Mari Pau Balaguer Grimaldo

Curcumin is a polyphenol with a wide range of biological properties, including antioxidant and antimicrobial activity; however, its use as a food preservative is limited because of its insolubility in water. The present work is an attempt to overcome this problem by means of matrix encapsulation of curcumin in gelatin through electrohydrodynamic atomization (EHDA). Compact spherical gelatin particles ranging from few nanometers to more than 1 μm in diameter loaded with 10% (w/w) curcumin were… Mostrar más

Curcumin is a polyphenol with a wide range of biological properties, including antioxidant and antimicrobial activity; however, its use as a food preservative is limited because of its insolubility in water. The present work is an attempt to overcome this problem by means of matrix encapsulation of curcumin in gelatin through electrohydrodynamic atomization (EHDA). Compact spherical gelatin particles ranging from few nanometers to more than 1 μm in diameter loaded with 10% (w/w) curcumin were successfully obtained, and the encapsulation efficiency being close to 100%. Fluorescence microscopy indicated that the curcumin was homogeneously distributed in the particles, while modulated differential scanning calorimetry analysis showed that the curcumin was intimately mixed with gelatin polymer, and a complete loss of curcumin crystallinity was observed in the solid dispersion. Furthermore, the UV–visible spectrum of dissolved/dispersed particles showed a shift of the maximum absorbance of curcumin toward lower wavelengths, indicating gelatin–curcumin interactions. The water solubility of curcumin increased 38.6-fold after it had been encapsulated in gelatin microparticles. With regard to antioxidant properties, they increased when blended with gelatin compared with commercial curcumin powder. Although antibacterial activity of raw curcumin was negligible at concentrations up to 100 mg/ml, gelatin-encapsulated curcumin at 4 mg/ml reduced the microbial population by 2.08, 1.67, 2.70, and 2.18 log counts (CFU/ml) for L. monocytogenes, S. enterica, S. aureus, and E. coli, respectively. Accordingly, it was proved that encapsulation of curcumin in gelatin particles by EHDA greatly improved its antioxidant and antimicrobial properties, thus broadening its potential use as a food preservative. Mostrar menos

Nanomaterials can provide plastics with great advantages on
mechanical and active properties (i.e. release and capture of specific
substances). Therefore, packaging is expected to become one of the
leading applications for these substances by 2020. There are some
applications already in the market. Nevertheless, there is still some
areas under development. A key issue to be analyzed is the end-of-life of
these materials once they become waste, and specifically… Mostrar más

Nanomaterials can provide plastics with great advantages on
mechanical and active properties (i.e. release and capture of specific
substances). Therefore, packaging is expected to become one of the
leading applications for these substances by 2020. There are some
applications already in the market. Nevertheless, there is still some
areas under development. A key issue to be analyzed is the end-of-life of
these materials once they become waste, and specifically when
nanomaterials are used in biodegradable products.
The present study evaluated the disintegration, biodegradability, and
ecotoxicity of poly(lactic acid) films reinforced with the three
following nanomaterials: (1) montmorillonite modified with an ammonium
quaternary salt, (2) calcium carbonate and (3) silicon dioxide.
Results on disintegration showed that films completely disintegrated into
visually indistinguishable residues after 6-7 weeks of incubation in
composting environment. Moreover, no differences were observed in the
evolution of the bioresidue with respect to color, aspect, and odor in
comparison with the control. It was also observed that nanomaterials did
not significantly reduce the level of biodegradability of PLA (p > 0.05).
In fact, biodegradation was higher, without finding significant
differences (p > 0.05), in all the nano-reinforced samples with respect
to PLA after 130 days in composting (9.4% in PLA+Nano-SiO2; 34.0% in
PLA+Clay1; 48.0% in PLA+Nano-CaCO3). Finally, no significant differences
(p > 0.05) in ecotoxicity in plants were observed as a result of the
incorporation of nanoparticles in the PLA matrix. Mostrar menos

