Microwave pretreatment for the extraction of anthocyanins from saffron flowers: Assessment of product quality

Producción CientíficaThe potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a feasible intensification step. The effectiveness of microwave pretreatment was assessed in terms of increased yield and improved quality of the final product. The operational variables studied were the pretreatment temperature (60–120 °C) and the solid–liquid ratio (0.30–0.50 g/mL). It was found that the addition of the microwave pretreatment to the conventional process allowed one to reduce extraction time by up to 12 times and to greatly improve the characteristics of the final product, using microwave energy densities as low as 0.16–0.54 kJ/mL. The extract quality was evaluated in terms of polyphenol richness (25% increase), product composition (80% of the anthocyanins was delphinidin), antioxidant capacity (boosted by the pretreatment) and color (variations in red and blue hue depending on conditions). To conclude, a microwave pretreatment in which the material is heated to a temperature of 65 °C with a solvent ratio of 0.30 g/mL was selected as the optimum to maximize process efficiency and product quality.Junta de Castilla y León - (Project VA040U16

Redefining conventional biomass hydrolysis models by including mass transfer effects. Kinetic model of cellulose hydrolysis in supercritical water

Producción CientíficaConventional kinetic models of cellulose hydrolysis in supercritical water do not accurately represent the operation with concentrated suspensions since they neglect the mass transfer effects. This work proposes a kinetic model which is able to reproduce cellulose hydrolysis at high concentrations providing the opt imum reaction conditions to obtain nanocellulose particles and oligomers of controlled size. The basic idea of the model, which is applicable to other lignocellulosic materials, is that the hydrolysis of the cellulose particles generates an oligosaccharides layer which creates a mass transfer resistance. Therefore, it considers both the diffusion of the water molecules from the bulk phase to the surfaces of the cellulose particles and the superficial hydrolysis kinetics. Experimental points were obtained working with two different cellulose types (Dp=75 μm and Dp=50 μm) at 390 °C and 25 MPa, residence times between 50 ms and 250 ms and initial cellulose suspension concentration from 3% to 7% w/w (1% to 2.3% w/w at the inlet of the reactor). The average deviation between the experimental points and the theoretical values is lower than 10% proving the applicability of the kinetic model. The experimental and theoretical results demonstrated that increasing the total number of cellulose particles, either increasing the initial concentration or decreasing the average particle diameter, reduces the hydrolysis rate

Extraction of phytocompounds from the medicinal plant Clinacanthus nutans Lindau by microwave-assisted extraction and supercritical carbon dioxide Extraction

Producción CientíficaThe composition and bioactivity of natural plant extracts strongly depends on the extraction technique employed. Clinacanthus nutans Lindau (C. nutans) is a well-known medicinal plant in South-East Asia that has been traditionally used for treatment of hepatitis, skin-rashes and snake venom poisoning, and recently has attracted attention for its applications for treatment and prevention of cancer diseases. In previous studies, the extraction of bioactive compounds from C. nutans by conventional Soxhlet solvent extraction has been described, but this method shows limitations in terms of selectivity, extraction yield and toxicity of the solvents employed. In this study, phytochemical compounds were extracted from leaves and stems of C. nutans by microwave-assisted extraction (MAE), pressurized microwave-assisted extraction (PMAE), supercritical carbon dioxide extraction (SFE) and Soxhlet method to investigate the best technique in terms of yield, extraction time and recovery of bioactive compounds: phenols, flavonoids, phytosterols and β-sitosterol. The extracted phytocompounds and phenolics were characterized by gas chromatography mass spectrometry (GC/MS) and ultra performance liquid chromatography (UPLC). The results showed that MAE was the best technique to achieve a high yield and a maximal total polyphenol content (11.30 ± 0.39 mg GAE/g DM) and flavonoids content (and 4.66 ± 0.20 mg GAE/g DM), whereas SFE was the best method for phytosterols and β-Sitosterol extraction. P-MAE merely enhanced the polyphenol and flavonoids yield to 14.56 ± 0.77 mg GAE/g DM and 5.29 ± 0.30 mg QE/g DM respectively, without significant variations on the type of compounds obtained. MAE appears as the most efficient technique for the extraction of phytochemical compounds from C. nutans in a short time with a reasonable yield and a good selectivity toward bioactive nutraceutical compounds, with high concentrations of antioxidants, anti-inflammatory and antimicrobial compounds.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA330U13

Phenolic Compounds Extraction of Arbutus unedo L.: Process Intensification by Microwave Pretreatment

