Rapid Solid-liquid Dynamic Extraction Research Articles

Comparison between Conventional Ageing Process in Barrels and a New Rapid Aging Process Based on RSLDE: Analysis of Bioactive Compounds in Spirit Drinks

“Aging” is a practice that allows alcoholic beverages to mature and gives them particular flavors and colors. In this context, oak or durmast wooden barrels are used in this process, thus providing different types of aging. This conventional process produces a slow enrichment of organic compounds in the spirit inside the barrels. Organic substances present in the internal part of the barrels slowly undergo the phenomenon of extraction by the liquid phase (solid–liquid extraction). In this work, a new procedure based on rapid solid–liquid dynamic extraction (RSLDE) was used to evaluate the potential of obtaining the effects of aging in spirits in shorter times than conventional methods. For this purpose, a comparison between two solid–liquid extraction techniques, RSLDE and conventional maceration, was made. Four water/ethanol 60:40 (v/v) model solutions were prepared and put in contact with medium-toasted chips using the two extraction procedures (conventional and non-conventional) and determining dry residue and total polyphenol content. Reversed phase high-performance liquid chromatography (RP-HPLC) analyses allowed the identification and quantification of furfural, ellagic acid and phenolic aldehydes (vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde). The aging procedure with medium-toasted chips was tested on a young commercial grappa using maceration and RLSDE.

Rapid solid-liquid dynamic extraction of Cachrys pungens Jan ex Guss. aerial parts: influence on the photobiological and antioxidant properties

Cachrys pungens Jan ex Guss. (Apiaceae) is a perennial plant native to Italy and Northwestern Africa. This species is known for its content in furanocoumarins, and the methanolic extract obtained with maceration previously demonstrated significant phototoxicity on 375 melanoma cells. Here, in order to better explain the biological effects, the apoptotic responses on melanoma cancer cell line were verified. The aerial parts were extracted with methanol through an innovative solid–liquid extraction technology, the Naviglio extractor®, and the raw extract was tested for its photobiological properties on human melanoma C32 cells irradiated with UVA light. The in vitro antioxidant potential was assessed as well. The sample exerted a concentration-dependent photocytotoxic activity (IC50 value = 3.00 ± 0.16 µg/mL). In line with these evidences, in C32-treated cells subjected to UV irradiation, further data have reported an up-regulation of p53 and PARP, both proteins involved in apoptotic response and DNA repair.

Efficiency of Recovery of the Bioactive Principles of Plants by Comparison between Solid-Liquid Extraction in Mixture and Single-Vegetable Matrices via Maceration and RSLDE.

The term "officinal" derives from the Latin and includes all medicinal, aromatic and perfume plant species, which have long been a subject of interest for multiple purposes: health, food, pharmacological, cosmetic and so on. In this work, a study on six different species of medicinal plants, particularly characterized by digestive, choleretic and diuretic properties, was carried out: rosemary (Rosmarinus officinalis), sage (Salvia officinalis), laurel (Laurus nobilis), gentian (Gentiana lutea), dandelion (Taraxacum officinale) and rhubarb (Rheum palmatum). The roots and aerial parts of plants were separately extracted with two different techniques-maceration and rapid solid-liquid dynamic extraction (RSLDE)-and the quali/quantitative analysis of active ingredients have been determined by applying dry residue, Folin-Ciocalteu and DPPH assays. Data obtained have provided useful answers regarding the efficiency of the extraction carried out on a mixture or on single plants, allowing us to evaluate the best choice according to the cases and the final uses.

High Efficiency and New Potential of RSLDE: A Green Technique for the Extraction of Bioactive Molecules from Not Completely Exhausted Plant Biomass and Organic Industrial Processing Waste

