Influence of different types of bacterial nanocellulose on development of oil-in-water Pickering emulsions

Bacterial nanocelluloses have been studied to stabilize oil-in-water emulsions due to its ability to adsorb on the oil-water interface, promoting highly stable and surfactant-free systems. However, several features of the bacterial nanocellulose may influence the resultant emulsion, such as the cellulose nature, size, surface charge, shape and chemical surface. Thus, this work aims to produce sunflower oil-in-water emulsions using bacterial nanocelluloses produced by fermentation of Komagataeibacter xylinus in Hestrin e Schramm (HS) medium and processed by two different treatments: 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO) mediated oxidation for the production of cellulose nanofibrils (CNF) and acid hydrolysis with sulfuric acid for the production of cellulose nanocrystals (CNC). The oxidized bacterial cellulose suspension was further nanofibrillated by high-speed homogenizer that produced the CNF (82 nm diameter and -46.5 mV surface charge). Nanocrystals had an average length of 491 nm, mean diameter of 70 nm and -50.3 mV of surface charge. For each nanocellulose, different o/w ratios were tested, in order to produce stable emulsions. The emulsions were formulated with an oil phase of 10-1% and an aqueous phase of 90-99%, with a nanocellulose concentration 0.5-1%. Different salt concentrations (NaCl) were tested in the aqueous phase (0-50 mM). The emulsion stability was evaluated by visual inspection considering that the absence of oil in the emulsion surface represents emulsion stability. Emulsions stabilized by CNC exhibited a mean droplet diameter varying between 1.2 and 2.0 m, with a white color and fluid texture. On the other hand, the emulsions stabilized by CNF formed droplets above 2.0 m with a less fluid texture, which confirmed the influence of the bacterial nanocellulose features on the characteristics of the emulsions formed. The microscopy analysis performed with polarized light demonstrated the presence of fibrils and crystals on the oil-water interface of the droplets. The oil droplets were also analysed by fluorescence microscopy after nile red staining. These results indicated that pickering emulsions composed by CNC and CNF, can be used as a carrier to encapsulate active compounds. Beta-carotene will be incorporated in the oil-in-water emulsions, as an hydrophobic model molecule, and digestibility studies will be performed to assess the beta-carotene bioaccessibility in different formulations.info:eu-repo/semantics/publishedVersio

Bacterial cellulose nanocrystals or nanofibrils as Pickering stabilizers in low-oil emulsions: A comparative study

Supplementary data to this article can be found online at https://doi. org/10.1016/j.foodhyd.2024.110427.This investigation assessed the potential of bacterial cellulose (BC) in two distinct forms, nanocrystals (BC-NC) and oxidized nanofibrils (BC-NF), as stabilizers for low oil-in-water emulsions (1 % v/v). The research explored the impact of ionic strength and BC concentration on the physico-chemical characteristics, stability, and rheological properties of those emulsions. Nanofibrils had diameters ranging from 25 to 146 nm and lengths in the micrometer range, while nanocrystals varied in length from 133 to 870 nm and in diameter from 20 to 60 nm. Both BC-NF and BC-NC exhibited high zeta potential values (>45 mV) and contact angles of 30-31°, indicating stability. Both nanocelluloses were effectively used as stabilizers in Pickering emulsions, namely in low-oil systems, producing small emulsion droplets with sizes between 1.42 and 4.13 m. Further results revealed that ionic strength influenced emulsion stability, with both BC-NF and BC-NC preferentially located on the surfaces of emulsion droplets in the presence of salt, as demonstrated by microscopy images. The presence of BC at the interface contributed to creating a more robust barrier against coalescence and Ostwald ripening, influencing droplet size and rheological properties. Higher BC concentrations (1 %) increased emulsion stability in the absence of salt, while at lower BC concentrations (0.5 %), salt concentration was determinant for the long-term stability of the emulsions. These findings provide valuable insights into the production of Pickering emulsions using nanocelluloses, highlighting the advantages of bio-based nanomaterials for applications in the food industry.The author Ana Isabel Bourbon acknowledges FCT funding, through the individual scientific employment program contract (2020.03447.CEECIND). The authors Morsyleide de Freitas Rosa and Nayra de Oliveira Frederico Pinto acknowledges funding by FCT/CAPES 99999.008530/2014–09.info:eu-repo/semantics/publishedVersio

Inhalation of bacterial cellulose nanofibrils triggers an inflammatory response and changes lung tissue morphology of mice

