Pulsed electric field processing as an alternative to sulfites (SO2) for controlling saccharomyces cerevisiae involved in the fermentation of Chardonnay white wine

The use of sulfites (SO2) for microbial control in the winemaking process is currently being questioned due to its potential toxicity. Pulsed Electric Fields (PEF) are capable of inactivating microorganisms at low temperatures, thus avoiding the negative effects of heat on food properties. In this study, the capacity of PEF technology for the decontamination of yeasts involved in the fermentation process of Chardonnay wine from a winery was evaluated. PEF treatments at 15 kV/cm of low (65 µs, 35 kJ/kg) and higher intensity (177 µs 97 kJ/kg) were selected for evaluating the microbial stability, physicochemical and volatile composition of wine. Even with the least intense PEF-treatment, Chardonnay wine remained yeast-free during 4 months of storage without sulfites. PEF-treatments did not affect the wine’s oenological parameters or its aroma during storage. This study, therefore, reveals the potential of PEF technology as an alternative to sulfites for the microbiological stabilization of wine

Defining winery processing conditions for the decontamination of must and wine spoilage microbiota by Pulsed Electric Fields (PEF)

This study investigated the PEF-resistance of Saccharomyces bayanus, Brettanomyces bruxellensis, Lactobacillus plantarum, and Oenococus oeni in must or wine under continuous PEF processing. Results showed the capacity of PEF to achieve 3.0-log10-cycles (CFU/mL) of inactivation of all the microorganisms under moderate conditions (< 155 kJ/kg). Developed tertiary models accurately predicted the effect of PEF parameters on microbial inactivation, and Monte Carlo simulation considered the variability of factors and the maximum assumable microbial load in the final treated product. Results showed that PEF-treatments at 15 kV/cm and 129 or 153 kJ/kg would ensure the adequate decontamination (< 10 CFU/mL) of spoilage microorganism in must or wine, respectively. Industrial relevance: PEF technology has been shown to achieve adequate levels of microbial inactivation (3-log10) in must and wine under industrial applicable processing parameters, making it a suitable alternative to SO2 or sterilizing filtration for microbial control in winemaking. Reductions of 3-log10 CFU/mL of must and wine microbiota were found by continuous flow PEF-processing at 15 to 25 kV/cm and 175 to 148 kJ/kg, parameters applicable at industrial scale at 1 ton/h

Organic-solvent-free extraction of carotenoids from yeast Rhodotorula glutinis by application of ultrasound under pressure

The extraction of Rhodotorula glutinis carotenoids by ultrasound under pressure (manosonication) in an aqueous medium has been demonstrated. The influence of treatment time, pressure, and ultrasound amplitude on R. glutinis inactivation and on the extraction of carotenoids was evaluated, and the obtained data were described mathematically. The extraction yields were lineal functions of those three parameters, whereas inactivation responded to a more complex equation. Under optimum treatment conditions, 82% of carotenoid content was recovered. Extraction of carotenoids in an aqueous medium was attributed to the capacity of ultrasound for cell disruption and emulsification. Cavitation caused the rupture of cell envelopes and the subsequent formation of small droplets of carotenoids surrounded by the phospholipids of the cytoplasmic membrane that would stabilize the emulsion. Analysis of the dispersed particle size of the extracts demonstrated that a fine, homogeneous emulsion was formed after treatment (average size: 230 nm; polydispersity <0.22). This research describes an innovative green process for extracting carotenoids from fresh biomass of R. glutinis in which only two unit operations are required: ultrasonic treatment, followed by a centrifugation step to discard cell debris. The extract obtained thanks to this procedure is rich in carotenoids (25 mg/L) and could be directly incorporated as a pigment in foods, beverages, and diet supplements; it can also be utilized as an ingredient in drugs or cosmetics

