Search

Large amounts of spent coffee grounds (SCGs) are produced annually worldwide. SCGs contain high levels of phenolics and other bioactive compounds that make them a potential source of reducing and stabilizing agents for the synthesis of metal nanoparticles. This study investigates the use of SCG extracts as a green strategy to produce silver nanoparticles (AgNPs). SCG extracts were obtained using aqueous ethanol as the solvent and then contacted with a silver nitrate solution under the selected conditions. A central composite design coupled with response surface methodology was used to evaluate the effects of solvent composition (C = 30–70% v/v), silver-to-phenolic ratio (R = 3–7 mol/mol), temperature (T = 25–55 °C) and pH (10–12) on the production of AgNPs. Characterization of AgNPs by DLS, TEM and XRD techniques showed that they were highly crystalline with a narrow size distribution. Under optimal reaction conditions, AgNPs with an average size of about 10 nm and a zeta potential of −30.5 to −20.7 mV were obtained. Overall, the results of this study indicate that SCGs are a promising material for the green synthesis of small-sized and stable AgNPs.

Three different deep eutectic solvent (DES)-based extraction procedures were rationally designed and optimized for the recovery of antioxidants from chestnut wood fiber (CWF), a clean and largely available solid waste of the tannin industry. First, a mild protocol was developed using a choline chloride (ChCl)/tartaric acid DES at 50 °C, for 90 min. Ellagic acid (EA) was identified as the only low molecular weight phenolic component of the extract. In other experiments, harsher conditions were explored involving treatment of CWF with ChCl-based DESs at 120 °C for 8 h, which afforded a solid sample characterized by high phenolic content (up to 1.0 mg of gallic acid equivalents/mg of sample) and antioxidant properties (EC50

Oxidative stress originates from an elevated intracellular level of free oxygen radicals that cause lipid peroxidation, protein denaturation, DNA hydroxylation, and apoptosis, ultimately impairing cell viability. Antioxidants scavenge free radicals and reduce oxidative stress, which further helps to prevent cellular damage. Medicinal plants, fruits, and spices are the primary sources of antioxidants from time immemorial. In contrast to plants, microorganisms can be used as a source of antioxidants with the advantage of fast growth under controlled conditions. Further, microbe-based antioxidants are nontoxic, noncarcinogenic, and biodegradable as compared to synthetic antioxidants. The present review aims to summarize the current state of the research on the antioxidant activity of microorganisms including actinomycetes, bacteria, fungi, protozoa, microalgae, and yeast, which produce a variety of antioxidant compounds, i.e., carotenoids, polyphenols, vitamins, and sterol, etc. Special emphasis is given to the mechanisms and signaling pathways followed by antioxidants to scavenge Reactive Oxygen Species (ROS), especially for those antioxidant compounds that have been scarcely investigated so far.

Oxidative stress is an elevated intracellular level of free oxygen radicals that cause lipid peroxidation, protein denaturation, DNA hydroxylation, and apoptosis, ultimately negotiating cells viability. Antioxidants can scavenge such free radicals, thus reducing the oxidative stress and eventually prevent cellular damage. Medicinal plants, fruits, and spices remain the prioritized sources of antioxidants and antimicrobial properties since the time immemorial, but in contrast to plants, microorganisms can be grown at a faster rate under controlled conditions. They are non-toxic, non-carcinogenic, and biodegradable as compared to synthetic antioxidants. Microorganisms including actinomycetes, archaea, bacteria, protozoa, yeast, and fungi are auspicious source of vital bioactive compounds. The list comprises ample of bioactive components from microorganisms. One of them is bacteriocins, which are ribosomally synthesized antimicrobial peptides product of Eurotium sp., Streptomyces parvulus, S. thermophiles, Lactococcus lactis, etc. It has a great potential as next-generation antibiotics targeting the multiple-drug resistant pathogens. Pneumocandins are antifungal lipohexapeptides derived from the fungus Glarea lozoyensis, and inhibit 1,3-β-glucan synthase of the fungal cell wall and act as a precursor for the synthesis of caspofungin. It is widely used against invasive fungal infections and has been recently approved by the FDA. Taxol (paclitaxel), a chemotherapeutic drug derived from the bark of Taxus brevifolia can also be produced by endophytic fungi Taxomyces andreanae and Nodulisporium sylviforme. It is known to inhibit several fungi such as Pythium, Aphanomyces and Phytophthora. Hispidin and its derivate isolated from P. hispidus, reduce inducible nitric oxide synthase (iNOS) expression, obstruct the transcriptional activity of NF-κB, and also decrease the production of reactive oxygen species (ROS) in macrophages. Astaxanthin, known as an “aquatic” carotenoid produced by H. pluvialis, also has excellent ROS quenching activity. This study mainly focuses on fascinating antioxidant and antimicrobial compounds that have been scarcely investigated in microorganisms and discuss the promise and challenges of microorganisms as providers of health benefits.

The increasing world population generates huge amounts of wastewater as well as large energy demand. Additionally, fossil fuel’s combustion for energy production causes the emission of greenhouse gases (GHG) and other pollutants. Therefore, there is a strong need to find alternative green approaches for wastewater treatment and energy production. Microalgae biorefineries could represent an effective strategy to mitigate the above problems. Microalgae biorefineries are a sustainable alternative to conventional wastewater treatment processes, as they potentially allow wastewater to be treated at lower costs and with lower energy consumption. Furthermore, they provide an effective means to recover valuable compounds for biofuel production or other applications. This review focuses on the current scenario and future prospects of microalgae biorefineries aimed at combining wastewater treatment with biofuel production. First, the different microalgal cultivation systems are examined, and their main characteristics and limitations are discussed. Then, the technologies available for converting the biomass produced during wastewater treatment into biofuel are critically analyzed. Finally, current challenges and research directions for biofuel production and wastewater treatment through this approach are outlined.

