Microwave-assisted Extraction Research Articles

Extraction of phenolic compounds from edible flowers (Phlogacanthus thyrsiflorus) using ultrasound‐microwave‐assisted extraction and its screening by HPLC

AbstractPhlogacanthus thyrsiflorus flowers have been consumed as a traditional delicacy in the north‐eastern region of India. The present investigation utilized the microwave‐assisted extraction (MAE) technique in conjunction with an ultrasound pretreatment (at 250 W for 15 min) to extract phenolic compounds from Phlogacanthus thyrsiflorus flowers. Here, independent factors for optimization of MAE were microwave power (300, 500, and 700 W) and extraction time (2, 4, and 6 min), and responses were total phenolic content (TPC), total flavonoid content (TFC) and DPPH (2,2‐dipheny‐1‐picrylhydrazyl) activity. For the experimental design, a Response surface methodology and a central composite design were followed. The optimum MAE condition was found at microwave power 700 W for 5 min resulting 30.204 mg GAE/g TPC, 81.26% DPPH and 22.50 mg QAE/g of TFC. The extraction of phenolic compounds was significantly impacted by both the microwave power and the extraction time. The high‐performance liquid chromatography (HPLC) analysis detected various phenolic compounds in both conventional and MAE extracts. However, compared to conventional extract, the majority of the identified phenolic compounds were found to be higher in quantities in MAE extract. These results highlighted that MAE‐optimized flower extract could be beneficial as a functional ingredient for food product development.Practical applicationsPhlogacanthus thyrsiflorus is a highly nutritious flower with medicinal properties. Though traditionally edible flowers have been consumed in the northeastern part of India but people are still neophobic and there is scanty awareness available regarding the benefits of consuming edible flowers. This scientific justification regarding the advantages of edible flowers makes them appealing for future novel use in food technology and also for further scientific study. High perishability of flowers makes them limited for market viability and extraction of its phenolic compounds is one of the novel solutions to utilize the flowers before spoilage. Also, using ultrasound as a pretreatment could enhance the efficiency of microwave‐assisted extraction techniques for a higher yield of phenolic compounds. Microwave‐assisted extraction technique as its novel and was proven an easy successful extraction technique on this flower. Also, the study of phenolic compounds through HPLC provides important information regarding the presence of various phenolic compounds in the Phlogacanthus thyrsiflorus flower. This research can be supportive of both food technology and the medicinal industry.

Formulation of Nanoemulsion of Gotu Kola (Centella asiatica (L.) Urban) Leaves Extract as Active Ingredients to Produce Antioxidant Facial Serum

Abstract: Free radicals can cause cell damage such as premature aging. To protect, ward off and stabilize free radicals, antioxidant compounds can be used. Plants that can be used as a source of antioxidants are gotu kola (Centella asiatica (L.) Urban). The aim of this research is formulating a nanoemulsion of gotu kola leaves extract as an active ingredient for producing the antioxidant serum. The steps of this research include: (1) extraction by maceration and Microwave-Assisted Extraction (MAE); (2) extract characterization; (3) formulation of nanoemulsion using Self-Nanoemulsifying Drug Delivery System (SNEDDS) method; (4) nanoemulsion testing: stability test, antioxidant activity test, and irritation test, (5) nanoemulsion characterization which includes particle size, transmittance, pH, and viscosity. The results showed that: (1) yields of the maceration method and MAE were 14,60% and 17,54%; (2) antioxidant compounds in gotu kola leaves extract are squalene, kaempferol, asiaticoside; The IC50 of the maceration and MAE extract were 93,152 ppm and 80,365 ppm; (3) nanoemulsions were made in 3 formulas (0,1; 0,3; and 0,5 g) with fixed variables of capryol 90, tween 20, and PEG 400 (1,5; 2,5; and 1); (4) stability test showed that only F1 was stable; the IC50 value of nanoemulsion is 2604,967 ppm; and the F1 irritation test showed no erythema and edema; (5) The particle size of F1 is 166,7 nm with a transmittance value of 97.4%, a pH of 5,33, and a viscosity of 75,35 cP.

