Vitor Alves | Universidade de Lisboa (original) (raw)
Papers by Vitor Alves
Bioengineering, Apr 5, 2020
Membranes
Tomato pomace is a low-cost, renewable resource that has been studied for the extraction of the b... more Tomato pomace is a low-cost, renewable resource that has been studied for the extraction of the biopolyester cutin, which is mainly composed of long-chain hydroxy fatty acids. These are excellent building blocks to produce new hydrophobic biopolymers. In this work, the monomers of cutin were extracted and isolated from tomato pomace and utilized to produce cutin-based films. Several strategies for the depolymerization and isolation of monomeric cutin were explored. Strategies differed in the state of the raw material at the beginning of the extraction process, the existence of a tomato peel dewaxing step, the type of solvent used, the type of alkaline hydrolysis, and the isolation method of cutin monomers. These strategies enabled the production of extracts enriched in fatty acids (16-hydroxyhexadecanoic, hexadecanedioic, stearic, and linoleic, among others). Cutin and chitosan-based films were successfully cast from cutin extracts and commercial chitosan. Films were characterized r...
Molecules
FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that inclu... more FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions (concentration, temperature, and time) for alkaline treatment were investigated to deacylate FucoPol. Complete deacetylation and desuccinylation was achieved with 0.02 M NaOH, at 60 °C for 15 min, with no significant impact on the biopolymer’s sugar composition, pyruvate content, and molecular mass distribution. FucoPol depyruvylation by acid hydrolysis was attempted, but it resulted in a very low polymer recovery. The effect of the ionic strength, pH, and temperature on the deacetylated/desuccinylated polysaccharide, d-FucoPol, was evaluated, as well as its emulsion and film-forming capacity. d-FucoPol aqueous solutions maintained the shear thinning behaviour characteristic of FucoPol, but the apparent viscosity decreased significantly. ...
Polymers
This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromo... more This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromonas strains recently isolated from different marine environments in French Polynesia atolls. The films were transparent and resulted in small colour alterations when applied over a coloured surface (ΔEab below 12.6 in the five different colours tested). Moreover, scanning electron microscopy showed that the EPS films were dense and compact, with a smooth surface. High water vapour permeabilities were observed (2.7–6.1 × 10−11 mol m−1 s−1 Pa−1), which are characteristic of hydrophilic polysaccharide films. The films were also characterised in terms of barrier properties to oxygen and carbon dioxide. Interestingly, different behaviours in terms of their mechanical properties under tensile tests were observed: three of the EPS films were ductile with high elongation at break (ε) (35.6–47.0%), low tensile strength at break (Ꞇ) (4.55–11.7 MPa) and low Young’s modulus (εm) (10–93 MPa), whereas...
Coatings
In the last decades, the overuse of synthetic polymers in the packaging industry has become a ser... more In the last decades, the overuse of synthetic polymers in the packaging industry has become a serious global environmental problem due to their nonbiodegradability. To overcome this issue, attention has been driven to study alternative materials, namely the use of biodegradable biopolymers extracted from agro-industrial residues, as materials for food packages. In this work, the polysaccharide arabinoxylan, previously extracted from corn fibre by alkaline hydrolysis, was used to produce composite and multilayer films. The composite films were produced by casting an oil-in-water emulsion with different quantities of oleic acid, while the multilayer films (beeswax-arabinoxylan-beeswax) were manufactured by submerging the arabinoxylan films in a beeswax solution. Both film types, along with a film composed only of arabinoxylan, were characterised in terms of their antioxidant activity, optical and mechanical properties, surface hydrophobicity, and barrier properties against water vapou...
Membranes, 2021
Corn fiber from the corn starch industry is a by-product produced in large quantity that is mainl... more Corn fiber from the corn starch industry is a by-product produced in large quantity that is mainly used in animal feed formulations, though it is still rich in valuable components, such as arabinoxylans, with proven film-forming ability. During arabinoxylans’ recovery under alkaline extraction, a dark-colored biopolymer fraction is obtained. In this work, a purified arabinoxylan extract from corn fiber with an intense brownish color was decolorized using hydrogen peroxide as the decolorizing agent. Biodegradable films prepared by casting the decolorized extract exhibited a light-yellow color, considered more appealing, envisaging their application in food packaging. Films were prepared with glycerol as plasticizer and citric acid as cross-linker. Although the cross-linking reaction was not effective, films presented antioxidant activity, a water vapor permeability similar to that of non-decolorized films, and other polysaccharides’ and mechanical properties that enable their applica...