Sustainability and renewability are demanding the most important challenges that need to be achieved. Therefore, microalgae and Natural deep eutectic solvents (NaDEs) are two classes that deserve particular attention that can allow to meet the sustainability. Microalgae, as raw materials, can produce a variety of value-added compounds, which have numerous applications in pharmaceutical, nutraceutical and cosmetics sector. While, NaDES have peculiar characteristics that allow the recovery of various value-added compounds from microalgae biomass in sustainable manner. Microalgal compounds can be extracted using organic acids, alcohols or sugars by employing the NaDES process. These solvents act as are non-toxic, non-volatile and renewable during NaDES process. Considering the properties shown by microalgae and NaDES separately, a combined microalgae-NaDES extraction is extremely promising for future industrial applications. However, this technology requires proper pre-treatment of microalgal biomass to attain the complete recovery of valuable compounds. In conclusion, this review summarize the potential application of NaDES for extraction of intracellular compounds from microalgal biomass and their related pre-treatments to improve the extraction efficiency.

The aim of this study was to assess the effects of commercially available and relatively inexpensive enzyme preparations based on endo 1,4-&beta, xylanase, pectinase and xyloglucanase on the thermal (TGA), morphological (SEM), chemical (FT-IR) and mechanical (single yarn tensile tests) properties of flax yarns. The preparation based on pectinase and xyloglucanase provided the best results, resulting in the effective removal of hydrophilic components such as hemicellulose and pectin, the individualization of yarns and increased thermal stability at the expense of a reduction in mechanical properties, depending on the treatment parameters. Single yarn fragmentation tests pointed out an improved interfacial adhesion after enzymatic treatment, with reduced debonding length values of 18% for an epoxy matrix and up to 36% for a vinylester resin compared to untreated flax yarns.

The feasibility of exploiting secondary raw materials from marine food-chains as a source of molecules of nutritional interest, to create high-value food products and to meet nutritional challenges, is described in this report. A reduction in food waste is urgent as many sectors of the food industry damage the environment by depleting resources and by generating waste that must be treated. The project herein described, deals with the recovery of natural molecules, omega-3 fatty acids (EPA, DHA) and of α-tocopherol, from fish processing by-products. This would promote the sustainable development of new food products for human nutrition, as well as nutraceuticals. The growing awareness of increasing omega-3 fatty acids intake, has focused attention on the importance of fish as a natural source of these molecules in the diet. Therefore, a study on the concentration of these bioactive compounds in such matrices, as well as new green methodologies for their recovery, are necessary. This would represent an example of a circular economy process applied to the seafood value chain. Fish processing by-products, so far considered as waste, can hopefully be reutilized as active ingredients into food products of high added-value, thus maximizing the sustainability of fish production.

The use of kiwifruit juice as a source of metal-reducing and stabilizing agents for the production of gold nanoparticles (AuNPs) was investigated. The reaction was carried out in batch by mixing appropriate amounts of kiwifruit juice and gold(III) chloride solution. The formation of AuNPs was monitored by measuring the intensity of the surface plasmon resonance (SPR) band of gold. The effects of temperature (20–60 °C), pH (8–12) and gold-to-polyphenol ratio (GPR) were investigated. Characterisation of AuNPs by XRD, DLS and zeta-potential measurements showed that they were highly crystalline, with an average hydrodynamic diameter of about 50 nm and a zeta-potential ranging between –29.2 and –21.7 mV. Under the best reaction conditions (60 °C, pH 9, GPR = 5 mol Au3+/mol GAE), AuNPs with an average size of about 30 nm were produced. The results obtained suggest that kiwifruit juice is a suitable medium for the production of small-sized and stable AuNPs.

The stability of lycopene in two vegetable oils, sunflower seed oil (SSO) and grape seed oil (GSO), was investigated by analysing the carotenoid degradation kinetics in the temperature range of 10–40°C. A tomato oleoresin containing 6% (w/w) of lycopene was used to prepare lycopene-enriched oil samples. Analysis of kinetic data showed that lycopene degradation follows first-order kinetics, with an apparent activation energy of 70.7 kJ mol–1 in SSO and 69 kJ mol–1 in GSO. The estimated half-life of lycopene was found to depend on oil type and storage temperature. At 20°C, it varied between 59 and 122 days, while at 4°C it was comprised between 302 and 650 days. At all temperatures, lycopene was more stable in SSO than in GSO, which is likely due to the higher content of antioxidant compounds in SSO.

The thermal properties of artichoke waste, a relatively rich source of phenolic antioxidants, were investigated before and after phenolic recovery in order to assess its suitability as a source of bioproducts and bioenergy. The two main fractions of the waste, the bracts and the stems, were submitted to solvent extraction with aqueous ethanol (0, 50, 100% v/v) and the resulting extracts were assayed for total phenolics, flavonoids and antioxidant activity. The polyphenol content of stems was 51.10 ± 0.74 mg GAE/g and that of bracts was 24.58 ± 0.57 mg GAE/g. Using 50% aqueous ethanol provided the highest extraction yields, with over 80% of phenolic compounds recovered. The higher heating value of artichoke waste was about 16 MJ/kg and changed very little after polyphenol extraction. The ash content of the two waste fractions was close to 5% (w/w) and was further reduced upon phenolic recovery. The elemental ash composition for the two fractions was very similar: silicon was the most abundant element (> 40% w/w) followed by phosphorus, calcium and potassium. Finally, TGA/DTG analysis showed no significant differences in the thermal properties of the extracted and unextracted materials, suggesting the possibility of recovering phenolic antioxidants from artichoke waste and bioenergy from the extraction residue. This could provide economic advantages to the artichoke industry and reduce its environmental impact.