Modeling and optimization of microwave-assisted extraction of total phenolics content from mango (Mangifera indica) peel using response surface methodology (RSM) and artificial neural networks (ANN)

Mango (Mangifera indica) is a fruit highly consumed for its flavor and nutrient content. The mango peel is rich in compounds with biological functionality, such as antioxidant activity among others. The influence of microwave-assisted extraction variables on total phenol compounds (TPC) and antioxidant activity (TEAC) of natural extracts obtained from mango peel var. Tommy and Sugar were studied using a response surface methodology (RSM) and Artificial Neural Networks (ANN). TPC of mango peel extract var. Tommy was significantly influenced by time extraction (X1), solvent/plant ratio (X2) and concentration of ethanol (X3) and while mango peel extract var. Sugar was influenced by X2. TEAC by ABTS was significantly influenced by X3. Maximum of TPC (121.3 mg GAE / g of extract) and TEAC (1185.9 μmol Trolox/g extract) for mango peel extract var. Tommy were obtained at X1=23.9s, X2=12.6mL/gand X3=63.2%, and for mango peel extract var. Sugar, the maximum content of TPC (224.86 mg GAE/g extract) and TEAC (2117.7 μmol Trolox/g extract) were obtained at X1=40s, X2=10mL/g and X3=74.9%. The ANN model presented a higher predictive capacity than the RSM (RANN2>RRSM2,RMSEANN<RMSERSMandAADANN<AADRSM). These extracts can be used for the development of new products.

High-Temperature Hydrothermal Extraction of Phenolic Compounds from Brewer's Spent Grain and Malt Dust Biomass Using Natural Deep Eutectic Solvents.

Aligned with the EU Sustainable Development Goals 2030 (EU SDG2030), extensive research is dedicated to enhancing the sustainable use of biomass waste for the extraction of pharmaceutical and nutritional compounds, such as (poly-)phenolic compounds (PC). This study proposes an innovative one-step hydrothermal extraction (HTE) at a high temperature (120 °C), utilizing environmentally friendly acidic natural deep eutectic solvents (NADESs) to replace conventional harmful pre-treatment chemicals and organic solvents. Brewer's spent grain (BSG) and novel malt dust (MD) biomass sources, both obtained from beer production, were characterized and studied for their potential as PC sources. HTE, paired with mild acidic malic acid/choline chloride (MA) NADES, was compared against conventional (heated and stirred maceration) and modern (microwave-assisted extraction; MAE) state-of-the-art extraction methods. The quantification of key PC in BSG and MD using liquid chromatography (HPLC) indicated that the combination of elevated temperatures and acidic NADES could provide significant improvements in PC extraction yields ranging from 251% (MD-MAC-MA: 29.3 µg/g; MD-HTE-MA: 103 µg/g) to 381% (BSG-MAC-MA: 78 µg/g; BSG-HTE-MA: 375 µg/g). The superior extraction capacity of MA NADES over non-acidic NADES (glycerol/choline chloride) and a traditional organic solvent mixture (acetone/H2O) could be attributed to in situ acid-catalysed pre-treatment facilitating the release of bound PC from lignin-hemicellulose structures. Qualitative 13C-NMR and pyro-GC-MS analysis was used to verify lignin-hemicellulose breakdown during extraction and the impact of high-temperature MA NADES extraction on the lignin-hemicellulose structure. This in situ acid NADES-catalysed high-temperature pre-treatment during PC extraction offers a potential green pre-treatment for use in cascade valorisation strategies (e.g., lignin valorisation), enabling more intensive usage of available biomass waste stream resources.

Optimization of toothtablets incorporating Albizia myriophylla Benth. stem extract obtained by eco-friendly microwave-assisted extraction

