Ana Silvia Prata

Release properties of chemical and enzymatic crosslinked gelatin-gum Arabic microparticles containing a fluorescent probe plus vetiver essential oil

Oil-containing gelatin-gum Arabic microparticles were prepared by complex coacervation followed by crosslinking with glutaraldehyde or transglutaminase. A fluorescent mixture, khusimyl dansylate (KD) as the fluorescent compound mixed to the vetiver essential oil, was used as oil model. The effect of the type of crosslinking of the coacervated gelatin-gum Arabic membrane, the physical state of microparticles, wet or freeze-dried and the type of release media, aqueous with surfactants, Sodium Dodecyl Sulphate (sds) or Tween 80 (tw) and anhydrous ethanol as organic media on the release rate of the KD from the microparticles, was experimentally investigated. It was shown that the oil was dispersed uniformly throughout the microparticles and the chemical crosslinked microparticles were more resistant to swelling, presenting smaller sizes after hydration. Also the crosslinking effect, transglutaminase or glutaraldehyde, could be confirmed by the integrity of the crosslinked gelatin-gum Arabic microparticles after incubation in the aqueous sds media, compared to complete dissolution of the uncrosslinked microparticles in this media. The cumulative fluorescent KD release from the gelatin-gum Arabic microparticles decreased in the following order of dissolution media: anhydrous ethanol>tw>sds and the wet microparticles have shown a faster KD release than freeze-dried ones. A mathematical model was used to estimate the diffusion coefficient (D). The chemically crosslinked gelatin-gum Arabic microparticles ensured a pronounced retard effect in the KD diffusion, presenting a D varying from 0.02 to 0.6 x 10(-11)cm(2)/s, mainly in an aqueous media, against D varying from 1.05 to 13.9 x 10(-11)cm(2)/s from the enzymatic crosslinked microparticles.

Production of microparticles with gelatin and chitosan

In the past few decades, the textile industry has significantly increased investment in research to develop functional fabrics, with a special focus on those aggregating values. Such fabrics can exploit microparticles inferior to 100 μm, such as those made by complex coacervation in their creation. The antimicrobial properties of chitosan can be attributed to these microparticles. Developing particles with uniform structure and properties would facilitate the control for the eventual release of the core material. Thus, a complex coacervation between gelatin and chitosan was studied, and the optimal conditions were replicated in the encapsulation of limonene. Spherical particles formed had an average diameter (D3,2) of 30 μm and were prepared with 89.7% efficiency. Cross-linking of these microparticles using glutaraldehyde and tripolyphosphate was carried out before spray drying. After drying, microparticles cross-linked with glutaraldehyde were oxidized and clustered and those that were cross-linked with tripolyphosphate resisted drying and presented a high yield.

Encapsulated thyme (Thymus vulgaris) essential oil used as a natural preservative in bakery product

The objective of this work was to design a particle using thyme (Thymus vulgaris) essential oil through complex coacervation. In vitro activity against bacteria and molds of free oil as well as the encapsulated oil was verified and then in situ assay was done. The free thyme oil presented high in vitro activity, with values below 0.50mg/mL for almost all the microorganisms tested. Also, MIC values for the encapsulated oil was lower than for the free oil, probably due to the protective micro-environment promoted by the particle wall. The microparticles applied to cakes samples conferred protection against the volatilization of the encapsulated oil and promoted a minimum shelf life of 30days without the use of synthetic preservatives.