The use of UV-C light as a means to inactivate pathogens in biological media containing blood components or plasma derivatives has recently been rediscovered. Although highly effective, these treatments may have deleterious effects on plasma proteins such as albumin, fibrinogen and immunoglobulins. Here we investigate the use of three natural antioxidants, gallic acid, nicotinic acid and ascorbic acid, as potential stabilizers of human albumin (HA) during irradiation by UV at 254 nm. The effects of UV-C on HA were monitored by measuring the absorbance changes in the protein spectrum at 320 nm. Experiments carried out at irradiance levels of 3.5–15 W m–2 and application times of up to 40 min showed that albumin undergoes rapid aggregation and that this process is dose-dependent. When added at 0.2 mM to the protein solution, all of the antioxidants inhibited HA aggregation, with ascorbic acid being the most effective. To quantitatively describe the observed effects, a fluence-based model was developed. The model predicted a quadratic dependence of the spectral changes of HA on the radiation dose and was validated by experiments performed under different exposure conditions.

A combined advanced oxidation process based on the electrochemical oxidation of chloramphenicol (CHL) on a boron-doped diamond (BDD) electrode under UV irradiation was investigated. The influence of the main process parameters (current density, pH, temperature, and chloride concentration) on CHL degradation and mineralization was assessed. An estimation of the energy consumption required to mineralize CHL was also made. The results showed that CHL can be completely degraded and extensively mineralized by 3-h UV-assisted anodic oxidation on BDD. The process can be further accelerated by chlorides, as these species act as precursors for the photo-induced formation of radical species contributing to CHL oxidation. Under optimal conditions (300 mA m–2, 0.01 M NaCl, ambient temperature, and pH 10), complete CHL removal occurred after 150 min of treatment, and approximately 95 % mineralization was achieved in 180 min. Overall, the results obtained suggest that the investigated process may represent a promising approach to treat wastewaters containing CHL or other recalcitrant antibiotics.

The role of polyphenolic compounds extractable from artichoke solid wastes in the formation of advanced glycation end products (AGEs) was studied. Outer bracts and stems were extracted using different water-ethanol mixtures and HPLC-DAD analyses indicated aqueous and hydro-alcoholic 20:80 stem extracts as the richest in polyphenols. The samples were characterized in their phenolic composition (using mass spectrometry) and antioxidant capacity. Antiglycative capacity was evaluated by in vitro BSA-sugars (glucose, fructose, and ribose) and BSA-methylglyoxal (MGO) tests, formation of Amadori products assay, direct glyoxal (GO) and MGO trapping capacity. Results indicated both extracts as effective inhibitors of fructosamine formation and antiglycative agents. In particular, aqueous extract showed the best activity in the systems containing glucose and fructose, differently from ethanolic extract, that was demonstrated able to better inhibit AGEs formation when ribose or MGO act as precursors. Ethanolic extract was also shown to be able to trap MGO and GO, with efficiency increasing after 24 hours of incubation time. These activities are partially correlated with the antioxidant effect of the extract, as demonstrated by the scavenger capacity against ABTS cation and DPPH stable radicals; this relationship is evident when the model system, containing protein incubated with ribose or MGO, is considered. The different activities of the tested extracts could probably be ascribed to the different composition in chlorogenic acids (CQAs), being aqueous extract richer in 1-CQA, 3-CQA, and 1,3-di-CQA, and ethanolic extract in 5-CQA, caffeic acid, 1,5-di-CQA. These findings support further investigations to study the stability of the different CQAs in simil-physiological conditions and the feasibility of artichoke waste as antiglycative agents in food or pharmacological preparations. Chemical compounds 5-caffeoylquinic acid (PubChem CID 5280633); 3-caffeoylquinic acid (PubChem CID 1794427); 1-caffeoylquinic acid (PubChem CID 10155076); 1,3-di-caffeoylquinic acid (PubChem CID 24720973); 1,5 – di-caffeoylquinic acid (PubChem CID 122685); caffeic acid (PubChem CID 689043); apigenin-7-glucuronide (PubChem CID 5319484); methylglyoxal PubChem CID (880); aminoguanidine hydrochloride (PubChem CID 2734687)

A combined treatment based on electrochemical oxidation on boron-doped diamond (BDD) anodes and UV-C irradiation was used to degrade the emerging contaminant coumarin, an ingredient of many personal care products. The efficiency of the process was assessed by monitoring the coumarin concentration decay and the total organic carbon (TOC). The effect of chloride was evaluated and the occurrence of inorganic chlorinated products was quantified. The photo-assisted electrochemical degradation resulted in a faster removal and mineralization of the pollutant, compared to the treatment without UV irradiation. The observed synergistic effect was mainly ascribed to the ability of UV light to activate the peroxides electrogenerated during the electrolysis on BDD. An additional contribution was due to the photolysis of electrogenerated hypochlorite/hypochlorous acid in the presence of chloride. UV irradiation reduced the amount of residual active chlorine but not of chlorates. TOC analysis showed that mineralization occurred together with coumarin removal from the solution, indicating that no persistent organic by-products were formed during the treatment. The possibility of reducing the energy consumption of the process by shortening the exposure time of the solution to UV light was also investigated.

