Rosemary Aparecida de Carvalho

Influência do grau de hidrólise do poli(vinil álcool) nas propriedades físicas de filmes à base de blendas de gelatina e poli(vinil álcool) plastificados com glicerol

The aim of this work was to study the effect of the Degree of Hydrolysis (DH) of poly(vinyl alcohol) (PVA) on the properties of films based on blends of pigskin gelatin and PVA with two DH. The films were made with solutions with 2 g macromolecules/100 g solution, containing 23.1 g PVA.100 g-1 macromolecules and 25 g glycerol/100 g macromolecules. The mechanical and thermal properties, color, opacity, moisture and solubility of the films were studied, as well as Fourier Transform Infrared (FTIR) spectra. The solutions were analyzed by dynamic rheometry. The films containing PVA with lower DH were more hygroscopic and more soluble. However, the type of PVA did not affect color, but affected the opacity and the gloss of the films. The PVA of higher DH produced films which were more resistant to puncture and stress, and the PVA of lower DH produced films which were more deformable upon stress, although less deformable upon puncture. The DH of PVA did not affect the first scan glass transition temperature of the films, but did affect this property in the second scan. The results from the FTIR analysis were in conformity with the results of the thermal analysis. The viscoelastic properties of the solutions determined by rheometry were not affected by the DH of PVA, possibly because the solutions studied were diluted.

Properties of active gelatin films incorporated with rutin-loaded nanoemulsions

Physico-chemical, mechanical, barrier, release profiles and antioxidant properties of composite gelatin based-films incorporated with rutin-loaded oil-in-water nanoemulsion, at various concentrations (5, 10, 15, or 20% (based on the weight of the gelatin powder)) were studied. All the gelatin/rutin-loaded nanoemulsion films displayed higher tensile strength and higher elongation at break than the gelatin control film. The composite films did not show significant differences in thickness, color, brightness and transparency. The structural properties evaluated by FTIR showed that the rutin-loaded nanoemulsion achieved complete miscibility within the gelatin matrix. All the gelatin/nanoemulsion films exhibited compact and homogenous microstructure. In addition, these films showed high antioxidant activities monitored by DPPH radical scavenging and reducing power activities. The Korsmeyer-Peppas model described well the rutin release profile. Rutin release was mainly governed by Fickian diffusion with simultaneous interfering swelling and disintegration phenomena. These results indicate that nanoemulsions-in-gelatin systems can function as potential active packaging systems to enhance shelf life of food products and then to provide a high-quality products (fresh/safe).

Lecithin, gelatin and hydrolyzed collagen orally disintegrating films: functional properties

Orally disintegrating films (ODFs) can transport natural active compounds such as ethanol extract of propolis (EEP). This paper aimed to investigate the effect of lecithin on different gelatin and hydrolyzed collagen (HC) polymeric matrices with addition of EEP. ODFs were prepared by casting technique and were characterized (color parameters, water content, mechanical properties, microstructure, disintegration time (DT), infrared spectroscopy (FTIR), contact angle (CA), swelling degree and total phenolic content). The mechanical properties were influenced by HC. The microstructure demonstrated increased porosity and roughness in films with EEP, and the addition of lecithin resulted in an increase in the number of pores. Lecithin-gelatin and lecithin-EEP-gelatin interactions were observed by FTIR. The addition of HC and EEP reduced the DT and CA, and HC and lecithin reduced the swelling capacity. However, the swelling capacity was not affected by presence of EEP. The addition of lecithin to gelatin and HC ODFs may improve the incorporation and the oral transport of active compounds such as EEP.

Orally Disintegrating Films Containing Propolis: Properties and Release Profile

The objective of this work was the production and characterization of orally disintegrating films of gelatin and hydrolyzed collagen containing the ethanol extract of propolis. The films were produced by casting with different concentrations of hydrolyzed collagen with and without the extract. The mechanical properties, mucoadhesive properties, swelling degree, in vitro release kinetics, stability of active compounds, Fourier transform infrared spectroscopy (FTIR), and antimicrobial activity of the films were evaluated. The films with the highest concentration of hydrolyzed collagen were less resistant and more elastic, and films containing the extract were more resistant than the control. In addition, the films with the extract showed higher mucoadhesion, which is important for ensuring the release of active compounds in the oral cavity. Generally, all formulations showed a high swelling capacity, which may have contributed to the quick release also demonstrated by the release kinetics model. Interactions between the extract compounds and the polymeric matrix were observed by FTIR spectroscopy, which may have contributed to an improvement in the mechanical properties. Films containing the extract had good stability and effective antimicrobial properties against Staphylococcus aureus, which shows that these films can potentially be used to release active compounds in the oral mucosa.

Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

The aim of this work was to study the effect of the hydrolysis degree (HD) and the concentration (CPVA) of two types of poly (vinyl alcohol) (PVA) and the effect of the type and the concentration of plasticizers on the phase properties of biodegradable films based on blends of gelatin and PVA, using a response-surface methodology. The films were made by casting and the studied properties were their glass (Tg) and melting (Tm) transition temperatures, which were determined by diferential scanning calorimetry (DSC). For the data obtained on the first scan, the fitting of the linear model was statistically significant and predictive only for the second melting temperature. In this case, the most important effect on the second Tm of the first scan was due to the HD of the PVA. In relation to the second scan, the linear model could be fit to Tg data with only two statistically significant parameters. Both the PVA and plasticizer concentrations had an important effect on Tg. Concerning the second Tm of the second scan, the linear model was fit to data with two statistically significant parameters, namely the HD and the plasticizer concentration. But, the most important effect was provoked by the HD of the PVA.

