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1.
Korean J Radiol ; 23(1): 42-51, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34983092

RESUMO

OBJECTIVE: This study aimed to investigate the direction of tissue contraction after microwave ablation in ex vivo bovine liver models. MATERIALS AND METHODS: Ablation procedures were conducted in a total of 90 sites in ex vivo bovine liver models, including the surface (n = 60) and parenchyma (n = 30), to examine the direction of contraction of the tissue in the peripheral and central regions from the microwave antenna. Three commercially available 2.45-GHz microwave systems (Emprint, Neuwave, and Surblate) were used. For surface ablation, the lengths of two overlapped square markers were measured after 2.5- and 5-minutes ablations (n = 10 ablations for each system for each ablation time). For parenchyma ablation, seven predetermined distances between the markers were measured on the cutting plane after 5- and 10-minutes ablations (n = 5 ablations for each system for each ablation time). The contraction in the radial and longitudinal directions and the sphericity index (SI) of the ablation zones were compared between the three systems using analysis of variance. RESULTS: In the surface ablation experiment, the mean longitudinal contraction ratio and SI from a 5-minutes ablation using the Emprint, Neuwave, and Surblate systems were 28.92% and 1.04, 20.10% and 0.53, and 24.90% and 0.45, respectively (p < 0.001). A positive correlation between longitudinal contraction and SI was noted, and a similar radial contraction was observed. In the parenchyma ablation experiment, the mean longitudinal contraction ratio and SI from a 10-minutes ablation using the three pieces of equipment were 38.60% and 1.06, 32.45% and 0.61, and 28.50% and 0.50, respectively (p < 0.001). There was a significant difference in the longitudinal contraction properties, whereas there was no significant difference in the radial contraction properties. CONCLUSION: The degree of longitudinal contraction showed significant differences depending on the microwave ablation equipment, which may affect the SI of the ablation zone.


Assuntos
Técnicas de Ablação , Ablação por Cateter , Ablação por Radiofrequência , Animais , Bovinos , Humanos , Fígado/cirurgia , Micro-Ondas
2.
Food Chem ; 374: 131820, 2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-35021582

RESUMO

Recently, several health benefits associated with the consumption of foods rich in chlorogenic acid (5-CQA) have been reported. However, an important issue is its low stability during extraction and food processing, resulting in isomerization to neochlorogenic and cryptochlorogenic acids and the formation of further degradation products. This work describes the evaluation of 5-CQA reactivity in commercial waters after microwave treatment. An optimized HPLC-UV method was used to monitor 5-CQA conversion to its main isomers, while LC-HRMS/MS was performed for the elucidation of transformation products. Results revealed different degrees of isomerization in 5-CQA depending on the water sample, and the formation of oxidation derivatives of CQA isomers. This study highlights the importance of analytical monitoring of food compounds, during microwave treatment for example. In the case of 5-CQA, understanding of the degradation process would allow better preservation of bioactive constituent in foods and beverages and health promoting effects.


Assuntos
Ácido Clorogênico , Micro-Ondas , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Água
3.
Food Chem ; 372: 131217, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-34619524

Assuntos
Micro-Ondas
4.
Sci Total Environ ; 806(Pt 4): 150903, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34653460

RESUMO

Co-pyrolysis of sophora wood (SW) and polyvinyl chloride (PVC) was conducted in a microwave reactor at different temperatures and different mixing ratios, and the transformation and distribution of chlorine in pyrolysis products were investigated. Microwave pyrolysis is a simple and efficient technique with better heating uniformity and process controllability than conventional heating. Compared with PVC pyrolysis, the addition of SW significantly reduced CO2 yield and greatly increased the yield of CO. The yield and quality of pyrolysis oil were effectively improved by SW, and the content of chlorine-containing compounds in the oil was suppressed to <1% at low temperatures (<550 °C). Co-pyrolysis of SW and PVC reduced the chlorine emissions from 59.07% to 28.09% and promoted the retention of chlorine in char (from 0.33% to 4.72%). Cellulose, hemicellulose, and lignin were co-pyrolyzed with PVC to investigate their effects on chlorine distribution. The experiments demonstrated that lignin had the most significant effects on reducing gas phase chlorine emission and achieving chlorine immobilization, and chlorine mainly existed in the form of sodium chloride in the char of lignin-PVC co-pyrolysis. Hence co-pyrolysis of lignocellulosic biomass and PVC provides a practical pathway for utilization of PVC waste in an environmentally friendly manner, realizing efficient chlorine retention and significantly reducing chlorine-related emissions.


