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•Egg yolk protein nanoparticles were prepared by a self-assembly method.•UV radiation showed a notable protein crosslinking effect for nanoparticle forming.•UV radiated nanoparticles ...showed a 309 % average size decrease at pH 7.•O/W emulsions formulated with 1 % of nanoparticles showed a high stability degree.•Storage stability, rheology and microstructure of Pickering emulsions were studied.
In this study, delipidated egg yolk proteins were used for the first time to prepare nanoparticles by the self-assembling method at pH 8.0, then treated with UV-C as a crosslinking agent, and their stability tested at pH 7.0, which is a more convenient pH for food applications. According to the results obtained, non-irradiated nanoparticles had a size of 431.8 ± 75.7 nm at pH 7.0, but the 10 min UV-C irradiated nanoparticles had an average size of 139.7 ± 5.9 nm. These nanoparticles also showed a high resistance to destabilization by SDS, urea or DTT and noticeable antioxidant and ferrous chelating activities. Pickering emulsions prepared at the nanoparticle concentration of 1 % (w/w) showed the smallest average droplet size and the lowest Turbiscan stability index value after 80 days of storage. All in all, these results have important implications for the utilisation of these proteins as a conventional Pickering emulsifying agent.
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•Classification of sludge products from hydrothermal treatments is proposed.•Chemical oxygen demand fractionation and the role of oxygen were studied.•Non-readily biodegradable ...fraction was twice in absence of oxygen.•Wet oxidation led to higher mineralisation and minimisation of solid fraction.•Oxygen turns intermediates and non-volatile hydroxy acids into volatile fatty ones.
As the wide variety of compounds that are solubilised and generated during hydrothermal treatments of sewage sludge cannot be defined individually, this study proposes a classification based on chemical characteristics and biodegradability. Moreover, it has deepened understanding of the role of oxygen in the reaction mechanisms and the evolution of chemical oxygen demand (COD) fractions and their components during hydrothermal treatments (180 °C, 80 bar). This information is necessary before separating specific compounds or using the hydrolysates directly as fertiliser or fermentation media. Results revealed the existence of an initial stage of sludge solubilisation (30 – 60 min), mainly produced by hydrolysis reactions and without mineralisation, followed by a second stage where oxygen promoted the conversion of solubilised compounds, mineralisation and the minimisation of the solid fraction. Total COD and total suspended solids (TSS) were reduced by 48% and 75% after 210 min of wet oxidation, compared to 28% and 50% after thermal hydrolysis. Oxygen led to a final liquid hydrolysate with fewer easily assimilable compounds (38% of the initial total COD converted into readily biodegradable), inorganic elements (17 g/kg TSSo) and refractory, inhibitory and less assimilable compounds (1.1 g O2/L of slowly and non-biodegradable COD) compared to that obtained in its absence (61%, 24 g/kg TSSo and 2.3 g O2/L, respectively). Oxidation mechanisms favoured the conversion of non-volatile hydroxy acids (NVHA) and intermediate compounds to volatile fatty acids (VFA), with VFA concentration being almost 3 times higher under an oxidising atmosphere, but with NHVFA 57% lower.
Lipids in the brain are major components playing structural functions as well as physiological roles in nerve cells, such as neural communication, neurogenesis, synaptic transmission, signal ...transduction, membrane compartmentalization, and regulation of gene expression. Determination of brain lipid composition may provide not only essential information about normal brain functioning, but also about changes with aging and diseases. Indeed, deregulations of specific lipid classes and lipid homeostasis have been demonstrated in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Furthermore, recent studies have shown that membrane microdomains, named lipid rafts, may change their composition in correlation with neuronal impairment. Lipid rafts are key factors for signaling processes for cellular responses. Lipid alteration in these signaling platforms may correlate with abnormal protein distribution and aggregation, toxic cell signaling, and other neuropathological events related with these diseases. This review highlights the manner lipid changes in lipid rafts may participate in the modulation of neuropathological events related to AD and PD. Understanding and characterizing these changes may contribute to the development of novel and specific diagnostic and prognostic biomarkers in routinely clinical practice.