Improving the performance of transglutaminase-crosslinked microparticles for enteric delivery

Various agents for cross-linking have been investigated for stabilizing and controlling the barrier properties of microparticles for enteric applications. Transglutaminase, in addition to being commercially available for human consumption, presents inferior cross-linking action compared to glutaraldehyde. In this study, the intensity of this enzymatic cross-linking was investigated in microparticles obtained by complex coacervation between gelatin and gum Arabic. The effectiveness of cross-linking in these microparticles was evaluated based on swelling, release of a model substance (parika oleoresin: colored and hydrophobic) and gastrointestinal assays. The cross-linked microparticles remained intact under gastric conditions, whereas the uncross-linked microparticles have been dissolved. However, all of the microparticles have been dissolved under intestinal conditions. The amount of oily core that was released decreased as the amount of transglutaminase increased. For the most efficient microparticles (50U/g of protein), the performance was improved by increasing the pH of cross-linking from 4.0 to 6.0, resulting in a release of 17.1% rather than 32.3% of the core material. These results were considerably closer to the 10.3% of core material released by glutaraldehyde-cross-linked microparticles (1mM/g of protein).

Composition and physicochemical properties of two protein fractions of bovine blood serum

O sangue animal de abatedouros representa uma fonte importante de ingrediente alimenticio subutilizado. A producao de sangue bovino no Brasil foi aproximadamente 3,6 x 106 tons em 2005. Alem do desperdicio de uma proteina de boa qualidade, a subutilizacao deste subproduto da industria animal e uma fonte importante de poluicao dos recursos hidricos e do solo. A concentracao de proteina albumina (BSA) e globulina (BSG) bovinas secas em spray ou liofilizadas foi, aproximadamente, 85,0%. O score de aminoacidos (EAAS) foi 72,7%, para BSA liofilizada, e 89,3%, para BSG. As propriedades emulsificantes e espumantes de ambas as fracoes proteicas foram altas, principalmente a pH 5,5. A capacidade emulsificante e espumante foi maior para BSA, no entanto, tanto a estabilidade da emulsao quanto a da espuma formada foram melhores para a BSG. A adicao de NaCl apresentou uma tendencia de reduzir as duas propriedades surfactantes, independentemente do pH. Considerando a solubilidade, a estabilidade ao calor, propriedades emulsificante e espumante, tanto a BSA quanto a BSG deveriam ser consideradas bons ingredientes funcionais para a manufatura de produtos alimenticios. O estudo nao apenas confirmou dados ja reportados na literatura, como tambem explorou novas propriedades, o que amplifica o potencial de aplicacoes do soro de sangue bovino.

Obtenção e caracterização química e nutricional in vitro das proteínas do soro de sangue bovino

The main objective of this work, was the isolation, chemical and nutritional (in vitro) characterization of the two main protein fractions of bovine blood serum. Immediatly after hygienic collection at the slaughter house the blood was coagulated and the cellular fraction separated by centrifugation under appropriate conditions. The globulin (GB) fraction was precipitated from blood serum by 50% saturation with ammonium sulfate. The supernalant was separated by centrifugation and the (NH4)2SO4 saturation elevated to 80%. Under this condition BSA precipitated. Precipitation (recovery) of proteins amounted to 98% of total serum protein, in the two fractions. Both GB and BSA were characterized as to proximate percent composition, mineral, amino acid profiles, essential amino acid score (EAE), protein digestibility, and protein digestibility corrected amino acid scoring (PDCAAS). Protein concentration in both fractions was around 85%. BSA presented high concentrations of lysine, histidine and sulfur amino acids, particulary cistine. The EAE for BSA was 70%, tryptophan being the most limiting amino acid, and for GB the EAE score was 87.8% with isoleucine as the most limiting amino acid. PAGE-SDS and densitometry permitted the fractions characterization as the number of protein bands molecular weight and relative proportions among the various proteins.

Alginate and whey protein based-multilayered particles: production, characterisation and resistance to pH, ionic strength and artificial gastric/intestinal fluid

Abstract Multiple layers of whey protein and sodium alginate were assembled onto gelled alginate microparticles using electrostatic interaction. An experimental design was employed to evaluate the effect of the concentration of both hydrocolloids on the amount of protein that was adsorbed. In the first layer, a higher protein adsorption 32.5% w/w was obtained at pH 3.75. In the multilayered particle, the protein adsorbed reached 64.9% w/w. An analysis of protein solubilisation verified that 22% w/w was solubilised at an acidic pH (pH 2.0). The protein solubilisation increased with ionic strength, reaching 19.5% w/w in the highest NaCl concentration evaluated (200 mM). The particles were partially resistant to gastric conditions, with 30.5% w/w of total nitrogen protein solubilisation occurring after 2 h at pH 2.0; however, they did not resist the artificial intestine conditions, reaching 86.0% w/w of total nitrogen protein solubilisation after 5 h.