Assuntos
Cloreto de Polivinila , Pirólise , Biomassa , Cloro , Temperatura Alta , Micro-Ondas
5.
Sci Total Environ ; 806(Pt 4): 150904, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34653470

RESUMO

The use of mineral fertilizers in agriculture has significantly increased to support the growing global food demand. Organic fertilizers are produced from renewable waste materials to overcome the drawbacks of inorganic fertilizers. The development of novel production processes of organic fertilizers entails a significant advance towards the circular economy that reincorporates waste materials into the production cycle. In this work, the economic and environmental feasibility of an industrial plant with a treatment capacity of 300 kg/h of organic waste for the production of liquid fertilizers has been performed. Two extraction technologies (conventional and microwave) and two solvents (water and alkaline) have been compared to select the most sustainable and profitable scenario for scaling-up. The extraction process consists of 2 steps: extraction followed by a concentration stage (necessary only if water extraction is applied). The resolution of the mass balances shows that the fertilizer production under alkaline conditions is ten times higher than for water-based extraction. The economic analysis demonstrated that the total investment cost of microwave technology (>3.5 M€) is three times higher compared to the conventional extraction technology (<1.5 M€), mainly due to the higher complexity of the equipment. These facts directly impact the minimum selling price, because the fertilizers obtained by conventional extraction with alkaline solvent would have a lower selling price (about 1 €/L). As for environmental assessment, the indicators show that the environmental impact produced by water-based extraction is higher than alkaline-solvent extraction, mainly due to the necessity of a concentration stage of the liquid extract to meet the requirements of European regulations. In view of the results obtained in the economic and environmental evaluation, it could be concluded that the most favourable scenario for scaling up the production of liquid fertilizers from organic waste is the conventional extraction under alkaline conditions.


Assuntos
Fertilizantes , Micro-Ondas , Agricultura , Meio Ambiente , Tecnologia
6.
J Environ Manage ; 302(Pt A): 114028, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34731716

RESUMO

Spent carbon cathode (SCC) produced in the process of aluminum electrolysis is a typical toxic and hazardous solid waste. Therefore, the harmless treatment of SCC is extremely important for the green development of aluminum electrolysis industry. In this paper, the microwave-assisted high-temperature roasting technology was developed to remove fluorides in SCC for recycling of this cathode. The melting point, dielectric parameter, crystalline structure, surface chemical property, elemental composition, morphological structure, carbon graphitization and surface area were characterized using thermogravimetric analysis and differential scanning calorimetry, high-temperature composite conductivity analyzer, X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy, scanning electronic microscopy, transmission electron microscopy, Raman spectroscopy and isothermal N2 adsorption-desorption method. The content of fluorides in raw and treated SCC was measured by ion activity meter. The results showed that the phase of sodium fluoride and cryolite would transform from solid to liquid when the temperature was higher than 1098.5 °C, and the SCC exhibited good performance on wave absorption with the action depth of 1 cm. The SCC was mainly composed of 57.94 wt% C, 14.23 wt% NaF, 1.80 wt%, CaF2, 15.06 wt% Na3AlF6, and 10.97 wt% Other. After treatment under microwave, the graphite carbon exhibited pitting structure and the fluorides could be effectively removed. In addition, the average layer spacing of graphite was increased from 0.34 to 0.36 nm. The defluorination of SCC could be enhanced with the increase of roasting temperature, which would attain 95.4% at 1500 °C. Compared with the traditional roasting method, the process under microwave showed more defects, which would provide a new guidance for the treatment and recycling of spent SCC.