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•Oxidised sewage sludge was an ideal substrate for the production of biolipids.•VFAs derived from sewage sludge were totally consumed during the production of ML.•Yarrowia lipolytica ...convert VFAs from sewage sludge to microbial lipids efficiently.•Lipid content of 35% was reached when the pH of the oxidised sewage sludge was 6.5.•Fatty acid profile of the lipids showed high suitability for biodiesel production.
Sewage sludge (SS) can be used as a fantastic source of organic compounds instead of being considered as a waste. Thus, these compounds could be converted into microbial lipids (ML) by oleaginous microorganisms, these biolipids being used as raw material for the sustainable production of biodiesel. Nevertheless, the organic compounds are trapped in the complex structures of the sludge flocs. Therefore, in this study an integrated process of sludge management was developed to produce ML as a valuable alternative to oils from agricultural sources. In this sense, wet oxidation (WO) was used as a pre-treatment process of SS in order to maximise the generation of volatile fatty acids (VFAs) mainly acetic and propionic acids. Thus, the liquid fraction was employed as a substrate to produce biolipids by Yarrowia lipolytica, without adding any kind of (micro)nutrients. The optimum conditions for the VFA generation were found to be 205 °C and 120 min, obtaining a concentration of acetic and propionic acids of 4323 ± 112 mg/L and 565 ± 25 mg/L, respectively. Besides, during the WO, ammonium nitrogen was also released, which is a vital nutrient in the metabolism of the oleaginous yeast for cell proliferation. Regarding the fermentation with Y. lipolytica, the best pH value was established at 6.5. Under these conditions, 95% of acetic acid and 100% of propionic acid were metabolised by the yeast. This implied that approximately 30% of the organic carbon present in the oxidised SS was transformed into biolipids in 48 h of cultivation. High lipid content and lipid yield coefficient (YL/S) were achieved using VFAs derived from SS, the values being 35 ± 1% and 0.23 ± 0.02 g/g, respectively. The lipid profile mainly contained monounsaturated fatty acids, such as oleic acid (46.4 ± 0.4%), making it an interesting raw material for biodiesel production. Therefore, the proposed strategy can be a promising approach to produce clean biofuels from SS.
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•Vegetable wastes was successfully hydrolysed by thermal or enzymatic treatments.•A new combined thermic-enzymatic hydrolysis maximised the fermentable sugars.•The kinetic model ...developed for enzymatic step properly fitted experimental data.
Fruits and vegetables have the highest wastage rates at retail and consumer levels. These wastes have promising potential for being used as substrates in bioprocesses. However, an effective hydrolysis of carbohydrates that form these residues has to be developed before the biotransformation.
In this work, vegetable wastes from supermarket (tomatoes, green peppers and potatoes) have been separately treated by acid, thermal and enzymatic hydrolysis processes in order to maximise the concentration of fermentable sugars in the final broth.
For all substrates, thermal and enzymatic processes have shown to be the most effective. A new combined hydrolysis procedure including these both treatments was also assayed and the enzymatic step was successfully modelled. With this combined hydrolysis, the percentage of reducing sugars extracted was increased, in comparison with the amount extracted from non-hydrolysed samples, approximately by 30% in the case of tomato and green peeper wastes. For potato wastes this percentage increased from values lower than 1% to 77%. In addition, very low values of fermentation inhibitors were found in the final broth.
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•ADL from sewage sludge digestion was treated by P. chrysosporium for first time.•The addition of 3 g/L glucose was key to improve the efficiency of the process.•P. chrysosporium ...removed 77 % of soluble COD in batch operation.•Biodegradability was increased in four times after 10 days of fungal treatment.•65 % of COD was removed during 20 days of continuous operation using an HRT of 240 h.