Análise dinâmico-mecânica: aplicações em filmes comestíveis

Edible films are thin materials based on biopolymers and food additives. The aim of this work is a review on the application of dynamic mechanical analysis in edible film technology. After a brief review of the linear visco-elasticity theory, a description of some practical aspects related to dynamic mechanical analysis, such as sample fixation and sample dehydration during analysis and types and modes of tests are presented. Thus, the use of temperature scanning analysis for glass transition and for plasticizer-biopolymer compatibility studies and frequency scanning tests, less common in edible film technology, are critically reviewed.

Characterization of oral disintegrating film of peanut skin extract-Potential route for buccal delivery of phenolic compounds

This paper aimed to develop and characterize oral disintegrating films (ODF) based on gelatin and hydroxypropyl methylcellulose (HPMC) incorporated with peanut skin extract (PSE) as phenolic compounds vehicle. Films were prepared by casting technique varying the polymer ratio (GEL:HPMC 100:0, 25:75, 50:50, 75:25, 0:100) and PSE concentration (20 and 30g/100g film-forming solution). Formulations with high content of gelatin presented insoluble complex possibly due to cross-linking between gelatin and polyphenols. For formulations which gelatin was in a minority or equal concentration of HPMC, the increase in the PSE concentration favored the association of rich phases in gelatin and HPMC. This also increased inter- and intramolecular bonding which led to a more compact matrix and reduction of films elongation and tensile strength around 45%. The HPMC film with PSE (20%) presented tensile strength of 26.63±1.89MPa, elongation of 4.97±0.41%, contact angle of 67.17±0.41° and disintegration time of 17.87±1.77s. In the in vitro release profile, 80% of phenolics were released in 5min, and in accelerated stability test the films retained 60% of the total phenolic compounds. HPMC-based film can be a good alternative to vehicle the active compounds present in peanut skin.

Gelatin/hydroxypropyl methylcellulose matrices — Polymer interactions approach for oral disintegrating films

Oral disintegrating film represents an optimal alternative for delivery system of active compounds. The choice of film-forming polymer is the first step in the development of oral disintegrating films and the knowledge of molecular interactions in this matrix is fundamental to advance in this area. Therefore, this study aimed to characterize gelatin and hydroxypropyl methylcellulose (HPMC) films and their blends as matrices of oral disintegrating films. The films were produced by casting technique and were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, mechanical properties, contact angle, time disintegration and bioadhesive strength. Differential scanning calorimetry showed that enthalpy of fusion and melting temperatures of the blends films were lower than those of the gelatin film, which may be associated with the lack of intra-chain interactions also observed in the Fourier transform infrared spectra. In blends, a less compact cross-section structure was observed in scanning electron microscopy images compared with isolated polymer films. The addition of HPMC increased the elongation, hydrophilicity and in vitro bioadhesive force and decreased in vitro disintegration time, important properties in the development of oral disintegrating films. Although the mixture of the polymers showed no synergistic behavior, this study may contribute to the development of new applications for polymeric matrices in the pharmaceutical industry.

Physical Properties of Gelatin Films Plasticized with Glycerol, Studied by Spectroscopic Methods

The effect of glycerol content on the physical properties of gelatin-based edible films was studied in this work, on the basis of the interactions between the plasticizer and polymeric matrix. In this work, some non-usual techniques were used to characterize edible films. For dielectric measurements and infrared spectroscopy, these films were conditioned in silica gel in order to minimize the water effect. For other analysis, the films were conditioned in NaBr. Infrared spectroscopy showed no apparent changes in the position peaks, suggesting an absence of new interactions between the plasticizer and film matrix. It seems that the plasticizers only occupy some specific regions between the polymeric matrix, increasing their distance, and thus, affecting their mobility, which results in more flexible films. Dielectric constant of the films increased with plasticizer content, and decreased over silica gel conditioning. The polarizability was found to arise mainly from water molecules present in the film. Microwave response was found to be also sensitive to water content in the films, due to plasticizer hydrophilic nature. According to the diffractograms, gelatin films presented essentially an amorphous nature, independently of the glycerol content. The results suggest, therefore, that the glycerol induces no chemical modifications in the films.

Efeito do tratamento térmico e enzimático nas propriedades de filmes de gelatina

The activity of transglutaminase (one crosslinking enzyme) can be affected by the temperature of reaction. Gelatin matrix gel formation depends on the balance between polymer-polymer interactions and a polymer-solvent solution. This balance also depends on the amount and type of thermal treatment to the gelatin solution. The aim of this work is to evaluate the effect of the temperature on the crosslinking reaction using transglutaminase. Mechanical properties, water vapor permeability, water solubility and color/opacity of the films were evaluated. Viscosity of the solutions was also evaluated. Native film (FN), enzymatically modified film (FME) and thermal treated film (FC) were produced. According to the results, the temperature which was used did not significantly change the mechanical properties and the solubility of the films produced using different treatments. Enzymatically modified films at 50 °C showed the lowest water vapor permeability compared to the other temperatures and treatments (FN e FC). Thermal treatment also caused a reduction in the water vapor permeability.