Multilayer emulsions stabilized by vegetable proteins

There is great interest in the food, cosmetic and pharmaceutical industry in the use of proteins and polysaccharides as natural hydrocolloids to create novel emulsion systems with improved stability and functionality. For example, the electrostatic interaction between proteins and polysaccharides may be used to form oil-in-water (O/W) emulsions with multilayered interfacial membranes around oil droplets or multilayer emulsions. This type of emulsions have been developed using the layer-by-layer (LbL) technique, which consists of direct adsorption of an oppositely charged polyelectrolyte layer (e.g. polysaccharides) on a primary layer of ionic emulsifiers (e.g. proteins). The polymeric structure and electrical charge of proteins make them a special class of compounds very suitable for its utilization in the LbL technique. In recent years, the utilization of proteins as emulsifier in the food and pharmaceutical industry has been turning towards plants as a preferred alternative to animal-based sources. This article reviews the current understanding of the utilization of different vegetable proteins as emulsifier in order to stabilize O/W multilayer emulsions systems. Additionally, it highlights some potential applications of the multilayer emulsion technology in the industry for improving the stability of emulsions to environmental stresses or and for developing controlled or triggered release systems

The production and physicochemical properties of a biosurfactant mixture obtained from Sphingobacterium detergens

The commercial application of a new biosurfactant such as the one produced by Sphingobacterium detergens needs a cost-effective process and knowledge of its properties. In the present study, a specific medium and a downstream process have been developed to enhance biosurfactant production. Optimal concentrations of nutrients in MCA medium were (g/L) the following: KH2PO4, 1; K2HPO4, 2; CO(NH2)2 0.88; CaCl2 0.01; FeSO4·7H2O, 0.01; MgSO4·7H2O 0.5; KCl, 1.0; trace elements 0.05mL. Biosurfactant production in the MCA medium required a bacterial co-metabolism of glucose and an n-alkane. A fed-batch culture with supernatant lyophilization prior to organic extraction produced 466mg/L of organic extract, which represents a 6.9-fold increase in production. The newly obtained biosurfactant was a complex mixture of molecules. The three characterized fractions consisted of the complete fraction and two second-level purification fractions with apolar and polar characteristics. The complete and apolar fractions have been shown to self-aggregate in the form of lamellar liquid crystals at a high concentration and bilayers at lower concentrations. Negatively charged particles were identified, which were neutralized at a low pH with a concomitant increase in size. The pH affected the surface tension of the solutions congruently with phosphate headgroups.We are grateful to J. Caelles of the SAXS-WAXS service at IQAC for technical assistance with SAXS measurements. I. Carrera is acknowledged for experimental help with the physicochemical characterization. Financial support from the Spanish Ministry of Economy and Competitiveness through projects CTQ2007-66244 and CTQ2010- 14897 and Generalitat de Catalunya though Grant 2009SGR1331 is gratefully acknowledged.Peer reviewe

Attitudes and experiences related to the deaths of COVID-19 patients among nursing staff: A qualitative evidence synthesis

