High-added Value Research Articles

Revisiting the Factors behind European External Imbalances

In this paper, we develop four hypotheses for the origins of European imbalances in the context of the European economic integration process. To test the validity of our hypotheses for Germany and Spain, we implement an Autoregressive Distributed Lag bounds testing approach. According to our results, in the German case, economic and financial integration and non-price competitiveness have played a key role in the evolution of the external balance, whilst for Spain, the external balance is related to catching-up. In addition, there is no evidence of a long-run relationship between public finance and external imbalances. We derive important policy implications. On the one hand, deficit countries should ensure that the capital inflows from abroad are allocated to industries with high-added value. On the other hand, surplus countries require the implementation of an expansive economic policy, to lessen the burden of deficit countries when trying to address external imbalances.

High-accuracy wire electrical discharge machining using artificial neural networks and optimization techniques

Abstract For many industrial sectors, high-added value components are related to high accuracy manufacturing technologies. Wire Electrical Discharge Machining (WEDM) is an advanced non-conventional machining method commonly used in the production of precision components in extremely hard materials. The precision of the process depends largely on the deformation of the wire tool. Whilst theoretical models allow a scientific understanding of the causes of a lack of accuracy, they still lack the level of precision required to predict actual deviations in industrial products. In this work, we propose a way to predict the accuracy of components produced by WEMD by using an Elman-based Layer Recurrent Neural Network (LRNN). The results reveal that the average deviation between network predictions and actual components is below 6μm, which implies extremely good performance of the net. In a further step, an algorithm was proposed for designing wire paths of variable radius, so that the deviations in the machined parts can be corrected via software. By combining the predictions of the developed LRNN with the Simulated Annealing (SA) optimization technique, wire paths of variable radius can be designed, so that radial deviations due to wire deformations can be minimized. The results show that the new proposal is very efficient in those situations in which wire deformation is greatest. In other words, when the part radius is low and part height is large, the stiffness of the wire is reduced and the error of the part sharply increases. In these cases, the average deviation was reduced by as much as 80%, and the Coefficient of Variation (CV) was decreased by 43%. The solution can be readily implemented on any existing WEDM machine.

Nanostructured insulators – A review of nanotechnology concepts for outdoor ceramic insulators

Nanotechnology is rapidly growing as a new technology alternative to create advance materials with unique characteristics and performance for different applications in several industrial sectors. In recent years, many nanotechnology-based products have appeared in our everyday life. On the other hand, industries have also considered nano-concepts to produce high-added value products with superior capacity, reliability and efficiency. Electric insulators are components with high importance in the electricity network system; reliability and high performance are essential characteristics demanded by actual markets. Recent studies have demonstrated the technical feasibility of innovative nano-concepts to improve the final properties of these electrical components. This paper reviews the state-of-the-art of nanotechnology applications for outdoor insulators. Nano-concepts for ceramic insulators are summarized and reported with the aim to provide an overview of applications and opportunities for electric industry. In addition, the future trends and challenges for this field are also considered in this work.

Recovery of Energy from Orange Peels Through Anaerobic Digestion and Pyrolysis Processes after d-Limonene Extraction

Currently, the citrus processing industry generates a voluminous waste stream in regions characterized by an important citrus production. This solid waste, mainly constituted by orange peel waste (OPW), represents more than half of the raw material, and it could be exploited for the production of bio-based products and bio-fuels, according to the waste hierarchy. d-limonene, the main component of citrus essential oils, is a high-added value molecule, which can be applied in several fields, ranging from cosmetics to the food industry. Because of the high moisture content in OPW (about 80% w/w), anaerobic digestion (AD) can be considered a suitable technique for waste valorization. However, this process is challenging, due to the potential toxicity of d-limonene on fermentative bacteria. For this reason, it is necessary to remove this high-added value compound in advance. After the recovery of d-limonene via solvent extraction, the porous residual matrix, posterior to exposure to the atmosphere for some days at room temperature, releases the moisture content, thus making pyrolysis a valid alternative for the recovery of energy.