A product is characterized by low environmental impact if, during the whole process (from extraction of raw materials from solid natural matter to disposal), its negative contribution to environment modification is significantly reduced or eliminated. According to circular economy, it is important to take into consideration other aspects, such as the possibility to improve the efficiency of extraction process by modifying the principle on which it is based and allowing the recovery of not completely exhausted waste, obtaining other active ingredients, and favoring the recycling of normally eliminated materials. The purpose of this work was to propose more efficient and greener alternatives to conventional solid–liquid extraction processes. Major features are the rapidity of the process, extraction at room temperature and high yields. Rapid Solid–Liquid Dynamic Extraction (RSLDE) represents an innovative solid–liquid extraction technology that allows the solid matrices containing extractable substances in an organic or inorganic solvent and their mixtures to be exhausted in shorter time than current techniques. The principle at the basis of this novel process consists of the generation of a negative pressure gradient between the inside and the outside of the solid matrix, which induces the extraction of compounds not chemically linked to the solid matter, being insoluble in the extractant liquid. Therefore, this work focuses on how RSLDE can potentially bring several improvements in the field of solid–liquid extraction, especially for industrial applications.

Various Applications of Processing of Olive Leaves Waste Extracted with RSLDE: A Green Technology

AbstractThere is no waste in nature. Everything that is produced has a purpose and everything that becomes waste can be transformed into a new resource, triggering a virtuous circuit that feeds itself. The circular economy of waste means a system in which the production‐consumption‐disposal process is overcome to replace it with a circular model, where the final waste product is re‐introduced into the circulation as a secondary raw material. The logic to follow is that after consumption and before any disposal, it is necessary to activate virtuous processes such as reduce, reuse, and recycling. This work focuses on the possible uses of a vegetable waste matrix, such as olive leaves.The olive tree (Olea europaea) is a fruit tree, cultivated for more than 3500 years for its fruits and edible oil. However, just like oil, olive leaf contains a high amount of polyphenols, in particular oleuropein, one of the most powerful natural antioxidants known and hydroxytyrosol, which also has powerful antiseptic properties. Therefore, olive leaf extracts, thanks to the presence of oleuropein associated with hydroxytyrosol, represent a powerful natural antioxidant, a valid ally of the cardiovascular system. In addition, olive leaves are an excellent regulator of the digestive system: they regulate intestinal transit and above all eliminate fungi and other unwanted parasites from the body. Starting from these premises, in this work, a green extraction technique such as rapid solid liquid dynamic extraction (RSLDE) is compared with conventional maceration to obtain an olive leaf extract rich in antioxidants to be used in various sectors.

Extraction and Purification of Phycocyanin from Arthrophira platensis Microalgae Using a Green Solid‐Liquid Extraction Technology (RSLDE)

AbstractSpirulina is a blue alga belonging to the class of Cyanobacteria. This alga is characterized by a high content of phycocyanin (PC), a blue photosynthetic pigment belonging to the phycobiliprotein family. As natural dye, PC has a lot of industrial applications, in several fields such as the cosmetic, food, and textile sectors. It is also used in the biomedical field as a fluorescent marker. Anti‐inflammatory, nephroprotective, and hepatoprotective properties are also reported, probably related to its antioxidant activity. However, the extraction of phycobiliproteins from cyanobacteria is a very complicated procedure due to the extreme resistance of the wall of the cellular aggregates that make up spirulina. In literature, several procedures have been used to cause rupture of cell envelopes, through cycles of freezing/thawing, sonication, and rupture of the cell wall with lysozyme. However, all these methods do not guarantee a high quality of the extract, due to the complexity of the mixture obtained. In order to improve the yield of PC and to reduce the extraction process time, in this work, the conventional extraction by sonication is compared with a green innovative extraction technique, the rapid solid liquid dynamic extraction (RSLDE). This technique can generate a pressure and a consequent depression on the matrix to be extracted. The final extract was immediately frozen at −20°C and then lyophilized. UV–Vis spectrophotometric analysis and acrylamide gel electrophoresis are performed to evaluate the extraction efficiency and purity of PC.

An Insight into Salvia haematodes L. (Lamiaceae) Bioactive Extracts Obtained by Traditional and Green Extraction Procedures.