Corn husks are an important byproduct of the corn processing industry. Although they are a rich source of bioactive compounds, especially flavonoids, corn husks are usually disposed of or used as animal feed. In this paper, we investigate their recovery by an enzyme-assisted extraction process consisting of a pretreatment of the plant material with cellulase followed by solvent extraction with aqueous ethanol. A four-factor, three-level Box&ndash, Behnken design combined with the response surface methodology was used to optimize the enzyme dosage (0.3&ndash, 0.5 g/100 g), incubation time (1.5&ndash, 2.5 h), liquid-to-solid ratio (30&ndash, 40 mL g&minus, 1) and ethanol concentration in the solvent (60&ndash, 80% v/v). Under the optimal conditions, about 1.3 g of total flavonoids per 100 g of dry waste were recovered. A statistical analysis of the results was performed to provide a quantitative estimation of the influence of the four factors, alone or in combination, on the extraction yields. Overall, the results from this study indicate that corn husks are a valuable source of flavonoids and that they can be easily recovered by a sustainable and environmentally friendly extraction process.

This study investigates distillery wastewater, commonly known as vinasse, as a potential culture medium for the production of Chlorella vulgaris and its most relevant metabolites. The effect of vinasse concentration on the composition of the biomass (proteins, carbohydrates and lipids) was evaluated in treatments performed in 6-L tubular air-lift reactors. The reactors were operated at 25 °C for 18 days, in total darkness, under a continuous flow of air. Results showed a rapid growth of microalgae in the first ten days, when an average production of 0.87 g/L was reached. Then, the daily biomass productivity began to decrease, up to an average value of 11.8 g/L at the 16th day. For all treatments, there was a significant reduction in the concentration of most metabolites in the first eight days. This was likely due to the adaptation of the biomass to the new conditions, with a transition from autotrophic to heterotrophic metabolism. From the 10th day, the concentration of metabolites in the biomass began to increase, reaching a nearly constant value at the 16th day. The observed maximum concentrations (%w/w) were: 48.95% proteins, 2.88% xylose, 7.82% glucose, 4.54% arabinose, 8.28% fructose and 4.82% lipids. These values were only marginally affected by the type of treatment. Overall, the results obtained suggest that vinasse is a promising and sustainable medium for the growth of C. vulgaris and the production of valuable metabolites.

This study investigates distillery wastewater, commonly known as vinasse, as a potential culture medium for the production of Chlorella vulgaris and its most relevant metabolites. The effect of vinasse concentration on the composition of the biomass (proteins, carbohydrates and lipids) was evaluated in treatments performed in 6-L tubular air-lift reactors. The reactors were operated at 25 °C for 18 days, in total darkness, under a continuous flow of air. Results showed a rapid growth of microalgae in the first ten days, when an average production of 0.87 g/L was reached. Then, the daily biomass productivity began to decrease, up to an average value of 11.8 g/L at the 16th day. For all treatments, there was a significant reduction in the concentration of most metabolites in the first eight days. This was likely due to the adaptation of the biomass to the new conditions, with a the transition from autotrophic to heterotrophic metabolism. From the 10th day, the concentration of metabolites in the biomass began to increase, reaching a nearly constant value at the 16th day. The observed maximum concentrations (%w/w) were: 48.95% proteins, 2.88% xylose, 7.82% glucose, 4.54% arabinose, 8.28% fructose and 4.82% lipids. These values were only marginally affected by the type of treatment. Overall, the results obtained suggest that vinasse is a promising and sustainable medium for the growth of C. vulgaris and the production of valuable metabolites.

The production of silver nanoparticles (Ag-NPs) from bilberry waste (BW) and red currant waste (RCW) extracts was studied. Red fruit extracts were obtained by treating BW and RCW with aqueous ethanol (50% v/v) at 40 &deg, C. The formation of nanoparticles was monitored spectrophotometrically by measuring the intensity of the surface plasmon resonance band (SPR) of silver. The effects of temperature (20&ndash, 60 &deg, C) and pH (8&ndash, 12) on the reaction kinetics and on the properties of Ag-NPs were investigated. Characterization by XRD and dynamic light scattering (DLS) techniques showed that Ag-NPs were highly crystalline, with a face-centered cubic structure and a hydrodynamic diameter of 25&ndash, 65 nm. The zeta potential was in the range of &minus, 35.6 to &minus, 20.5 mV. Nanoparticles obtained from BW were slightly smaller and more stable than those from RCW. A kinetic analysis by the initial-rate method showed that there was an optimum pH, around 11, for the production of Ag-NPs. Overall, the results obtained suggest that BW and RCW can be advantageously used as a source of reducing and stabilizing agents for the green synthesis of Ag-NPs.

Brewers&rsquo, spent grain (BSG) is the most abundant by-product of the brewing process. BSG is currently disposed of or used as a supplement for animal feed, although it contains significant amounts of bioactive compounds of great interest to the pharmaceutical, cosmetic and food sectors. In this study we investigate the feasibility of using a simple solvent extraction procedure to recover phenolic antioxidants from BSG. Acetone&ndash, water and ethanol&ndash, water mixtures were used as extraction solvents. Phenolic extracts obtained by treatment of BSG with the two solvent systems were characterized in terms of total phenolics and antioxidant activity. For both systems, the extraction yield was maximum at 60% (v/v) organic solvent concentration. At all solvent compositions, mixtures containing acetone provided higher extraction yields. As suggested by the strong correlation between the antioxidant activity of BSG extracts and their phenolic content, the antioxidant capacity of the extracts can be mainly attributed to polyphenols. Overall, the obtained results strongly support the exploitation of BSG as a source of phenolic antioxidants and the possibility of recovering them by a mild and green extraction process.

