Hepatopreventive properties of hydroxytyrosol and mannitol-rich extracts obtained from exhausted olive pomace using green extraction methods.

Exhausted olive pomace (EOP) is produced in olive-pomace oil extractors as a by-product. However, the obtention of bioactive compounds from EOP can reinsert it into the economy as a new bioresource before applying other exploitation ways. The objective of the present study was to investigate the phytochemical differences between aqueous and aqueous acetonic extracts from EOP (AE-EOP and AAE-EOP, respectively) obtained by hydrothermal and ultrasound-assisted extraction, respectively. The in vitro antioxidant activities and the in vivo hepatopreventive potential were evaluated. Using RP-HPLC-ESI-QTOF-MS, the chemical profile revealed that AE-EOP and AAE-EOP showed similar qualitative profiles, with some quantitative differences. Hydroxytyrosol and mannitol were the major compounds of the extracts. The investigation of antioxidant properties in vitro highlighted that AE-EOP was slightly more efficient in scavenging DPPH, ABTS, superoxide, and hydrogen peroxide radicals, when compared to AAE-EOP. Additionally, AE-EOP and AAE-EOP showed dose-dependent suppressive effects on pancreatic lipase activity. In vivo studies showed that AE-EOP and AAE-EOP presented interesting hepatopreventive capacities against CCl4 induced liver injury, as evidenced by (i) the preventive effects against DNA damage, (ii) the normalised hepatic biomarker parameters (ALT, AST, GGT, and LDH) and (iii) the normalised lipid profile (LDL-C, TC, TG, and HDL-C) through diminishing their levels, (iv) which was supported by Oil Red O analysis. Furthermore, AE-EOP and AAE-EOP reduced the oxidative stress in liver tissue by inhibiting lipid peroxidation together with the enhancement of the hepatic antioxidant activities (CAT, SOD and GPx) and GSH content. Additionally, AE-EOP and AAE-EOP exhibited an antifibrotic effect, which was clearly demonstrated by the histopathological examination using Picrosirius red staining. The obtained results support the use of EOP extracts in industries without further purification as antioxidants and against free radical induced damage.

Biotechnological use of the ubiquitous fungus Penicillium sp. 8L2: Biosorption of Ag(I) and synthesis of silver nanoparticles.

In this work, the efficiency of the ubiquitous fungus Penicillium sp. 8L2 to remove Ag(I) ions from synthetic solutions and its potential to synthesize silver nanoparticles (AgNPs) was evaluated. Using a Rotatable Central Composite Design pH and biomass concentration were optimized. Maximum biosorption capacity 51.53 mg/g, by Langmuir model, comparing favourably with other reports. The fungal biomass was characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and analyzed before and after the biosorption process by different techniques: X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra-High Resolution Transmission Electron Microscopy and Energy Dispersive X-ray (HR-TEM-EDX) and Ultraviolet-Visible Spectrophotometry (UV-vis). The results showed that the fungus applied several mechanisms to remove Ag(I) ions from the solution and that some of them induced the synthesis of AgNPs. This fact could be verified in the synthesis tests from the cell extract in which aqueous suspensions with high concentrations of AgNPs were obtained. These nanoparticles had diameters between 2 and 9 nm and therefore a high potential for their use as biocidal agents. The results indicated that the synthesis of nanoparticles could be an added value to the heavy metal biosorption process.

Valorization of renewable resources to functional oligosaccharides: Recent trends and future prospective.

Lignocellulosic wastes have the ability to be transformed into oligosaccharides and other value-added products. The synthesis of oligosaccharides from renewable sources bestow to growing bioeconomies. Oligosaccharides are synthesized chemically or biologically from agricultural residues. These oligosaccharides are functional food supplements that have a positive impact on humans and livestock. Non-digestible oligosaccharides, refered as prebiotics are beneficial for the colonic microbiota inhabiting the f the digestive system. These microbiota plays a crucial role in stimulating the host immune system and other physiological responses. The commonly known prebiotics, galactooligosaccharides (GOS), xylooligosaccharides (XOS), fructooligosaccharides (FOS), mannanooligosaccharides (MOS), and isomaltooligosaccharides (IOS) are synthesized either through enzymatic or whole cell-mediated approaches using natural or agricultural waste substrates. This review focusses on recent advancements in biological processes, for the synthesis of oligosaccharides using renewable resources (lignocellulosic substrates) for sustainable circular bioeconomy. The work also addresses the limitations associated with the processes and commercialization of the products.

Characterization of the lignocellulosic and sugars composition of different olive leaves cultivars.

Olive leaves are an under valorized residue of olive tree pruning and olive fruit harvesting and that are usually removed by either burning or grinding and scattering them on fields. However, as plant material easily available, they may be used as raw material in biorefineries, or for the industrial manufacture of many diverse products, given their lignocellulosic composition. Like other lignocellulosic biomasses, the composition of olive leaves depends on cultivar and to know it is essential for an adequate use. Therefore, this work tackles a characterization analysis of the lignocellulosic fraction of some olive leaf cultivars, both commercial and wild. In general, the cultivars studied did not show large differences in their quantitative composition, except for the content of ethanolic extractives and cellulose of the commercial and wild cultivars. In addition, the high lignin content (around 15%) is remarkable.