Glycerol oligomers production by etherification using calcined eggshell as catalyst

The growing expansion of biodiesel industries led to an increasing formation of by-products as glycerol, which can be considered as building block molecule to high-added value products. The use of natural materials, formed by calcium carbonate, has recently become an interesting approach to the development of inexpensive and widely available basic catalysts. In this work, the use of eggshell waste as catalytic precursor was evaluated in the glycerol etherification reaction to obtain glycerol oligomers. Both raw and calcined eggshell were characterized by XRD, FTIR, N2 adsorption-desorption at −196°C, particle size analysis, SEM, CO2-TPD and TG/DTG. For comparative purposes, commercial CaO was also tested. The solids were tested as-received and calcined in the reaction. Several parameters as catalyst loading, reaction temperature, reaction time and the leaching of calcium to the reaction medium were evaluated. The optimal reaction conditions for the calcined eggshell were catalyst loading of 2wt.%, temperature of 220°C and reaction time of 24h, promoting 85% glycerol conversion and oligomers yielding of 43% (Di- and Triglycerol). The material tested shows leaching; however, taking account its low cost and good basic properties, calcined eggshell can be considered as promising catalyst for glycerol oligomerization.

Ultrasound-assisted enzyme catalyzed hydrolysis of olive waste and recovery of antioxidant phenolic compounds

Abstract The ultrasound-assisted enzyme hydrolysis (UAEH) procedure for extraction of phenolics from olive waste (OW) was established. The optimized conditions obtained with response surface methodology (RSM) were pH 5.75, treatment 40 min and temperature 55 °C, the yield obtained reached to 4.0%. The extraction kinetics model was fitted well to the ln ( C t / C 0 ) = kt , and the rate constants ( k ) increased with the increased in the extraction temperature. Moreover, the values of k were higher and the activation energy was lower than ultrasound treatment alone. The thermodynamic parameters indicated the extraction process was easier under the UAEH. Compared with the petroleum ether and n-butyl alcohol, ethyl acetate extract fraction had high phenolic content (64.4 mg/g), especially hydroxytyrosol and tyrosol (17.2 mg/g and 14.1 mg/g), and exhibited excellent antioxidant activities in DPPH·, ABTS + ·and FRAP assay. These finding revealed that OW could be used for a enrich source of natural phenolic compounds for development of food industry. Industrial relevance Olive waste (OW) has been widely paid attention as sources of high-added value compounds, such as phenolic which can be obtained by the several methods. And phenolic extract as a food additive can not only improve the sensory quality of food, but also can enhance antioxidant capacity in fatty food matrices. Moreover, the use of this extract has better economic benefits than synthetic additives usually used in food industry. In this study, a novel green, simple and efficient technology was employed to extract the phenolic compounds, which was suitable for large-scale industrial use. The results indicated that ultrasound-assisted enzyme hydrolysis (UAEH) has significant potential in the extraction process of phenolics from OW exhibiting higher phenolic yield in shorter extraction times.

Direct regeneration of recycled cathode material mixture from scrapped LiFePO 4 batteries

Abstract A new green recycling process (named as direct regeneration process) of cathode material mixture from scrapped LiFePO4 batteries is designed for the first time. Through this direct regeneration process, high purity cathode material mixture (LiFePO4 + acetylene black), anode material mixture (graphite + acetylene black) and other by-products (shell, Al foil, Cu foil and electrolyte solvent, etc.) are recycled from scrapped LiFePO4 batteries with high yield. Subsequently, recycled cathode material mixture without acid leaching is further directly regenerated with Li2CO3. Direct regeneration procedure of recycled cathode material mixture from 600 to 800 °C is investigated in detail. Cathode material mixture regenerated at 650 °C display excellent physical, chemical and electrochemical performances, which meet the reuse requirement for middle-end Li-ion batteries. The results indicate the green direct regeneration process with low-cost and high added-value is feasible.

An approach to turn olive mill wastewater into a valuable food by-product based on spray drying in dehumidified air using drying aids

Several methods have been investigated for olive mill wastewater (OMW) management. However, there has been little success in finding an environmentally friendly and economically viable solution to be generally adopted. The main objective of this work was to develop a new method for OMW management, which simultaneously will lead to the recovery of high-added value substances, based on screening and spray drying. The polyphenol enriched solid fraction derived from screening (OMWS) is spray dried to make an olive powder product rich in antioxidants for dietary uses. A new technique for spray drying OMWS using dehumidified air as drying medium and maltodextrin as drying agent was developed. Different drying experiments were conducted varying the inlet air temperature, the drying air flow rate, the compressed air flow rate, the type of drying agent, and the ratio (OMWS solids)/(drying aid solids). Data for the product collected in the receiving vessel were gathered and the OMWS powders were analyzed for moisture content, bulk density, and solubility. The achieved values of product recovery (87–94%) were much higher than those obtained in a typical spray drying system (<3%). Thus, the combination of maltodextrin addition and use of dehumidified air as drying medium seems to be an effective way of producing a free-flowing olive mill wastewater powder to be included in food formulations.