In this study, Phanerochaete chrysosporium was tested for first time to treat the liquid effluent from a sewage sludge digestion. This anaerobic digestion liquor (ADL) has a COD concentration of around 7500 mg/L, a very low biodegradability (BOD5/COD = 0.02) and deep colour, being impossible their effective treatment by conventional biological methods. Assays inoculating the fungi were carried out at 26 °C during 10 days in a batch reactor, following the evolution of colour, COD and BOD5. The effect of adding different concentrations of glucose was evaluated, resulting to be a key factor for increasing the efficacy of the treatment. Based on batch results, a continuous fungal water-jacketed bioreactor was successfully started up. COD removals above 65 % were achieved both in batch and continuous operations. These results show the possibilities of this sustainable and economic approach to remove refractory COD in the low-biodegradable effluents derived from anaerobic digestion of sludge or other complex wastes.
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•The presence of oxygen had a negative impact on the production of acids.•190 °C was the optimal temperature to obtain the highest concentrations of acids.•Wet oxidation generated a ...less concentrated but more purified stream of acids.•The longer the chain of the non-volatile hydroxy acid, the greater its reactivity.•The longer the chain of the volatile acid, the lower its reactivity.
The present study assesses, for the first time, the use of the non-lignin residue from Kraft black liquor as a renewable source of carboxylic acids. For this purpose, the liquid fraction obtained after separating the lignin from the black liquor by acid precipitation was subjected to different hydrothermal treatments. It was found that the formation of carboxylic acids can be maximized at 190 °C, 70 bar and under an inert atmosphere, with concentrations after 2 h of 29.0 g/l of oxalic acid, 1.8 g/L of malic acid, 10.0 g/L of lactic acid, 4.1 g/L of formic acid, 11.8 g/L of acetic acid and 3.4 g/L of propionic acid. The presence of an oxidizing atmosphere generated a less concentrated, but more purified, stream of acids than that obtained by thermal hydrolysis, simplifying the subsequent downstream processing.
Waste activated sludge (WAS) is the main by-product of wastewater treatment plants. Its management is considered one of the major environmental challenges worldwide, due to the large volume ...generated, along with the presence of pathogens and hazardous substances. Nevertheless, the biopolymers present in its structure can make it a promising source of nutrients to obtain high value-added products. Therefore, this study is focused on the use of WAS as a renewable feedstock to produce proteases by Bacillus licheniformis. To this end, both thermal hydrolysis (TH) and wet oxidation (WO) were evaluated as strategies for the solubilization of the valuable compounds. The results revealed that an operation time of 90 min (at 140 °C) was optimal for both pretreatments, which allowed obtaining concentrations of carbohydrates, proteins and humic acids up to 2.7 ± 0.1 g/L, 5.3 ± 0.1 g/L and 5.1 ± 0.1 g/L, respectively. Regarding bioconversion processes, the initial pH of the medium significantly influenced the assimilation of the biopolymers, bacterial growth and enzyme biosynthesis. In this sense, a pH of 5.5 for the WAS pretreated by TH (WAS-TH) and 7.5 for the WAS pretreated by WO (WAS-WO) allowed maximizing the proteolytic activities, reaching values of 767 ± 2 U/mL and 838 ± 6 U/mL, respectively. Additionally, higher initial inoculation levels positively influenced the performance of the fermentative process. Consequently, a 30 % inoculum resulted in enzymatic activities of 828 ± 11 U/mL for WAS-TH and 903 ± 4 U/mL for WAS-WO. Partial purification of the medium with ammonium sulphate increased the enzymatic activity by 7 times for WAS-TH and 3 times for WAS-WO.
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•Hydrothermal pretreatments of sludge led to biopolymer concentrations up to 5.3 g/L.•Optimum fermentation pHs were 7.5 for oxidized sludge and 5.5 for hydrolysed sludge.•Maximum specific growth rate (0.17 h−1) obtained at pH 5.5 in hydrolysed sludge.•Maximum enzymatic activity (903 U/mL) achieved with 30 % inoculum in oxidized sludge.•Enzyme activity in (NH4)2SO4-purified hydrolysed sludge increased 7-fold to 8366 U/mg.