Growth trajectories in children with cleft lip and/or palate

Introduction: the nutritional status and growth of children with cleft lip and/or palate (CL/P) can be affected due to feeding difficulties caused by their anatomy and the surgical interventions. Objective: this retrospective longitudinal study aims to analyse the growth trajectories of a cohort of children with CL/P and compare them with a healthy representative cohort of children from Aragon (Spain). Methods: type of cleft, surgical technique and sequelae, and weight, length/height and body mass index (BMI) (weight/height2) at different ages (0-6 years) were recorded. Normalized age- and sex-specific anthropometric Z-scores values were calculated by World Health Organization (WHO) charts. Results: forty-one patients (21 male, 20 female) were finally included: 9.75 % cleft lip (n = 4/41), 41.46 % cleft palate (n = 17/41) and 48.78 % cleft lip and palate (n = 20/41). The worst nutritional status Z-scores were achieved at the age of three months (44.44 % and 50 % had a weight and a BMI lower than -1 Z-score, respectively). Mean weight and BMI Z-scores were both significantly lower than controls at one, three and six months of age, recovering from that moment until the age of one year. Conclusions: the highest nutritional risk in CL/P patients takes place at 3-6 months of age, but nutritional status and growth trajectories get recovered from one year of age compared to their counterparts. Nevertheless, the rate of thin subjects among CL/P patients is higher during childhood

Post-incubation pH Impacts the Lipid Extraction Assisted by Pulsed Electric Fields from Wet Biomass of Auxenochlorella protothecoides

Pulsed electric field (PEF) treatment is a promising technology for efficient lipid extraction from microalgae. This study focusses on under-investigated processing parameters, such as media pH, pulse application, and incubation protocols. The lipid yield and electroporation level of PEF-treated Auxenochlorella protothecoides were determined at a medium pH of 3.0 and 5.0 under variation of the pre- or post-PEF incubation time and for split-dose treatments. Low energetic PEF treatments with 40 kV/cm and 1 μs pulses at 9.6 and 19.2 kJ/L were performed either in batch mode or in continuous flow. Post-PEF incubation significantly increased the shared electroporated cells (>60%) in medium pH 3.0, while no change was observed at pH 5.0. Split-dose PEF treatments at pH 5.0 caused significantly higher electroporation levels and lipid extraction yields than equivalent single-dose treatments. Results have shown that medium pH is critical in the final electroporation and lipid extraction yields of A. protothecoides and therefore should be considered in further studies

Post-incubation pH Impacts the Lipid Extraction Assisted by Pulsed Electric Fields from Wet Biomass of "Auxenochlorella protothecoides"

Pulsed electric field (PEF) treatment is a promising technology for efficient lipid extraction from microalgae. This study focusses on under-investigated processing parameters, such as media pH, pulse application, and incubation protocols. The lipid yield and electroporation level of PEF-treated Auxenochlorella protothecoides were determined at a medium pH of 3.0 and 5.0 under variation of the pre- or post-PEF incubation time and for split-dose treatments. Low energetic PEF treatments with 40 kV/cm and 1 μs pulses at 9.6 and 19.2 kJ/L were performed either in batch mode or in continuous flow. Post-PEF incubation significantly increased the shared electroporated cells (>60%) in medium pH 3.0, while no change was observed at pH 5.0. Split-dose PEF treatments at pH 5.0 caused significantly higher electroporation levels and lipid extraction yields than equivalent single-dose treatments. Results have shown that medium pH is critical in the final electroporation and lipid extraction yields of A. protothecoides and therefore should be considered in further studies

Microbial Decontamination by Pulsed Electric Fields (PEF) in Winemaking

Pulsed Electric Fields (PEF) is a non-thermal technique that causes electroporation of cell membranes by applying very short pulses (μs) of a high-intensity electric field (kV/cm). Irreversible electroporation leads to the formation of permanent conductive channels in the cytoplasmic membrane of cells, resulting in the loss of cell viability. This effect is achieved with low energy requirements and minimal deterioration of quality. This chapter reviews the studies hitherto conducted to evaluate the potential of PEF as a technology for microbial decontamination in the winemaking process for reducing or replacing the use of SO2, for guaranteeing reproducible fermentations or for wine stabilization