Even though Salvia is one of the most known genera of the Lamiaceae family, some traditionally used Salvia species are still now less investigated. To that end, the present study aims to evaluate the chemical profile and the potential bioactivities of extracts and related fractions obtained from the endemic sage Salvia haematodes L. by applying a traditional extraction method such as Soxhlet apparatus (SHS) and the rapid solid–liquid dynamic extraction (RSLDE) by Naviglio extractor® (SHN), considered among the “green techniques” operating at room temperature and with minimum solvent employment and minimum energy. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity was measured by a modified Ellman’s method. The antioxidant activity was investigated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability power (FRAP), and β-carotene bleaching tests. The SHN methanol fraction resulted the most active in all assays in particular in inhibiting lipid peroxidation with IC50 of 1.7 and 1.6 μg/mL, respectively, after 30 and 60 min of incubation. The SHN n-hexane fraction exhibited a selective activity against AChE with half-maximal inhibitory concentration (IC50) of 22.9 μg/mL, while the SHS n-hexane extract was more active against BChE (IC50 of 30.9 μg/mL). Based on these results, these fractions were subjected to further bio-fractionation by Medium Pressure Liquid Chromatography (MPLC) and the relative obtained fractions were investigated for their AChE and BChE inhibitory activity. A comparative analysis with bio-activity and chemical profile was performed. The observed biological effects provided us with a good starting point for further studies on S. haematodes extracts and fractions such as agents beneficial for the treatment of AD.

Crucial Challenges in the Development of Green Extraction Technologies to Obtain Antioxidant Bioactive Compounds from Agro-industrial By–Products

Exploitation of agro-industrial by-products represents an important source of bioactive compounds that can be used both directly as ingredients and for the production of <br /> functional ingredients. Among these compounds, polyphenols are capable of strengthening endogenous antioxidant defences in human tissues, preventing cardiovascular and neurodegenerative diseases. The present paper aims to evaluate and review various green extraction technologies for a cheap, fast, eco-friendly procedure to obtain these bioactive molecules. Several physicochemical approaches can be used with the aim of optimizing the use of energy, solvents, and pressure; among them are ultrasound-assisted extraction, subcritical and supercritical fluid extraction, extraction with neoteric solvents (ionic liquids, deep eutectic solvents, and natural deep eutectic solvents), microwave-assisted extraction, pressurized liquid extraction, pulsed electric field, multi-frequency multimode modulated technology, rapid solid liquid dynamic extraction, and enzyme-assisted extraction. The challenges and future work regarding the development of these green products for the commercial markets were comprehensively evaluated.

Chemical Composition and Antioxidant Activity of Thyme, Hemp and Coriander Extracts: A Comparison Study of Maceration, Soxhlet, UAE and RSLDE Techniques.

Appropriate and standardized techniques for the extraction of secondary metabolites with interesting biological activity from plants are required. In this work, a comparison of different conventional and unconventional extraction techniques (maceration—M, Soxhlet—S, ultrasound assisted extraction—UAE, and rapid solid-liquid dynamic extraction—RSLDE) was investigated. Bioactive compounds were extracted from Thymus vulgaris L. (thyme), Cannabis sativa L. (industrial hemp) and Coriandrum sativum L. (coriander) and chemically characterized for their volatile fraction and polyphenolic content by means of gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-ultraviolet (HPLC-UV). Linalool (48.19%, RSLDE) and carvacrol (21.30%, M) for thyme, caryophyllene (54.78%, S) and humulene (14.13%, S) for hemp, and linalool (84.16%, RSLDE) for coriander seeds were the main compounds among terpenes, while thyme was the richest source of polyphenols with rosmarinic acid (51.7 mg/g dry extract-S), apigenin (7.6 mg/g dry extract-S), and luteolin (4.1 mg/g dry extract-UAE) being the most abundant. In order to shed light on their potential as natural food preservatives, the biological activity of the extracts was assessed in terms of antioxidant activity (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid—ABTS˙+, ferric reducing antioxidant power—FRAP, 2,2-diphenyl-1-picrylhydrazyl—DPPH˙ assays) and phenolic content (Folin–Ciocâlteu method). For thyme, Soxhlet extracts showed best performances in FRAP and ABTS˙+ assays (74 mg TE/g dry extract and 134 mg TE/g dry extract, respectively), while Soxhlet and RSLDE extracts recorded similar activity in DPPH˙ (107–109 mg TE/g dry extract). For hemp and coriander, indeed, RSLDE extracts accounted for higher antioxidant activity as evidenced by FRAP (80 mg TE/g dry extract and 18 mg TE/g dry extract, respectively) and ABTS˙+ (557 mg TE/g dry extract and 48 mg TE/g dry extract, respectively) assays. With respect to DPPH˙, the best results were observed for UAE extracts (45 mg TE/g dry extract and 220 mg TE/g dry extract, respectively). Our findings suggest that all the investigated techniques are valid extraction methods to retain bioactive compounds and preserve their activity for application in food and pharmaceutical formulations. Among them, the innovative RSLDE stands out for the slightly higher antioxidant performances of the extracts, coupled with the facility of use and standardization of the extraction process.

