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Binders are the products that are used to bind, glue or hold the various feed ingredients together in order to maintain pellet integrity. For aqua-culturists, feed manufacturing is an expensive exercise due to the high cost of ingredients along with traditional artificial binders. The use of grain starches as aqua feed binders have advantages which include availability of that binder, nutritional contribution, and minimization of feed cost. A research trial was conducted to test physical properties such as palatability, water stability, dustiness, friability, settling velocity and floatation time of locally available starch i.e. wheat gluten, pea starch and guar gum and to assist their incorporation in on-farm aqua feed. Results revealed that among these three starch, the starch from pea source was proved superior over other two (wheat gluten and guar gum) as all physical quality parameters (dustiness, water stability and friability) revealed better performance of pea starch except pelletability in which guar gum performed best. Although not a single diet proved best in case of flotation time (Tf) and settling velocity (Vset) at varying lengths (6mm, 9mm and 12 mm). This finding indicates the significance of suitable binders for optimal water pollution and sustainable aquaculture. The use of these binders i.e. wheat gluten, pea starch and guar gum in fish feed pellets may also reduce dependence on synthetic binders and minimizes cost.
Aglutinantes são produtos usados para unir, colar ou manter juntos os vários ingredientes da ração, a fim de conservar a integridade do pellet. Para os aquicultores, a fabricação de ração é uma atividade difícil e cara por causa do alto preço dos aglutinantes artificiais tradicionais. O uso de amidos de grãos como aglutinantes de rações aquáticas tem vantagens que incluem acessibilidade, disponibilidade, contribuição nutricional e minimização do custo da ração. Um ensaio de pesquisa foi conduzido para testar propriedades físicas, como palatabilidade, estabilidade em água, pulverulência, friabilidade, velocidade de sedimentação e tempo de flutuação de amido disponível localmente, ou seja, glúten de trigo, amido de ervilha e goma de guar, e para auxiliar sua incorporação em rações aquáticas. Os resultados revelaram que, entre esses três amidos, o amido de ervilha se mostrou superior aos outros dois (glúten de trigo e goma de guar), pois todos os parâmetros de qualidade física (pulverulência, estabilidade da água e friabilidade) obtiveram melhor desempenho, exceto peletabilidade, em que a goma de guar se destacou. Nenhuma dieta se mostrou melhor no caso de tempo de flotação (Tf) e velocidade de sedimentação em comprimentos variados (6 mm, 9 mm e 12 mm). Essa descoberta indica a importância de aglutinantes adequados para a poluição ótima da água e a aquicultura sustentável. O uso desses aglutinantes, ou seja, glúten de trigo, amido de ervilha e goma de guar, em pellets de ração para peixes também pode reduzir a dependência de aglutinantes sintéticos e minimizar o custo.
Assuntos
Amido , Aquicultura , Glutens , Ração Animal/economiaRESUMO
Abstract Binders are the products that are used to bind, glue or hold the various feed ingredients together in order to maintain pellet integrity. For aqua-culturists, feed manufacturing is an expensive exercise due to the high cost of ingredients along with traditional artificial binders. The use of grain starches as aqua feed binders have advantages which include availability of that binder, nutritional contribution, and minimization of feed cost. A research trial was conducted to test physical properties such as palatability, water stability, dustiness, friability, settling velocity and floatation time of locally available starch i.e. wheat gluten, pea starch and guar gum and to assist their incorporation in on-farm aqua feed. Results revealed that among these three starch, the starch from pea source was proved superior over other two (wheat gluten and guar gum) as all physical quality parameters (dustiness, water stability and friability) revealed better performance of pea starch except pelletability in which guar gum performed best. Although not a single diet proved best in case of flotation time (Tf) and settling velocity (Vset) at varying lengths (6mm, 9mm and 12 mm). This finding indicates the significance of suitable binders for optimal water pollution and sustainable aquaculture. The use of these binders i.e. wheat gluten, pea starch and guar gum in fish feed pellets may also reduce dependence on synthetic binders and minimizes cost.