Bergamot peel oil is highly attractive for food and pharmaceutical industries due to its content of valuable essential oil, which is enriched with high-added valuable compounds, such as limonene, linalool and linalyl acetate. Nevertheless, there are some limitations for the separation of such compounds. In this framework, pervaporation (PV) technology was proposed as a tool for the separation of limonene, linalool, and linalyl acetate from bergamot oil by using two different commercial organophilic membranes (PDMS-1070 and POMS-PEI). The use of an enzymatic pre-treatment was also investigated in order to enhance the performance of selected membranes. All PV experiments were carried out at different temperatures (ranging from 25-40 ºC) in order to analyze the temperature dependence by the Arrhenius relationship. Experimental data indicated that both investigated membranes did not present significant differences in terms of enrichment factor, independently from the enzymatic pre-treatment (at 25 ºC). However, the enrichment factors increased significantly at 40°C when enzymes were applied. The experimental results clearly indicate that PV is a viable approach for the recovery of such aroma solutes from bergamot peel oils as it yields good separations under mild operating conditions. The efficiency of the pervaporative process is indeed enhanced if assisted by an enzymatic treatment.

The presence of azo dyes in textile effluents is an issue of major concern due to their potential impact on the environment and human health. In this study we investigate the photocatalytic degradation under visible light of Reactive Violet 5 (RV5), an azo dye widely used in the textile industry. A preliminary screening of different titania-based catalysts was carried out to identify the best candidate for RV5 removal. The selected catalyst was then tested in a stirred and aerated lab-scale reactor illuminated with a blue light-emitting diode (LED) source emitting in the wavelength range of 460&ndash, 470 nm. The effects of pH, catalyst load, and hydrogen peroxide additions on the efficiency of dye removal were evaluated. Under the best conditions (pH 10, 3 g/L of catalyst, and 60 mM hydrogen peroxide), the dye solution was completely decolorized in about 2 h. Overall, the results obtained suggest that the proposed process may represent a suitable method for the removal of RV5 from textile effluents.

Extensive and improper utilization of water from industrial, municipal, and agricultural activities generate 380 trillion L/y of wastewater worldwide. Wastewaters from different sources contain enormous amounts of nutrients such as carbon, nitrogen, and phosphorus. Thus, the recovery of these nutrients via appropriate sustainable process becomes a necessity. Among various processes microalgae-based technologies has attracted considerable attention and its strategies for sustainable and low-cost treatment of wastewater has allowed removal of over 70% nutrient loads from the wastewater. After the treatment of wastewater, the harvested microalgae biomass contains value-added biomolecules which can used for bioenergy production and nanoparticle synthesis. At present, high operational costs represent a major limitation for the development of microalgae-based biorefineries. Thus, the main aim of the review is to provide the knowledge about the potential of low-cost microalgae-based integrated biorefinery for wastewater treatments and resource recovery. Also, this review provides the insight of microalgae biomass-based bioenergy products, nanoparticles synthesis their application within the concept of circular bioeconomy. Furthermore, this review also provides information on different established industries which used microalgae for wastewater treatment.

Cell wall disruption is one of the most critical and energy-consuming steps in the overall process of lipid extraction from microalgae. In this paper we investigate a multi-enzyme pretreatment based on the use of cellulase (CEL) and mannanase (GMA) for the recovery of lipids from the marine microalga Nannochloropsis sp. A central composite design coupled with response surface methodology was used to optimize the treatment and evaluate the effect of temperature ( T = 15–75 °C), pH (2–8), pretreatment time ( P = 30–270 min), CEL dosage ( D 1 = 0–20 mg/g) and GMA dosage ( D 2 = 0–2 mg/g) on lipid extraction. About 90% of lipids were recovered from Nannochloropsis cells pretreated under optimal process conditions ( T = 53 °C, pH = 4.4, P = 210 min, D 1 = 13.8 mg/g and D 1 = 1.5 mg/g). FTIR spectra and TEM images of Nannochloropsis cells showed that the enzymatic treatment produced significant alterations in the algal cell wall structure, with extensive loss of cell boundaries and release of intracellular material. Overall, the results obtained indicate that the proposed approach can significantly improve the recovery of lipids from Nannochloropsis sp., further supporting the use of enzymes in microalgal processes.

Artichoke waste was investigated as a potential source of phenolic compounds and bioenergy. The total phenolic content of the waste, expressed as gallic acid equivalents (GAE) per unit dry weight, was 32.2 mg GAE/g. Polyphenols were recovered from the waste by an environmentally friendly solvent extraction procedure using 50% (v/v) aqueous ethanol as solvent. Experiments were conducted according to a central composite design and response surface methodology was used to evaluate the effect of temperature (T), extraction time (E) and liquid-to-solid ratio (R) on the yield of phenolic extraction. Under optimal conditions (T = 53.3 °C, E = 110.4 min and R = 3.3 mL/g), over 90% of the phenolic compounds present in the waste were recovered. The three main factors T, E and R were all statistically significant and their influence on the extraction efficiency increased in the order: R