Electrotechnologies, microwaves, and ultrasounds combined with binary mixtures of ethanol and water to extract steviol glycosides and antioxidant compounds from Stevia rebaudiana leaves

The aim of this work was to investigate the potential use of non-conventional technologies (microwaves, ultrasounds, pulsed electric fields, and high voltage electrical discharges) to enhance the extraction of high-added value compounds (mainly stevioside and rebaudioside A), and antioxidants (total phenolic compounds, flavonoids, chlorophylls, and carotenoids), from Stevia rebaudiana leaves. After treatment at equivalent energy, a supplementary diffusion was performed until 1 h. Results demonstrated that when water (100%) was used as solvent, the maximum recovery of stevioside (50.8 ± 0.1 mg/g) was obtained after ultrasound-assisted extraction, while microwave allowed the highest yields of rebaudioside A (22.7 ± 0.1 mg/g). However, pulsed electric field technology was the most efficient to recover stevioside (44.2 ± 0.1 mg/g) and rebaudioside A (22.4 ± 0.3 mg/g) when using 50% ethanol-water. Results obtained through this work pave the way toward the possible scaling-up of some of these non-conventional technologies for a multistep selective extraction of valuable compounds from Stevia leaves. Practical applications Recovering high added value compounds (i.e. stevioside and rebaudioside A) from stevia leaves in food industry is usually performed using thermal extraction under agitation after drying and grinding. Although efficient, this technique generates an extract not only rich in targeted compounds but also in impurities, which complicates the downstream processing steps. Selective extraction of stevioside and rebaudioside A using non-conventional extraction technologies (i.e. pulsed electric field, etc.) may allow reducing the processing steps (grinding, downstream purification, etc.), and thus an alternative to the conventional method. For this reason, investigating the impact of these technologies at laboratory scale to recover target molecules from stevia leaves is of paramount importance before scaling up the process.

Comparison of Emerging Technologies to Extract High-Added Value Compounds from Fruit Residues: Pressure- and Electro-Based Technologies

Fruit consumption has significantly increased due to their attractive sensory properties and the growing recognition of its nutritional and therapeutic values. Nevertheless, several tons of fruits are processed by the food industry for the production of different products such as juices and jams, leading to the production of a great amount of fruit waste. Until a few decades ago, fruit residues were not considered a cost neither a benefit but resulted in a significant negative impact on the environment, ending up being used as animal feed, brought to landfills or sent to composting sites. The extraction of high-added value compounds from fruit residues is usually done through conventional methods, such as Soxhlet, hydrodistillation, maceration, and enzyme-assisted extraction. Although these methods are easy to perform and cheap to operate, they present several concerns mainly due to thermo-sensible compound degradation and environment pollution. Recently, new extraction technologies have been in development to improve extraction of high-value compounds, such as high pressure, pressurized liquid extraction, instantly controlled pressure drop, pulse electric fields, and high-voltage electrical discharges, as well its combinations between each other’s. These technologies are considered environmentally friendly, allow the use of lower amounts of organic solvents and the reduction in extraction time and energetic consumption, conducting to higher yields and high-quality final extracts.

Bioconversion of Sugarcane Vinasse into High-Added Value Products and Energy.

Vinasse, a residue from bioethanol production containing high organic matter concentration, was used as substrate in submerged fermentation of Pseudomonas aeruginosa PA1 for biosurfactant production. About 2.7 g/L of rhamnolipids was obtained, with surface tension of 29.2 mN/m and critical micelle concentration of 80.3 mg/L. After separation of rhamnolipid and biomass, residual fermentation media were submitted to anaerobic biodegradation in mesophilic conditions. The residual medium derived from fermentation with vinasse diluted to 1 : 1, without addition of nitrogen, C : N 21, and for 168 h, led to 63.2% chemical oxygen demand (COD) removal and 97.6 mL CH4/g CODremoved. Compared to results obtained with fresh vinasse (73.7% COD removal and 112.4 mL CH4/g CODremoved), it could be concluded that both processes can be integrated in order to add value to the residue and obtain energy, reducing production costs and at the same time environmental impacts related to vinasse disposal.