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•Both lignin recovery and wet oxidation greatly reduced the black liquor’s COD.•A partial purification of the organic acids was achieved after ultrafiltration.•30% trioctylamine in ...heptane at 40 °C was found to be the most suitable solvent.•Increasing temperature up to 55 °C had a positive effect on organic acid extraction.•The highest final organic acid recovery was achieved after lignin recovery.
Kraft black liquor (BL) is a toxic residue from paper manufacture that can be revalorized to obtain high value-added products. In this study, different integrated processes, consisting of a pre-treatment (lignin recovery LR or partial wet oxidation PWO) followed by ultrafiltration (UF) and liquid–liquid extraction (LLE), have been evaluated in order to recover short-chain organic acids (OA) from BL.
After the UF step, a partial purification of OA was observed. Thus, the COD fraction attributable to OA increase 26.0%, 36.6% and 11.3% for untreated BL, BL after lignin recovery (LRBL) and partially oxidised BL (WOBL), respectively.
The final LLE step was optimised analysing different combinations of extractants (trioctylamine, trioctylphosphine oxide and tributylphosphate), diluents (n-hexane and heptane) and temperatures (25, 40 and 55 °C), concluding that the most suitable solvent was 30% trioctylamine in heptane (v/v) at 40 °C, in which 76% of the OA mass was recovered in LRBL, 72% in BL and 68% in WOBL.
The pre-treatment of BL improved the final recovery yield of OAs, increasing from 24.7% to 28.1% and 29.4% through PWO and LR, respectively. Therefore, LR was considered the most suitable pre-treatment due to its lower operating cost, widespread use, and greater recovery of OA.
Agri-environment schemes (AES) and greening of the Common Agricultural Policy (CAP) are crucial tools for biodiversity conservation in Europe. However, they have not been associated formally to any ...performance monitoring program that supports their actual benefits for biodiversity, and their effectiveness is recurrently questioned.
We present an extensive evaluation of the potential of CAP conservation tools to support farmland bird diversity throughout the most representative cereal regions in Spain. We explore bird diversity responses to AES application in pairs of cereal plots with and without AES. We also explore bird responses to a set of habitat indicators, both of productive (farmed) and semi-natural components (i.e., field margins and natural vegetation remnants), within plots and in the surrounding landscape. We use these habitat indicators as proxies of distinct greening measures (e.g., hedges, fallow, crop diversification).
Our results point at the prospective success of measures focused on promoting, particularly at landscape scales, certain productive habitats (e.g., fallow land and legume crops), mainly but not exclusively for open land birds. Promoting semi-natural habitats (both areal and linear elements) also resulted positive, primarily for forest and ecotone birds, but also open land birds.
Our results evince high variability in the capacity of AES and distinct greening measures to support bird diversity among regions and groups of birds. More regionally-targeted conservation measures (i.e., focused on specific requirements of targets, considering explicitly regional species pools and landscape constraints) are thus required. These measures could be assembled in the new CAP by means of compulsory measures applied throughout the agricultural landscape (i.e., advanced environmental conditionality likely replacing cross-compliance and greening) and voluntary instruments (i.e., eco-schemes and AES) with enough farmers' uptake that ensures its impact at landscape scale. Performance evaluation and subsequent adaptation based on the results obtained ought to accompany the implementation of conservation tools.
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•Local habitat management only affect abundance of foraging and wintering birds.•Landscape configuration and composition alone affect diversity of breeding birds.•Bird diversity responses greatly vary across regions, seasons and groups of birds.•Regionally-targeted conservation tools should be implemented at landscape scale.•Performance monitoring and subsequent adaptation of these tools should be mandatory.
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