD-ESI/QTOF and their biological activities were determined by in vitro tests, as: the antioxidant activity by the ORAC method and the anti-inflammatory activity by the hyaluronidase inhibition method. Ethanol volume in water (%, v/v) was the variable with most significant (p ≤ 0.05) effect in the target responses (bioactive content and biological activities). The best results were obtained at 50% ethanol in water (v/v) and 25°C temperature (run 10) obtaining extracts with betalains as 2.34 ± 0.18 mg of betanin/g dry weight, 2.51 ± 0.04 mg of 5′´-O-E-sinapoyl-2′-apyosil-phyllocactin/g dry weight, 2.32 ± 0.19 mg of neobetanin/g dry weight and phenolic compounds, 2.08 ± 0.07 mg of piscicid acid/g dry weight and 0.25 ± 0.02 mg of isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2) /g dry weight. The betalain and phenolic profile of the PLE extracts was quite similar to the profile from the conventional extraction, but PLE extraction process enhanced the extraction of some bioactives as neobetanin (39%) andpiscidic acid (124%). All employed PLE process CCD combinations significantly upgrade the in vitro biological activities (antioxidant and anti-inflammatory) of the Opuntia stricta var. Dillenii's PLE green extracts.

Green Extraction Methods for Recovery of Antioxidant Compounds from Epicarp, Seed, and Seed Tegument of Avocado var. Hass (Persea americana Mill.).

The present study compared the extracts obtained from the epicarp, seed, and seed tegument of avocado var. Hass with pressurized liquid extraction (PLE) and ultrasound-assisted extraction (UAE). The extracts were quantified in terms of total phenolic content (TPC) and antioxidant capacity (AC). The PLE extracts had a global yield (X0) like that obtained with UAE using ethanol (Et) as the solvent. For the TPC, the extracts obtained with both techniques showed no significant differences (p > 0.05). On the other hand, the epicarp extracts obtained with PLE had higher values for AC: 829.8 μmol TE/gDe (ABTS) and 3,215.1 μmol Fe2+/g De (FRAP), recorded for UAE/Et. The AC in the avocado residue extracted with PLE suggested a high potential for applications in food, pharmaceutical, and cosmetology products.

Neuroprotective potential of terpenoid-rich extracts from orange juice by-products obtained by pressurized liquid extraction.

Pressurized liquid extraction (PLE) conditions were optimized to improve the recovery of orange (Citrus sinensis) by-products terpenoids. The neuroprotective potential of the PLE extracts were tested against a set of in-vitro assay (antioxidant (ABTS), reactive oxygen/nitrogen species (ROS/RNS)) as well as enzymatic tests (acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and lipoxygenase (LOX)). Gas chromatography coupled to high-resolution mass spectrometry (GC-q-TOF-MS) analysis revealed a higher enrichment in mono- and sesquiterpenoids of the PLE extracts with the highest neuroprotection capacity. In-silico molecular docking analysis showed the specific interaction of representative terpenoids with enzymes active sites. The results demonstrate that the selected extract at 100°C and 30 minutes possesses high antioxidant (ABTSIC50=13.5μgmL-1; ROSIC50 = 4.4μgmL-1), anti-cholinesterase (AChEIC50=137.1 vg L-1; BChEIC50=147.0μgmL-1) and anti-inflammatory properties (against IL-6 and LOXIC50=76.1μgmL-1), with low cytotoxicity and protection against L-glutamic acid in cell models.

Non-conventional techniques for the extraction of antioxidant compounds and lycopene from industrial tomato pomace (Solanum lycopersicum L.) using spouted bed drying as a pre-treatment

This study aimed to use the non-conventional microwave-assisted extraction (MAE) and pressurized liquid extraction (PLE) techniques for recovering bioactive compounds from tomato pomace, a valuable agro-industrial waste. The raw material was previously dried using a spouted bed dryer and then submitted to extraction with green solvents. A response surface methodology (RSM) performed the optimization of MAE and PLE. Next, the yield and the antioxidant activity results were maximized, and the lycopene content of the optimum MAE and PLE extracts was assessed by high-performance liquid chromatography (HPLC). Additionally, a fraction of raw material was oven dried as a comparison. The PLE extract exhibited the highest antioxidant activity, whereas the MAE extract showed the highest lycopene content (59.66 µg lycopene/g extract), which represents a 66.93% lycopene recovery compared to a standard technique with acetone. The remarkable results show that the non-conventional drying and extraction techniques were effective in valorizing this neglected material.