Evaluation of Two Extraction Methods for the Analysis of Hydrophilic Low Molecular Weight Compounds from Ganoderma lucidum Spores and Antiproliferative Activity on Human Cell Lines

Background: The genus Ganoderma includes about 80 species of mushrooms. Ganoderma lucidum is the best-known fungal species in mycotherapy and likely has the highest number of studies. Numerous bioactive compounds seem to be responsible for its beneficial effects; in particular, triterpenes, peptidoglycans and polysaccharides are the main physiologically active constituents. The aim of the present work is to identify the main bioactive components in aqueous extracts of G. lucidum spores obtained by two different extraction processes. Methods: The spores were at first extracted by a Soxhlet apparatus with n-hexane and the aqueous solutions were submitted to two different procedures: hot water extraction (HWE) and rapid solid-liquid dynamic extraction (RSLDE) using the Naviglio extractor. The extracts were then dialyzed to separate the compounds with higher molecular weight from polar compounds with lower molecular weight. The aqueous extracts and dialyzed fractions were tested on two human cell lines: human colonic epithelial cells (Caco-2) and human colorectal carcinoma cells (HTC-116). Results: GC-MS and NMR data revealed the presence of a mixture of glucose and mannitol in ratio 3.7:1 in the most active fraction. Conclusions: The outside dialysis phase of RSLDE extract seems to be particularly cytotoxic for HTC-116 and, interestingly, solutions with different concentrations of pure mannitol showed cytotoxic activity against this cell line too, although to a lesser extent.

Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE)

In the present work, the kinetics of the extraction process from female inflorescences of Canapa sativa subsp. sativa var. sativa were studied, on the basis of determination of the content of cannabinoids: cannabidiolic acid (CBDA), Δ9-tetrahydrocannabinolic acid (THCA), cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), before and after decarboxylation in the oven, in order to evaluate the possible use of the hemp extract obtained in the food sector. Therefore, both conventional maceration (CM) and rapid solid-liquid dynamic extraction (RSLDE), also known as cyclically pressurized extraction (CPE), were carried out, using parts of the plant approximately of the same size. The alcoholic extracts thus obtained were analyzed by high-performance liquid chromatography (HPLC) in order to calculate the percentages of cannabinoids present in the inflorescences and thus be able to evaluate the degree of decarboxylation. Furthermore, the extracts were dried to calculate the percentage of solid material present in it, that was made mainly by cannabinoids. The amount of substance extracted from the inflorescences was about 10% (w/w), for both cases considered. Therefore, the extraction yield was the same in the two cases examined and the final qualities were almost identical. However, the extraction times were significantly different. In fact, the maceration of hemp inflorescences in ethyl alcohol was completed in no less than 24 h, while with the RSLDE the extraction was completed in only 4 h. Finally, for a better understanding of the extraction process with cyclically pressurized extraction, a numerical simulation was carried out which allowed to better evaluate the influence of extractive parameters.

Allium ursinum and Allium oschaninii against Klebsiella pneumoniae and Candida albicans Mono- and Polymicrobic Biofilms in In Vitro Static and Dynamic Models.