Chitosan coated nanostructured lipid carriers (NLCs) for loading Vitamin D: A physical stability study

A nanostructured lipid carrier (NLC) has been developed as a loading system for Vitamin D (VD). The NLCs were obtained by melt-emulsification method and coated with chitosan (CHI) by electrostatic deposition. The lipids used in the formulations were selected in order to provide higher encapsulation efficiency. Thermophysical properties of particles were evaluated by differential scanning calorimetry; particle stability was characterized by size distribution, polydispersity index, zeta-potential and light backscattering. The coating over NLCs was carried out by potentiometric titration with CHI at concentrations of 1.0, 1.5, 2.0 and 2.5% (w/v). Stearic (SA) and oleic acids (OA) were the lipids that showed higher compatibility with VD. The NLC 70(SA):30(OA) was the particle with the lowest polydispersity, size variation and less tendency to physical instability during the storage time. This formulation also presented encapsulation efficiency higher than 98%. In the particles coating, CHI adsorption into the colloidal dispersion provided an initial electrostatic stabilization of the system. A long-term steric barrier was established through further incorporation of CHI. Coated NLCs showed a core-shell structure and a positive zeta-potential (+30 mV), remaining stable for 60 days at 25 °C. During storage time, no expulsion of VD out of the particle was observed.

Obtaining functional powder tea from Brazilian ginseng roots: Effects of freeze and spray drying processes on chemical and nutritional quality, morphological and redispersion properties

In this work, the aqueous extract obtained from Brazilian ginseng (Pfaffia glomerata) roots (BGR), rich in beta-ecdysone and fructooligosaccharides (FOS), was powdered by spray drying and freeze drying techniques aiming to obtain a novel functional food product. The effects of these drying techniques on the chemical and nutritional quality, morphological and redispersion properties of the BGR powders were evaluated. The BGR powders obtained by both spray drying and freeze drying techniques maintained their beta-ecdysone and FOS contents after drying, demonstrating the stability of these functional compounds. It was found that the wettability of the powders obtained by different treatments was affected by the drying technique because freeze-dried particles reached the lower values (66 ± 5 s) while spray-dried particles showed a greater time for dispersion into water (150 ± 25 s). This behavior was mainly associated with differences between powder morphological properties since the freeze-dried particles presented a more porous structure, resulting in a greater water diffusivity into microstructure during the redispersion process. Drying process did not affect the storage stability of powders because the glass transition temperature (Tg) for both samples was approximately 160 °C at a relative humidity of 56%. Thus, both BGR powders presented adequate redispersion properties to constitute a new functional tea or even to be used as a functional ingredient in food products.

Comparison of microparticles produced with combinations of gelatin, chitosan and gum Arabic

The complexation between proteins and/or polysaccharides has been studied during decades and despite the knowledge of how these interactions occur provides a basis for identifying the conditions of microparticle formation, the presence of the oil phase complicates the application of available theory to explain the complexation between polymers. In this work, we identified some parameters which can interfere with this interaction, highlighting the influence of molecular arrangements by modifying the combination of gelatin (GE) and gum Arabic (GA) including the chitosan (CHI), a comparatively stronger polycation, to form particles in the presence or not of an essential oil. The results indicated the influence of the polymeric system in the morphological structure of particles as well as in the capacity of oil retention. The encapsulation of oil was more efficient for systems containing GA, due to the ability of these systems to form complexes. However, GE-GA particles presented as multinucleous while CHI-GA as a mononucleous structure.