Resumo Aglutinantes são produtos usados para unir, colar ou manter juntos os vários ingredientes da ração, a fim de conservar a integridade do pellet. Para os aquicultores, a fabricação de ração é uma atividade difícil e cara por causa do alto preço dos aglutinantes artificiais tradicionais. O uso de amidos de grãos como aglutinantes de rações aquáticas tem vantagens que incluem acessibilidade, disponibilidade, contribuição nutricional e minimização do custo da ração. Um ensaio de pesquisa foi conduzido para testar propriedades físicas, como palatabilidade, estabilidade em água, pulverulência, friabilidade, velocidade de sedimentação e tempo de flutuação de amido disponível localmente, ou seja, glúten de trigo, amido de ervilha e goma de guar, e para auxiliar sua incorporação em rações aquáticas. Os resultados revelaram que, entre esses três amidos, o amido de ervilha se mostrou superior aos outros dois (glúten de trigo e goma de guar), pois todos os parâmetros de qualidade física (pulverulência, estabilidade da água e friabilidade) obtiveram melhor desempenho, exceto peletabilidade, em que a goma de guar se destacou. Nenhuma dieta se mostrou melhor no caso de tempo de flotação (Tf) e velocidade de sedimentação em comprimentos variados (6 mm, 9 mm e 12 mm). Essa descoberta indica a importância de aglutinantes adequados para a poluição ótima da água e a aquicultura sustentável. O uso desses aglutinantes, ou seja, glúten de trigo, amido de ervilha e goma de guar, em pellets de ração para peixes também pode reduzir a dependência de aglutinantes sintéticos e minimizar o custo.
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Hydrogels are three-dimensional structures with specific features that render them useful for biomedical applications, such as tissue engineering scaffolds, drug delivery systems, and wound dressings. In recent years, there has been a significant increase in the search for improved mechanical properties of hydrogels derived from natural products to extend their applications in various fields, and there are different methods to obtain strengthened hydrogels. Cationic guar gum has physicochemical properties that allow it to interact with other polymers and generate hydrogels. This study aimed to develop an ultra-stretchable and self-healing hydrogel, evaluating the influence of adding PolyOX [poly(ethylene oxide)] on the mechanical properties and the interaction with cationic guar gum for potential tissue engineering applications. We found that variations in PolyOX concentrations and pH changes influenced the mechanical properties of cationic guar gum hydrogels. After optimization experiments, we obtained a novel hydrogel, which was semi-crystalline, highly stretchable, and with an extensibility area of approximately 400 cm2, representing a 33-fold increase compared to the hydrogel before being extended. Moreover, the hydrogel presented a recovery of 96.8% after the self-healing process and a viscosity of 153,347 ± 4,662 cP. Therefore, this novel hydrogel exhibited optimal mechanical and chemical properties and could be suitable for a broad range of applications in different fields, such as tissue engineering, drug delivery, or food storage.
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Foam mat drying is a widely used technique for liquid products because it has a number of advantages; however, for an efficient process, the choice of additives and temperatures is extremely important. The objective of this study was to evaluate the effect of additives and drying temperatures on the powders obtained from the blend of tropical red fruits, such as acerola, guava, and pitanga. The foam formulations were prepared by mixing the pulps of the three fruits in equal proportions (1:1:1), all added with 6% albumin and 1% stabilizing agent: E1, gum Arabic; E2, guar gum; E3, gelatin. The combinations were subjected to beating, and subsequently, they were dried in an oven with forced air circulation at four temperatures (50 to 80 °C), with a mat thickness of 0.5 cm. The obtained powders showed low levels of water and water activity and high levels of bioactive compounds, colors with a predominance of yellow, intermediate cohesiveness, poor fluidity, and solubility above 50%. The best temperature for obtaining the powders was 60 °C. The formulation that produced the best results for the production of the tropical red fruit blend powder was the combination of albumin and gelatin.
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Since the number of antibiotic-resistant bacterial infections is growing and cases are getting worse every year, the search for new alternative bactericidal wound dressing treatments is becoming crucial. Within this context, the use of polysaccharides from plants and seeds in innovative biopolymer technologies is of key importance. In this work, bio-nano-composite guar gum/polyvinyl alcohol (PVOH) membranes loaded with aluminum-doped zinc oxide nanoparticles were produced via electrospinning. Citric acid was added to the mixture to increase spinnability. However, depending on the pH, zinc oxide nanoparticles are partially dissociated, decreasing their bactericidal efficiency. Thus, a second successful alkaline thermo-chemical regrowth step was added to the process to treat the obtained fibers. This alkaline thermo-chemical treatment reconstituted both the nanoparticles and their bactericidal properties. The Staphylococcus aureus antibacterial assay results show that the membranes obtained after the alkaline thermo-chemical treatment presented a 57% increase in growth inhibition.