Producción CientíficaArbutus unedo L., commonly known as the strawberry-tree fruit, is an endemic species of the Mediterranean flora. Microwave extraction technology has been considered as a fast and “green” method for the production of extracts rich in bioactive compounds, although the energy consumption is high. To overcome this bottleneck, microwave was used as a pretreatment procedure in short time periods. This technique promotes the burst of intracellular vacuoles leading to an increase in the lixiviation of phenolic compounds. Different approaches were tested, namely a solvent-free irradiation (SFI), a solvent-assisted irradiation (SAI) and a pressurized solvent-assisted irradiation (PSAI). After irradiation, a solid–liquid extraction procedure was performed using a mixture of water and ethanol. A kinetic evaluation of the total phenolic content (TPC) was performed using the Folin–Ciocalteu method. For the total anthocyanin content, a UV-spectrophotometric method was used. HPLC-UV and LC-MS were used for TPC and identification of present compounds. Microwave irradiation led to an increase in TPC of extracts after SAI (52%) and PSAI (66%) along with a reduction in time of extraction from 30 min to less than 2 min. The anthocyanin content also increased by 66% for the SAI and PSAI extractions.Fundação para Ciência e Tecnologia (fellowship SFRH/BD/52532/2014)Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência - Fondo Europeo de Desarrollo Regional (partnership PT2020)Portuguese National Mass Spectrometry Network (contracts RNEM—REDE/1518/REM/2005, ROTEIRO/0028/2013 and LISBOA-01-0145-FEDER-022125)Marie Curie Industry - Academia Partnerships and Pathways (project FP7-PEOPLE-2013-IAPP-612208

Microwave pretreatment to improve extraction efficiency and polyphenol extract richness from grape pomace. Effect on antioxidant bioactivity

Producción CientíficaMicrowave assisted extraction advantages are widely recognised. However, its implementa-tion at industrial scale is restricted due to microwave limitations. In this work, a microwavepretreatment is proposed as an easy scale-up alternative for grape pomace polyphenolextraction, especially for anthocyanins. The double effect of this pretreatment on extractionyield and on product richness is assessed. Microwaves accelerate the extraction kineticsof most compounds, but their effect on polyphenols is more pronounced than in othersubstances (like sugars and fibres). These differentiated rates are exploited to improve thepolyphenol richness of the final dry product. By selecting the appropriate operating condi-tions, polyphenol yield was increased by 57% and, simultaneously, dry product richness wasenhanced by 32%. Also, anthocyanin extraction boost was remarkable. Its content in the finaldry product was 85% higher than the one obtained without the microwave pretreatment.The cellular bioactivity of these extracts was improved by 83% and 133%

Horno microondas para el calentamiento de flujos continuos de líquidos y semisólidos

Número de publicación: 2 698 150 Número de solicitud: 201831140Horno microondas aplicable industrialmente para el calentamiento de flujos continuos de líquidos y semisólidos, cuya cavidad resonante presenta una sección con arcos circulares que permiten la concentración de la radiación de microondas multimodal en su eje central; donde el horno dispone de guías de onda cilíndricas metálicas al corte a modo de filtros electromagnéticos que permiten el paso del tubo dieléctrico hueco y el producto a procesar impidiendo la radiación de microondas al exterior, sintonizadores dieléctricos y/o metálicos para el ajuste de la distribución multimodal de la energía en el interior de la cavidad, y soportes dieléctricos sin pérdidas; donde la energía de microondas se propaga a través de una guía de onda rectangular alimentada por un sistema generador de microondas; y donde dicha guía de onda se encuentra cortocircuitada al final de la misma y se comunica con la cavidad cuasicilíndrica a través de ranuras.Universidad Politécnica de Cartagen

Polyphenol-Rich Extracts Obtained from Winemaking Waste Streams as Natural Ingredients with Cosmeceutical Potential

Producción CientíficaPhenolics present in grapes have been explored as cosmeceutical principles, due to their antioxidant activity and ability to inhibit enzymes relevant for skin ageing. The winemaking process generates large amounts of waste, and the recovery of bioactive compounds from residues and their further incorporation in cosmetics represents a promising market opportunity for wine producers and may contribute to a sustainable development of the sector. The extracts obtained from grape marc and wine lees, using solid–liquid (SL) extraction with and without microwave (MW) pretreatment of the raw material, were characterized in terms of antioxidant activity through chemical (ORAC/HOSC/HORAC) and cell-based (keratinocytes—HaCaT; fibroblasts—HFF) assays. Furthermore, their inhibitory capacity towards specific enzymes involved in skin ageing (elastase; MMP-1; tyrosinase) was evaluated. The total phenolic and anthocyanin contents were determined by colorimetric assays, and HPLC–DAD–MS/MS was performed to identify the main compounds. The MW pretreatment prior to conventional SL extraction led to overall better outcomes. The red wine lees extracts presented the highest phenolic content (3 to 6-fold higher than grape marc extracts) and exhibited the highest antioxidant capacity, being also the most effective inhibitors of elastase, MMP-1 and tyrosinase. The results support that winemaking waste streams are valuable sources of natural ingredients with the potential for cosmeceutical applications.European project WineSense (project FP7-386 MC-IAPP)Junta de Castilla y León (project VA040U16)Ministerio de Educación y Formación Profesional (fellowship FPU13/04678)Portuguese Fundação para a Ciência e Tecnologia (FCT) (grants PEst-OE/EQB/LA0004/2011 and UID/Multi/04462/2013)iNOVA4Health (grant UID/Multi/04462/2013