In view of the growing industrial use of Bacterial cellulose (BC), and taking into account that it might become airborne and be inhaled after industrial processing, assessing its potential pulmonary toxic effects assumes high relevance. In this work, the murine model was used to assess the effects of exposure to respirable BC nanofibrils (nBC), obtained by disintegration of BC produced by Komagataeibacter hansenii. Murine bone marrow-derived macrophages (BMM) were treated with different doses of nBC (0.02 and 0.2 mg/mL, respectively 1 and 10 g of fibrils) in absence or presence of 0.2% Carboxymethyl Cellulose (nBCMC). Furthermore, mice were instilled intratracheally with nBC or nBCMC at different concentrations and at different time-points and analyzed up to 6 months after treatments. Microcrystaline Avicel-plus® CM 2159, a plant-derived cellulose, was used for comparison. Markers of cellular damage (lactate dehydrogenase release and total protein) and oxidative stress (hydrogen peroxidase, reduced glutathione, lipid peroxidation and glutathione peroxidase activity) as well presence of inflammatory cells were evaluated in brochoalveolar lavage (BAL) fluids. Histological analysis of lungs, heart and liver tissues was also performed. BAL analysis showed that exposure to nBCMC or CMC did not induce major alterations in the assessed markers of cell damage, oxidative stress or inflammatory cell numbers in BAL fluid over time, even following cumulative treatments. Avicel-plus® CM 2159 significantly increased LDH release, detected 3 months after 4 weekly administrations. However, histological results revealed a chronic inflammatory response and tissue alterations, being hypertrophy of pulmonary arteries (observed 3 months after nBCMC treatment) of particular concern. These histological alterations remained after 6 months in animals treated with nBC, possibly due to foreign body reaction and the organisms inability to remove the fibers. Overall, despite being a safe and biocompatible biomaterial, BC-derived nanofibrils inhalation may lead to lung pathology and pose significant health risks.The authors acknowledge Embrapa Tropical Agroindustry and Coordination for the Improvement of Higher Education Personnel (CAPES) and the project under the bilateral program FCT/CAPES: Bacterial Cellulose: a platform for the development of bionanoproducts for funding this research. This work was also financially supported by: European Investment Funds by FEDER/COMPETE/POCI - Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958, National Funds by FCT - Portuguese Foundation for Science and Technology, Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy - LEPABE funded by FEDER, funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) - and by national funds through FCT. Rui Gil da Costa is supported by grant nº SFRH/BPD/85462/2012 from FCT, financed by the Portuguese Government and the Social European Fund. This study was supported by the Portuguese Foundation for Science and Technology (FCT) also under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Bacterial cellulose nanofiber-based films incorporating gelatin hydrolysate from tilapia skin: production, characterization and cytotoxicity assessment

In this work, films based on bacterial cellulose nanofibers (BCNFs) incorporating gelatin hydrolysate (GH) from tilapia skin were produced. The effect of plasticizer (sorbitol or glycerol) and GH incorporation was evaluated on the physicalchemical and optical properties of films. BCNFs were produced using bacterial cellulose obtained from Hestrin and Schramm (HS) medium (BCNF-HS) or cashew apple juice (BCNF-CM), which was studied as an alternative to HS. Films with sorbitol showed the best properties and were selected for further characterization, using 40% (w/w) of BCNF-HS, 40% (w/w) of GH and 20% (w/w) of sorbitol (BCNF-HS-S-GH films). These films exhibited an antioxidant activity of 7.8 µmols Trolox Eq/g film, a water vapor permeability (WVP) of 1.6 g.mm/kPa.h.m2 and an Youngs modulus of 0.57 GPa. Films produced with BCNFs obtained from cashew apple juice revealed enhanced tensile strength, elongation at break, and thermal stability. Caco-2 cells viability after incubation with BCNF-based films incorporating GH was evaluated and showed non-cytotoxicity, reinforcing the safety of the developed materials and their potential use in food applications.The authors would like to thank: Foundation of Support to the Scientific and Technological Development (FUNCAP, Brazil), Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil), National Counsel of Technological and Scientific Development (CNPq, Brazil), Minho University (Braga, Portugal) and International Iberian Nanotechnology Laboratory (Braga, Portugal). This work was funded by research projects CNPq n 485465/2012-4, CNPq n 310368/2012-0 and CNPq n 476978/2013-0. Funding from Fundac¸a ˜o para a Cie ˆncia e Tecnologia through the project ‘‘Bacterial Cellulose: a platform for the development of bionanoproducts’’, under the bilateral program FCT/CAPES, is acknowledged. The authors acknowledge also the funding from QREN (‘‘Quadro de Referência Estratégica Nacional’’), ADI (‘‘Agência de Inovação’’) through the project Norte-070202-FEDER-038853, and BioTecNorte operation (NORTE01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte. This research was supported by Norte Regional Operational Program 2014–2020 (Norte2020) through the European Regional Development Fund (ERDF) Nanotechnology based functional solutions (NORTE-01-0145FEDER-000019).info:eu-repo/semantics/publishedVersio

Caracterização morfológica de nanocristais de celulose por microscopia de força atômica

