Search Results (34)

This study investigates the valorization of two agri-food residues, specifically olive pomace (alperujo, A) and banana peel (B), into efficient N-doped carbon-based catalysts for polluted wastewater treatment. The residues were converted into hydrochar (HA and HB), which were subsequently N-doped using polyethylenimine (PEI) in combination with cross-linkers (glutaraldehyde (GTA) or 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)) to optimize their catalytic properties. The enhanced hydrochars were utilized as catalysts for the removal of organic pollutants from water by activation of peroxymonosulfate (PMS). Characterization techniques, including CHNS, FTIR, XPS, SEM and electrochemical analysis, were employed to understand the physicochemical properties of the materials. The catalytic activity was evaluated using Reactive Black 5 (RB5) as a model pollutant, with the N-doped alperujo-derived hydrochar cross-linked with EDC (N-HA-EDC) showing the best performance, achieving 80% removal in 60 min and an adsorption capacity of 97 mg/g. The versatility of this functionalization approach was assessed through tests with three pharmaceuticals, corroborating the adaptability and efficacy of the catalyst and demonstrating its potential for wastewater treatment applications. This study provides insights into the development of sustainable, cost-effective carbocatalysts, aligning with circular economy and zero waste principles. Full article

Alperujo, a solid by-product from the two-phase olive oil extraction process, poses significant environmental challenges due to its high organic load, phytotoxicity, and phenolic content. At the same time, it represents a promising feedstock for recovering value-added compounds such as phenols and volatile fatty acids (VFAs). When used as a substrate for white rot fungi (WRF), it also produces ligninolytic enzymes. This study explores the use of two native WRF, Anthracophyllum discolor and Stereum hirsutum, for the biotransformation of alperujo under solid-state fermentation conditions, with and without supplementation of copper and manganese, two cofactors known to enhance fungal enzymatic activity. S. hirsutum stood out for its ability to release high concentrations of phenolic compounds (up to 6001 ± 236 mg gallic acid eq L⁻¹) and VFAs (up to 1627 ± 325 mg L⁻¹) into the aqueous extract, particularly with metal supplementation. In contrast, A. discolor was more effective in degrading phenolic compounds within the solid matrix, achieving a 41% reduction over a 30-day period. However, its ability to accumulate phenolics and VFAs in the extract was limited. Both WRF exhibited increased enzymatic activities (particularly Laccase and Manganese Peroxidase) with the addition of Cu-Mn, highlighting the potential of the aqueous extract as a natural source of biocatalysts. Phytotoxicity assays using Solanum lycopersicum seeds confirmed a partial detoxification of the treated alperujo. However, none of the fungi could entirely eliminate inhibitory effects on their own, suggesting the need for complementary stabilization steps before agricultural reuse. Overall, the results indicate that S. hirsutum, especially when combined with metal supplementation, is better suited for valorizing alperujo through the recovery of bioactive compounds. Meanwhile, A. discolor may be more suitable for detoxifying the solid phase strategies. These findings support the integration of fungal pretreatment into biorefinery schemes that valorize agroindustrial residues while mitigating environmental issues. Full article

Two methanogenesis inhibition strategies for enhancing volatile fatty acid (VFA) production through the anaerobic fermentation of alperujo, a byproduct of olive oil production, were evaluated. Methanogenesis inhibition was implemented via two different approaches, one by pH adjustment to 5.0 and another one by chemical inhibition using 2-bromoethanesulfonate (BES) at pH 7. The VFA accumulation at the end of the experiment was 67% higher under the BES condition than under the pH 5 condition. Interestingly, the VFA profiles were similar under both conditions, with acetic acid as the dominant product, followed by propionic and butyric acids. The results demonstrated a 25% increase in alperujo solubilization under the BES condition, compared to under the pH 5 condition. This latest finding, together with the similar VFA profiles on both strategies, suggests that the hydrolysis step in alperujo solubilization was impacted by the pH difference. These findings highlight the effectiveness of chemical inhibition in enhancing solubilization, hydrolysis, and VFA accumulation during anaerobic fermentation of alperujo and, most importantly, the negative effect of pH 5 on the solubilization step. Full article