The disintegration, biodegradation and ecotoxicity of cross-linked wheat gliadin films with antimicrobial properties were assessed under controlled composting conditions. Gliadins were chemically modified with different percentages of cinnamaldehyde (1.5%, 3% and 5%) increasing their cross-linking degree and imparting antimicrobial activity. After the films were subjected to simulated conditions of use in a food packaging application, they were composted. The most cross-linked gliadin film… Mostrar más

The disintegration, biodegradation and ecotoxicity of cross-linked wheat gliadin films with antimicrobial properties were assessed under controlled composting conditions. Gliadins were chemically modified with different percentages of cinnamaldehyde (1.5%, 3% and 5%) increasing their cross-linking degree and imparting antimicrobial activity. After the films were subjected to simulated conditions of use in a food packaging application, they were composted. The most cross-linked gliadin film showed a very fast disintegration profile. It completely disintegrated into fine visually indistinguishable residues after 4 days of being inserted in compost medium. Scanning electron microscopy revealed the rapid microbial colonization of the films’ surface. Biodegradation was assessed by measuring the amount of carbon dioxide produced in a static system specifically designed for this study. The cross-linking degree of the proteinaceous matrices modified their biodegradation rate without impairing their complete biodegradation. The presence of residual cinnamaldehyde in the films, which can exert antimicrobial activity, did not hamper their biodegradation neither caused ecotoxicity on tomato seeds germination and plant growth. Mostrar menos

The aim of this work has been to study the effectiveness of gliadin films cross-linked with cinnamaldehyde as systems for the release of the natural antimicrobial compound lysozyme. Prior to the incorporation of lysozyme, the gliadin film-forming solution was treated with different percentages of cinnamaldehyde as cross-linker, and glycerol was added as plasticizer. The effect of the concentration of the cross-linker on the swelling capacity and kinetics of release of the antimicrobial agent… Mostrar más

The aim of this work has been to study the effectiveness of gliadin films cross-linked with cinnamaldehyde as systems for the release of the natural antimicrobial compound lysozyme. Prior to the incorporation of lysozyme, the gliadin film-forming solution was treated with different percentages of cinnamaldehyde as cross-linker, and glycerol was added as plasticizer. The effect of the concentration of the cross-linker on the swelling capacity and kinetics of release of the antimicrobial agent from the protein matrix was evaluated at pH 6.2. The antimicrobial activity of the films was assayed against Listeria innocua. The gliadin films cross-linked with cinnamaldehyde incorporating lysozyme preserved their integrity in water. The release rate of the antimicrobial agent was controlled by the reticulation of the protein matrix, thus a greater degree of cross-linking led to slower release of the active agent. Films with a loosely cross-linked structure released a greater amount of lysozyme, exhibiting greater antimicrobial activity. Mostrar menos

Gliadin films cross-linked with cinnamaldehyde (1.5, 3, and 5%) and incorporated with natamycin (0.5%) were prepared by casting, and their antifungal activity, water resistance, and barrier properties characterized. Incorporation of natamycin gave rise to films with greater water uptake, weight loss and diameter gain, and higher water vapor and oxygen permeabilities. These results may be associated to a looser packing of the protein chains as a consequence of the presence of natamycin. The… Mostrar más

Gliadin films cross-linked with cinnamaldehyde (1.5, 3, and 5%) and incorporated with natamycin (0.5%) were prepared by casting, and their antifungal activity, water resistance, and barrier properties characterized. Incorporation of natamycin gave rise to films with greater water uptake, weight loss and diameter gain, and higher water vapor and oxygen permeabilities. These results may be associated to a looser packing of the protein chains as a consequence of the presence of natamycin. The different cross-linking degree of the matrices influenced the natamycin migration to the agar test media, increasing from 13.3 to 23.7 (μg/g of film) as the percentage of cinnamaldehyde was reduced from 5% to 1.5%. Antifungal activity of films was assayed against common food spoilage fungi (Penicillium species, Alternaria solani, Colletotrichum acutatum). The greatest effectiveness was obtained for films containing natamycin and treated with 5% of cinnamaldehyde. The level of cinnamaldehyde reached in the head-space of the test assay showed a diminishing trend as a function of time, which was in agreement with fungal growth and cinnamaldehyde metabolization. Developed active films were used in the packaging of cheese slices showing promising results for their application in active packaging against food spoilage. Mostrar menos