Albizia myriophylla Benth. stems are composed of the bioactive compound lupinifolin, which has exhibited anti-Streptococcus mutans activity. Extracting this plant for incorporation into oral healthcare products is challenging. This study aimed to optimize the eco-friendly microwave-assisted extraction of A. myriophylla stems. It also optimized toothtablets incorporating A. myriophylla stem extract. First, lupinifolin was isolated, and its structure was determined for use as a biomarker in this study. Next, three extraction parameters—the solvent-to-solid ratio, microwave power, and microwave time—were screened using a one-factor-at-a-time approach before being optimized using a Box–Behnken design. The results showed that the optimized conditions that maximized the extraction yield and lupinifolin content were a solvent-to-solid ratio of 23:1, microwave power of 800 W, and microwave time of 70 s. This extract contained 16.27 ± 0.43 % lupinifolin. The extract exhibited a minimum inhibitory concentration of 32 μg/mL and a minimum bactericidal concentration of 256 μg/mL. The half-maximal inhibitory concentration with human gingival fibroblast cells was 102.70 ± 1.02 μg/mL for the extract and 76.75 ± 1.03 μg/mL for lupinifolin. The extract was solidified using microcrystalline cellulose and colloidal silicon dioxide before being incorporated into the toothtablet formulation. Three factors in toothtablet production—compression force, microcrystalline cellulose content, and hydrated silica content—were also screened using a one-factor-at-a-time approach before being optimized using a Box–Behnken design. The results showed that the optimized conditions that approached the desired properties were a compression force of 2500 psi, microcrystalline cellulose content of 12 %, and hydrated silica content of 10 %. The developed toothtablets contained 35.64 ± 0.45 mg of lupinifolin per 650 mg toothtablet (or approximately 5.5 % lupinifolin per toothtablet) and retained their anti-S. mutans activity. They appeared safe for human gingival fibroblasts, even when treated for 2 min, with a maximum concentration of 2000 μg/mL. In conclusion, the developed toothtablets incorporating A. myriophylla stem extract can potentially serve as a high-quality, antibacterial, and safe alternative to traditional toothpaste.

Microwave assisted extraction of cellulose from lemon grass: Effect on techno-functional and microstructural properties

The study focused on utilizing lemon grass straw to generate cellulose through the process of delignification, which involves the removal of hemicelluloses, followed by bleaching. The study involves the microwave-assisted alkali extraction, followed by characterizing the extracted material. At microwave power of 540 W using 8 % NaOH for 3 min for lignin removal and 540 W for 2 min for bleaching showed the maximum yield of 37.46 %. Fourier transform infrared spectroscopy is employed to analyze the physical properties of extracted cellulose, namely the hydroxyl (OH), carbonyl (C=O), C–H bonds, C–O and C–C bonds, and glycosidic linkage (C–O–C) within the cellulose polymer chain. The extracted cellulose exhibited excellent thermal stability, as indicated by its high breakdown temperature. The X-ray diffraction (XRD) analysis revealed prominent peaks at 14.8°, 16.5°, and 22.5°, demonstrating the presence of crystalline cellulose. The crystallinity index value of 70.02 % further confirmed the crystalline nature of the extracted cellulose.

Investigation on Optimized Flavonoid Extraction from Leucas zeylanica and Its Anthelmintic Activity

Extraction has been the primary method of concentrating and obtaining a crude essence of plants, and to an extend fruits and nuts. In modern times, there are many methods of extraction developed from simple maceration to using Soxhlet extractor to microwave assisted extraction and ultrasound assisted extraction. However, the more time saving and energy efficient method for the extraction of plants needs to be investigated. This research explored optimization of ultrasound assisted extraction of flavonoids from Leucas zeylanica and the optimization was done on parameters of sonication time (minutes), water bath temperature (°C), volume of solvent to solid ratio (ml/g) and solvent concentration (%) using response surface methodology (RSM). By measuring the total flavonoid content using aluminium colorimetric method and UV visible spectrophotometry, highest flavonoid yield is achieved with 30.38% increase compared to unoptimized method. This occurred with sonication time of 42 minutes, temperature of 55°C, solvent to solid ratio of 40 ml/g and solvent concentration of 100%. The resulting extract was then tested for its anthelmintic (anti-worm) ability, obtaining 40% efficacy of that of Albendazole.

Differences in physicochemical properties of pectin extracted from pomelo peel with different extraction techniques

In order to obtain high yield pomelo peel pectin with better physicochemical properties, four pectin extraction methods, including hot acid extraction (HAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction, and enzymatic assisted extraction (EAE) were compared. MAE led to the highest pectin yield (20.43%), and the lowest pectin recovery was found for EAE (11.94%). The physicochemical properties of pomelo peel pectin obtained by different methods were also significantly different. Pectin samples obtained by MAE had the highest methoxyl content (8.35%), galacturonic acid content (71.36%), and showed a higher apparent viscosity, thermal and emulsion stability. The pectin extracted by EAE showed the highest total phenolic content (12.86%) and lowest particle size (843.69 nm), showing higher DPPH and ABTS scavenging activities than other extract methods. The pectin extracted by HAE had the highest particle size (966.12 nm) and degree of esterification (55.67%). However, Fourier-transform infrared spectroscopy showed that no significant difference occurred among the different methods in the chemical structure of the extracted pectin. This study provides a theoretical basis for the industrial production of pomelo peel pectin.