The production of olive oils implies the generation of high quantities of solid residues and/or wastewater that may have a great impact on terrestrial and aquatic environments because of their phytotoxicity. Alperujo is a combination of liquid and solid waste from olive oil processing. Few studies are known that show their high biological potential. Indeed, wastes remaining after the production of olive oil are a heterogeneous mixture of many chemical components, such as metal ions, carbohydrates, and polyphenols, that may exert different biological activities, primarily acting as antioxidants. The samples of “alperujo” were obtained as waste from industries that work on olive oil production. Three ethanolic organic extracts were prepared using solvent maceration, ultrasound and reflux extraction methods. Yields of each extract were determined and evaluated for their ability to trap free radicals, using the DPPH and ABTS assays contributing to the calculation of SC₅₀ (free radical scavenging). The extracts were subjected to preliminary phytochemical testing, analyzing phenolic content by the Folin method and heavy metal concentration using atomic absorption spectrometry. The extraction method was decisive for the yield obtained, with the reflux system being highly efficient, and the antioxidant activity shows the potential of these wastes as a source of bioactive compounds of interest for possible reuse. Full article

Olive cultivation is a key agricultural activity in Spain, primarily for producing oil. The extraction process of olive oil from the drupe yields a by-product known as ‘alperujo’, which can be composted and utilized as fertilizer. This research examines the impact of composted ‘alperujo’ on arthropod assemblages in the tree canopy, comparing it to mineral fertilization over the years 2021 and 2022. The study was conducted in two olive groves with different management systems (superintensive and traditional). Two types of sampling methods were used for the canopy: visual survey and sweep net. Under superintensive management, the presence and damage of Eriophyidae (Acari; Trombidiformes) in the shoots was significantly lower in the compost treatment in 2022 (20% of the shoots were occupied/damaged) compared to the mineral treatment (60% of the shoots were occupied/damaged). Araneae abundance was significantly higher (p = 0.033) in the compost treatment compared to the mineral treatment. However, under traditional management, no clear effect on arthropod assemblage was observed. In conclusion, the addition of compost to the superintensive grove helped to limit the presence of some arthropod pests compared to mineral treatment, contributing to a more sustainable crop. Grove type management appeared to play a significant role in the arthropod assemblages and effect of compost addition, but future research utilizing a greater number of groves (replicates) and an extended observation period should be performed to confirm these results. Full article

This research explores the health-promoting properties of the pectin–polyphenol complex extracted from alperujo, a by-product of olive oil production. This study investigates the chemical composition and antioxidant activity of the extracts, revealing their high antioxidant activity in vitro. Cell viability assays conducted on colon carcinoma cells (Caco-2) demonstrate the inhibitory effect of the extracts on cell proliferation. However, the extracts do not affect the viability of differentiated Caco-2 cells, suggesting a selective antiproliferative action. Additionally, the extracts reduce intracellular reactive oxygen species (ROS) and nitrite (NO) production in LPS-stimulated murine peritoneal macrophages. Furthermore, the extracts exhibit anti-inflammatory effects by downregulating the secretion of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 in these macrophages. These findings highlight the potential of pectin–polyphenol complexes as functional ingredients with significant health benefits, demonstrating antioxidant, antiproliferative, and anti-inflammatory properties. Full article

Olive oil extraction by two-phase systems generates a by-product called “alperujo” which presents several difficulties for its valorization. The present work evaluated an industrial approach, based on the application of thermal treatments to alperujo followed by solid/liquid separation using standard two-phase olive oil mill equipment. Treatments consisted of the thermo-malaxation of alperujo at 70 °C for 45 or 90 min, with or without acid addition, followed by solid/liquid separation in an industrial decanter. The solid was characterized concerning subsequent use for composting, while total and hydrophilic phenolics were analyzed in liquid for their recovery. Additionally, a laboratory-scale trial to compare phenolic purification by ethylic acetate extraction with chromatographic procedures was also included. The static respiration index showed that solid fractions presented higher susceptibility to biodegradation processes than raw alperujo. The phenolic content of treated liquid fractions was higher than in raw alperujo. Total phenolics were maximum at the longest exposure time without acid addition, while hydrophilic phenolics were highest at the shortest exposure time in acidified samples. The use of non-ionic resins seemed attractive for obtaining highly concentrated phenolic fractions. The proposed thermal treatments can be applied in olive oil industries, allowing in situ pomace valorization and the recovery of phenolic-enriched liquid fractions. Full article

Sperm cryopreservation is a fundamental tool for the conservation of avian genetic resources; however, avian spermatozoa are susceptible to this process. To cope with the high production of reactive oxygen species (ROS), the addition of exogenous antioxidants is beneficial. Pectoliv30 is a substance derived from alperujo, and in this study, its effect was analyzed on seminal quality after its addition to the cryopreservation extender of roosters at different concentrations. For this purpose, 16 Utrerana breed roosters were used, and seminal collection was performed in six replicates, creating a pool for each working day with ejaculates of quality. After cryopreservation, one sample per treatment and replicate was thawed, and several seminal quality parameters were evaluated. Statistical analysis revealed numerous correlations between these variables, both positive and negative according to the correlation matrix obtained. Furthermore, the chi-squared automatic interaction detection (CHAID) decision tree (DT) reported significant differences in the hypo-osmotic swelling test (HOST) variable between groups. Moreover, results for this parameter were more desirable at high concentrations of Pectoliv30. The application of this substance extracted from the by-product alperujo as an antioxidant allows the improvement of the post-thawing seminal quality in roosters and facilitates optimization of the cryopreservation process as a way to improve the conservation programs of different endangered poultry breeds. Full article