This work investigates the feasibility of using coffee silverskin (CSS), one of the most abundant coffee waste products, as a reinforcing agent in biopolymer-based composites. The effect of using two compatibilizers, a maleinized linseed oil (MLO) and a traditional silane (APTES, (3-aminopropyl)triethoxysilane), on mechanical and thermal behavior of sustainable composites based on a poly(butylene adipate-co-terephthalate/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PBAT/PHBV blend filled with coffee silverskin, in both the as-received state and after the extraction of antioxidants, was studied. Thermal (by differential scanning calorimetry), mechanical (by tensile testing), and morphological properties (by scanning electron microscopy) of injection molded biocomposites at three different weight contents (10, 20, and 30 wt %) were considered and discussed as a function of compatibilizer type. The effects of extraction procedure and silane treatment on surface properties of CSS were investigated by infrared spectroscopy. Obtained results confirmed that extracted CSS and silane-treated CSS provided the best combination of resistance properties and ductility, while MLO provided a limited compatibilization effect with CSS, due to the reduced amount of hydroxyl groups on CSS after extraction, suggesting that the effects of silane modification were more significant than the introduction of plasticizing agent.

This work investigates the feasibility of using coffee silverskin (CSS), one of the most abundant coffee waste products, as a reinforcing agent in biopolymer based composites. The chemical composition, antioxidant activity and morphology of CSS were studied by specific chemical essays and scanning electron microscopy, whilst the thermal stability and the functional groups available on the surface were investigated by thermogravimetric analysis and infrared spectroscopy, respectively. The thermal stability and fibrous structure of CSS make it suitable as a reinforcing filler in polymer composites, which was confirmed by manufacturing biocomposites with improved stiffness and tensile strength, not degraded by CSS addition when compared to the neat biopolymer.

An enzymatic treatment with cell wall degrading enzymes aimed at improving the recovery of lipids from Chlorella sorokiniana was investigated. Six commercial enzyme preparations containing cellulase, pectinase, lysozyme and three different hemicellulases were preliminary tested. The most effective preparations were then used as basic components for the formulation of enzyme cocktails with high cell wall degrading activity. Experiments were carried out according to the mixture design methodology. Analysis of the results revealed the occurrence of both synergistic and antagonistic effects which were, respectively, attributed to the cooperative destructuring of the cell wall and to non-productive competitive adsorption phenomena. A numerical optimization procedure was used to design an optimal enzyme mixture containing β-1,4-xylanase and β-1,4-mannanase in the ratio of 61:39 (% w/w). Pretreatment of C. sorokiniana by this mixture provided a lipid extraction yield of (74.74 ± 1.02)%. For comparison, the extraction yields from the untreated and water-pretreated biomass were, respectively, equal to (36.19 ± 2.33)% and (58.36 ± 1.22)%.

The effects of an enzymatic treatment with cellulase and mannanase on the properties of marine microalgae Nannochloropsis sp. were investigated. The combined use of these enzymes synergistically promoted the recovery of lipids from the microalgae, increasing the extraction yield from 40.8 to over 73%. Untreated and enzymatically treated microalgae were characterized by chemical analysis and by TGA/DTG, FTIR, XRD and SEM. Significant changes were observed in the chemical composition and thermal behavior of the microalgae. The enzymatic treatment also resulted in an increase of the crystalline-to-amorphous cellulose ratio. SEM images revealed dramatic changes in cell morphology, extensive cell damage and release of intracellular material. Overall, the results obtained indicate that the enzymes used are capable of disrupting the microalgal cell wall and that a combination of common analytical techniques can be used to assess the enzyme-induced damage.

A deeper knowledge of the chemical composition of coffee silverskin (CS) is needed due to the growing interest in its use as a food additive or an ingredient of dietary supplements. Accordingly, the aim of this paper was to investigate the metabolic profile of aqueous extracts of two varieties of CS, Coffee arabica (CS-A), Coffee canephora var. robusta (CS-R) and of a blend of the two (CS-b) and to compare it to the profile of Coffee arabica green coffee (GC). Chlorogenic acids, caffeine, furokauranes, and atractyligenins, phytotoxins not previously detected in CS, were either identified or tentatively assigned. An unknown compound, presumably a carboxyatractyligenin glycoside was detected only in GC. Caffeine and chlorogenic acids were quantified while the content of furokauranes and atractyligens was estimated. GC and CS were also characterized in terms of total polyphenols and antioxidant capacity. Differences in the metabolites distribution, polyphenols and antioxidant capacity in GC and CS were detailed.

The presence of toxic dyes in aquatic environments has become an issue of increasing concern worldwide. In this paper we investigate the adsorption behavior of azo dyes on non-living cells of Nannochloropsis oceanica . Nannochloropsis is a marine microalga widely used in aquaculture facilities as a feed material due to its valuable nutritional properties. Reactive Violet 5 (RV5) was selected as a model dye because of its widespread use in textile dyeing. The kinetics and equilibrium of RV5 adsorption on the biomass were studied at 10, 25 and 40 °C. Equilibrium data were found to be well described by the Temkin equation, with an apparent enthalpy change of 41.8 kJ mol −1 . A kinetic model assuming local equilibrium and a linear driving force (LDF) mass-transfer mechanism was developed. The estimated LDF mass-transfer coefficient varied between 1.18 10 −3 and 1.31 10 −3 min −1 . The model fitted the experimental data well and was used to simulate a treatment for the removal of RV5 from dyeing wastewater. Overall, the results obtained indicate that non-living cells of Nannochloropsis oceanica can be an effective adsorbent for the treatment of textile effluents containing azo dyes. The kinetic model developed can help evaluate the effect of the main treatment conditions on dye removal.

