New and effective cassava bagasse-modified biochar to adsorb Food Red 17 and Acid Blue 9 dyes in a binary mixture.

A promissory technic for reducing environmental contaminants is the production of biochar from waste reuse and its application for water treatment. This study developed biochar (CWb) and NH4Cl-modified biochar (MCWb) using cassava residues as precursors. CWb and MCWb were characterized and evaluated in removing dyes (Acid Blue 9 and Food Red 17) in a binary system. The adsorbent demonstrated high adsorption capacity at all pH levels studied, showing its versatility regarding this process parameter. The equilibrium of all adsorption experiments was reached in 30 min. The adsorption process conformed to pseudo-first-order kinetics and extended Langmuir isotherm model. The thermodynamic adsorption experiments demonstrated that the adsorption process is physisorption, exhibiting exothermic and spontaneous characteristics. MCWb exhibited highly efficient and selective adsorption behavior towards the anionic dyes, indicating maximum adsorption capacity of 131 and 150 mg g-1 for Food Red 17 and Acid Blue 9, respectively. Besides, MCWb could be reused nine times, maintaining its original adsorption capacity. This study demonstrated an excellent adsorption capability of biochars in removing dyes. In addition, it indicated the recycling of wastes as a precursor of bio composts, a strategy for utilization in water treatment with binary systems. It showed the feasibility of the reuse capacity that indicated that the adsorbent may have many potential applications.

Influence of gelatin type on physicochemical properties of electrospun nanofibers.

This study explores the fabrication of nanofibers using different types of gelatins, including bovine, porcine, and fish gelatins. The gelatins exhibited distinct molecular weights and apparent viscosity values, leading to different entanglement behavior and nanofiber production. The electrospinning technique produced nanofibers with diameters from 47 to 274 nm. The electrospinning process induced conformational changes, reducing the overall crystallinity of the gelatin samples. However, porcine gelatin nanofibers exhibited enhanced molecular ordering. These findings highlight the potential of different gelatin types to produce nanofibers with distinct physicochemical properties. Overall, this study sheds light on the relationship between gelatin properties, electrospinning process conditions, and the resulting nanofiber characteristics, providing insights for tailored applications in various fields.

Chitosan-based nanocapsules by emulsification containing PUFA concentrates from tuna oil.

Chitosan nanocapsules containing polyunsaturated fatty acid (PUFA) concentrates from tuna oil, with EPA + DHA contents around 57% (w w-1), were developed by emulsification process, using different chitosan concentration (1.0%, 1.5%, 2.0%, w v-1) and stirring speed (10,000, 15,000, 20,000 rpm). The effects of these parameters on particle size and zeta potential were evaluated. The physical and oxidative stabilities were used to measure the product quality during storage. Chitosan concentration, stirring speed and its interaction significantly affected (p < 0.05) the particle size. In addition, chitosan concentration significantly affected (p < 0.05) the zeta potential of nanocapsules emulsion. Based on the results of physical and oxidative stabilities, the nanocapsules were stable for 30 days under refrigeration temperature (7 °C), and with 1.5-2% chitosan resulted in improved protection against oil oxidation. The nanocapsules produced with 2% chitosan and 10,000 rpm showed the lowest variations of polydispersity index and nanocapsules size after 30 days of storage (221.8 ± 3.0 nm). These conditions can be considered the most suitable to produce nanocapsules of PUFA concentrates from tuna oil using chitosan as wall material. These nanocapsules showed physical characteristics and oxidative stability, which could enable their application in the food industry, representing an important source of EPA and DHA fatty acids.

Spray-Dried Microcapsules of Cheese Whey and Whey Permeate as a Strategy to Protect Chia Oil from Oxidative Degradation.

Research background: Cheese whey and whey permeate are dairy industry by-products usually sent to effluent treatment or incorrectly disposed in the environment, generating costs for the production of dairy products and environmental problems due to the high organic load. Cheese whey and whey permeate can be reused as wall materials to form chia oil microcapsules, which act as a barrier to prooxidants. This study aims to develop an encapsulation method by spray-drying to protect chia oil using dairy by-products as wall materials. Experimental approach: We evaluated cheese whey, whey permeate and mixtures of m(cheese whey):m(whey permeate)=50, 70 and 80% as encapsulating agents with the spray-drying process. Initially, we characterized the chia oil and encapsulating materials. Chia oil emulsions were prepared using the encapsulating materials and an emulsifier. The stability of the emulsions was evaluated by creaming index, and they were characterized according to size distribution and polydispersity index. Emulsions were encapsulated in a spray dryer with inlet and outlet air temperature at 125 and 105 °C, respectively. After encapsulation, we assessed the oxidative degradation of chia oil over 30 days of storage by determining the peroxide index. Results and conclusions: Emulsions presented creaming index between 51 and 83% in all formulations, and the oxidative stability of microencapsulated chia oil was significantly higher than that of free chia oil after 30 days. Wall material combination affected both encapsulation efficiency and oxidation protection. The cheese whey and whey permeate (8:2) mixture exhibited the highest encapsulation efficiency (70.07%) and ability to protect the chia seed oil. After 30 days, the peroxide value was below the maximum limit considered safe for human consumption. Novelty and scientific contribution: According to these results, dairy by-products can be used for encapsulation of oxidation-sensitive oils. This represents an alternative use for dairy by-products, which otherwise are discarded and can impact the environment due to their high organic load. Our findings suggest that dairy by-products can be effectively used as wall materials to generate value-added products.

