On the Unique Morphology and Elastic Properties of Multi-Jet Electrospun Cashew Gum-Based Fiber Mats.

This study investigates the unique morphology and mechanical properties of multi-jet electrospun cashew gum (CG) when combined with high-molecular-weight polyethylene oxide (PEO) and glycerol. Cashew gum (CG) is a low-cost, non-toxic heteropolysaccharide derived from Anacardium occidentale trees. Initially, the electrospinnability of aqueous solutions of cashew gum alone or in combination with PEO was evaluated. It was found that cashew gum alone was not suitable for electrospinning; thus, adding a small quantity of PEO was needed to create the necessary molecular entanglements for fiber formation. By using a single emitter with a CG:PEO ratio of 85:15, straight and smooth fibers with some defects were obtained. However, additional purification of the cashew gum solution was needed to produce more stable and defect-free straight and smooth fibers. Additionally, the inclusion of glycerol as a plasticizer was required to overcome material fragility. Interestingly, when the optimized formulation was electrospun using multiple simultaneous emitters, thicker aligned fiber bundles were achieved. Furthermore, the resulting oriented fiber mats exhibited unexpectedly high elongation at break under ambient conditions. These findings underscore the potential of this bio-polysaccharide-based formulation for non-direct water contact applications that demand elastic properties.

Bilayer Films of Poly(lactic acid) and Cottonseed Protein for Packaging Applications.

Poly(lactic acid) (PLA) is a common biobased film-former made from renewable biomass, such as polysaccharides from sugarcane, corn, or cassava. It has good physical properties but is relatively expensive when compared to the plastics used for food packaging. In this work, bilayer films were designed, incorporating a PLA layer and a layer of washed cottonseed meal (CSM), an inexpensive agro-based raw material from cotton manufacturing, where the main component is cottonseed protein. These bilayer films were made through the solvent casting method. The combined thickness of the PLA/CSM bilayer film was between 47 and 83 µm. The thickness of the PLA layer in this film was 10%, 30%, or 50% of the total bilayer film's thickness. Mechanical properties of the films, opacity, water vapor permeation, and thermal properties were evaluated. Since PLA and CSM are both agro-based, sustainable, and biodegradable, the bilayer film may be used as an eco-friendlier food packaging material, which helps reduce the environmental problems of plastic waste and microplastics. Moreover, the utilization of cottonseed meal may add value to this cotton byproduct and provide a potential economic benefit to cotton farmers.

Synthesis and Characterization of Hydrophobically Modified Xylans.

Xylan is a major type of hemicellulose that has attracted a lot of research and development activities. It is often derivatized in order to improve its properties. In the literature, hydrophobic modification of polymers is often used to produce surfactant-like materials and associative thickeners. In this work, we have derivatized xylan with alkyl ketene dimer (AKD) and two types of alkenyl succinic anhydrides (ASAs). The xylan-AKD derivatives have been made at 90 °C, using dimethyl sulfoxide as solvent and 4-dimethylaminopyridine as promoter. Samples with degrees of substitution (DS) up to 0.006 have been produced. The xylan-ASA derivatives have been synthesized at 120 °C in dimethyl sulfoxide with DS up to 0.105-0.135. The structures of these products have been confirmed with NMR and FT-IR. These xylan derivatives increase the structural diversity of xylan and provide additional options for people seeking to use hydrophobically modified polysaccharides in their applications.

Hydrophobic Modification of Cashew Gum with Alkenyl Succinic Anhydride.

Cashew gum (CG) shows promise of being useful as an agro-based raw material for the production of eco-friendly and biodegradable polymers. In this work, we modified this water-soluble polymer with alkenyl succinic anhydride in order to attach a hydrophobic group to it. The modification used two reagents: octenyl succinic anhydride and tetrapropenyl succinic anhydride. Reactions were conducted at 120 °C using dimethyl sulfoxide as a solvent, with conversions better than 88%. Samples with degrees of substitution (DS) between 0.02 and 0.20 were made. The resulting polymers were characterized using 1H NMR, 13C NMR, FTIR, TGA, and GPC. The addition of the hydrophobe decreased the affinity of cashew gum for water absorption. Hydrophobically modified polysaccharides are often used as polymeric emulsifiers, thickeners, and compatibilizers; we anticipate that these new hydrophobically modified CGs may be used for the same applications.

