Integration of pulsed electric fields technology in the biorefinery of agri-food wastes and microalgae

2017 - 2018Recently, the idea of valorizing industrial agro-food wastes and microalgal biomass, through an efficient recovery of their major bioactive constituents to be used as ingredients in food, feed, pharmaceutical and cosmetic sectors, is gaining interest, due to the increasing demand of consumers for natural products. However, the extraction of these compounds is problematic, due to the presence of a “physical barrier” (cell wall/membrane) when removing intracellular substances. Pre-treatment stage (thermal, mechanical or enzymatic) to permeabilise cellular tissues and facilitate the diffusion of the intracellular compounds in the external medium are required, together with the use of large amount of organic solvents and long contact times. This lead to high energy consumption, the formation of undesired compounds as well as to the eventual degradation of the target molecules to be recovered. Physical pretreatments operations have been proposed in the last year to overcome these problems and among them Pulsed electric fields (PEF) technology has shown promising results as to obtain mild, sustainable and efficient permeabilisation of cell membranes with respect to conventional cell disintegration methods. PEF consists in exposing biological cells to repetitive short voltage pulses (μs – ms in width) with an electric field strength in the range 0.5 - 50 kV/cm and an energy input up to 150 kJ/kg, mainly depending on cell size and morphology. This technique exploits its potential via the “electroporation” of membranes, which rapidly favors the leakage of valuable compounds from the cells. ... [edited by Author]XXXI cicl

Influence of mechanical comminution of raw materials and PEF treatment on the aqueous extraction of phenolic compounds from artichoke wastes

In this study the combined effect of mechanical comminution and pulsed electric fields (PEF) treatments on both cell disintegration and extractability of phenolic compounds during aqueous extraction from artichoke external bracts, was investigated. Different-sized bract discs were treated with varying PEF conditions, namely 0.5 – 5 kV/cm of electric field strength (E), and 1 - 20 kJ/kg of total specific energy input (WT). The cell disintegration index (Zp) of bract tissues, as well as the total phenolic content (TPC) and antioxidant activity (FRAP) of the extracts, were assessed. The results showed that increasing the comminution process intensity led to greater cell disintegration, resulting in a peak extraction yield of phenolic compounds (17.61 ± 1.24 mgGAE/100g FW) achieved with the smallest sample size. Moreover, the application of PEF treatment further increased the Zp value of the bract tissues in a size-dependent manner. The greater the sample size, the stronger the PEF efficiency. Coherently, under optimized PEF conditions (E = 3 kV/cm, WT = 5 kJ/kg), the extracts exhibited higher TPC (+ 112 – 361%) and FRAP values (+ 83 – 836 %) as compared to the control samples after 120 min of diffusion. The extraction rate of phenolic compounds increased when the comminution degree was increased for both untreated and PEF-treated samples, and this was successfully predicted using Peleg's model. These findings suggest that PEF can be a viable alternative to energy-intensive comminution pretreatment, thus enhancing the extraction of phenolic compounds without requiring finely ground raw material handling

Pectin-based Films for Applications in the Horticultural Sector: a Preliminary Characterization

Plastic containers in the horticulture sector largely rely on plastics of fossil origin. Although these plastics have excellent mechanical properties, resilience towards chemical/microbiological degradation, durability, and affordable price, they have a high environmental impact due to their inherent non-biodegradability. In line with the most recent EU strategies on a trans-sectorial transition to sustainable systems, the horticultural sector is seeking for new materials to produce plant nursery plugs as an alternative to conventional plastics. The present work is a part of the project "BBPlug”, which aims to add value to agri-food industry wastes, reducing plastics and fertilizers in horticulture. Here, we propose a new material made of pectin extracted from citrus peel as a green and biodegradable substrate to produce plant nursery plugs. To this purpose, pectin-based films were fabricated by solvent-casting from film-forming solutions with increasing amounts of glycerol as plasticizer (6.7 – 33.3 gGlycerol/gPectin), microfibrillated cellulose (MFC) as reinforcing agent (2.7 – 8.1 mgMFC/gPectin), and at two different pH values (3.5 and 7.0). Puncture resistance, water solubility, and oxygen-barrier properties of the films were then investigated. Films from formulations at pH = 3.5 exhibited an overall better mechanical behavior over their counterpart at pH = 7. The best puncture resistance and water solubility were displayed by films from the least glycerol-loaded formulations. The addition of MFC to the film-forming solution improved the oxygen-barrier properties of the films but led to a reduction in their water solubility. In other tests, a selection of different plant growth-promoting (PGP) bacteria was demonstrated to have a boosting effect on the development of a model vegetable (i.e., lettuce), thus offering creative opportunities for the advancement of the “BBPlug” project