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In this work, we describe the synthesis, the characterization, and the potential application of a pH-responsive guar gum-based hydrogel. The polysaccharide produced permanent hydrogels with improved biocompatibility. In this work, we report the chemical modification of guar gum (with glycidyl methacrylate) and its use, as the main constituent, in obtaining chemically cross-linked hydrogels. The morphology, swelling properties, and cytotoxicity of the resulting materials were studied in-depth. The hydrogels showed to be pH-responsive, and non-toxic being safe to use it as a biomaterial. In addition, we tested the potential of this one as a drug carrier. Herein, we have chosen hydrocortisone (HCS) as a drug model. The mechanism of HCS release changed as a function of pH, owing to different responses in each medium. Our results indicate that the guar gum hydrogels have great potential to be used, with safety, as a drug carrier.
Assuntos
Hidrocortisona , Hidrogéis , Galactanos/química , Hidrogéis/química , Concentração de Íons de Hidrogênio , Mananas , Gomas Vegetais/química , ÁguaRESUMO
Edible coatings are safe, legal, and sensory acceptable for food applications and they can be incorporated as natural additives due to their antimicrobial activity, thickening capacity, nutrient content, and bioactive agents for protecting seafood from physical, chemical, and microbiological damage that affects its shelf-life. This study aimed to evaluate the effect of the guar gum bioactive coating with thyme oil on the quality of tilapia fish fillets for 15 days of storage at 4 °C, as a means to extend shelf-life. pH, moisture, ash, fat, color, thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), microbiological, and sensory examinations were investigated, and the results were analyzed by analysis of variance. The treatments were control (uncoated, UC), GGC (coated with guar gum, GGC), and guar gum combined with thyme oil (GGCTH). Tilapia fillets were stored at 4 °C, the safe temperature for refrigerated storage for 15 days. GGCTH had a slower increase of pH after 15 days of storage in comparison with GGC and UC (p < 0.05). GGC and GGCTH resulted in lower and lowest lightness (L*; p < 0.05) values, lower and lowest redness (a*; p < 0.01) values, and greater and greatest yellowness (b*; p < 0.05) values compared to UC, respectively. UC reduced shear force at 5 (0.37 kgf), 10 (0.32 kgf), and 15 (0.30 kgf) days post-storage in comparison with GGC (0.43, 0.43, and 0.43 kgf) and GGCTH (0.43, 0.44, and 0.44 kgf), respectively. There was less (p < 0.05) deterioration, as well as differences in textural and sensorial variables between uncoated and coated fish fillets. The microbiological analyses demonstrated that there was greater microbial growth in the uncoated fillets than in the coated ones. It was concluded that this bioactive coating with thyme oil retards microbial colonization of fish and reduces degradability of quality variables, therefore, it is a reliable and effective alternative to extend the shelf-life of tilapia fillets.
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The interaction between galactomannans, guar gum (GG) with sodium lauryl ether sulphate (SLES) was demonstrated using conductometric, tensiometric, pyrene probe and 1H NMR analyses. SLES and GG formed aggregates and reduced the surface tension at a critical aggregation concentration. The interaction was attributed to the presence of surfactant ethoxyl (EO) groups, since in conductometric, tensiometry and pyrene probe analyses using the non-ethoxylated form, sodium lauryl sulphate - SLS, no aggregation was observed. The aggregates formed between SLES and GG presented a negative zeta potential indicating that the polymer is surrounded by SLES and according to the dynamic light scattering analysis (DLS), presented a size of approximately 26 nm. The determination of the thermodynamic parameters showed that the aggregation occurs spontaneously and is a driven-enthalpy and entropy process. SLES and GG interaction could be explored to produce formulations with lower concentrations of surfactants, using commonly used thickeners as GG.