Mini-Review on Coumarins: Sources, Biosynthesis, Bioactivity, Extraction and Toxicology

Coumarins are a class of naturally occurring compounds found in various plants, fungi, and microorganisms, each with a unique chemical profile. These compounds exhibit a broad range of bioactivities, including antithrombotic, anti-inflammatory, antioxidant, antimicrobial, antiviral, anticancer, and neuroprotective properties. The effective extraction of coumarins, facilitated by methods such as maceration and microwave-assisted extraction, is integral to unlocking their potential across various applications. Nevertheless, safety and toxicology considerations assume paramount importance, particularly in pharmaceuticals, cosmetics, and food additives. While moderate dietary consumption of coumarin-rich foods is generally safe, excessive intake, whether through foods or supplements, raises concerns linked to hepatotoxicity and photosensitivity. Notably, specific coumarin derivatives, including the widely used anticoagulant warfarin, necessitate precise dosing and vigilant monitoring to mitigate the risk of bleeding complications. In conclusion, the versatile biological activities of coumarins underscore their significance; yet, their safety and toxicity profiles are contingent on multiple factors, encompassing compound type, dosage, and individual susceptibility. This review provides a holistic understanding of coumarins, encompassing their natural origins, biosynthesis, bioactivity spectrum, extraction techniques, and insights into safety, and toxicology.

Ekstraksi Bunga Kecombrang dan Rosela dengan Metode MAE serta Aplikasinya pada Produk Permen Jelly

Research in recent years has shown the antioxidant activities of kecombrang and roselle flowers, as well as the antibacterial properties of kecombrang, so these materials have potentials to be developed as a functional food product. With an easy manufacturing process and basic ingredients that are easy to obtain, jelly candy is one of the preparations that can be applied to kecombrang and roselle flower extracts. This research aims 1) to determine the effect of variations in microwave-assisted extraction time and power on the physicochemical characteristics of the resulting extract and 2) to determine the effect of variations in the ratio of kecombrang and roselle flower extracts as ingredients for jelly candy products on the physical, chemicall, and sensory characteristics of the product. Research on the extraction of kecombrang and roselle flower powder used a randomized block design (RBD). Treatment consisted of two factors: 1) extraction power (150, 200, and 250 watts); 2) extraction time (3, 5, and 7 minutes). The data obtained were analyzed using the SPSS program. The analysis results showed that the best extraction of kecombrang and roselle flowers were at 250 watts of power and 5 minutes of extraction time. The best extraction results are then processed into jelly candy with the best sensory results in the 15%:25% sample. This jelly candy product contains reduced sugar levels of 12.41%, vitamin C levels of 23.58 mg/100g, total phenol levels of 47.58 mg/100g, total flavonoid levels of 18.80 mg/100g, and antioxidant activity amounting to 28.24 mg/100g. Keywords: extraction, jelly candy, kecombrang, MAE, rosella

Characterization of melon (var Sky Rocket) peel pectin using microwave-assisted extraction at different powers and extraction times

Characterization of melon (var Sky Rocket) peel pectin using microwave-assisted extraction at different powers and extraction times

Antioxidant and flexible bioplastics based on microwave-assisted extracted coffee fruit cascara pectic polysaccharides