Electrochemical immunosensors for Salmonella detection in food.

Pathogen detection is a critical point for the identification and the prevention of problems related to food safety. Failures at detecting contaminations in food may cause outbreaks with drastic consequences to public health. In spite of the real need for obtaining analytical results in the shortest time possible, conventional methods may take several days to produce a diagnosis. Salmonella spp. is the major cause of foodborne diseases worldwide and its absence is a requirement of the health authorities. Biosensors are bioelectronic devices, comprising bioreceptor molecules and transducer elements, able to detect analytes (chemical and/or biological species) rapidly and quantitatively. Electrochemical immunosensors use antibody molecules as bioreceptors and an electrochemical transducer. These devices have been widely used for pathogen detection at low cost. There are four main techniques for electrochemical immunosensors: amperometric, impedimetric, conductometric, and potentiometric. Almost all types of immunosensors are applicable to Salmonella detection. This article reviews the developments and the applications of electrochemical immunosensors for Salmonella detection, particularly the advantages of each specific technique. Immunosensors serve as exciting alternatives to conventional methods, allowing "real-time" and multiple analyses that are essential characteristics for pathogen detection and much desired in health and safety control in the food industry.

Practical use of immobilized lysozyme for the remediation process of Escherichia coli in aqueous solution

The lysozyme enzyme was immobilized on vitreous surface (fragments with diameters of 0.3 and 1.0 mm) for remediation of the microorganism Escherichia coli JM 109 into fresh water and saline solutions with 0.9 percent NaCl (w/v). Characterization of enzymatic film was carried out by infrared spectroscopy and atomic force microscopy techniques. Bactericide activity of the enzyme was evaluated by spectrophotometric analysis. It was verified that the enzymatic film was strongly coupled with the vitreous surface. The topographic analysis demonstrated that the deposited film was uniform and homogeneous. It was observed bactericide activity of film deposited on vitreous surface with 0.3 mm in fresh and saline solutions. This fact was not verified to vitreous fragments with 1.0 mm of diameter.

Atividade larvicida de óleos essenciais contra Aedes aegypti L. (Diptera: Culicidae) / Larvicidal activity of essential oils against Aedes aegypti L. (Diptera: Culicidae)

Na busca por controle químico alternativo contra Aedes aegypti L., muitas pesquisas são desenvolvidas e estimuladas no intuito de se descobrirem novas substâncias inseticidas de origem vegetal. Neste trabalho, o efeito larvicida de dez óleos essenciais foi avaliado contra A. aegypti. Os óleos foram obtidos por arraste a vapor e sua composição química foi determinada por cromatografia gasosa acoplada a espectrometria de massa. Os óleos essenciais foram diluídos em solução aquosa de dimetil sufóxido nas concentrações: 100, 50, 10 e 1 mg/ml. A atividade larvicida, baseada na percentagem de larvas mortas, foi avaliada 24h após o tratamento. O óleo essencial de Vanillosmopsis arborea Baker induziu a maior atividade larvicida, com CL50 de 15,9 mg/ml e CL90 de 28,5 mg/ml., enquanto o de O. gratissimum L. apresentou a menor atividade com CL50 de 95,80 mg/ml e CL90 de 102,86 mg/ml. Os resultados indicam que os óleos essenciais avaliados, principalmente o de V. arborea, são compostos por substâncias com efeito larvicida contra A. aegypti.

In the search for alternative chemical control against Aedes aegypti L., many researches are developed and encouraged in order to find new insecticidal plant substances. In this work, the larvicidal effect of ten essential oils was tested on A. aegypti. The oils were extracted by steam distillation and their chemical composition determined by GL-chromatography coupled with massspectroscopy. The essential oils were diluted in aqueous solutions of dimethyl sulfoxide with concentrations of: 100, 50, 10, and 1 mg/ml. The larvicidal activity, based on the percentage oflarval mortality, was evaluated after 24h exposure to the treatments. The essential oil of Vanillosmopsis arborea Baker presented the highest larvicidal activity, with CL50 of 15.9 mg/ml and CL90 of 28.5 mg/ml. On the other hand the essential oil of O. gratissimum L. showed the lower activity with CL50de 95,80 mg/ml and CL90 de 102,86 mg/ml. The results indicate that the tested essential oils, and particularly the V. arborea, are composed by substances with larvicidal properties for A. aegypti.