Assuntos
Carbono , Micro-Ondas , Eletrodos , Reciclagem , Temperatura
7.
Food Chem ; 366: 130562, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34289442

RESUMO

In this work, new approaches for the green extraction of polyphenols from sour cherry pomace were explored. Three Natural Deep Eutectic Solvents (NADES) systems based on choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and malic acid, urea, and fructose (MalA, Ur, and Fru) as hydrogen bond donors (HBD) were used. NADES systems were prepared by heating and stirring (H&S), ultrasound (US), and microwave (MW) methods. It was found that MW-assisted preparation was the fastest requiring less than 30 s. Polyphenol extraction from cherry pomace was performed also by three mentioned methods, and compared with conventional methods. MW extraction was the most rapid with less than 5 min necessary for the extract preparation. All three NADES systems were highly efficient for anthocyanin extraction, but the most efficient was ChCl:MalA system. Extract based on ChCl:MalA system was for 62.33% more efficient for anthocyanin extraction comparing with the conventional solvent.


Assuntos
Polifenóis , Prunus avium , Micro-Ondas , Extratos Vegetais , Solventes
8.
Bioresour Technol ; 344(Pt B): 126279, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34752889

RESUMO

The co-pyrolysis characteristics and product yield of Chlorella vulgaris (CV) and polypropylene (PP) under different mixing ratios (10:0, 8:2, 6:4, 5:5, 4:6, 2:8 and 0:10) were studied by microwave oven. Then the effects of different graphite (GP) additions (10%, 20%, 30% and 40%) on the optimum mixing ratio of CV and PP were investigated. The composition of bio-oil was analyzed by GC-MS. The results indicated that the C8P2 (CV/PP = 8:2) group had the best pyrolysis characteristics. The maximum weight loss rate (Rm) and average weight loss rate (Rv) of the C8P2 with 30% GP addition achieved the peak value. In the absence of GP, compared with C10P0 group, the contents of nitrogen compounds in bio-oil of the C8P2 group decreased by 21.58%. After adding GP to the C8P2 group, the nitrogen compounds in bio-oil of 30% GP group was 1.93% lower than that in 0% GP group.


Assuntos
Chlorella vulgaris , Biocombustíveis , Temperatura Alta , Micro-Ondas , Polipropilenos , Pirólise
9.
J Environ Manage ; 303: 114240, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34902653

RESUMO

The high demand for plastic has led to plastic waste accumulation, improper disposal and environmental pollution. Even though some of this waste is recycled, most ends up in landfills or flows down rivers into the oceans. Therefore, researchers are now exploring better ways to solve the plastic waste management problem. From a socio-economic perspective, there is also a concerted effort to enable energy recovery from plastic waste and convert it into useful products to generate income for targeted segments of the population. In fact, this concept of waste-to-wealth has been adopted by the United Nations as part of its Sustainable Development Goals strategies. The current article begins by reviewing the strengths and weaknesses of plastic recycling before focusing specifically on microwave pyrolysis as an alternative to conventional technologies in plastic waste management, due to its benefit in providing fast and energy-efficient heating. The key parameters that are reviewed in this paper include different types of plastic, types of absorbent, temperatures, microwave power, residence time, and catalysts. The yield of the final product (oil, gaseous and char) varies depending on the main process parameters. Key challenges and limitations of microwave pyrolysis are also discussed in this paper.


Assuntos
Pirólise , Gerenciamento de Resíduos , Micro-Ondas , Plásticos , Reciclagem
10.
J Colloid Interface Sci ; 607(Pt 2): 1036-1049, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34571293

RESUMO

In this work, we successfully synthesize the core-shell structure carbon@titanium dioxide (C@TiO2) composite microspheres with wrinkled surface through a three-step method and build up the relationship between the TiO2 layer thickness and the microwave absorption property. The absorbing mechanism of the novel microsphere is revealed. Interface polymerization is applied for preparation of wrinkled poly glycidyl methacrylate/divinylbenzene polymer microspheres (PGMA/PDVB); Then, TiO2 layer is controllably coated on the surface of PGMA/PDVB microspheres by hydrolysis of tetrabutyl titanate (TBT); C@TiO2 composite microspheres are obtained by vacuum carbonization with PGMA/PDVB@TiO2 microspheres as the precursor. TiO2 layer thickness on the surface of C@TiO2 composite microspheres can be effectively adjusted by controlling the amount of TBT. When the amount of TBT is 0.75 mL, C@TiO2 composite microspheres exhibit the outstanding electromagnetic loss performance. The maximum reflection loss value (RLmax) reaches -49.21 dB at the thickness of 2 mm, corresponding effective absorption bandwidth is 5.27 GHz. The maximum effective absorption bandwidth is 5.5 GHz at 2.2 mm. The results show that the introduction of TiO2 can regulate electromagnetic parameters and enhance interface polarization ability. Meanwhile, the surface wrinkle structure offers more opportunities for multiple reflections of electromagnetic and introduces a large number of defective skeleton structure. The synergy of multiple advantages makes the absorbing performance of C@TiO2 composite microspheres significantly improved. This work plays a guiding role for the composition and the structure optimization of existing microwave absorbers.