Pectic polysaccharides with film-forming ability are often recovered from renewable agrifood by-products through solid-liquid extraction (SLE). Targeting an organic solvent-free approach, in this work, it is hypothesized that pectic polysaccharides of interest for bioplastics development can be recovered by microwave-assisted extraction (MAE) and purified by ultrafiltration. Coffee fruit cascara (CFC) was used as raw material. MAE of CFC-derived pectic polysaccharides was carried out at 120 °C at different times (2 min, 5 min, and 10 min). A 3-times (1 h each) sequential SLE with 2% acetic acid under reflux at atmospheric pressure was also performed. High molecular weight (HMW) extracts obtained by MAE for 2 min (HMW_MAE 2′) and by SLE for 1 h (HMW_SLE1), composed of 60 mol% and 54 mol% uronic acids with 18% and 17% methyl-esterification, and 7% and 8% acetylation, respectively, were selected for bioplastics development. HMW_MAE 2’ originated slightly transparent, dark brown, hydrophilic (ca. 32° water contact angle), and antioxidant (90% ABTS•+ inhibition after 5 min) bioplastics, similar to HMW_SLE1-derived materials, but 10-fold more stretchable (20% and 2% elongation at break, respectively). Therefore, MAE followed by ultrafiltration showed to be a fast and clean strategy to recover low methyl-esterified CFC pectic polysaccharides with the ability to develop antioxidant and flexible bioplastics.

Sustainable Valorization of Coffee Silverskin: Extraction of Phenolic Compounds and Proteins for Enzymatic Production of Bioactive Peptides.

Coffee silverskin (CS), a by-product of the coffee roasting process, has high protein content (16.2-19.0%, w/w), making it a potential source for plant protein and bioactive peptide production. This study aims to develop innovative extraction methods for phenolic compounds and proteins from CS. The conditions for hydrothermal (HT) extraction of phenolic compounds from CS were optimized by varying CS loading (2.5-10%, w/v), temperature (110-130 °C), and time (5-30 min) using a one-factor-at-a-time (OFAT) approach. The highest TPC of 55.59 ± 0.12 µmole GAE/g CS was achieved at 5.0% (w/v) CS loading and autoclaving at 125 °C for 25 min. Following hydrothermal extraction, CS protein was extracted from HT-extracted solid fraction by microwave-assisted alkaline extraction (MAE) using 0.2 M NaOH at 90 W for 2 min, resulting in a protein recovery of 12.19 ± 0.39 mg/g CS. The CS protein was then subjected to enzymatic hydrolysis using protease from Bacillus halodurans SE5 (protease_SE5). Protease_SE5-derived CS protein hydrolysate had a peptide concentration of 0.73 ± 0.09 mg/mL, with ABTS, DPPH, and FRAP values of 15.71 ± 0.10, 16.63 ± 0.061, and 6.48 ± 0.01 µmole TE/mL, respectively. Peptide identification by LC-MS/MS revealed several promising biological activities without toxicity or allergenicity concerns. This study's integrated approach offers a sustainable and efficient method for extracting valuable compounds from CS, with potential applications in the food and pharmaceutical industries.

Pomegranate seed oil extraction by cold pressing, microwave and ultrasound treatments

AbstractIn this study, pomegranate seed oil was extracted by microwave-assisted extraction, ultrasound-assisted extraction, and cold pressing techniques. Dimethyl succinate was the solvent of microwave and ultrasound-assisted extraction methods. The optimum conditions were determined by using response surface methodology (RSM, Design Expert software version 7.0 and Box-Behnken design). The ultrasound-assisted extraction technique was found to be superior to the microwave-assisted extraction technique in terms of extraction efficiency. The maximum extraction efficiency of microwave-assisted extraction was 22.01% under the optimized conditions (liquid/solid ratio, 5/1; time, 3 min; and microwave power, 300 W). The maximum extraction efficiency obtained by ultrasound-assisted extraction was 26.31% under the optimized conditions (liquid/solid ratio, 10/1; pulse duration/pulse interval ratio, 1; temperature 60 °C; and time, 20 min). The extraction efficiencies were compared at the optimum conditions with hexane, which is the most used solvent for pomegranate seed oil extraction, and the difference was insignificant. The results of this study are very important, especially in the field of green chemistry and chemical engineering.

Valorization of avocado (Persea americana) residual paste: Microwave-assisted extraction, optimization and addition to an artisanal pork ham

ABSTRACT Recovering biocompounds from industrial by-products is crucial to avoid food waste. Microwave-assisted extraction (MAE) has been employed to recover some biocompounds from vegetal matrices using ethanol and his solutions as solvent. Optimization of MAE conditions over total soluble polyphenols (TSP) and antioxidant capacity (DPPH and FRAP) from avocado residual paste (ARP) from oil industry was carried out. Optimal extract was used to elaborate an artisanal ham. Using response surface methodology (RSM), optimal conditions for MAE were 480 W of power, absolute ethanol as solvent, and extraction time of 180 s. The extract contained TSP of 31.24 mg GAE/g DW, DPPH inhibition of 24.51 mg TE/g DW and FRAP inhibition of 21.58 mg TE/g DW. The extract was added in the ham formulation at 0, 0.5, 1, and 1.5% w/w. Ham with 1% extract had the highest scores for acceptance. Extracts from ARP may be used in ham with adequate sensory attributes.