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Galactanos/química , Mananas/química , Gomas Vegetais/química , Dodecilsulfato de Sódio/química , Tensoativos/química , Galactose/análogos & derivadosRESUMO
RESUMEN La creciente demanda de productos libres de gluten ha dado lugar al estudio y desarrollo de alimentos que suplan las necesidades de los consumidores. El objetivo de esta investigación fue elaborar productos libres de gluten tipo tallarín y evaluar sus propiedades fisicoquímicas. Para ello, se empleó plátano o yuca como fuentes alternativas a la harina de trigo. Se determinaron sus propiedades fisicoquímicas. Se extrajeron harina y almidones y, a partir de ellas, se evaluaron sus propiedades térmicas, empleando calorimetría de barrido diferencial y termogravimetría. Se formularon y elaboraron productos similares a los tallarines empleando las harinas y se analizaron sus propiedades fisicoquímicas, microbiológicas y sensoriales, usando, como control, un producto comercial de trigo. La yuca presentó mayor humedad que el plátano, lo que está relacionado con su susceptibilidad a la degradación. En el análisis termogravimétrico, los productos de yuca mostraron mayor reducción de peso en la zona de alta volatilidad, asociado a la pérdida de humedad. Las harinas y los almidones de plátano presentaron temperaturas de gelatinización mayores que las registradas para los productos de yuca. La humedad y acidez de los tallarines elaborados presentaron valores dentro de la norma (NTC 1055-2014). En ambos casos, su contenido de cenizas fue superior al fideo comercial. Los tallarines elaborados, se pueden considerar inocuos, con buenos parámetros de aceptación sensorial. Estos resultados constituyen un punto de partida en el estudio y aplicación de fuentes de harinas y almidones no tradicionales, permitiendo la generación de valor agregado a cultivos de importancia en la región.
ABSTRACT The growing demand of free gluten products has shown the necessity to study and develop new products in order to supply the consumer request. The objective of this research was to elaborate gluten-free products similar to noodles and to evaluate their physicochemical properties. Plantain or cassava were employed to replace wheat flour. Physical and chemical properties were determined in plantain and cassava samples. Both, Plantain and Cassava Flour and their starches were extracted. Thermal characteristics of flour and starch were evaluated employing differential scanning calorimetry and thermal gravimetric analysis. Products similar to noodle were formulated and elaborated employing plantain or cassava flour. Noodle physicochemical, microbiological and sensorial characteristics were analyzed, employing a commercial product as a control. Cassava presented higher humidity values than plantain, it is related to their susceptibility to degradation. In thermogravimetric analysis, cassava products shown upper weight reduction in high volatility zone associated to humidity lost. Plantain flours and starches presented gelatinization temperatures higher than registered for cassava products. Both plantain and cassava noodles presented humidity and acidity values according to the legal legislation (NTC 1055-2014). Developed products showed ash content higher than commercial noodles. According to microbiological and sensorial analyses, the plantain and cassava products could be considered innocuous with good consumer acceptation. These results could constitute a starting point in the study and application of different flours and starches from non-traditional sources, which allow to increase the value of crops in the region.
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In this paper, a 400â¯ppm aqueous solution of guar gum polysaccharide was submitted to a turbulent flow regime in order to monitor molecular degradation and drag reduction. Guar gum samples were isolated and analyzed by spectroscopic, thermoanalytical and viscosimetric techniques. The drag reduction promoted by guar gum is compromised as the polysaccharide undergoes degradation. Viscosimetric analysis of guar gum showed a reduction in viscous molecular mass. Mid-infrared spectra and hydrogen nuclear magnetic resonance suggest that mechanical degradation promotes hydrolysis of the glycosidic bond α (1â¯ââ¯6) releasing (d)-galactose owing to the appearance of the carbonyl functional group. Thermal analysis revealed the reduction of the polysaccharide's thermal stability by reduction of the polymer chain. A comprehensive analysis of these combined parameters affords a foundation for the development of more efficient biopolymers in the context of improved drag reduction.