We have investigated the recovery of lycopene from tomato processing waste (TPW) by treating the peel fraction of the waste with pectinolytic and cellulolytic enzyme preparations. To optimize the enzyme-assisted extraction, we used a two-level factorial design with five factors: extraction temperature (T), pretreatment time (P), extraction time (E), enzyme solution-to-solid ratio (R), enzyme load (L). A 7-to 16-fold increase was observed in lycopene recovery, compared to the untreated TPW. From a response surface analysis of the data, a second-degree polynomial equation was developed which provided the following optimal extraction conditions: T = 30 °C, P = 3.5 h, E = 3.2 h, R = 30 dm3/kg, L = 0.17 kg/kg.

Low-grade coffee beans (LCBs), a waste produced in large quantities by the coffee industry, was investigated as a potential low-cost adsorbent for the removal of methylene blue (MB) from wastewater. The waste was characterized by SEM analysis and FTIR spectroscopy. Equilibrium and kinetic experiments were performed to study the adsorption process. The equilibrium data were found to be well described by the Langmuir model, from which a maximum adsorption capacity of 476.2 mg g1was derived. A half-adsorption time ranging from 12.5 to 96.2 min was estimated by fitting the experimental kinetic data to the pseudo-second-order model.

The efficacy of the UV-H2O2 treatment to degrade the antibiotic chloramphenicol (CHL) was investigated at 20 °C using a low-pressure mercury lamp as UV source. A two-level factorial design was used to study the effects of initial CHL (c0 = 4080 mg L1) and H2O2 (h0 = 2050 mM) concentrations, reaction time (t = 3070 min) and irradiance level (I = 400800 μW cm2) on CHL degradation. Under the best conditions (c0 = 40 mg L1, h0 = 20 mM, t = 70 min, I = 800 μW cm2), almost 96% of the antibiotic was degraded. No residual antibiotic activity was detected in the treated solution, thereby confirming the efficacy of the UV-H2O2 process.

Triclosan (TCS), an antimicrobial agent widely used in consumer and medical products, was complexed with 2-hydroxypropyl-β-cyclodextrin (HPβCD) and methyl-β-cyclodextrin (MβCD). Phase-solubility studies indicated that inclusion complexes of 1:1 stoichiometry were formed and allowed estimation of the associated equilibrium constants and free-energy changes. At the highest cyclodextrin concentrations investigated, an almost 20-fold increase in the apparent water solubility of TCS was determined. Susceptibility tests against Escherichia coli and Staphylococcus aureus showed that the TCS-HPβCD and TCS-MβCD complexes exhibited antibacterial properties higher than those of uncomplexed TCS. The two complexes were also found capable of interfering with cell-to-cell communication mechanisms in the C. violaceum model system relying on N-acylhomoserine lactone autoinducers. The inhibitory activity of TCS increased significantly upon inclusion of the drug in HPβCD or MβCD, with small differences between the two CDs. The results obtained suggest that the investigated complexes could be used for treating infections caused by TCS-susceptible pathogens or for preventing biofilm formation on indwelling medical devices such as catheters, stents and orthopedic implants.

The electrochemical decolorization of the Reactive Violet 5 azo dye on a boron-doped diamond anode was used as a model process to test a novel definitive screening design (DSD). This method allows a dramatic reduction in the number of experiments needed to investigate those systems characterized by a large number of variables. In this study, the effect of nine quantitative parameters was investigated: initial dye concentration (60–120 mg L−1), current density (100–500 A m−2), NaCl concentration (5–20 mM), Na2SO4 concentration (35–65 mM), pH (3–11), temperature (20–45 °C), inter-electrode distance (0.5–3.5 cm), stirring rate (250–750 rpm) and electrolysis time (2–8 min). Analysis of DSD data showed that four out of the nine factors (initial dye concentration, current density, pH and electrolysis time) were statistically significant. These factors were retained for process characterization using a subsequent central composite design. Overall, the number of experiments was reduced from over 500 to only 41, thus confirming the validity of the proposed approach as a time-saving and efficient method.

A statistical mixture design approach was used to investigate the effects of cell wall degrading enzymes on the recovery of lipids from Nannochloropsis sp. A preliminary screening of potentially suitable enzyme preparations, including lysozyme, cellulase and different types of hemicellulases, was carried out. The most effective preparations were then taken as basic components for the formulation of enzyme mixtures. Optimized ternary mixtures consisting of cellulase and two hemicellulases were obtained which allowed the recovery of up to 37.2g of lipids per 100g of dry biomass. SEM and TEM images of the enzymatically treated microalga revealed extensive cell damage, with degradation of the cell wall and release of intracellular material. Overall, the results obtained demonstrate that the mixture design method can be used to prepare cell wall degrading enzyme cocktails that can significantly improve the recovery of lipids or other valuable components from microalgae.

In this chapter, the applications of cellulases, alone or in combination with other enzymes, to the recovery of bioactive compounds from plant sources are discussed. Terrestrial and marine plants are rich sources of pigments and bioactive compounds of industrial importance, such as carotenoids, flavonoids, chlorophylls, alkaloids, and peptides. Over the last years, the increasing demand for natural products has stimulated research efforts to identify new bioactive compounds and elucidate their mechanisms of action. In food or cosmetic applications, the interest in using natural compounds as replacement for the synthetic ones is mainly due to the fact that the latter may be toxic and potentially carcinogenic. In the therapeutic field, mounting evidence indicates that plant-derived bioactives may have mechanisms of action different from those of conventional drugs, thus providing new opportunities for the treatment of many human diseases.