Assuntos
Micro-Ondas , Titânio , Microesferas , Fenômenos Físicos
11.
Chemosphere ; 286(Pt 1): 131631, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34315073

RESUMO

Conventional thermochemical conversion techniques for biofuel production from lignocellulosic biomass is often non-selective and energy inefficient. Microwave assisted pyrolysis (MAP) is cost and energy-efficient technology aimed for value-added bioproducts recovery from biomass with less environmental impacts. The present review emphasizes the performance of MAP in terms of product yield, characteristics and energy consumption and further it compares it with conventional pyrolysis. The significant role of biochar as catalyst in microwave pyrolysis for enhancing the product selectivity and quality, and the influence of microwave activation on product composition identified through sophisticated techniques has been highlighted. Besides, the application of MAP based biochar as soil conditioner and heavy metal immobilization has been illustrated. MAP accomplished at low temperature creates uniform thermal gradient than conventional mode, thereby producing engineered char with hotspots that could be used as catalysts for gasification, energy storage, etc. The stability, nutrient content, surface properties and adsorption capacity of biochar was enhanced by microwave activation, thus facilitating its use as soil conditioner. Many reviews until now on MAP mostly dealt with operational conditions and product yield with limited focus on comparative energy consumption with conventional mode, analytical techniques for product characterization and end application especially concerning agriculture. Thus, the present review adds on to the current state of art on microwave assisted pyrolysis covering all-round aspects of production followed by characterization and applications as soil amendment for increasing crop productivity in addition to the production of value-added chemicals, thus promoting process sustainability in energy and environment nexus.


Assuntos
Carvão Vegetal , Micro-Ondas , Biomassa , Pirólise , Solo
12.
J Colloid Interface Sci ; 605: 193-203, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34325341

RESUMO

High-performance electromagnetic (EM) wave absorption and shielding materials integrating with flexibility, air permeability, and anti-fatigue characteristics are of great potential in portable and wearable electronics. These materials usually prepared by depositing metal or alloy coatings on fabrics. However, the shortcomings of heavy weight and easy corrosion hamper its application. In this work, the cellulose nanofiber (CF) fabric was prepared by electrospinning technology. Then, conductive polyaniline (PANI) was deposited on the CF surface via a facile in-situ polymerization process. The interweaving cellulose/polyaniline nanofiber (CPF) composite constructs a conductive network, and the electrical conductivity can be adjusted by polymerization time. Benefiting from optimal impedance matching, strong conductive loss, as well as interfacial polarization, the CPF possesses excellent EM absorption performance. The minimum reflection loss (RLmin) value is -49.24 dB, and the effective absorption bandwidth (RL < -10 dB, fe) reaches 6.90 GHz. Furthermore, the CPF also exhibits outstanding electromagnetic interference (EMI) shielding capability with shielding efficiency (SE) of 34.93 dB in the whole X band. Most importantly, the lightweight CPF fabrics have the merits of mechanical flexibility, breathability and wash resistance, which is highly applicable for wearable devices.


Assuntos
Celulose , Micro-Ondas , Compostos de Anilina , Têxteis
13.
Food Chem ; 367: 130694, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34359007

RESUMO

The current study focusses on investigating the impact of pulsating microwave (MW) treatment to develop an efficient wheat parboiling method through comparative assessment with conventional parboiling. Three independent variables i.e., MW power level, effective treatment time, and pulsating mode on-off combination were tried for the process optimization. Higher moisture gain was observed during pulsating MW treatment, irrespective of the power level. The optimised gelatinization was obtained at 900 W power level and 9 min treatment time with on-off combination of 30 s -120 s considering specific energy absorption, water quality and degree of gelatinization. The microwave parboiled sample showed no major difference in molecular rearrangement, surface morphology and starch deformation as compared to the conventionally parboiled (CP) samples analysed using XRD, SEM, and FTIR study, whereas slight variation in protein conformations were noticed. This technological and structural study revealed that the proposed method can effectively replace the CP method.