The present study assesses the in vitro antibiofilm potential activity of extracts of wild Allium ursinum and Allium oschaninii. The active ingredients of the extracts were obtained with a technique named Naviglio (rapid solid–liquid dynamic extraction, RSLDE) which is based on an innovative and green solid–liquid extraction methodology. The extracts were tested against models of mono- and polymicrobial biofilm structures of clinically antibiotic-resistant pathogens, Klebsiella pneumoniae ATCC 10031 and Candida albicans ATCC 90028. Biofilms were studied using a static and a dynamic model (microtiter plates and a CDC reactor) on three different surfaces reproducing what happens on implantable medical devices. Antimicrobic activities were determined through minimum inhibitory concentration (MIC), while antibiofilm activity was assessed by minimum biofilm eradication concentration (MBEC) using a crystal violet (CV) biofilm assay and colony forming unit (CFU) counts. Results showed that both Allium extracts eradicated biofilms of the tested microorganisms well; biofilms on Teflon were more susceptible to extracts than those on polypropylene and polycarbonate, suggesting that when grown on a complex substrate, biofilms may be more tolerant to antibiotics. Our data provide significant advances on antibiotic susceptibility testing of biofilms grown on biologically relevant materials for future in vitro and in vivo applications.

Silymarin from Silybum marianum by Naviglio's extractor: a new and very efficient approach

The aim of this work is to compare new and traditional extraction methods to obtain silymarin from Silybum marianum, a biennial herbaceous plant of the Asteraceae family, present throughout the Mediterranean basin and used to treat several diseases. Silymarin primarily contains flavonolignans and flavonoids and is used in some pharmaceutical preparations to improve of liver function and as a protective against some hepatotoxins. In six extracts obtained by new and traditional extraction methods, the total contents of silymarin and its main flavonolignans, total phenols and condensed tannins were evaluated in addition to their respective antioxidant capacities. By the Naviglio extractor, that is a rapid solid-liquid dynamic extraction method, it is possible to obtain a fraction quantitatively more abundant than other methods, and with a lower content of tannins and phenolic compounds but with a higher content of flavonolignans, rare and expensive, and therefore easier to separate and purify.

Fatty Acids from Paracentrotus lividus Sea Urchin Shells Obtained via Rapid Solid Liquid Dynamic Extraction (RSLDE)

Sea urchins (Echinodermata, Echinoidea) are good a source of bioactive compounds belonging to different classes of natural substances. The edible Mediterranean sea urchin Paracentrotus lividus is a renowned animal model for study in different fields of biology, but it is intensively harvested for high commercial value due to the delicacy of its gonads. Most studies have focused on the composition and the nutritional value of P. lividus gonads (the edible part), but little interest has been taken in the other body parts, such as the shells and spines, which are generally considered waste material. The purpose of this study was to obtain an extract from sea urchin shells, with a green methodology of extraction, and to characterize the lipophilic components for potential applications. The shells of P. lividus were extracted via a very well performing technology based on rapid solid liquid dynamic extraction (RSLDE) implemented via an automated device (Naviglio Extractor®). The obtained extract shows the presence of fatty acids and their esters (methyl, ethyl and 1-glycerol esters). Gas chromatography-mass spectrometry (GC-MS) measurements were used to determine fatty acid abundance in the chromatographic fractions of the extract. Arachidonic acid (ARA), 5,8,11,14,17-eicosapentanoic acid (EPA), and 11-eicosenoic acids and their esters are the most abundant components. The presence of many polyunsaturated fatty acids (PUFA) in the extract, even in low percentages allows a future application in nutrition or medical use.

Rapid Solid-Liquid Dynamic Extraction (RSLDE): A Powerful and Greener Alternative to the Latest Solid-Liquid Extraction Techniques.