The practices (tillage and flooding) used for rice crops are unsustainable, especially in areas characterized by water shortages, such as the Mediterranean region. Therefore, it is necessary to develop sustainable methods in order to ensure the viability of rice production. However, it is essential to understand the effects that alternative management can have on herbicide behavior. In this context, this paper describes the first field experiment conducted to evaluate the medium-term effects of different agricultural practices on the fate of bispyribac sodium (BPS). Thus, the treatments were as follows: tillage and flooding (TF), tillage and sprinkler (TS), and no-tillage and sprinkler (NTS). In addition, “alperujo” compost (AC) from olive mill waste was used in each treatment (TF-AC, TS-AC, and NTS-AC). The AC was applied only once in 2015 when the TS and NTS treatments were implemented. The AC amendment increased the adsorption of BPS and its irreversibility, thereby decreasing the BPS leaching capacity. Furthermore, throughout this study, the BPS persistence was up to 1.85 times greater with sprinklers than in the flooding condition, which could explain the high values of BPS effectiveness (increased by a factor of 1.45 on average) found with sprinklers. Therefore, the implementation of sprinklers in combination with AC can be considered a sustainable strategy for Mediterranean rice production, at least in the medium term, as it reduces BPS water pollution and increases its weed control efficiency. Full article

The pectin from the cell walls of olive waste (alperujo) and apple, orange and strawberry fruits was extracted using choline chloride (ChCl) and the yield and chemical and structural compositions were compared to pectin extracted using citric acid (CA) and ammonium oxalate/oxalic acid (AOOA). According to the results, the alperujo pectin extracted using ChCl from alcohol-insoluble residue (AIR) showed a higher yield (2.20–2.88% on the basis of dry weight of AIR) than using CA (0.65–1.22%) but lower than using AOOA (3.92–5.42%). For fruit pectin, the highest yield was obtained using CA (8.81–16%), followed by AOOA (5.4–6.63%), although for apple pectin, ChCl gave a similar yield (5.36%) to AOOA. The uronic acid contents in all ChCl pectins (45.9–70.6% dry basis AIR) were higher or similar to that of the other extracting agents (30.6–65.2%), although a lower level of neutral sugar side chains was detected, with a lower degree of branching and degree of methylation. The NMR and FT-IR spectroscopy of the pectin isolated using ChCl confirmed its slightly different structural composition with respect to CA and AOOA pectin. Therefore, depending on the source material and functionality, pectin isolated using ChCl could be an acid-free alternative to pectin production. Full article

The pomace olive oil sector needs to improve its use of the main olive oil by-product, called alperujo, which is currently used mainly for combustion after extraction of pomace oil, with all the problems this process entails due to the high degree of humidity, organic load and phytotoxic substances. In this work, a solution at an industrial level that uses thermo-malaxation at a temperature close to 65 °C for one or two hours followed by centrifugation in three phases is proposed. In this way, over 40% of the pomace oil that is rich in minor compounds, a solid with a lower degree of humidity (55%), and a liquid aqueous fraction that is rich in bioactive compounds such as phenolics and sugars are obtained. This aqueous fraction can be treated through subsequent storage stages to increase its content of the main phenolic, hydroxytyrosol, to up to 1.77 g/L, decreasing its percentage of insoluble solids by up to 1.9%, making it possible to obtain extracts that are rich in hydroxytyrosol using systems that are commonly in place at the industrial level. The aqueous fraction, without phenolics, could be used for energy production. A solid with a slightly higher fat content than the initial alperujo remains, thus the rest of the oil content can be extracted from it using solvent, making it, once defatted, suitable for application in subsequent bioprocesses. Full article