Síntesis asimétrica de compuestos de interés biológico

En este trabajo fin de grado se ha llevado a cabo la síntesis de ácidos β-aminofosfónicos protegidos utilizando como reacción clave la adición de litiometilfosfonatos a nitronas cíclicas polisustituidas. Como sustratos de dicha reacción se escogieron diversas nitronas con diferentes sustituciones y estereoquímicas en los sustituyentes. La preparación de dichas nitronas cíclicas se llevó a cabo a partir de derivados comerciales de fuentes naturales. Posteriormente, se estudió la reacción de adición y se elaboraron los correspondientes aductos para obtener los ácidos β-aminofosfónicos protegidos

Synergetic effect of combining PEF treatments with sublethal doses of SO2 on the inactivation of Saccharomyces bayanus and Brettanomyces bruxellensis in red wine

Certain microorganisms are capable of proliferating in wine despite its low pH and high ethanol content. The yeasts of the Saccharomyces genus responsible for alcoholic fermentation can alter wines with residual sugars; the proliferation of Brettanomyces bruxellensis brings about thoroughly unpleasant sensory changes. The main strategy currently applied in wineries for microbial control is the addition of sulfites (SO2). However, sulfites are being researched due to the symptoms they can cause in allergic individuals. Pulsed electric field (PEF) technology has the capability of inactivating vegetative cells of microorganisms at non-lethal temperatures and could thus prove to be an alternative to SO2. In this study, the resistance of Saccharomyces bayanus and B. bruxellensis suspended in wine to a series of different PEF treatments (10–25 kV/cm; 25–1000 µs; 40–170 kJ/kg) combined with sublethal concentrations of SO2 (10, 25, and 50 ppm) was evaluated. The results showed that even the least intense PEF treatments (10 kV/cm; 115 kJ/kg) inactivated more than 4.0 Log10 cycles in both types of yeasts immediately after treatment. The subsequent incubation of the treated yeasts for 24 h in wine managed to increase inactivation by 3.0 Log10 cycles. The combination of a moderate PEF treatment with sublethal doses of SO2 had a synergistic lethal effect on the two yeasts under study after 24 h of incubation in wine, leading to counts lying below the detection limit (&gt;5.0 Log10 cycles). This synergistic effect was attributed to the existence of a portion of the population that had been sublethally damaged by PEF and in which SO2 could more easily penetrate the cytoplasm. These results demonstrate the capacity of PEF technology for microbial control of spoilage yeasts in wine. PEF could thus represent an alternative with the potential of eliminating or reducing SO2 levels in the winemaking process

Computational mechanistic study of thionation of carbonyl compounds with Lawesson's reagent

The thionation reaction of carbonyl compounds with Lawesson's reagent (LR) has been studied using density functional theory methods and topological analyses. After dissociation of LR, the reaction takes place through a two-step mechanism involving (i) a concerted cycloaddition between one monomer and the carbonyl compound to form a four-membered intermediate and (ii) a cycloreversion leading to the thiocarbonyl derivative and phenyl(thioxo)phosphine oxide. Topological analyses confirmed the concertedness and asynchronicity of the process. The second step is the rate-limiting one, and the whole process resembles the currently accepted mechanism for the lithium salt-free Wittig reaction. No zwitterionic intermediates are formed during the reaction, although stabilizing electrostatic interactions are present in initial stages. Phenyl(thioxo)phosphine oxide formed in the thionation reaction is capable of performing a second thionation, although with energy barriers higher than the first one. The driving force of the thionation reactions is the formation of trimers from the resulting monomers. In agreement with experimental observations, the amides are the most reactive when compared with esters, aldehydes, and ketones and the reaction is slightly influenced by the polarity of the solvent. Whereas for amides and esters substituents have little effect, aldehydes and ketones are influenced by both steric and electronic effects.This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) (Project CTQ2013-44367-C2-1-P), by the Fondos Europeos para el Desarrollo Regional (FEDER), and by the Gobierno de Aragon (Zaragoza, Spain, Bioorganic Chemistry Group, E-10). M.A.C. thanks the University of Catania for partial financial support.Peer Reviewe