RESUMO O isolamento de nanocristais de celulose (CNCs) de fibras vegetais é uma alternativa promissora para sua aplicação como reforço em matrizes poliméricas. A caracterização dos CNCs é fundamental para a confiabilidade da técnica, além de determinar as aplicações possíveis a partir de cada tipo de fibra. A partir da técnica de microscopia de força atômica, um estudo da morfologia e distribuição dos CNCs de semente de manga, vagem de algaroba, pseudocaule da bananeira e fibra do mesocarpo de dendê foi realizado neste trabalho. Os CNCs foram obtidos via reação hidrolítica com ácido sulfúrico em concentrações que variaram de acordo com a fonte da fibra. Os resultados obtidos revelaram dimensões variando de 300 a 500 nm em comprimento e 4 a 16 nm em diâmetro. A apresentação morfológica em forma de agulha demonstrou que o isolamento das fibras de celulose em CNCs foi efetiva. A razão de aspecto associada à formação cilíndrica em agulha dos CNCs isolados evidenciou o alto potencial das fontes de dendê e de vagem de algaroba para o reforço de bionanocompósitos

Cellulose nanocrystals-reinforced core-shell hydrogels for sustained release of fertilizer and water retention

International audienceCore-shell (CS) hydrogels show great potential for the controlled release of fertilizers. In this work, we prepared an alginate-coated gelatin-cellulose nanocrystals (CNCs) hydrogel by a simple layer-by-layer process. CNCs were prepared from cotton linter fibers by the sulfuric acid process. They were incorporated into the gelatin hydrogel, and an external alginate membrane was applied to the inner membrane. Compared to neat gelatin hydrogel, the compressive modulus of the nanocomposite with 5.0 wt% CNCs was enhanced by 288 %. In addition, the CS hydrogel showed a slow-release property and better water retention capacity than neat gelatin hydrogel. The main results of this work are listed below: compression test revealed that the addition of the CNC increases the mechanical properties of the hydrogel, and ii) the addition of a second layer of alginate to CNC-reinforced gelatin hydrogel increase the water retention and improve the sustained release of fertilizer. Our study provides easy and green routes to produce CS hydrogels for potential agricultural applications

Seleção dos indicadores da qualidade das águas superficiais pelo emprego da análise multivariada

Os fatores antrópicos e naturais que determinam a qualidade das águas superficiais na Bacia do Baixo Acaraú foram identificados pelo emprego da técnica de Análise Fatorial/Análise da Componente Principal (AF/ACP). Foram realizadas quatro campanhas no período de fev./2003 a mar./2004, em sete pontos de amostragem localizados ao longo do Rio Acaraú. Foram analisados 25 parâmetros físico-químicos e bacteriológicos. Pelo emprego da AF/ACP, identificou-se que o modelo de melhor ajuste para expressar a qualidade das águas na Bacia do Baixo Acaraú foi aquele composto por quatro fatores, explicando 82,1% da variância total. O primeiro fator representa a componente de sólidos em suspensão, expressando o processo de erosão e escoamento superficial. O segundo fator é definido por uma componente de nutrientes associados aos esgotos sanitários, às áreas agrícolas e a outras fontes de poluição difusa; o terceiro fator é indicativo da ação antrópica (componente orgânica), enquanto o quarto representa os sais solúveis que expressam o processo natural do intemperismo das rochas. Outro ponto observado é que a análise fatorial não resultou em grande redução no número de variáveis, uma vez que o melhor ajuste do modelo ocorreu com a inclusão de 18 das 25 variáveis analisadas

Uso da casca de coco verde como adsorbente na remoção de metais tóxicos The use of green coconut shells as absorbents in the toxic metals

<abstract language="eng">Green coconut shells were treated with acid, base and hydrogen peroxide solutions for 3, 6, 12 and 24 h for removing toxic metals from synthetic wastewater. The removal of ions by the adsorbent treated with 0.1 mol L-1 NaOH/ 3h was 99.5% for Pb2+ and 97.9% for Cu2+. The removal of Cd2+, Ni2+, Zn2+, using adsorbent treated with 1.0 mol L-1 NaOH/3 h, was 98.5, 90.3 and 95.4%, respectively. Particle size, adsorbent concentration and adsorption kinetics were also studied. An adsorbent size of 60-99 mesh and a concentration of 30-40 g/L for 5 min exposure were satisfactory for maximum uptake of Pb2+, Ni2+, Cd2+, Zn2+ and Cu2+ and can be considered as promising parameters for treatment the aqueous effluents contaminated with toxic metals

Edible films from alginate-acerola puree reinforced with cellulose whiskers

Fruit purees, combined or not with polysaccharides, have been used in some studies to elaborate edible films. The present study was conducted to evaluate tensile properties and water vapor barrier of alginate-acerola puree films plasticized with corn syrup, and to study the influence of cellulose whiskers from different origins (cotton fiber or coconut husk fiber, the latter submitted to one- or multi-stage bleaching) on the film properties. The whiskers improved the overall tensile properties (except by elongation) and the water vapor barrier of the films. The films with coconut whiskers, even those submitted only to a one-stage bleaching, presented similar properties to those of films with cotton whiskers, despite the low compatibility between the matrix and the remaining lignin in coconut whiskers. This was probably ascribed to a counterbalancing effect of the higher aspect ratios of the coconut whiskers. (C) 2011 Elsevier Ltd. All rights reserved.CNPqCNPqEmbrapaEmbrap