The hypothesis of this experiment was that a liquid rich in hydroxytyrosol (HT) obtained from “alperujo”, an olive oil by-product, could replace part of the added vitamin E (VE) as an antioxidant in poultry diets. There were five diets that differed exclusively in the substitution of supplemental VE (0 to 40 mg/kg, with differences of 10 mg/kg) by HT (30 to 0 mg/kg, with differences of 7.5 mg/kg). The basal diet was based on corn and soybean meal and provided 10 mg VE/kg. From 0 to 39 d of age, the growth performance of the birds was not affected by diet. The birds were slaughtered at 39 d of age to evaluate the quality of the breast, and malonaldehyde concentration, pH, color, and drip loss were measured. In terms of meat lipid oxidation, the combination of 22.5 mg HT/kg and 10 mg of added VE/kg equalized to a diet supplemented with 40 mg VE/kg. Meat color improved in broilers fed 7.5 mg HT/kg and 30 mg VE/kg. It is concluded that once the nutritional requirements of the birds in VE are satisfied, the dietary supplementation with the olive oil by-product rich in HT can be used as a strategy to spare VE in broiler diets. Full article

In Spain and other Mediterranean countries, significant quantities of semi-solid olive mill waste are generated, which should be preferentially applied to agricultural soils to close nutrient cycles. However, two-phase olive mill waste (termed alperujo in Spanish) is known to pose risks to soil quality and plant production when applied to soil in large quantities. Alperujo has high contents of polyphenol substances, which can inhibit microbial growth and are also phytotoxic in nature. However, when applied in appropriate quantities and following specific methods, it is possible that the practice may not pose any risks, and this requires evaluation. As a waste management option, direct application of alperujo can supply plant nutrients and organic matter to degradation-prone Mediterranean soils. In order to validate this circular economy fertilization and soil protection strategy, an 18-month field experiment was undertaken, applying moderate quantities of alperujo on permanent crop groves throughout the Spanish region of Valencia. Eleven experimental parcels with permanent crops managed by farmers were identified to test two scenarios: a single application of 10 t/ha, and a second application of 10 t/ha after 10 months. Soil chemical parameters were assessed at 0, 6, 10, and 18 months. Soil organic carbon, total Kjeldahl nitrogen, pH, electrical conductivity, nitrates, and polyphenol contents were modified by alperujo application, but these effects were highly transient in nature, with generally no lasting effects after 4–6 months for either application scenario. Also, qualitative evaluations carried out by farmers revealed few effects, although some reductions in erosive processes and improvements in plant vigor were noted. As such, based on the measured parameters, it is concluded that the direct soil application of alperujo olive mill wastes at low application rates did not lead to any lasting detrimental effects on soil quality or compromise the productivity of permanent crops in this Mediterranean region. Full article

Industrial production of olive oil generates large amounts of solid waste called ‘alperujo’. Its compost can fertilize many crops, especially olives. Furthermore, superintensive orchards are increasing their surface globally due to higher production and savings in different costs. Ants are considered an important part of the arthropod community in olive orchards and could even play a significant role in pest control. The tree canopy and ground were sampled to compare the ant assemblage in plots fertilized with compost and mineral products in two groves with different types of crop management (superintensive and traditional) over two years. The numbers of ants in both types of fertilization in each grove were not statistically different (p > 0.05), indicating that the type of fertilization did not have a significant impact on its populations in the ground or in the canopy, but the number of individuals was significantly higher in the superintensive grove than in the traditional grove (both in the ground and in the canopy, p < 0.01). The most frequent species in the ground were Pheidole pallidula, Plagiolepis smitzii and Aphaenogaster senilis (superintensive grove) and Pheidole pallidula, Tetramorium gr semilaeve, Plagiolepis pygmaea, and Tapinoma nigerrimum (traditional grove). In the canopy, the most frequent species were Plagiolepis spp. in both groves. Differences in ant densities and species between the groves could be due to the different management, especially of the soil, but it must be confirmed using more replicas and longer periods of study. Full article

The utilization of compost to enhance plant productivity and symbiotic nitrogen fixation (SNF) has been recognized as an effective alternative to synthetic nitrogen fertilizers. This environmentally sustainable method is readily accessible to farmers. This study investigated the effect of olive pomace (“alperujo”, AL) compost on the nodulation and SNF of soybeans (Glycine max L.) and their natural symbiont (Bradyrhizobium diazoefficiens). For that, soybean plants were subjected to several doses of AL compost under controlled greenhouse conditions. At the end of the experiment, the dry weight of plant biomass (aerial part and roots), the number and fresh weight of nodules, and nitrogen and leghaemoglobin contents were analyzed. The application of AL compost significantly improved soybean growth, as demonstrated by an increase in both plant biomass and height. Furthermore, nodular leghaemoglobin content and nitrogen content were found to be enhanced by the addition of AL compost (7 and 40%, respectively), indicating an increase in nodule effectiveness and symbiotic efficiency. Our results provide clear evidence of the synergetic effect of AL compost on the soybean-B. diazoefficiens association, probably due to AL-compost improved soybean roots development, and rhizospheric organic matter and nutrients assimilation by rhizobia. Full article