In this work a new methodology based on thermo-pressing a resin made from gliadins and glycerol has been developed to obtain water resistant films. The effect of processing temperature was studied on the functional properties of the films. The results of SDS-PAGE analysis of the molecular weight profiles of the resulting films were indicative of disulfide/sulfhydryl interchange reactions giving rise to the formation of intermolecular disulfide bonds between the gliadin units. These reactions… Mostrar más

In this work a new methodology based on thermo-pressing a resin made from gliadins and glycerol has been developed to obtain water resistant films. The effect of processing temperature was studied on the functional properties of the films. The results of SDS-PAGE analysis of the molecular weight profiles of the resulting films were indicative of disulfide/sulfhydryl interchange reactions giving rise to the formation of intermolecular disulfide bonds between the gliadin units. These reactions augmented the degree of cross-linking of the matrix, which increased with thermo-pressing temperature, as evidenced by the residual reaction enthalpy values determined by MDSC as well as by cross-link density values determined from tensile tests. In consequence the films produced at high temperature had better water resistance upon immersion, greater maximum tensile strength and Young's modulus values, and lower water vapor and oxygen permeabilities compared with cast films. Based on the analytical test results, thermo-pressing the resin in successive time/force steps along with a temperature of 130 °C produced gliadin films with improved properties. Mostrar menos

Gliadin films incorporating 1.5, 3 and 5% cinnamaldehyde (g/100 g protein) were tested against food-spoilage fungi Penicillium expansum and Aspergillus niger in vitro, and were employed in an active food packaging system for sliced bread and cheese spread. Gliadin films incorporating cinnamaldehyde were highly effective against fungal growth. P. expansum and A. niger were completely inhibited after storage in vitro for 10 days in the presence of films incorporating 3% cinnamaldehyde. Indeed… Mostrar más

Gliadin films incorporating 1.5, 3 and 5% cinnamaldehyde (g/100 g protein) were tested against food-spoilage fungi Penicillium expansum and Aspergillus niger in vitro, and were employed in an active food packaging system for sliced bread and cheese spread. Gliadin films incorporating cinnamaldehyde were highly effective against fungal growth. P. expansum and A. niger were completely inhibited after storage in vitro for 10 days in the presence of films incorporating 3% cinnamaldehyde. Indeed 1.5% cinnamaldehyde was sufficient in the case of P. expansum. The amount of cinnamaldehyde retained in films after storage for 45 days at 20 °C and 0% RH was also sufficient in most cases to prevent fungal growth in vitro. Active food packaging with gliadin films incorporating 5% cinnamaldehyde increased the shelf-life of both sliced bread and cheese spread. Mold growth was observed on sliced bread after 27 days of storage at 23 °C with active packaging, whereas in the control bread packaged without the active film fungal growth appeared around the fourth day. In the cheese spread, no fungi were observed after 26 days of storage at 4 °C when the product was packaged with the active film. However, growth of fungi was observed in control packaged cheese after 16 days of storage. This work demonstrates a noteworthy potential of these novel bioplastics incorporating natural antimicrobial compounds as innovative solutions to be used in active food packaging to extend shelf-life of food products. Mostrar menos

Cinnamaldehyde treatment of gliadin films provided a means of decreasing their solubility, increasing their molecular weight profile, and reducing their overall migration into food simulants as a consequence of the high degree of polymerization achieved. Despite losses incurred in the film manufacturing process, and the amount that remained covalently bonded with protein because of cross-linking, the addition of 1.5, 3, and 5% of cinnamaldehyde (g/100 g protein) to gliadins at pH 2 rendered… Mostrar más