Traditionally, solid-liquid extractions are performed using organic and/or inorganic liquids and their mixtures as extractant solvents in contact with an insoluble solid matrix (e.g., the Soxhlet method) or using sequential atmospheric pressure systems that require long procedures, such as maceration or percolation. The objective of this procedure is the extraction of any compounds that can be carried out from the inner solid material to the outlet, resulting in a solution containing colorants, bioactive compounds, odorous substances, etc. Over the years, in the extraction techniques sector, there have been many important changes from the points of view of production, quality, and human and environmental safety due to improvements in technology. In more recent times, the interest of the scientific community has been aimed at the study of sustainable processes for the valorization of extracts from vegetables and food by-products, through the use of non-conventional (innovative) technologies that represent a valid alternative to conventional methods, generally through saving time and energy and the formation of fewer by-products. Therefore, with the development of principles based on the prevention of pollution, on a lower risk for human health, and on a low environmental impact, new systems have been implemented to reduce extraction times and solvent consumption, to improve efficiency, and to increase the productivity of the extracts. From this point of view, rapid solid-liquid dynamic extraction (RSLDE), performed using the Naviglio extractor, compared to traditional applications, is a technique that is able to reduce extraction times, generally leads to higher yields, does not require heating of the system, allows one to extract the active ingredients, and avoids their degradation. This technique is based on a new solid-liquid extraction principle named Naviglio’s principle. In this review, after reviewing the latest extraction techniques, an overview of RSLDE applications in various research and production sectors over the past two decades is provided.

A water extraction process for lycopene from tomato waste using a pressurized method: an application of a numerical simulation

Lycopene is a red carotenoid pigment found in fresh tomatoes. Several epidemiological studies show that the lycopene content of tomatoes and tomato-based products is related to a variety of health benefits due to its antioxidant activity, which is fundamental in treating cardiovascular diseases, slowing down cellular ageing and preventing some forms of cancer. Furthermore, several studies in the past few years have shown that by-products of tomato processing contain significant amounts of bioactive phytochemicals, including lycopene, that once extracted from the tomato skin could be used as natural antioxidants for the formulation of functional foods or as additives in food systems to extend their shelf life. The purpose of this study was to evaluate the extractive process of lycopene, starting from tomato skin waste, performing a cyclically pressurized extraction process or rapid solid–liquid dynamic extraction, using a Naviglio Extractor. This is an alternative approach to recent solid–liquid extractive processes that depends on diffusion and the pressure/de-pressure mechanism, which was considered to account for the driving force (convective effect) of the accelerated extraction of compounds contained in vegetables (or, more generally, solid matrices) and those not chemically bonded to the chemical structure of solids that are insoluble in the liquid extractant. The chromatographic analysis by high-performance liquid chromatography of the lycopene extract obtained showed a purity of more than 98% (w/w). Finally, a numerical simulation of the process was performed, obtaining useful information about the kinetics of the process (time history) as well as its mathematical description. The numerical simulation supports the validity of Naviglio’s principle.

Mathematical optimization of the green extraction of polyphenols from grape peels through a cyclic pressurization process

In the current era of high consumption and increasing waste, many products that are believed to be unusable can find a new purpose in the market. For example, the grape peel waste resulting from the production of wine contains numerous bioactive compounds. In reality, grape peels are by-products of winemaking that can be conveniently reused in many different ways, including agronomic use and cosmetic industry applications. Moreover, the by-products can also be used in the energy field as biomass for the production of biogas or in food plants for the production of energy. In this article, to extract polyphenols, grape peels were processed via a cyclically pressurized extraction method known as rapid solid-liquid dynamic extraction (RSLDE), which does not require the use of any organic solvent or include heating or cooling processes that can cause the loss of substances of interest. To better understand the cyclically pressurized extraction process, a numerical simulation was performed to evaluate the exchange between the grape piece solid matrix and water during the extraction process. Furthermore, a finite element model was used to numerically determine the time-dependent concentration distribution at specific times.

Impact of conventional/non-conventional extraction methods on the untargeted phenolic profile of Moringa oleifera leaves