Aim To identify and synthesize the experiences and attitudes of nursing staff regarding the deaths of COVID-19 patients. Review Methods A qualitative evidence synthesis was carried out, using Noblit and Hare's meta-ethnographic approach. The review protocol was listed in PROSPERO (CRD42022330928). Studies published from January 2020 to January 2022 that met the criteria were searched in PubMed, Web of Science, Scopus, CINAHL, CUIDEN and PsycInfo. A total of 12 articles were included. Results Thirty-three metaphors emerged, which were grouped into three main themes: Determining factors of care, Feelings about death and Strategies for coping with death. Nurses reported the high emotional toll, the absence of family and the lack of staff, protocol and training as determining factors. Furthermore, staff had doubts about the quality of care that COVID-19 patients received. As coping strategies, nurses developed avoidance behaviours towards COVID-19 patients, selective memories, resilience, and/or leaving the profession. Conclusions The difficulty in providing adequate nursing care and the high number of deaths has increased anxiety and stress among nurses. These factors, alongside their lived experiences of seeing patients suffering, many dying alone without family members, have had psychological repercussions on nursing staff. Implications for the Profession and/or Patient Care The results demonstrate a high emotional toll and doubts surrounding their caregiving role caused by the lack of professional training needed to face a pandemic. This research shows what has been learned for future pandemics and highlights basic components that could provide a foundation for coping interventions for healthcare professionals. Impact What Problem did the Study Address? The challenges posed by COVID-19 patient deaths for nursing staff around the world and also by the pandemic circumstances in which those deaths occurred. What were the Main Findings? The high number of deceased patients who were isolated from family members, communication with family members and doubts surrounding care given during the pandemic have created feelings of fear, stress and anxiety, as well as obsessive thoughts that have changed nursing staff's perception of death due to COVID-19. Where and on whom will the Research have an Impact? Results will be useful for preparing for future pandemics, and for policymakers and health staff in supporting healthcare professionals by creating programmes to help them cope with the emotional toll they have felt after dealing with death in such unprecedented circumstances. Reporting Method The authors have adhered to the PRISMA guidelines and the eMERGe Reporting Guidance. Patient or Public Contribution No patient or public contribution

Biotensioactivos producidos por "Sphingobacterium detergens" sp. nov.: Producción, caracterización y propiedades

[spa] A consecuencia de la elevada versatilidad de sus propiedades, los tensioactivos pueden encontrase en diferentes productos de uso cotidiano, pero su posible toxicidad y falta de degradabilidad hacen que se les considere como agentes contaminantes para el medio ambiente. Por esta razón, en los últimos años, los biotensioactivos (BT) han atraído mucho la atención como una alternativa a los tensioactivos sintetizados químicamente debido principalmente a su alta biode-grabilidad y baja toxicidad. A estas propiedades remarcables se suma su posible producción a partir de materiales de desecho. El objetivo principal de la presente tesis doctoral es la producción de nuevos tensioactivos de origen bacteriano y su caracterización. La cepa 6.2S, aislada de suelos volcánicos e identificada como Sphingobacterium detergens sp. nov., es el primer microorganismo de este género descrito como productor de biotensioactivos. Después de 48 h de cultivo en el medio optimizado MCA se obtienen 466 mg/L de extracto crudo gracias al empleo de diferentes estrategias de cultivo (alimentación y control del pH) junto con la optimización de la extracción, lo que permitió aumentar la producción 7 veces con respecto al medio de crecimiento inicial (S-MSM). S. detergens produce una mezcla de compuestos con actividad superficial, tales como fosfolípidos, lípidos