Transforming Enhanced Landfill Mining Derived Gasification/Vitrification Glass into Low-Carbon Inorganic Polymer Binders and Building Products

The current paper reviews the concept of the production of high-added value construction materials produced as part of a zero waste enhanced landfill mining process. The calorific fraction of the excavated waste is concentrated to produce a solid recovered fuel, which is introduced to a gasification/vitrification process to be converted to a synthetic gas, a slag and a metal alloy. The slag is subsequently cooled to produce a glass. The glass is milled and blended with an alkaline silicate solution to produce an inorganic polymer binder. The binder can be used as an alternative for ordinary Portland cement (OPC) in concrete to produce precast construction materials, such as pavers, tiles and wall elements. Pilot industrial production and testing of the durability, environmental footprint and economic feasibility of the process are currently being performed. Traditional OPC based production lines can be used, and when comparing with OPC based concrete, materials with similar to improved properties (e.g. higher hardening rate and higher final strength) can be produced.

Use of Supercritical Assisted Atomization to produce nanoparticles from olive pomace extract

Abstract Olive pomace is one of the most interesting wastes containing bioactive compounds; the extraction of polyphenols can represent an innovative solution for the reduction of the environmental hazard of this solid and the simultaneous recovery of high-added value compounds. In this study, Supercritical Assisted Atomization (SAA) was employed for the encapsulation in maltodextrin of phenolic compounds extracted from olive pomace. The effect of the ratio of maltodextrin content to total solid content of the extract and drying temperature on physical characteristics, total phenolic content and antioxidant properties of the powdered product were studied. The results confirmed the efficiency of the SAA process to encapsulate phenolic compounds from olive pomace extract. Particles with average diameter of 712 nm with high total polyphenol content (105.0 ± 0.1 mgCaffeic Acid Equivalent/gDry Powder) and antiradical power (98.8 ± 3.0 mgDPPH/mLextract) were obtained. These particles rich in bioactive compounds can be used as functional component in formulations of new food, cosmetic or pharmaceutical products. Industrial relevance Olive pomace is considered to be a low-cost and renewable source of high-added value compounds, such as polyphenols which can be valorized by several methodologies. In this work, we assessed the efficiency of Supercritical Assisted Atomization (SAA) in order to encapsulate phenolic compounds extracted from olive pomace. The particles obtained by SAA have spherical morphology with average diameter of 712 nm. The polyphenol-rich nanoparticles produced using this technique can be potentially used in the formulation of novel food or nutraceutical products.

From Classical to High Throughput Screening Methods for Feruloyl Esterases: A Review.

Feruloyl esterases (FAEs) are a diverse group of hydrolases widely distributed in plants and microorganisms which catalyzes the cleavage and formation of ester bonds between plant cell wall polysaccharides and phenolic acids. FAEs have gained importance in biofuel, medicine and food industries due to their capability of acting on a large range of substrates for cleaving ester bonds and synthesizing highadded value molecules through esterification and transesterification reactions. During the past two decades extensive studies have been carried out on the production, characterization and classification of FAEs, however only a few reports of suitable High Throughput Screening assays for this kind of enzymes have been reported. This review is focused on a concise but complete revision of classical to High Throughput Screening methods for FAEs, highlighting its advantages and disadvantages, and finally suggesting future perspectives for this important research field.