Unveiling the mechanisms for the development of rosehip-based dermatological products: an updated review.

Rosa spp., commonly known as rosehips, are wild plants that have traditionally been employed as herbal remedies for the treatment of a wide range of disorders. Rosehip is a storehouse of vitamins, including A, B complex, C, and E. Among phytonutrients, vitamin C is found in the highest amount. As rosehips contain significant levels of vitamin C, they are perfect candidates for the development of skincare formulations that can be effectively used in the treatment of different skin disorders (i.e., scarring, anti-aging, hyperpigmentation, wrinkles, melasma, and atopic dermatitis). This research focuses on the vitamin C content of several Rosa sp. by their botanical and geographic origins, which according to research studies are in the following order: R. rugosa > R. montana > R. canina > R. dumalis, with lower levels in R. villosa and R. arvensis, respectively. Among rosehip species, R. canina is the most extensively studied species which also displays significant amounts of bioactive compounds, but also antioxidant, and antimicrobial activities (e.g., against Propionibacterium acnes, Staphylococcus aureus, S, epidermis, and S. haemolyticus). The investigation also highlights the use of rosehip extracts and oils to minimise the harmful effects of acne, which primarily affects teenagers in terms of their physical appearance (e.g., scarring, hyperpigmentation, imperfections), as well as their moral character (e.g., low self-confidence, bullying). Additionally, for higher vitamin C content from various rosehip species, the traditional (i.e., infusion, maceration, Soxhlet extraction) and contemporary extraction methods (i.e., supercritical fluid extraction, microwave-assisted, ultrasonic-assisted, and enzyme-assisted extractions) are highlighted, finally choosing the best extraction method for increased bioactive compounds, with emphasis on vitamin C content. Consequently, the current research focuses on assessing the potential of rosehip extracts as medicinal agents against various skin conditions, and the use of rosehip concentrations in skincare formulations (such as toner, serum, lotion, and sunscreen). Up-to-date studies have revealed that rosehip extracts are perfect candidates as topical application products in the form of nanoemulsions. Extensive in vivo studies have revealed that rosehip extracts also exhibit specific activities against multiple skin disorders (i.e., wound healing, collagen synthesis, atopic dermatitis, melasma, and anti-aging effects). Overall, with multiple dermatological actions and efficacies, rosehip extracts and oils are promising agents that require a thorough investigation of their functioning processes to enable their safe use in the skincare industry.

Microwave-assisted extraction of lipid and eicosapentaenoic acid from the microalga Nanochloropsis sp. using imidazolium-based ionic liquids as an additive in water

Microwave-assisted extraction of lipid and eicosapentaenoic acid from the microalga Nanochloropsis sp. using imidazolium-based ionic liquids as an additive in water

Green Approach for Synthesis of Silver Nanoparticles with Antimicrobial and Antioxidant Properties from Grapevine Waste Extracts.

The present work aims to study the possibilities of developing silver nanoparticles using natural extracts of grape pomace wastes originating from the native variety of Fetească Neagră 6 Șt. This study focused on investigating the influence of grape pomace extract obtained by two different extraction methods (classical temperature extraction and microwave-assisted extraction) in the phytosynthesis process of metal nanoparticles. The total phenolic content of the extracts was assessed using the spectrophotometric method with the Folin-Ciocâlteu reagent, while the identification and quantification of specific components were conducted through high-performance liquid chromatography with a diode array detector (HPLC-DAD). The obtained nanoparticles were characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), along with assessing their antioxidant and antimicrobial properties against Gram-positive bacteria. The data collected from the experiments indicated that the nanoparticles were formed in a relatively short period of time (96 h) and, for the experimental variant involving the use of a 1:1 ratio (v/v, grape pomace extract: silver nitrate) for the nanoparticle phytosynthesis, the smallest crystallite sizes (from X-ray diffraction-4.58 nm and 5.14 nm) as well as spherical or semispherical nanoparticles with the lowest average diameters were obtained (19.99-23 nm, from TEM analysis). The phytosynthesis process was shown to enhance the antioxidant properties (determined using the DPPH assay) and the antimicrobial potential (tested against Gram-positive strains) of the nanoparticles, as evidenced by comparing their properties with those of the parent extracts; at the same time, the nanoparticles exhibited a selectivity in action, being active against the Staphylococcus aureus strain while presenting no antimicrobial potential against the Enterococcus faecalis strain.