Effect of Dietary Fiber and Thermal Conditions on Rice Bran Wax-Based Structured Edible Oils

In this work, extra-virgin olive oil (EVO)- and sunflower oil (SFO)-based oleogels were structured using rice bran wax (RBW) at 10% by weight (w/w). Bamboo fiber milled with 40 (BF40), 90 (BF90) and 150 (BF150) µm of average size was added as a structuring agent. The effect of fiber addition and cooling temperature (0, 4, and 25 ◦C) on thermal and structural parameters of achieved gels was assessed by rheological (both in rotational and oscillatory mode), texture, and differential scanning calorimetry tests. Oleogelation modified the rheological behavior of EVO and SFO, thus shifting from a Newtonian trend typical of oils to a pseudoplastic non-Newtonian behavior in gels. Moreover, oleogels behaved as solid-like systems with G’ > G”, regardless of the applied condition. All samples exhibit a thermal-reversible behavior, even though the presence of hysteresis suggests a partial reduction in structural properties under stress. Decreasing in cooling temperature negatively contributed to network formation, despite being partially recovered by low-granulometry fiber addition. The latter dramatically improved either textural, rheological, or stability parameters of gels, as compared with only edible oil-based systems. Finally, wax/gel compatibility affected the crystallization enthalpy and final product stability (gel strength) due to different gelator–gelator and gelator–solvent interactions

Relationship between low Ankle-Brachial Index and rapid renal function decline in patients with atrial fibrillation: A prospective multicentre cohort study

OBJECTIVE: To investigate the relationship between Ankle-Brachial Index (ABI) and renal function progression in patients with atrial fibrillation (AF). DESIGN: Observational prospective multicentre cohort study. SETTING:Atherothrombosis Center of I Clinica Medica of 'Sapienza' University of Rome; Department of Medical and Surgical Sciences of University Magna Græcia of Catanzaro; Atrial Fibrillation Registry for Ankle-Brachial Index Prevalence Assessment-Collaborative Italian Study. PARTICIPANTS: 897 AF patients on treatment with vitamin K antagonists. MAIN OUTCOME MEASURES: The relationship between basal ABI and renal function progression, assessed by the estimated Glomerular Filtration Rate (eGFR) calculated with the CKD-EPI formula at baseline and after 2 years of follow-up. The rapid decline in eGFR, defined as a decline in eGFR >5 mL/min/1.73 m(2)/year, and incident eGFR<60 mL/min/1.73 m(2) were primary and secondary end points, respectively. RESULTS: Mean age was 71.8±9.0 years and 41.8% were women. Low ABI (ie, ≤0.90) was present in 194 (21.6%) patients. Baseline median eGFR was 72.7 mL/min/1.73 m(2), and 28.7% patients had an eGFR60 mL/min/1.73 m(2), 153 (23.9%) had a reduction of the eGFR <60 mL/min/1.73 m(2). ABI ≤0.90 was also an independent predictor for incident eGFR<60 mL/min/1.73 m(2) (HR 1.851, 95% CI 1.205 to 2.845, p=0.005). CONCLUSIONS: In patients with AF, an ABI ≤0.90 is independently associated with a rapid decline in renal function and incident eGFR<60 mL/min/1.73 m(2). ABI measurement may help identify patients with AF at risk of renal function deterioration

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M&gt;70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0&lt;e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level