Bioconversion of olive mill wastewater into high-added value products

Olive mill wastewater (OMW) contains a variety of assimilable carbon sources and therefore it can be regarded as fermentation medium for the production of high-added value products rather than as a waste material. In this study, OMW enriched with low cost carbon sources was used as culture medium for selected yeast strains cultivated in flasks and bioreactors. Lipomyces starkeyi NRRL Y- 11557 and Yarrowia lipolytica strains showed a noteworthy ability to accumulate lipids (15–25%, w/w) cultivated on OMW based media. Oleic acid was the major fatty acid in the lipids produced by the above mentioned yeasts followed by palmitic acid. On OMW media enriched with glycerol Y. lipolytica A6 strain produced also mannitol in considerable amounts (i.e. 13.4 g/L), while Y. lipolytica LGAM S (7) strain produced high quantities of citric acid (i.e. 30.3 g/L). Candida tropicalis LFMB 16 and Saccharomyces cerevisiae MAK-1, cultivated under non-aseptic conditions on OMW media enriched with glucose produced 21.9 and 31.3 g/L of ethanol, respectively. Remarkable phenolic removal was performed by strains of Y. lipolytica, C. tropicalis and S. cerevisiae, while color removal was only observed in trials performed with C. tropicalis and S. cerevisiae. The present study provides a new perspective for the production of high-added value metabolites having biotechnological interest from OMW based media along with OMW management.

New Features on the Environmental Regulation of Metabolism Revealed by Modeling the Cellular Proteomic Adaptations Induced by Light, Carbon, and Inorganic Nitrogen in Chlamydomonas reinhardtii.

Microalgae are currently emerging to be very promising organisms for the production of biofuels and high-added value compounds. Understanding the influence of environmental alterations on their metabolism is a crucial issue. Light, carbon and nitrogen availability have been reported to induce important metabolic adaptations. So far, the influence of these variables has essentially been studied while varying only one or two environmental factors at the same time. The goal of the present work was to model the cellular proteomic adaptations of the green microalga Chlamydomonas reinhardtii upon the simultaneous changes of light intensity, carbon concentrations (CO2 and acetate), and inorganic nitrogen concentrations (nitrate and ammonium) in the culture medium. Statistical design of experiments (DOE) enabled to define 32 culture conditions to be tested experimentally. Relative protein abundance was quantified by two dimensional differential in-gel electrophoresis (2D-DIGE). Additional assays for respiration, photosynthesis, and lipid and pigment concentrations were also carried out. A hierarchical clustering survey enabled to partition biological variables (proteins + assays) into eight co-regulated clusters. In most cases, the biological variables partitioned in the same cluster had already been reported to participate to common biological functions (acetate assimilation, bioenergetic processes, light harvesting, Calvin cycle, and protein metabolism). The environmental regulation within each cluster was further characterized by a series of multivariate methods including principal component analysis and multiple linear regressions. This metadata analysis enabled to highlight the existence of a clear regulatory pattern for every cluster and to mathematically simulate the effects of light, carbon, and nitrogen. The influence of these environmental variables on cellular metabolism is described in details and thoroughly discussed. This work provides an overview of the metabolic adaptations contributing to maintain cellular homeostasis upon extensive environmental changes. Some of the results presented here could be used as starting points for more specific fundamental or applied investigations.

Valorization of CH4 emissions into high-added-value products: Assessing the production of ectoine coupled with CH4 abatement

This study assessed an innovative strategy for the valorization of dilute methane emissions based on the bio-conversion of CH4 (the second most important greenhouse gas (GHG)) into ectoine by the methanotrophic ectoine-producing strain Methylomicrobium alcaliphilum 20 Z. The influence of CH4 (2–20%), Cu2+ (0.05–50 μM) and NaCl (0–9%) concentration as well as temperature (25–35 °C) on ectoine synthesis and specific CH4 biodegradation rate was evaluated for the first time. Concentrations of 20% CH4 (at 3% NaCl, 0.05 μM Cu2+, 25 °C) and 6% NaCl (at 4% CH4, 0.05 μM Cu2+, 25 °C) supported the maximum intra-cellular ectoine production yield (31.0 ±1.7 and 66.9 ±4.2 mg g biomass−1, respectively). On the other hand, extra-cellular ectoine concentrations of up to 4.7 ± 0.1 mg L−1 were detected at high Cu2+concentrations (50 μM), despite this methanotroph has not been previously classified as an ectoine-excreting strain. This research demonstrated the feasibility of the bio-conversion of dilute emissions of methane into high-added value products in an attempt to develop a sustainable GHG bioeconomy.