Chitosan-based nanofibers for enzyme immobilization.

The widespread application of soluble enzymes in industrial processes is considered restrict due to instability of enzymes outside optimum operating conditions. For instance, enzyme immobilization can overcome this issue. In fact, chitosan-based nanofibers have outstanding properties, which can improve the efficiency in enzyme immobilization and the stability of enzymes over a wide range of operating conditions. These properties include biodegradability, antimicrobial activity, non-toxicity, presence of functional groups (amino and hydroxyl), large surface area to volume ratio, enhanced porosity and mechanical properties, easy separations and reusability. Therefore, the present review explores the advantages and drawbacks concerning the different methods of enzyme immobilization, including adsorption, cross-linking and entrapment. All these strategies have questions that still need to be addressed, such as elucidation of adsorption mechanism (physisorption or chemisorption); effect of cross-linking reaction on intramolecular and intermolecular interactions and the effect of internal and external diffusional limitations on entrapment of enzymes. Moreover, the current review discusses the challenges and prospects regarding the application of chitosan-based nanofibers in enzyme immobilization, towards maximizing catalytic activity and lifetime.

Chitosan-coated sand and its application in a fixed-bed column to remove dyes in simple, binary, and real systems.

Adsorption of tartrazine yellow food dye, in a fixed-bed column, was carried out using a single system, a binary system (in the presence of sunset yellow food dye), and in a real effluent provides from an ice cream industry. Chitosan was used to coat sand particles by the dip-coating technique, and these particles were applied in fixed-bed adsorption. The assays were performed in flow rates of 3 mL min-1 and 5 mL min-1. The best performance was reached at 3 mL min-1. In this flow rate, for single and binary systems, the breakthrough time was 95 min and 65 min, and the maximum capacity of the column was around 595 mg g-1 and 497 mg g-1, respectively. In the assay conducted with the real effluent, the breakthrough time was 10 min, and the maximum adsorption capacity of the column was reduced to 191 mg g-1 for tartrazine dye. The dynamic models of Thomas and Yoon-Nelson were used, and both were suitable to represent the breakthrough curves.

Chitosan hydrogel scaffold modified with carbon nanotubes and its application for food dyes removal in single and binary aqueous systems.

This work developed one promising adsorbent based on chitosan hydrogel scaffold modified with carbon nanotubes, for food dye removal in single and binary aqueous systems. The modified hydrogel scaffold was characterized in relation to the gel strength, swelling degree, surface attributes, and infrared spectrum. Adsorption isotherms were performed using dyes, food red 17 (FdR17) and food blue 1 (FdB1), in single and binary aqueous systems. The experimental data were adjusted to the Langmuir model and the thermodynamic parameters were estimated. The kinetic behavior was evaluated and, desorption studies were performed to verify the reuse capacity of the modified hydrogel scaffold. The results showed that maximum adsorption capacities were of 1508 and 1480 mg g-1 for the single system and of 955 and 902 mg g-1 for the binary system, for FdB1 and FbR17, respectively. The thermodynamic parameters indicated that the adsorption was the spontaneous, exothermic and favorable process. The model that best represented the kinetic data was that of Avrami. In desorption, the adsorbent can be used until four times and maintaining the adsorption capacity of the adsorbent in 71% of the initial capacity.

Production of low molecular weight chitosan by acid and oxidative pathways: Effect on physicochemical properties.

Chitosan-based biomaterials with a low molecular weight (LMW) have been drawn attention due to the promising applications in the pharmaceutical and food fields. For this reason, the aim of this work was to study the effect of two distinct depolymerization pathways on the chitosan physicochemical properties. Chitosan was submitted to depolymerization reaction to obtain chitosan with low molecular weight (LMW), using the oxidative pathway (H2O2) and the acid pathway (HCl). The molecular weight reduction was investigated by kinetic study and chain scission mechanism. Chitosan characterization was performed according to its viscosimetric average molecular weight and deacetylation degree, respectively, through the viscosimetric method and proton nuclear magnetic resonance spectroscopy (1H NMR). The structural integrity was evaluated by Fourier transform infrared (FTIR) and energy dispersive spectroscopy (EDS). The crystalline and thermal properties were investigated, respectively, by X-ray diffraction (XRD) spectroscopy and thermogravimetric (TGA)/ differential thermal (DTA)/ differential scanning calorimetry (DSC) analysis. The water-chitosan interaction study was used to estimate the chitosan solubility. The results pointed out that both pathways resulted in chitosan with low molecular weight (<50 kDa). Moreover, the structural integrity of chitosan polymeric chains was preserved after depolymerization by oxidative pathway, while the acid pathway modified the polymer chain arrangement. Therefore, the chemical pathways resulted in two distinct low molecular weight chitosans, which allows different applications in food science.