nitrogenados y glicolípidos. La mezcla de biotensioactivos producida por este microorganismo presenta una CAC de 2,05 g/L, una CMC de 4,9 g/L y tiene la capacidad de reducir marcadamente la tensión superficial a valores de 22 mN/m, siendo este valor el más bajo descrito en biotensioactivos. Después de una purificación realizada al extracto orgánico, se obtuvieron las fracciones A y B. La fracción A (40% del extracto orgánico) está formada por una mezcla de fosfolípidos, siendo la fosfatidiletanolamina el más abundante, reduce la tensión superficial a 33 mN/m y presenta una CMC de 0,18 g/L. La fracción B (60% del extracto orgánico) está formada por una mezcla de lípidos nitrogenados, es capaz de reducir la tensión superficial a 23 mN/m, presenta una CAC de 2,7 g/L y una CMC de 6,3 g/L. Además la mezcla de tensioactivos presentó estabilidad térmica, capacidad emulsionante y mayor eficiencia a pH ácido. Un estudio más detallado sobre las propiedades fisicoquímicas de la mezcla de BT, ha indicado que al aumentar la fuerza iónica, la CMC del extracto completo desciende a pH 3, mientras que a pH 7 la CMC no se ve afectada, indicando el carácter aniónico del BT. Además se observó que tanto la fracción completa como la fracción A forman bicapas en solución acuosa, con 5 nm de espesor y con un núcleo hidrofóbico de 1,5 nm, que puede corresponder a cadenas hidrocarbonadas (C14-18) interdigitadas. Por otro lado, el potencial Z es independiente del la concentración del biotensioactivo, obteniéndose un valor promedio de -57±9 mv. A concen-traciones inferiores a 12 g/L, el diámetro de partícula medido del extracto completo y de la fracción B es independiente de la concentración, indicando la presencia de vesículas estables. El pH presenta un efecto sobre el potencial Z y el diámetro de partícula tanto de la fracción completa como de las fracciones A y B. A pHs ácidos (3-1,5) el potencial Z tiende a neutralizarse y el diámetro de partícula a aumentar su tamaño. Finalmente el extracto orgánico producido por S. detergens presentó interesantes propiedades biológicas. La fracción B induce un 83% de hemólisis en hematíes de conejo, mientras que la fracción A un 100% de hemólisis, con una tasa de hemólisis 115 veces superior que la fracción B. La fracción B es mucho menos citotóxica que la fracción A y ambas presentan menor toxicidad que el SDS en fibroblastos y queratinocitos, indicando una baja irritabilidad dérmica. Por último la fracción A (0,2 g/L) y la fracción B (1,5 g/L) inducen la apoptosis en el 44% y en el 75% de las células cancerígenas Caco-2.[eng] As a consequence of their high versatility, surfactants constitute large-scale production chemicals and the demand for them is expected to rise rapidly over the next few years. With the increasing importance of environmental acceptability, biosurfactants (BS) have attracted attention as alternatives to chemically synthesized surfactants, due to their biodegradability, lack of toxicity and availability from waste products. The aim of the present study was the production and characterization of new bacterial biosurfactants. Strain 6.2S, identified as Sphingobacterium detergens, was isolated from soil and was selected on the basis of its capacity to decrease surface tension. After 48 h culture in the optimized medium (MCA-lio) for BS production, 3.8 mg/mL of protein and 400 mg/L crude extract were obtained. With medium MCA, the production was increased six times from initial production. The crude extract obtained strongly reduced surface tension (22mN/m at 10 g/L), producing one of the lowest values recorded for a microorganism-produced surfactant. The BS was thermostable and surface activity improve at low pH. Chromatographic fractioning of the crude BS produced two distinct fractions. Fraction A, a phospholipids mixture, reduce surface tension to 33 mN/m and presented a CMC of 0.18 g/L. Fraction B was a mixture of lipopeptides and at least one glycolipids, reduced surface tension to 23 mN/m. The surface tension-concentration curve showed two plateaux, the first of which can be attributed to a critical aggregation concentration of the biosurfactant with a protein (2.7 g/L) and the second to the true CMC in water (6.3 g/L)