Extraction, separation and identification of anthocyanins from red wine by-product and their biological activities

By-products of grape processing constitute the major disposal problem of winery industries. However, these by-products could be used as a source of the phenolic compounds that are responsible for the beneficial effects of wine. The aim of this work was to utilize these wastes, namely red grape pomace, by extracting high-added value natural products, the anthocyanins. The exact anthocyanin content of the extract was determined; 21 anthocyanins were identified using liquid chromatography coupled with photodiode array and mass spectrometry (HPLC-PDA-MS), and its dominant anthocyanins [malvidin-3-O-glucoside, malvidin-3-(6″-acetylglucoside) and malvidin-3-(6-O-p-coumaroylglucoside)] were isolated and collected in three different fractions that contained the compounds of interest at relative concentrations above 80%. The antioxidant, antibacterial, and anti-inflammatory activity of the extract, the fractions, and standard compounds were evaluated while experiments were performed to compare these results with those of the wine variety (Syrah) from which the specific byproducts were produced. Both the by-products extract and condensed wine exhibited high antibacterial activity against the tested bacteria, as well as anti-inflammatory activity against COX-1 and COX-2. Furthermore, the antioxidant activity results suggested a synergistic effect among phenolic compounds, while it was also estimated that 1 gram of by-products corresponds to 6.79 mM Trolox, a higher value compared to the 0.12 mM Trolox of 1 millilitre of wine.

Ultrasonic Sensing of Plant Water Needs for Agriculture.

Fresh water is a key natural resource for food production, sanitation and industrial uses and has a high environmental value. The largest water use worldwide (~70%) corresponds to irrigation in agriculture, where use of water is becoming essential to maintain productivity. Efficient irrigation control largely depends on having access to reliable information about the actual plant water needs. Therefore, fast, portable and non-invasive sensing techniques able to measure water requirements directly on the plant are essential to face the huge challenge posed by the extensive water use in agriculture, the increasing water shortage and the impact of climate change. Non-contact resonant ultrasonic spectroscopy (NC-RUS) in the frequency range 0.1–1.2 MHz has revealed as an efficient and powerful non-destructive, non-invasive and in vivo sensing technique for leaves of different plant species. In particular, NC-RUS allows determining surface mass, thickness and elastic modulus of the leaves. Hence, valuable information can be obtained about water content and turgor pressure. This work analyzes and reviews the main requirements for sensors, electronics, signal processing and data analysis in order to develop a fast, portable, robust and non-invasive NC-RUS system to monitor variations in leaves water content or turgor pressure. A sensing prototype is proposed, described and, as application example, used to study two different species: Vitis vinifera and Coffea arabica, whose leaves present thickness resonances in two different frequency bands (400–900 kHz and 200–400 kHz, respectively), These species are representative of two different climates and are related to two high-added value agricultural products where efficient irrigation management can be critical. Moreover, the technique can also be applied to other species and similar results can be obtained.

Recovery of colorants from red prickly pear peels and pulps enhanced by pulsed electric field and ultrasound

The aim of this work was to evaluate the potential of the non-conventional pre-treatments; pulsed electric fields (PEFs) and ultrasounds (USNs), to enhance the extraction of red colorants from red prickly pear (Opuntia stricta Haw.) peels and pulps. The overall goal was to valorize the thick part of the fruit, being discarded for fruit's consumption. PEF and USN treatments were first optimized using fruit slices, followed by a supplementary aqueous extraction (+ SAE) up to 1 h. The optimal conditions were then applied for peels and pulps, separately. Results showed that PEF + SAE and USN + SAE enhanced significantly the extraction of red colorants (betanin/isobetanin), compared to untreated tissues. Promising results for colorants recovery were obtained from fruit peels, using both pre-treatments, compared to that obtained from pulps, and without pre-treatment. Scanning electron microscopy revealed cell denaturation after PEF and USN pre-treatments, which can provide better recovery of the intracellular compounds with less impurity. Wastes and by-products generated during fruit processing constitute a great source of high-added value compounds, which have the potential to be used as food additives and/or as nutraceuticals. Opuntia fruits constitute a great source of bioactive compounds. In particular, Opuntia fruit processing by-products are interesting as they contain a great amount of potential food additives, including food colorants (i.e. betanin/isobetanin), thus constituting an important alternative to replace synthetic colorants that have been restricted by governmental organizations. In this line, pulsed electric field and ultrasounds are proposed in this work as promising technologies for the enhancement of the extraction of colorants from red prickly pear peels and pulps.