Measuring aliphatic hydrocarbons in sediments by direct thermal desorption-gas chromatography-mass spectrometry: Matrix effects and quantification challenges

Direct sample introduction thermal desorption (TD) coupled to GC–MS was investigated for the analysis of paraffinic hydrocarbons (HCs) from polluted sediments. TD-GC–MS is sometimes used for analysing paraffinic HCs from atmospheric particles but rarely for their direct desorption from sediments. So, the new TD methodology, applied to sediments, required development, optimization and validation. A definitive screening experimental design was performed to discriminate the critical factors on TD efficiency, from model sediments containing various organic matter (OM) amounts. Low molecular weight HCs had extraction behaviours markedly different from high molecular ones (HMW-HCs), but a compromise was found using very few sediment amount (5 mg), high temperature rate (55 °C min−1) and final temperature (350 °C). Linear HCs (n-C10 to n-C40) could be quantified using the matrix-matched calibration method, with very low detection limits (3.8–13.4 ng). The amount of the overall paraffinic alkanes was also determined as a sum of unresolved components between predefined equivalent carbon ranges. The developed solventless methodology was compared to an optimized solvent microwave assisted extraction (MAE). Matrix effects could be higher for TD compared to MAE but it depended on sediment matrix. When matrix effect was strong, particularly on HMW-HCs signal depletion, a dilution with pure non-porous sand was favourable for accurate quantification. The sum of resolved and unresolved HCs gave comparable results between MAE and TD extractions, with an exception of alkanes greater than C30 which were less quantitatively extracted via TD. However, TD-GC–MS was more sensitive than MAE-GC–MS. So TD-GC–MS is useful for analyzing sediments containing a great range of paraffinic HCs (C9-C34) and it has the advantages of being fully automated, with few sample preparation and operator intervention, using very low amounts of solvent, and generating few wastes.

Hibiscus sabdariffa-loaded nanostructured lipid carriers (NLC) for fortified nutraceutical milks

The Hibiscus sabdariffa (H. sabdariffa) belongs to the Malvaceae family, and originates from Africa. It is characterized by a high polyphenols content (e.g., quercetin and anthocyanins), and has recognized bioactivity, that makes this plant an interesting resource for possible addition of its extracts to dairy beverages and obtain functional beverages. Nonetheless, it may be observed that many of these phenolic compounds are not stable depending on the environmental conditions. In this work, we propose the use of nanostructured lipid carriers (NLC) as a carrier for the loading of H. sabdariffa extracts, for further incorporation in daily beverages. Polyphenols-enriched extracts from H. sabdariffa were obtained using two distinct extraction approaches: by (i) microwave-assisted extraction (MAE), or by (ii) pressurized liquid extraction (PLE). The obtained extracts were then loaded into NLC to obtain two distinct samples identified as: HS-MAE-NLC and HS-PLE-NLC. The developed nanoparticles were then incorporated into a dairy beverage for the production of fortified milks identified with the same names. The long-term stability, texture properties and in vitro release profile were evaluated. The results show that the fortified milks, HS-MAE-NLC and HS-PLE-NLC, were stable under stress conditions attributed to the enhanced stability provided by the protein content present in the milk. The in vitro release profile of quercetin and anthocyanins from NLC-enriched dairy beverage was more prolonged than the milk containing the non-loaded extract, fitting better to the Korsmeyers–Peppas model. From our results, NLC may be considered a potential approach to formulate photoprotective, anti-inflammatory, and antioxidant bioactives from H. sabdariffa adding the extracts into dairy beverages to increase their bioavailability, and bioactivity.