Comparative study of factors affecting the recovery of proteins from malt rootlets using pressurized liquids and ultrasounds

Malt rootlets (MR) are a waste from brewing with high protein content. This work proposes to study the impact of extracting parameters on the recovery of proteins and the characteristics of extracts from MR using ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE). A Box-Behnken experimental design was employed to study the effect of extracting parameters on the protein yield, while characterization comprised the study of antioxidant properties, the identification of extracted proteins using high-resolution tandem mass spectrometry, and the evaluation of the co-extraction of phenolic compounds. Protein extraction was promoted at an ultrasounds amplitude of 68%, for 20 min at 52 °C in UAE, while adding 33% ethanol resulted in the highest yield in PLE. While UAE extracted 53 ± 5% of MR proteins, PLE reached a 73 ± 7%, using more sustainable conditions. Significant antioxidant activities were observed in the PLE extract, although undermined by gastrointestinal digestion. Proteomic analysis detected 68 proteins from Hordeum vulgare in the UAE extract and 9 in the PLE extract. Proteins in MR are very different to that from barley grains or brewer's spent grains. PLE also co-extracted phenolic compounds while this was not significant by UAE.

Polyphenolic QTOF-ESI MS Characterization and the Antioxidant and Cytotoxic Activities of Prunus domestica Commercial Cultivars from Costa Rica.

There is an increased interest in plum research because of their metabolites’ potential bioactivities. In this study, the phenolic profiles of Prunus domestica commercial cultivars (Methley, Pisardii and Satsuma) in Costa Rica were determined by Ultra Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry using a quadrupole-time-of-flight analyzer (UPLC-ESI-QTOF MS) on enriched phenolic extracts obtained through Pressurized Liquid Extraction (PLE) under acidic and neutral extraction conditions. In total, 41 different phenolic compounds were identified in the skin and flesh extracts, comprising 11 flavan-3-ols, 14 flavonoids and 16 hydroxycinnamic acids and derivatives. Neutral extractions for the skins and flesh from all of the cultivars yielded a larger number of compounds, and were particularly rich in the number of procyanidin trimers and tetramers when compared to the acid extractions. The total phenolic content (TPC) and antioxidant potential using the DPPH and ORAC methods exhibited better results for neutral extracts with Satsuma skins and Methley flesh, which showed the best values (685.0 and 801.6 mg GAE/g extract; IC50 = 4.85 and 4.39 µg/mL; and 12.55 and 12.22 mmol TE/g extract, respectively). A Two-Way ANOVA for cytotoxicity towards AGS gastric adenocarcinoma and SW620 colon adenocarcinoma indicated a significant difference (p < 0.05) for PLE conditions, with better results for neutral extractions, with Satsuma skin delivering the best results (IC50 = 60.7 and 46.7 µg/mL respectively) along with Methley flesh (IC50 = 76.3 and 60.9 µg/mL, respectively). In addition, a significant positive correlation was found between TPC and ORAC (r = 0.929, p < 0.05), as well as a significant negative correlation (p < 0.05) between TPC and cytotoxicity towards AGS and SW620 cell lines (r = −0.776, and −0.751, respectively). A particularly high, significant, negative correlation (p < 0.05) was found between the number of procyanidins and cytotoxicity against the AGS (r = −0.868) and SW620 (r = −0.855) cell lines. Finally, the PCA clearly corroborated that neutral extracts are a more homogenous group exhibiting higher antioxidant and cytotoxic results regardless of the part or cultivar; therefore, our findings suggest that PLE extracts under neutral conditions would be of interest for further studies on their potential health benefits.

Impact of Pressurized Liquid Extraction and pH on Protein Yield, Changes in Molecular Size Distribution and Antioxidant Compounds Recovery from Spirulina.

The research aims to extract nutrients and bioactive compounds from spirulina using a non-toxic, environmentally friendly and efficient method—Pressurized Liquid Extraction (PLE). In this work, Response Surface Methodology (RSM)–Central Composite Design (CCD) was used to evaluate and optimize the extraction time (5–15 min), temperature (20–60 °C) and pH (4–10) during PLE extraction (103.4 bars). The multi-factor optimization results of the RSM-CCD showed that under the pressure of 103.4 bars, the optimal conditions to recover the highest content of bioactive compounds were 10 min, 40 °C and pH 4. Furthermore, the compounds and antioxidant capacity of PLE and non-pressurized extraction extracts were compared. The results showed that under the optimal extraction conditions (10 min, 40 °C and pH 4), PLE significantly improved the antioxidant capacity (2870.5 ± 153.6 µM TE), protein yield (46.8 ± 3.1%), chlorophyll a (1.46 ± 0.04 mg/g), carotenoids (0.12 ± 0.01 mg/g), total polyphenols (11.49 ± 0.04 mg/g) and carbohydrates content (78.42 ± 1.40 mg/g) of the extracts compared with non-pressurized extraction (p < 0.05). The protein molecular distribution of the extracts was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the results showed that there were more small-molecule proteins in PLE extracts. Moreover, Liquid Chromatography Triple Time of Flight Mass Spectrometry (TOF–LC–MS–MS) was used to analyze the phenolic profile of the extracts, and the results showed the extracts were rich on phenolic compounds, such as p-coumaric acid and cinnamic acid being the predominant phenolic compounds in the PLE extract. This indicates that PLE can promote the extraction of bioactive compounds from Spirulina, which is of great significance for the application of PLE technology to obtain active substances from marine algae resources.