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Fenômenos Químicos , Galactanos/química , Mananas/química , Gomas Vegetais/química , Análise Espectral , Termogravimetria , Biopolímeros/química , Hidrólise , Estrutura Molecular , Peso Molecular , ViscosidadeRESUMO
The use of the high pressure homogenizer has been studied in fruit juices, but researches in model system for application in fruit nectar are scarce. Therefore, it is necessary to evaluate the application of these technologies and how the homogenization pressure (PH) can interfere in the sensorial profile of the samples. To prepare the solutions we used guar gum (0.1%), organic acids (0.3%), and sucrose (10%), which were later homogenized (0-control, 25 and 50 MPa) at 25 â. The rheological behavior and the temporal profile of the samples were evaluated. The model systems presented pseudoplastic behavior without residual tension and were fitted to the Ostwald-de Waele model. The consistency index reduced and the flow behavior index increased with processing. Apparent viscosity also decreased due to homogenization. In the time-intensity sensorial analysis, it was observed that the samples differed among the evaluated parameters, demonstrating that the samples with tartaric acid presented higher intensity for the sour taste. However, for sweetness, no change was observed. In the viscosity attribute, the model systems presented similar temporal profiles. Therefore, it was noted that the homogenization process favored a greater temporal profile of sour taste, making sensory perception more lasting in a model system for fruit nectar.
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Manipulação de Alimentos/métodos , Leite/química , Ácidos , Animais , Galactanos , Concentração de Íons de Hidrogênio , Mananas , Modelos Teóricos , Gomas Vegetais , Pressão , Reologia , Sacarose , Fatores de Tempo , ViscosidadeRESUMO
The adsorption of commercial trypsin (Try) onto epichlorohydrin cross-linked alginate-guar gum matrix has been studied at equilibrium in batch and in fixed bed column. Experiments were conducted to study the effect of ionic strength, temperature and to obtain a thermodynamic characterization of the adsorption process. The resulting adsorption isotherm fitted the Hill equation. Experimental breakthrough curve profiles were compared with the theoretical breakthrough profiles obtained from the mathematical model, bed depth service time. At pH 5.0, 1.0 g hydrated matrix adsorbed 480.0 milligram of Try per gram of dried bed. The desorption process showed 80% of Try recovery in 50 mM phosphate buffer, pH 7.00-500 mM NaCl-20% propylene glycol. The obtained results were applied to an adsorption/washing/desorption process with fresh pancreas homogenate yielded 20% of recovery and 5.7 purification factor of Try. The matrix remained functional until the fifth cycle of repeated batch enzyme adsorption. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018.
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Alginatos/química , Pâncreas/metabolismo , Tripsina/química , Tripsina/metabolismo , Adsorção , Animais , Bovinos , Concentração de Íons de Hidrogênio , TermodinâmicaRESUMO
This work addresses the obtaining and characterization of alginate-guar gum matrix, cross-linked with epichlorohydrin in the presence of different flexible chain polymers: polyvinyl alcohol, polyvinyl pyrrolidine and Pluronic® F68. These matrixes were used for the adsorption of chymotrypsinogen and showed an increasing uptake in presence of the flexible chain polymer in the sense: noneâ¯<â¯Pluronic 68â¯<â¯polyvinyl pyrrolidineâ¯<â¯polyvinyl alcohol. The adsorption process was found to follow a first order kinetics model and was not influenced by the polymer type. It was found that Freundlich model was more suitable for our data. Polyvinyl alcohol and polyvinyl pyrrolidine addition increase the adsorption capacity of the original bed due to an increment in the rigidity of the gel caused by the formation of hydrogen bound between the polysaccharides and synthetics polymers.
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Alginatos/química , Quimotripsinogênio/química , Quimotripsinogênio/isolamento & purificação , Epicloroidrina/química , Galactanos/química , Mananas/química , Gomas Vegetais/química , Adsorção , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Cinética , Fenômenos MecânicosRESUMO
BACKGROUND: Large amounts of honey and liquid whey derived from the dairy industry are produced in Argentina. Honey is exported in bulk and whey is transformed into whey protein concentrates and isolates. The objective of this work was to investigate the effect of pH, composition and storage time on the properties of dried gels with honey, whey proteins and hydrocolloids. RESULTS: Color properties varied according to pH and composition. The fracture stress of dried gels prepared with corn starch was higher than that of gels prepared with guar gum in all conditions assayed. Young's modulus was higher at pH 7 for both compositions and increased with storage time. Rubbery characteristics were found in dried gels with guar gum, while both corn starch and guar gum made the microstructure rougher. Multivariate analysis showed that samples could be grouped by pH. Panelists preferred pH 7 products over acidic ones, and no significant differences in sensory properties were found using either corn starch or guar gum in the formulation. CONCLUSION: The results demonstrated that it is possible to generate a new product, which may open new applications for honey and whey in food formulations. © 2017 Society of Chemical Industry.