The impact of different extraction methods, namely maceration, homogenizer-assisted extraction, rapid solid-liquid dynamic extraction, microwave-assisted extraction and ultrasound-assisted extraction, on polyphenols of Moringa oleifera leaves was studied. The phenolic composition of alcoholic (methanol 100%) and hydroalcoholic (methanol/water 50:50, v/v) extracts was compared by using an untargeted metabolomics-based profiling approach followed by multivariate statistics. With this aim, ultra-high-pressure liquid chromatography coupled to a quadrupole-time-of-flight mass spectrometry was used to profile phenolic compounds under the different extraction conditions. Besides, the in vitro antioxidant activities of Moringa leaves were also investigated as ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). The metabolomic approach allowed to putatively annotate 262 phenolic compounds. In particular, glycosidic forms of quercetin (i.e., quercetin 3-O-galactoside, quercetin 3-O-glucoside, and quercetin 4’-O-glucoside) were the most represented compounds among flavonoids. Furthermore, protocatechuic acid was found to be the most abundant hydroxybenzaldheyde derivative, while the isomeric forms of hydroxybenzoic acid characterized the phenolic acids class. Overall, the extractions in methanol 100% were found to be the most effective for phenolic compounds recovering, when compared with those in methanol/water (50:50, v/v). Homogenizer-assisted extraction of M. oleifera leaves using 100% methanol allowed extracting the highest amounts of polyphenols (35.19 mg/g) and produced the highest oxygen radical absorbance capacity (536.27 μmol Trolox Equivalents/g). The supervised orthogonal projection to latent structures discriminant analysis identified phenolic acids as the phenolic class mostly affected by the different extraction technologies. These findings demonstrate that each extraction method promoted the recovery of specific phenolic subclasses with different efficiencies.

Comparison between Two Solid-Liquid Extraction Methods for the Recovery of Steviol Glycosides from Dried Stevia Leaves Applying a Numerical Approach

Stevia rebaudiana Bertoni is a perennial shrub belonging to the Asteraceae family. The leaves contain a mixture of steviol glycosides with extraordinary sweetening properties, among which the most important are stevioside and rebaudioside A. These components have a high sweetening power, which is about 300 times that of sucrose, and a negligible calorie content. However, their extraction and purification are not easy. In this paper, the extraction technique under cyclic pressure, known as rapid solid-liquid dynamic extraction (RSLDE), was compared using a Naviglio extractor (NE) with conventional maceration. The aim was to identify an efficient and economically viable method for obtaining high amounts of steviol glycosides in a short time. Furthermore, a numerical model was set up for the solid-liquid extraction process of value-added compounds from natural sources. Several parameters must be evaluated in relation to the characteristics of the parts of the plant subjected to extraction. Therefore, since diffusion and osmosis are highly dependent on temperature, it is necessary to control the temperature of the extraction system. On the other hand, the final aim of this work was to provide a scientific and quantitative basis for RSLDE. Therefore, the results obtained from stevia extracts using the corresponding mathematical model allowed hypothesizing the application of this model to the extraction processes of other vegetable matrices.

Analysis and Comparison of the Antioxidant Component of Portulaca Oleracea Leaves Obtained by Different Solid-Liquid Extraction Techniques

Portulaca oleracea is a wild plant pest of orchards and gardens, but is also an edible vegetable rich in beneficial nutrients. It possesses many antioxidant properties due to the high content of vitamins, minerals, omega-3 essential fatty acids and other healthful compounds; therefore, the intake of purslane and/or its bioactive compounds could help to improve the health and function of the whole human organism. Accordingly, in this work it was analyzed and compared to the extractive capacity of the antioxidant component of purslane leaves obtained by solid-liquid extraction techniques such as: hot-maceration, maceration with ultrasound, rapid solid-liquid dynamic extraction using the Naviglio extractor, and a combination of two techniques (mix extraction). The chromatographic analysis by High Performance Liquid Chromatography (HPLC) of the methanolic extract of dried purslane leaves allowed the identification of various polyphenolic compounds for comparison with the standards. In addition, the properties of the different extracts were calculated on dry matter and the antioxidant properties of the total polyphenol components analyzed by the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The results showed that mix extraction was the most efficient compared to other techniques. In fact, it obtained a quantity of polyphenols amounting to 237.8 mg Gallic Acid Equivalents (GAE)/100 g of fresh weight, while in other techniques, the range varied from 60–160 mg GAE/100 g fresh weight. In addition, a qualitative analysis by Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS) of the phenolic compounds present in the purslane leaves examined was carried out. The compounds were identified by comparison of their molecular weight, fragmentation pattern and retention time with those of standards, using the “Multiple Reaction Monitoring” mode (MRM). Therefore, this study allowed the re-evaluation of a little-known plant that possesses as its beneficial properties, a great potential for use in both the food and the nutraceuticals and cosmetic field.