Assuntos
Oryza , Triticum , Culinária , Temperatura Alta , Micro-Ondas , Amido
14.
Food Chem ; 374: 131772, 2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-34896952

RESUMO

Bioactive substances are very important components of human milk (HM), especially for premature newborns. The effects of convection (CH) and microwave heating (MWH) at 62.5 and 66 °C, on the level of selected bioactive components of HM: lysozyme (LZ), lactoferrin (LF), secretory immunoglobulin A (sIgA), basal lipase (BL), cytokine TGF-2, vitamin C and total antioxidant capacity (TAC) was compared. Regardless of the used heating methods the TAC of HM, determined by TEAC and ORAC-FL assay, proved to be insensitive to temperature pasteurization, in contrary to BL. MWH in the conditions of 62.5 for 5 min and 66 °C for 3 min are ensuring microbiological safety with a higher retention of most of the tested active HM proteins compared to CH. Only in the case of LZ the MWH had a more degradative effect on its concentration. Controlled conditions of MWH preserve the bioactive components of the HM better than CH.


Assuntos
Convecção , Leite Humano , Calefação , Humanos , Recém-Nascido , Micro-Ondas , Pasteurização
15.
Food Chem ; 374: 131707, 2022 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-34896955

RESUMO

Wheat germ albumin (WGA) is rich in nutrients and contains a number of antioxidant polypeptides. The effects of microwave-assisted alkaline protease, neutral protease, papain and compound protease on the degree of hydrolysis of WGA and the clearance rate of DPPH• were comparatively studied. The results showed that papain had the best proteolytic activity. The functional properties of WGA and its hydrolysis polypeptides were determined. The results showed that the solubility of WGA increased after papain hydrolysis, and the apparent viscosity and foam stability reduced. Compared with the amino acids of WGA, the proportions of proline, histidine, glycine, lysine, and glutamic acid in the enzymatic hydrolysis products increased, while the proportions of leucine, phenylalanine, arginine and isoleucine decreased.  After papain hydrolysis, the surface structure was loose, and the surrounding blocks became more rounded.


Assuntos
Micro-Ondas , Triticum , Albuminas , Hidrólise , Nutrientes , Peptídeos
16.
J Environ Sci (China) ; 115: 286-293, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34969456

RESUMO

The creation of an environmentally friendly synthesis method for silver nanomaterials (AgNPs) is an urgent concern for sustainable nanotechnology development. In the present study, a novel straightforward and green method for the preparation of silver nanoparticle/reduced graphene oxide (AgNP/rGO) composites was successfully developed through the combination of phytosynthesis, continuous flow synthesis and microwave-assistance. Oriental persimmon (Diospyros kaki Thunb.) extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites. The experimental parameters were optimized and the morphologies of the prepared materials were investigated. The characterization results reveal that spherical AgNPs were quickly synthesized and uniformly dispersed on rGO sheets using the proposed online system. Fourier transform infrared spectroscopy analysis confirmed that phenols, flavonoids, and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites. Using sodium borohydride (NaBH4) degradation of p-nitrophenol (4-NP) as a model, the catalytic activity of the prepared AgNP/rGO materials was evaluated. The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials, and the composite had a much better catalytic activity than the bare AgNPs and rGO had. Compared with the conventional chemical method, our online method is facile, fast, cost-efficient, and environmentally friendly.


Assuntos
Grafite , Nanopartículas Metálicas , Luz , Micro-Ondas , Prata
17.
Bioresour Technol ; 343: 126022, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34600092

RESUMO

Microwave-assisted guanidine hydrochloride deep eutectic solvents (DESs) was developed for rapid and efficient pretreatment of castor stalk. The DES synthesized with guanidine hydrochloride and lactic acid showed a better delignification (92.02%) and enzymatic saccharification yield (96.3%) than choline chloride and lactic acid DES resulted. In addition, high-purity (up to 98%) lignin was recovered from the pretreatment liquor. The good recyclability of the guanidine hydrochloride-based DES was also proven with up to 90% cellulose hydrolysis with third-time recycled DES without post purification. The proposed microwave-assisted guanidine hydrochloride/lactic acid DES showed its great potentials as a highly effective and recyclable pretreatment solvent for future biorefinery strategies.