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Coloides/química , Aditivos Alimentares/química , Mel/análise , Proteínas do Soro do Leite/química , Soro do Leite/química , Argentina , Géis/química , Amido/químicaRESUMO
The equilibrium isotherms and adsorption kinetics of lysozyme (LZ) on epichlorohydrin (Epi) cross-linked alginate-guar gum (Alg-GG) matrix were studied. Adsorption kinetics followed a pseudo-first-order model while the equilibrium isotherm could be represented by the Freundlich equation. The maximal amount of LZ adsorbed onto this matrix was around 2.4mg per g of hydrated matrix at pH 7.00. The adsorption mechanism was associated to a simple diffusion process with a weak columbic interaction between LZ and the matrix. The presence of NaCl 0.3M induced a total displacement of the LZ from the matrix. Under this condition, the percentage of desorbed protein was 95%. Successive cycles of adsorption-washing-elution were performed and the results showed the reversibility of the process and the usefulness of the method for enzyme purification and separation. A last successful step was carried out for the purification of LZ from egg white as natural source. The model proved to be useful applied as a platform design in the isolation and purification of proteins.
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Alginatos/química , Galactanos/química , Mananas/química , Muramidase/química , Gomas Vegetais/química , Adsorção , Animais , Clara de Ovo/química , Epicloroidrina/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , CinéticaRESUMO
Guar (GG) and locust bean (LBG) galactomannans (GMs) oxidation at C-6 was performed with catalyst TEMPO, in which the reaction progress was monitored by consume of NaOH solution. The products were characterized by spectroscopic analysis, infrared, and (1)H-nuclear magnetic resonance, confirming the presence of aldehydes groups as intermediate of reaction to carboxylic acid. From high performance anion exchange chromatography with pulsed amperometric detection Man/Gal molar ratio was determined and demonstrated a preference to oxidize Man during the reaction on both GMs, following a first order kinetics of oxidation. The comparative macromolecular behavior of native and oxidized GMs was obtained through the analysis by high performance size exclusion chromatography, and the persistence length (Lp) was 6nm and 4nm to native LBG and GG, respectively. A more accessible OH-6 at mannose residue in LBG could be related with a two times faster reaction than GG. The selective oxidation with catalyst TEMPO proved to be efficient to increase the flexibility of the GMs during oxidation. Short reaction time and ß-elimination process were mainly observed to LBG, probably due to a more favorable oxidation access to the polysaccharide main chain.
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Protein-free guar gum (DGG) was oxidized (DGGOX) or sulfated (DGGSU) by insertion of new groups in C-6 (manose) and C-6 (galactose), for DGGOX and DGGSU, respectively. Rats were subjected to anterior cruciate ligament transection (ACLT) of the knee, joint pain recorded using the articular incapacitation test, and the analgesic effect of intraarticular 100µg DGG, DGGOX or DGGSU solutions at days 4-7 was evaluated. Other groups received DGG or saline weekly, from days 7 to 70 and joint damage assessed using histology and biochemistry as the chondroitin sulfate (CS) content of cartilage. The molar mass of CS samples was obtained by comparing their relative electrophoretic mobility to standard CS. DGG but not DGGOX or DGGSU significantly inhibited joint pain. DGG significantly reversed the increase in CS, its reduced electrophoretic mobility, and histological changes following ACLT, as compared to vehicle. Structural integrity accounts for DGG benefits in experimental osteoarthritis.