Cinnamaldehyde treatment of gliadin films provided a means of decreasing their solubility, increasing their molecular weight profile, and reducing their overall migration into food simulants as a consequence of the high degree of polymerization achieved. Despite losses incurred in the film manufacturing process, and the amount that remained covalently bonded with protein because of cross-linking, the addition of 1.5, 3, and 5% of cinnamaldehyde (g/100 g protein) to gliadins at pH 2 rendered 1.8, 4.8, and 11.0 mg cinnamaldehyde/g film, respectively, available to be released, and therefore to exert antimicrobial activity. Cinnamaldehyde diffusivity was largely dependent on environmental conditions, increasing from 0.49·10–15 m2/s at 30% RH to 13.1·10–15 m2/s at 90% RH and 23 °C. This water sensitivity of films provides a mechanism with a noteworthy potential to retain the compound before its use, to trigger its release when needed, and to modulate the release rate according to the product humidity. Mostrar menos

The degree of cross-linking of gliadin films was increased by chemical treatment with cinnamaldehyde. The formation of a more reticulated network was able to achieve a simultaneous reduction of water vapor, oxygen, and carbon dioxide permeabilities, enhancing barrier properties by up to 64%, 75%, and 79%, respectively. The evaluation of solubility and diffusivity coefficients involved in water vapor permeation highlights the complexity of the mechanisms implicated in water transport through… Mostrar más

The degree of cross-linking of gliadin films was increased by chemical treatment with cinnamaldehyde. The formation of a more reticulated network was able to achieve a simultaneous reduction of water vapor, oxygen, and carbon dioxide permeabilities, enhancing barrier properties by up to 64%, 75%, and 79%, respectively. The evaluation of solubility and diffusivity coefficients involved in water vapor permeation highlights the complexity of the mechanisms implicated in water transport through hydrophilic films. Water vapor sorption isotherms followed a non-linear profile, which was fitted with the D’Arcy and Watt model. Water vapor diffusivity was concentration-dependent, being affected by plasticization and water clustering. Temperature-dependence of water vapor permeability showed a discontinuous behavior when the Arrhenius law was applied, indicating possible changes in the matrix structure. Oxygen permeability was positively influenced by relative humidity and temperature. The higher selectivity to carbon dioxide permeation in comparison with oxygen diminished as the water content of the film increased, which is in accordance with the loss of barrier properties at high relative humidities. This study underlines the importance of the evaluation of environmental conditions during end-use applications in order to optimize the performance of biopolymer-based films. Mostrar menos

Nanoparticles with a compact spherical structure and a narrow size distribution were prepared from a zein protein polymer by electrohydrodynamic atomization. The effects of key parameters of the process (polymer concentration, flow rate and applied voltage) on the size and morphology of the particles was studied. Zein nanoparticles could be obtained from zein concentrations ranging from 2.5% to 15% (w/w). The sizes of these particles, ranging from 175 to 900 nm, increased with increasing… Mostrar más

Nanoparticles with a compact spherical structure and a narrow size distribution were prepared from a zein protein polymer by electrohydrodynamic atomization. The effects of key parameters of the process (polymer concentration, flow rate and applied voltage) on the size and morphology of the particles was studied. Zein nanoparticles could be obtained from zein concentrations ranging from 2.5% to 15% (w/w). The sizes of these particles, ranging from 175 to 900 nm, increased with increasing polymer concentration. Compact nanostructures were obtained for 2.5% and 5% zein solutions whereas 10% and 15% solutions yielded collapsed and shrunken particles. Flow rate also exerted an effect, the lower the flow rate the smaller the nanoparticles. The morphology of the nanoparticles did not change after incorporating curcumin in proportions ranging from 1:500 to 1:10 (curcumin:zein), and the encapsulation efficiency was around 85–90%. Fluorescence microscopy images showed that the nanostuctures obtained took the form of matrix systems with the curcumin homogeneously distributed in the zein matrix. The curcumin remained in the amorphous state in the nanoparticle, as revealed by X-Ray diffractometry, evidencing intimate contact with the polymer. After three months of storage at 23 °C and 43% relative humidity in the dark, neither the size or the morphology of the nanoparticles had undergone significant changes, nor had the curcumin content altered. Thanks to encapsulation, the curcumin presented good dispersion in an aqueous food matrix: semi-skimmed milk. Mostrar menos