Assuntos
Lignina , Micro-Ondas , Biomassa , Guanidina , Solventes
18.
Spectrochim Acta A Mol Biomol Spectrosc ; 266: 120442, 2022 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-34601368

RESUMO

Carbon nanoparticles (CNPs) are getting wide attention due to their fluorescence and low level of toxicity compared to other semiconducting photoluminescent materials. CNPs show strong 'solvatochromism', and the emission mechanism is still under discussion. Florescent carbon in the form of films would tremendously increase its potential for applications. In this work, we report for the first time the fluorescent emission characteristics of carbon films formed by aggregation of CNPs. Films of carbon were grown on glass substrates by using a novelCold Vapour Deposition System. We have performed a detailed comparative study of the emission spectra of film and CNPs (prepared using the microwave synthesis method) in various solvents. A qualitative model based on solvatochromism of CNPs is used to understand the emission pathways in the film.


Assuntos
Carbono , Nanopartículas , Fluorescência , Micro-Ondas , Solventes
19.
Food Chem ; 372: 131151, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34601422

RESUMO

Chloropycean microalgae are looked up as a prospective alternate source for the production of xanthophyll carotenoid lutein. Despite, the market significance and multitude of nutraceutical applications of lutein commercial production from microalgae still remains a challenge due to the prohibitive downstream cost. This necessitates innovative less energy intensive, high lutein yielding green processes. The present work presents a comprehensive study on the rapid green microwave assisted extraction (MAE) of lutein from marine chlorophycean microalgae Chlorella sorokiniana (NIOT-2). The process parameters of microwave assisted alkali pre-treatment like exposure time (ET), alkali concentration (AC) and solid (biomass): liquid (aqueous Potassium hydroxide-KOH) ratio (S: L ratio) were optimized using single factor and response surface method (RSM) experiments. The optimized conditions for microwave assisted alkali pre-treatment (ET:1.47 min; AC: 8.16 M KOH and S:L ratio of 36.8:1 (mg/mL) augmented the lutein yield (20.69 ± 1.2 mg/g) 3.26 fold when compared to conventional extraction (6.35 ± 0.44 mg/g). Lutein extracted using optimized MAE conditions was purified and characterized. Visualization of the MAE extracted algal biomass using Scanning electron microscope confirmed the effective cell disruption. X-ray diffraction (XRD) analysis of microwave assisted alkali treated biomass (83.85%) revealed a significantly higher crystallinity index when compared to untreated control (17.28%). MAE pre-treatment can thus be propounded as a suitable process for lutein extraction from marine microalgae due to its amalgamated rapidity, homogenous heating, less energy intensiveness and high extraction yield.


Assuntos
Chlorella , Microalgas , Biomassa , Luteína , Micro-Ondas , Estudos Prospectivos
20.
Food Chem ; 370: 130966, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34624693

RESUMO

A rapid and solvent-saving method, based on microwave-assisted saponification (MAS) followed by epoxidation and on-line liquid chromatography (LC) - gas chromatography (GC) - flame ionization detection (FID), was optimized and validated for high-sensitivity MOAH determination in extra virgin olive oils. Quantitative recoveries and good repeatability were obtained even at concentrations of added mineral oils close to the LOQ (0.5 mg/kg for the total hump, 0.2 mg/kg for each single C-fraction). The validated method, also applied for MOSH determination (C-fraction LOQ: 0.5 mg/kg), was used to analyse 18 extra virgin olive oils from the Italian market or oil mills, and 10 additional samples extracted in the laboratory (with an Abencor apparatus) from hand-picked olives. The former resulted contaminated with variable amounts of MOSH and MOAH (on average 19.0 mg/kg and 2.5 mg/kg, respectively), while the latter showed no detectable MOAH, and low and rather constant MOSH (generally below 2.0 mg/kg).


Assuntos
Hidrocarbonetos Aromáticos , Óleo Mineral , Contaminação de Alimentos/análise , Hidrocarbonetos Aromáticos/análise , Micro-Ondas , Óleo Mineral/análise , Azeite de Oliva
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