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Galactanos/química , Galactanos/farmacologia , Mananas/química , Mananas/farmacologia , Osteoartrite/tratamento farmacológico , Gomas Vegetais/química , Gomas Vegetais/farmacologia , Animais , Artralgia/complicações , Artralgia/tratamento farmacológico , Cartilagem Articular/efeitos dos fármacos , Cartilagem Articular/patologia , Modelos Animais de Doenças , Galactanos/uso terapêutico , Masculino , Mananas/uso terapêutico , Osteoartrite/complicações , Osteoartrite/patologia , Oxirredução , Gomas Vegetais/uso terapêutico , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Sulfatos/química , ViscosidadeRESUMO
The adsorption kinetics of chymotrypsin, a pancreatic serine protease, onto an alginate-gum guar matrix cross-linked with epichlorohydrin has been performed using a batch-adsorption technique. The effect of various experimental parameters such as pH, salt presence, contact time and temperature were investigated. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data which shows that the adsorption of the enzyme followed the pseudo-second-order rate expression. The Langmuir, Freundlich and Hill adsorption isotherm models were applied to describe the equilibrium isotherms, and the isotherm constants were determined. It was found that Hill model was more suitable for our data because the isotherm data showed a sigmoidal behavior with the free enzyme concentration increasing in equilibrium. At 8°C and at pH 5.0, 1g hydrate matrix adsorbed about 7mg of chymotrypsin. In the desorption process 80% of the biological activity of chymotrypsin was recovered under the condition of 50mM phosphate buffer, pH 7.00-500mM NaCl. When successive cycles of adsorption/washing/desorption were performed, it was observed that the matrix remained functional until the fourth cycle of repeated batch enzyme adsorption. These results are important in terms of diminishing of cost and waste generation.
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Quimotripsina/química , Quimotripsina/metabolismo , Galactanos/química , Galactanos/metabolismo , Mananas/química , Mananas/metabolismo , Gomas Vegetais/química , Gomas Vegetais/metabolismo , Adsorção , Cinética , TermodinâmicaRESUMO
The effect of xanthan gum, guar gum, oil and the structure promoted by these compounds on the growth of Zygosaccharomyces bailii and on physical stability of emulsified systems simulating acid sauces was studied. Furthermore, the effect of yeast growth on physical stability of emulsions was also evaluated. Yeast growth was evaluated by plate count and modeled by the modified Gompertz equation. Emulsions characteristics and their stability were determined by droplet size, zeta potential and rheological measurements. The latter was also used to evaluate structure's effect on yeast growth. Physical characteristics of emulsions depended on system composition. Yeasts slightly affected droplet size. Z. bailii growth was satisfactorily modeled by the modified Gompertz equation. The specific growth rate (µm) and the asymptotic value (A) obtained depended on xanthan gum, guar gum and oil content. Furthermore, the structure promoted by these compounds exerted a significant effect on growth. In general, an increase in the solid character and yield stress through the addition of xanthan gum promoted a decrease in A parameter. On the contrary, a decrease in the solid character through the addition of guar gum promoted an increase in the A parameter. The results obtained stressed that stabilizers, oil and their structuring ability play an important role on Z. bailii growth.
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Screening of biopolymeric gel beads containing Silver NanoParticles (Ag-NPs) stabilized in Guar Gum Alkyl Amine (GGAA) and Ciprofloxacin (Cip) was carried out in order to obtain a novel nanocomposite with controlled release profile of both antimicrobians. The selected matrix composed of Alginate/High Methoxyl Pectin (HMP)/GGAA (4:4:1) was able to co-incorporate Ag-NPs and Cip with encapsulation efficiency higher than 70%. SEM images revealed good cohesivity and compatibility between the biopolymers and the cargos. Beads provided protection against Ag-NPs degradation at acidic pHs and HMP would played a key role providing hydrophobic regions. While Cip release profile showed a pH independent diffusional process, Ag-NPs release was restricted to matrix erodability. Calcium quelating agents and/or alginate degrading enzymes could modulate the release profile. The bactericidal activity of beads was tested in liquid medium, showing cooperative effects between the antimicrobials against Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus and Staphylococcus aureus. TEM images confirmed interaction of Ag-NPs with bacterial surfaces followed by membrane damage. Results suggested the nanocomposite matrix as a promising system for oral treatment of intestinal infectious diseases caused by multidrug resistant and unknown microorganisms, since both Cip and Ag-NPs would be able to reach intestine in the active form.