Biosorption of glycerol impurities from biodiesel production onto electrospun chitosan-based nanofibers: equilibrium and thermodynamic evaluations.

The increase in biodiesel production has been leading to an excess amount of crude glycerol and, consequently, serious environmental issues. For this reason, electrospun chitosan-based nanofibers (CB-EN), composed by chitosan and poly(ethylene oxide) (PEO), were synthesized to apply in the biosorption of impurities from industrial glycerol. To evaluate the biosorption efficiency, the chitosan-based nanofiber was compared to other chitosan-based biosorbents (chitosan biopolymeric film and chitosan powder). The equilibrium and thermodynamic studies were successfully performed to comprehend the interaction mechanisms through the biosorption of glycerol pigments onto electrospun chitosan-based nanofibers. The temperature effect was evaluated by experimental equilibrium curves. Freundlich and BET models were used to estimate isotherm parameters. Gibbs free energy change, enthalpy change, entropy change, and isosteric heat of biosorption were quantified. The equilibrium curves showed that the highest equilibrium relative adsorption (340.7 g-1) was reached at 60 °C. The BET model was the most suitable to represent the equilibrium behavior. The thermodynamic parameters indicated that the biosorption was spontaneous, exothermic, random, and energetic heterogeneous. Therefore, this work developed a green and efficient alternative to refine industrial glycerol. Graphical abstract Note: This data is mandatory. Please provide.

Adsorption of a textile dye onto piaçava fibers: kinetic, equilibrium, thermodynamics, and application in simulated effluents.

This research was conducted to evaluate the methylene blue dye adsorption by piaçava fibers. The effects of adsorbent amount, pH, kinetics, equilibrium, and thermodynamics were analyzed, as well as the adsorbent performance in the treatment of synthetic textile effluents. The adsorbent characterization was also performed. Experimental kinetic data were fitted with pseudo-first-order, pseudo-second-order, and Elovich models. The equilibrium tests were done at 298, 308, and 318 K, and the models of Freundlich, Langmuir, Redlich-Peterson, and Sips were used. The adsorption was favored using 0.025 g of adsorbent, pH 10, and 318 K. The Elovich model provided better fit to kinetic data. The equilibrium experimental points were well represented by the Sips model. The maximum experimental adsorption capacity of methylene blue dye was 427.3 mg g-1. It was verified a spontaneous, favorable, and endothermic adsorption. Piaçava fiber was a promising low-cost material to be used for color removal in effluents containing methylene blue.

Chitosan-functionalized nanofibers: A comprehensive review on challenges and prospects for food applications.

Chitosan exhibits outstanding properties, which allow a wide range of applications. For this reason, chitosan-based biomaterials have been developed over the years and, among these biomaterials, chitosan-based nanomaterials may significantly change the material properties, which could result in some exceptional features. Indeed, chitosan-based nanofibers have a larger surface area:volume ratio than the bulk materials at macro scale. Moreover, chitosan-based nanofibers could lead to enhanced porosity and mechanical properties, which could also improve surface functionalities, and consequently, the range of applications. However, the diversity in sources of raw materials and the production processes for the development of chitosan might provide distinct physicochemical characteristics. Because the varieties of chitosan have been limited in the most part the nanofibers synthesis, the current review describes an extensive research concerning the development of chitosan-based nanofibers and summarizes the different techniques for the nanofibers production; in addition to point out the effects of chitosan characteristics on the spinnability of the solution. Furthermore, the present review explores some potential studies in relation to the chitosan-based nanofibers applied to food technology, including active food packaging, nanofood carrier and enzyme immobilization.

Product characteristics and quality of bovine blood-enriched dried vegetable paste.

BACKGROUND: The aim of this study was to evaluate a preparation of vegetable paste with bovine blood in order to maximize the protein content using linear programming, and to analyze the product characteristics and quality of bovine blood-enriched vegetable paste dried in a spouted bed. The drying experiments were performed by evaluating the effects of inlet air temperature, paste flow rate and paste solids concentration on the dried product characteristics and quality (functional and nutritional properties). RESULTS: The vegetable paste enriched with bovine blood was a good source of protein (∼0.20 g g(-1) , dry basis), and the linear programming was adequate to select the constituents (carrot, onion, potato, kale, tomato, soybean oil and bovine blood) and optimize their quantities. The drying conditions of bovine blood-enriched vegetable paste in the spouted bed that gave the best product characteristics were an air temperature of 110 °C and a paste flow rate of 600 mL h(-1) with 0.07 g g(-1) solids concentration. CONCLUSION: The addition of bovine blood to vegetable paste by linear programming increased the protein content of the paste and improved its functional properties and digestibility. The powder obtained from the spouted bed drier showed suitable functional and nutritional properties and was also a good source of antioxidant compounds.