Advances in the research of new biosurfactants and their potential use in the biomedical and pharmaceutical industry

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/32393Biosurfactants (BS) are a structurally diverse group of surface-active substances produced by microorganisms. Interest in BS production has markedly increased during the past decade, although large-scale production has not been possible because of low production yields and high total costs. At present, BS have gained importance in environmental applications, while new applications in the pharmaceutical, biomedical, cosmetic and food industry, with a high added value, are still developing. This article describes classical and new BS producer bacteria together with their new BS applications. With these specialized and costeffective applications, BS can be considered as an interesting option for the near future

Ectopic expression of cytosolic superoxide dismutase and ascorbate peroxidase leads to salt stress tolerance in transgenic plums

To fortify the antioxidant capacity of plum plants, genes encoding cytosolic antioxidants ascorbate peroxidase (cytapx) and Cu/Zn-superoxide dismutase (cytsod) were genetically engineered in these plants. Transgenic plum plants expressing the cytsod and/or cytapx genes in cytosol have been generated under the control of the CaMV35S promoter. High levels of cytsod and cytapx gene transcripts suggested that the transgenes were constitutively and functionally expressed. We examined the potential functions of cytSOD and cytAPX in in vitro plum plants against salt stress (100 mm NaCl). Several transgenic plantlets expressing cytsod and/or cytapx showed an enhanced tolerance to salt stress, mainly lines C5-5 and J8-1 (expressing several copies of sod and apx, respectively). Transformation as well as NaCl treatments influenced the antioxidative metabolism of plum plantlets, including enzymatic and nonenzymatic antioxidants. Transgenic plantlets exhibited higher contents of nonenzymatic antioxidants glutathione and ascorbate than nontransformed control, which correlated with lower accumulation of hydrogen peroxide. Overall, our results suggest that transformation of plum plants with genes encoding antioxidant enzymes enhances the tolerance to salinity.This work was supported by the Spanish Ministry of Economy and Competitiveness (Project CICYT BFU2009-07443) cofinanced by FEDER funds. PDV acknowledges the CSIC and the Spanish Ministry of Economy and Competitiveness for his ‘Ramon y Cajal’ research contract, cofinanced by FEDER funds. GBE and CP thank CSIC for their ‘JAE-pre’ and ‘JAE-doc’ fellowships.Peer reviewe

Effect of Enzymatic Hydrolysis on Solubility and Emulsifying Properties of Lupin Proteins (<i>Lupinus luteus</i>)

Solubility and emulsifying properties are important functional properties associated with proteins. However, many plant proteins have lower techno-functional properties, which limit their functional performance in many formulations. Therefore, the objective of this study was to investigate the effect of protein hydrolysis by commercial enzymes to improve their solubility and emulsifying properties. Lupin protein isolate (LPI) was hydrolyzed by 7 commercial proteases using different E/S ratios and hydrolysis times while the solubility and emulsifying properties were evaluated. The results showed that neutral and alkaline proteases are most efficient in hydrolyzing lupin proteins than acidic proteases. Among the proteases, Protamex® (alkaline protease) showed the highest DH values after 5 h of protein hydrolysis. Meanwhile, protein solubility of LPI hydrolysates was significantly higher (p 0.05) than untreated LPI at all pH analyzed values. Moreover, the emulsifying capacity (EC) of undigested LPI was lower than most of the hydrolysates, except for acidic proteases, while emulsifying stability (ES) was significantly higher (p Lupinus luteus) proteins can be improved by enzymatic hydrolysis using commercial enzymes

Food-grade Pickering stabilizers obtained from a protein-rich lupin cultivar (AluProt-CGNA®): Chemical characterization and emulsifying properties

Pickering stabilizers exhibit unique interfacial properties; however, only limited types of these particles are available for the food industry. Therefore, the main aim of this study was to develop a food-grade Pickering stabilizer using a protein isolate obtained from the protein-rich lupin variety AluProt-CGNA® (LPIA). Lupin protein aggregate particles (LP-APs), obtained from LPIA, were produced through a facile and scalable technology based on heat-induced particle formation. LP-APs with high surface charge and partial wettability were effective for stabilizing O/W emulsions. These emulsions were prepared by using high-speed homogenization with LP-APs dispersions. The creaming index, microstructure and physicochemical properties of Pickering emulsions were investigated. The results showed that LP-APs exhibit great potential to perform as stabilizers for O/W Pickering emulsions (O/W). Additionally, LP-APs exhibited much better interfacial and emulsifying properties than did the unheated LPIA. Heating greatly improved the emulsification performance of protein particles, especially at high concentrations (>3%, w/v). The formed emulsions were highly stable against creaming upon storage over 14 days. These findings are of great importance for the formulation of LP-APs-based emulsions with improved properties (e.g., stable against creaming and coalescence) and will also significantly extend the application of lupin proteins in the food industry. © 2018 Elsevier LtdThis research was supported by CONICYT through FONDECYT project N°11160080 . We acknowledge the Regional Government from La Araucanía Region (Chile) . We also acknowledge the CGNA's lupin Genomic and genetic group for their lupin technical assistance and BIOREN-UFRO. Finally, we would like to thank the researcher Jordi Esquena from the IQAC-CSIC (Barcelona–Spain) for the technical assistance. Appendix APeer reviewe

Utilization of proteins from AluProt‐CGNA (a novel protein‐rich lupin variety) in the development of oil‐in‐water multilayer emulsion systems

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