XXXV Jornadas Nacionales de Ingeniería Química

Producción CientíficaMicrowave assisted extraction of natural products has been studied over the past decades as an alternative process for high-value bioactive compounds. The main advantages claimed for this technique are high extraction rates, high extraction yields and low degradation. Despite the high number of publications on this topic, most of them are considered only for analytical purposes, and only a few ones are studied for industrial implementation. Olive-oil industry produces a by-product that corresponds to the residue of the olive-pulp after the first press, known as olive-pomace. This is a low-value residue, mainly to produce olive-pomace oil, but the price paid for this by-product barely covers the cost of transport. However, olive-pomace has a high content of active compounds (hydroxytyrosol, oleuropein…) that make it valuable for the extraction of bioactives. Most of the recovery methods reported in literature make use of high temperature conditions, which can degrade some thermolabile compounds, or use non-authorized solvents for foodstuffs purposes (benzene, hexane…). In this work a microwave assisted extraction pretreatment has been developed to enhance the extraction recovery of bioactive compounds from this residue, while reducing the residence time for extraction. Operating conditions are initially studied in a laboratory microwave oven. The analysed operating variables were material/solvent ratio and specific energy. Microwave pretreatment is followed by a fast conventional solid-liquid extraction process. Extraction kinetics are determined not only for polyphenol content or specific compounds, but also for the total solid extract residue. This way, in addition to recovery, also the richness of the final dry product can be optimized to obtain simultaneous maximum extraction yield and final product concentration. Extraction richness (mgGAE/gDry Extract) may be improved more than 40% by this technique, compared to conventional extraction processes

11th European Symposium on Biochemical Engineering Sciences (ESBES 2018)

Producción CientíficaOlive pomace is a waste of the olive industry, with little use as a by-product. However, its high content in active compounds, like oleocanthal, hydroxytyrosol or oleuropein, makes this material a source of valuable bioactive extracts in food and health industry. Some of these compounds are highly bounded to the biomass structure, what entails the use of severe hydrothermal conditions (for instance, 180ºC for 90 minutes) or non-edible solvents (such as benzene and hexane). Accordingly, conventional solid-liquid extraction of polyphenols from olive pomace presents yet severe drawbacks to overcome. A short and intense microwave pretreatment is presented in this work as a greener effective resolution to enhance yield, final product quality and throughput capacity. Two pretreatments have been tested: an atmospheric-microwave one, which provided enough energy to reach the solvent boiling point, and a pressurized-microwave pretreatment, where a pressure of 3 bars was reached. Both pretreatments were followed by a conventional solid-liquid extraction that was also used by itself as a reference to assess the efficiency changes associated to the pretreatments. Although extraction yield (mgGAE/gDry pomace) is not highly enhanced with the addition of the pretreatments, extraction richness is. Extraction richness (mgGAE/gDry Extract) is understood as the proportion of active compounds in the possible commercial final product. This is usually a solid product, since de solvent must be removed from the extract to obtain a stable dry product. A 47% and a 39% richer extracts are obtained with the pressurized and atmpspheric microwave pretreatments, respectively. It is also noteworthy the high proportion of hydroxytyrosol obtained when pretreatments are used. The implementation of the pretreatment provides an improvement in the extraction of this compound, since a 3-fold richer extract in this compound is attained. This enhancement is also found in the antioxidant capacity of the extract, which is around 30% higher in the pretreated process than in the standalone conventional solid-liquid extraction. Such enhancements support the scale-up of the process. To achieve this goal, the dielectric properties of the complex mixture water-ethanol-pomace have been measured under microwave heating as a function of temperature. Data has also been correlated to a model able to predict multiphase mixture permittivity. The resulting model is able to estimate the dielectric constant with an accuracy of 12%, and the loss factor with a deviation of 36%. These preliminary results will be used in the near future to adapt and operate a continuous microwave extraction oven to explore the possibilities of its utilization in a real processing plant

Thermal degradation of grape marc polyphenols

Producción CientíficaBioactive compounds of wine making by-products are of interest in food, cosmetics and pharmaceutical industries. Extraction of antioxidants under mild conditions is time-consuming, giving ground to the development of intensification processes where the operation at high temperature may deteriorate extract quality. This study examined thermal degradation of grape marc and its filtered extract (80,100 and 150 _C). The decrease in anthocyanin content was modelled under non-isothermal conditions by first order kinetics, using the Arrhenius equation. Simulated degradation under isothermal heating showed that the grape marc is more sensitive by one order of magnitude to heat than the filtered extract. This tendency was also confirmed by analyses of the total phenolic content and antioxidant activity. It is suggested that an optimal combination of temperature, treatment time and also raw material environment could be found in process intensification.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA330U13