Large amounts of a waste known as tomato pomace and consisting mainly of the fruit peel and seeds are generated annually from the industrial processing of tomatoes. This material is rich in lycopene, a phytochemical with antioxidant and chemopreventive properties, and contains many valuable nutrients. In this study, we have investigated the possibility of using the whole waste to produce a lycopene-enriched seed oil. The oil was obtained by cold-pressing the seeds and was subsequently enriched in lycopene (up to 500 ppm) by incorporation of a tomato oleoresin derived from the peels. To increase lycopene recovery, the peels were pretreated with cell-wall-degrading enzymes and solvent extracted. This procedure allowed the production of about 25 kg/ton oleoresin with an average lycopene content of 6.8 wt.%. The compositional characteristics of the oil combined with the production of significant amounts of oleoresin strongly support the use of tomato pomace for producing lycopene-based functional products.

The interaction between lead (Pb2+) and bovine serum albumin (BSA) was studied in the temperature range of 10–40 °C through metal-titration experiments under equilibrium conditions. Lead binding to BSA was monitored by measuring the intensity changes in the difference absorption band at 243 nm following the addition of increasing amounts of lead ions to an aqueous solution at constant protein concentration (2.5 × 10−5 M). The equilibrium binding data were found to be well described by a Langmuir-type equation, with an almost temperature-independent saturation value. According to the estimated ΔH0 and ΔS0, the binding of Pb2+ to BSA was both enthalpy-driven and entropy-driven, with the entropic contribution providing the major driving force. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

A central composite design was used to optimize the enzyme-assisted extraction of lycopene from the peel fraction of tomato processing waste. Tomato skins were pretreated by a food-grade enzyme preparation with pectinolytic and cellulolytic activities and then subjected to hexane extraction. The factors investigated included extraction temperature (10–50 °C), pretreatment time (0.5–6.5 h), extraction time (0.5–4.5 h), enzyme solution-to-solid ratio (10–50 dm 3 /kg) and enzyme load (0–0.2 kg/kg). Overall, an 8- to 18-fold increase in lycopene recovery was observed compared to the untreated plant material. From a response surface analysis of the data, a second-degree polynomial equation was developed which provided the following optimal extraction conditions: T = 30 °C, extraction time = 3.18 h and enzyme load = 0.16 kg/kg. The obtained results strongly support the idea of using cell-wall degrading enzymes as an effective means for recovering lycopene from tomato waste.

Four commercial enzyme preparations containing cell-wall degrading enzyme activities were tested for their ability to facilitate lycopene extraction from tomato paste. At 25°C, up to 75.6% of the lycopene present in the tomato product was extracted by a two-stage procedure that consisted of a preliminary 5 hour enzyme incubation followed by a 3 hour solvent (hexane or ethyl acetate) extraction. Increasing the duration of the enzymatic treatment to 12–18 h allowed the recovery of 85–90% of total lycopene. The highest extraction yields were achieved by using enzyme preparations with polygalacturonase and pectin methylesterase in addition to pectin lyase or cellulase activities.

Four commercial enzyme preparations with pectinolytic, cellulolytic and hemicellulolytic activities were tested for their ability to enhance lycopene extraction from tomato peels. Screening experiments were performed at 25 °C by subjecting the peels to a 4-h enzyme incubation followed by 1-h hexane extraction. Peclyve EP and LI were the most efficient, with an almost 20-fold increase in extraction yield. Peclyve LI was used to evaluate the influence of solvent type and enzyme incubation time on lycopene recovery. Hexane, ethyl acetate and the mixture hexane/acetone/ethanol 50:25:25 (v/v) were used as solvents. Under the best extraction conditions (1-h enzyme incubation followed by a 3-h solvent extraction at 40 °C) up to 440 mg of lycopene per 100 g of dry tomato peels were obtained. The percentage recoveries were in the range of 3–30%, for the untreated peels, and 77–98% for the enzymatically treated material.

A membrane-free electrochemical reactor with a boron-doped diamond (BDD) anode was used to degrade Reactive Green 19 (RG19), an azo dye widely used in the textile industry. Oxidation experiments were carried out under galvanostatic conditions according to a central composite design. The factors investigated were current density (100–500 A/m 2 ), pH (3–11), chloride concentration (0–0.5 M) and agitation rate (250–750 rpm), while the response variables were the efficiencies of color and TOC removal. Color removal was strongly affected by chloride concentration and, to a lesser extent, by current density and stirring rate. In contrast, current density was the factor with the greatest influence on TOC removal, followed by pH and chloride concentration. Under optimal degradation conditions, the efficiencies of color and TOC removal reached values close to 90% and 80%, respectively. Taken together, the results of this study suggest that the anodic oxidation of RG19 on a BDD thin-film electrode can be a suitable method to degrade this dye, once the optimum operating conditions have been established.

The anodic oxidation of diazo dye Reactive Green 19 on a boron-doped diamond electrode was investigated. A membrane-free reactor was used to evaluate the effect of chloride concentration (0–0.5 M), current density (100–500 A m−2), pH (3–11) and stirring rate (250–750 rpm) on color and TOC removal. Complete decolorization was obtained in less than 30 min, whereas total mineralization was never achieved within 3 h of electrolysis. Color removal was significantly enhanced by increasing chloride concentration and, to a lesser extent, current density and stirring rate. TOC removal was positively affected by current density, pH and chloride concentration.