The sorption and transport properties of gliadin and chitosan films with respect to four representative food aroma components (ethyl caproate, 1-hexanol, 2-nonanone and α-pinene) have been studied under dry and wet environmental conditions. The partition coefficients (K) of the selected volatiles were also obtained using isooctane and soybean oil as fatty food simulants. The results showed that gliadin and chitosan films have very low capacities for the sorption of volatile compounds, and these… Mostrar más

The sorption and transport properties of gliadin and chitosan films with respect to four representative food aroma components (ethyl caproate, 1-hexanol, 2-nonanone and α-pinene) have been studied under dry and wet environmental conditions. The partition coefficients (K) of the selected volatiles were also obtained using isooctane and soybean oil as fatty food simulants. The results showed that gliadin and chitosan films have very low capacities for the sorption of volatile compounds, and these capacities are influenced by the nature of the sorbate, the environmental relative humidity and the presence of glycerol as a plasticizer in the polymeric matrix. The volatile compounds also present a low partitioning in the biopolymer film/food stimulant system. Given the low levels of interaction observed with the volatiles, gliadin and chitosan films are of potential interest for the packaging of foods in which aroma is one of the most important quality attributes. Mostrar menos

The aim of this work has been to study the modification of gliadin films with cinnamaldehyde as a potential cross-linker agent. The molecular weight profile and cross-linking density showed that cinnamaldehyde increased reticulation in the resulting films. The participation of free amino groups of the protein in the newly created entanglements could be a possible mechanism of connection between the polypeptidic chains. The combination of a Schiff base and a Michael addition is a feasible… Mostrar más

The aim of this work has been to study the modification of gliadin films with cinnamaldehyde as a potential cross-linker agent. The molecular weight profile and cross-linking density showed that cinnamaldehyde increased reticulation in the resulting films. The participation of free amino groups of the protein in the newly created entanglements could be a possible mechanism of connection between the polypeptidic chains. The combination of a Schiff base and a Michael addition is a feasible approach to understanding this mechanism. The protein solubility in different media pointed to lower participation by both noncovalent and disulfide bonds in stabilizing the structure of the cross-linked films. The new covalent bonds formed by the cinnamaldehyde treatment hampered water absorption and weight loss, leading to more water-resistant matrices which had not disintegrated after 5 months. The properties of this novel bioplastic could be modified to suit the intended application by using cinnamaldehyde, a naturally occurring compound. Mostrar menos

Cinnamaldehyde is a naturally occurring α,β-unsaturated aldehyde. Its potential as a natural cross-linker to improve the physical performance of cast wheat gliadin films was evaluated. The cross-linking reaction was found to be dependent on the pH of the reaction medium, with pH 2 as the optimum. The water resistance (weight loss after immersion), mechanical properties (Young's modulus, tensile strength and elongation at break), thermal properties (Tg and decomposition behavior), optical… Mostrar más

Cinnamaldehyde is a naturally occurring α,β-unsaturated aldehyde. Its potential as a natural cross-linker to improve the physical performance of cast wheat gliadin films was evaluated. The cross-linking reaction was found to be dependent on the pH of the reaction medium, with pH 2 as the optimum. The water resistance (weight loss after immersion), mechanical properties (Young's modulus, tensile strength and elongation at break), thermal properties (Tg and decomposition behavior), optical properties and morphology of films were evaluated. Cross-linked films showed high transparency, maintained their integrity after immersion, and displayed significant improvements in tensile strength and Young’s modulus without impairment of their elongation properties. These effects, which were proportional to the amount of cinnamaldehyde added, highlight the possible formation of intermolecular covalent bonds between “monomeric” gliadins, leading to a polymerized network. Thus, this treatment could provide a new alternative to the toxic cross-linkers commonly employed and so extend the use of gliadin films. Mostrar menos