Content of phenolic compounds and mannitol in olive leaves extracts from six Spanish cultivars: Extraction with the Soxhlet method and pressurized liquids.

Olive leaves are considered a promising source of bioactives such as phenolic compounds and mannitol. The extraction of high added value products is an issue of great interest and importance from the point of view of their exploitation. However, the content of these compounds can differ between cultivars and extraction methods. In this work, six olive leaves cultivars, including three wild cultivars, and two extraction processes (an innovative and alternative technique, pressurized liquid extraction, and a conventional Soxhlet extraction) were evaluated and compared towards the selective recovery of bioactive compounds. The wild cultivars showed the highest content of phenolic and flavonoid compounds, being oleuropein the compound present in higher amount. Findings also revealed that the highest mannitol content in the extracts was observed with the commercial cultivars, specifically in Arbequina. It is thus possible to decide which cultivars to use in order to obtain the highest yield of each bioproduct.

Effect of Olive-Pine Bottom Ash on Properties of Geopolymers Based on Metakaolin.

In this research, the feasibility of using bottom ashes generated by the combustion of biomass (olive pruning and pine pruning) as a source of aluminosilicates (OPBA) has been studied, replacing the metakaolin precursor (MK) in different proportions (0, 25, 50, 75, and 100 wt.% substitution) for the synthesis of geopolymers. As alkaline activator an 8 M NaOH solution and a Na2SiO3 have been used. The geopolymers were cured 24 h in a climatic chamber at 60 °C in a water-saturated atmosphere, subsequently demoulded and cured at room temperature for 28 days. The results indicated that the incorporation of OPBA waste, which have 19.7 wt.% of Ca, modifies the characteristics of the products formed after alkaline activation. In general terms, the incorporation of increasing amounts of calcium-rich ashes results in geopolymers with higher bulk density. The compressive strength increases with the addition of up to 50 wt.% of OPBA with respect to the control geopolymers, contributing the composition of the residue to the acquisition of better mechanical behavior. The results indicate the potential use of these OPBA waste as raw material to produce unconventional cements with 28-day curing strengths greater than 10 MPa, and thermal conductivities less than 0.35 W/mK.

Extraction of oleuropein and luteolin-7-O-glucoside from olive leaves: Optimization of technique and operating conditions.

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Valorisation of olive agro-industrial by-products as a source of bioactive compounds.

A large amount of olive-derived biomass is generated yearly in Spain, which could be used as a potential source of bioactive compounds. The present work evaluates the recovery of natural antioxidants from olive tree pruning (OTP) and olive mill leaves (OML). For this purpose, the effect of different solvents on the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity was evaluated. The solvent was found to have a significant effect (p < 0.05) on the TPC, TFC, and the DPPH, ABTS, and FRAP activity, affording similar results for the extracts from the two by-products. The extracts obtained using 50% ethanol showed high TPC (23.85 and 27.54 mg GAE/gdw for OTP and OML, respectively) and TFC (52.82 and 52.39 mg RE/gdw for OTP and OML, respectively). Also, the OTP and OML extracts exhibited notable antioxidant activity as measured by the ABTS method (45.96 and 42.71 mg TE/gdw, respectively). Using pyrolysis-gas chromatography/mass spectrometry, 30 bioactive compounds were detected in both extracts. Additionally, UPLC-DAD-ESI-MS allowed the identification of 15 compounds in the samples. Furthermore, the antioxidant extracts were found to inhibit the growth of several food pathogenic bacteria. This research demonstrates that these by-products from olive grove farming are a good source of antioxidant compounds with antibacterial properties, which have potential applications in the food and pharmaceutical industries.

A model biorefinery for avocado (Persea americana mill.) processing.

This research investigated and evaluated a biorefinery for processing avocado Hass variety into microencapsulated phenolic compounds extract, ethanol, oil and xylitol. Avocado was first characterized for its potential valuable compounds; then, the techno-economic and environmental aspects of the biorefinery were developed and finally the total production costs and potential environmental impact of the proposed biorefinery were investigated. Four scenarios of the biorefinery were evaluated with different extent of mass and energy integration as well as the incorporation of a cogeneration system. Results indicated that the main fatty acid in the pulp of the investigated avocado variety was oleic acid (50.96%) and that this fruit contained significant amount of holocellulose (52.88% and 54.36% in the peel and seed, respectively). Techno-economic and environmental assessment suggested an attractive opportunity for a biorefinery for complete utilization of the avocado fruit as well the importance of the level of integration.

Valorisation of wastewater from two-phase olive oil extraction in fired clay brick production.

Wastewater issued from oil-washing stage (OWW) in the two-phase olive oil extraction method was used to replace fresh water in clay brick manufacture. The extrusion trials were performed with one of the ceramic bodies currently being used in a local brick factory for red facing bricks (RB) production. Fresh water or OWW was added to a final consistency of 2.4 kg/cm(2), the same value as used at industrial scale for this kind of clay mixture. Comparative results of technological properties of facing bricks are presented. Results show that the products obtained with olive oil wastewater are comparable to traditional ones in terms of extrusion performance and technological properties of end products. Even dry-bending strength of the body formed by wastewater improves by 33% compared to fresh water body. In addition, heating requirements can be reduced in the range 2.4-7.3% depending on the final product. This application can alleviate environmental impacts from the olive oil extraction industry and, at the same time, result in economic savings for the brick manufacturing industry.