Fruit Juices, 2018
Abstract Enzymes are an integral component of modern fruit juice manufacturing, having several ad... more Abstract Enzymes are an integral component of modern fruit juice manufacturing, having several advantages from a commercial and environmental point of view. The enzymes used in the fruit juice industry are primarily mixtures of pectinolytic enzymes. These enzymes break down complex polysaccharides of fruit tissues into simpler molecules. Pectin degradation by enzyme action (enzyme-assisted extraction) leads to an increase in the yield of the extraction of juice from raw material, improves the production efficiency, reduces energy costs and waste, and generates visually attractive final products with improved quality. In this chapter, the discussion is focused on the enzyme-assisted extraction method of fruit juices, particularly in the occurrence and nature of pectic substances in fruits, chemistry of enzymes and their substrates, as well as their biotechnological applications for the processing of different fruits and their effects on the properties of the resulting fruit juices.
ACS Applied Bio Materials, 2021
Food Bioscience, 2021
Abstract Structured guava (SG) was produced by inducing gelation of guava pulp adding agar and ge... more Abstract Structured guava (SG) was produced by inducing gelation of guava pulp adding agar and gellan gum (GG). The rheological properties, as well as in vitro bioaccessibility of ascorbic acid (AA), total antioxidant activity (TAA) and total extractable polyphenols (TEP) were investigated. The results illustrated that the SG gel network made from agar and low acyl gellan (LAG) was completely developed at temperatures close to 20 °C. LA75/HA25 showed higher elastic behavior in time sweep. The AA analysis of the pulp and SG revealed that these compounds remained practically unchanged after gastrointestinal digestion in vitro (GID), with a higher bioaccessibility percentage. The average values of TAA and TEP of the structured products were close to those of the guava pulp, with no interference from the use of agar and GG. The Optimized Descriptive Profile showed that the hydrocolloid used influenced the sensory attributes of the SG, changing the texture and appearance.
Membranes, 2020
Corn fiber, a by-product of the starch industry, is presently incorporated in animal feed. Howeve... more Corn fiber, a by-product of the starch industry, is presently incorporated in animal feed. However, it has arabinoxylans as added-value components (besides ferulic acid) that should be valorized. In this work, the raw material, a fraction enriched in arabinoxylans from corn fiber, previously produced by alkaline extraction from corn fiber and pre-concentrated by ultrafiltration, was further purified. The use of ultrafiltration operated in diafiltration mode (dia-ultrafiltration) was evaluated for the purification of the arabinoxylans fraction. The objective was to maximize the removal of the small contaminants from the fraction and to maximize the permeability and/or the permeate flux, by selecting the relevant operating conditions involved in this process. The removal of contaminants (%) was estimated when their apparent rejection stabilized. Edible films were produced, from the resultant purified arabinoxylans fraction, using glycerol as plasticizer (30% dry basis). Additionally, ...
International Journal of Polymeric Materials and Polymeric Biomaterials, 2019
Bioengineering, 2020
Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from ... more Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although th...
Journal of Food Engineering, 2018
International journal of biological macromolecules, Jan 5, 2017
The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobac... more The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7μm and presented thin walls (thickness from 222 to 1094nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products.
International Journal of Biological Macromolecules, 2016
Carbohydrate Polymers, 2016
International Journal of Polymeric Materials and Polymeric Biomaterials, 2016
ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical charac... more ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. GRAPHICAL ABSTRACT
Bioengineering, Apr 5, 2020
Membranes
Tomato pomace is a low-cost, renewable resource that has been studied for the extraction of the b... more Tomato pomace is a low-cost, renewable resource that has been studied for the extraction of the biopolyester cutin, which is mainly composed of long-chain hydroxy fatty acids. These are excellent building blocks to produce new hydrophobic biopolymers. In this work, the monomers of cutin were extracted and isolated from tomato pomace and utilized to produce cutin-based films. Several strategies for the depolymerization and isolation of monomeric cutin were explored. Strategies differed in the state of the raw material at the beginning of the extraction process, the existence of a tomato peel dewaxing step, the type of solvent used, the type of alkaline hydrolysis, and the isolation method of cutin monomers. These strategies enabled the production of extracts enriched in fatty acids (16-hydroxyhexadecanoic, hexadecanedioic, stearic, and linoleic, among others). Cutin and chitosan-based films were successfully cast from cutin extracts and commercial chitosan. Films were characterized r...
Molecules
FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that inclu... more FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions (concentration, temperature, and time) for alkaline treatment were investigated to deacylate FucoPol. Complete deacetylation and desuccinylation was achieved with 0.02 M NaOH, at 60 °C for 15 min, with no significant impact on the biopolymer’s sugar composition, pyruvate content, and molecular mass distribution. FucoPol depyruvylation by acid hydrolysis was attempted, but it resulted in a very low polymer recovery. The effect of the ionic strength, pH, and temperature on the deacetylated/desuccinylated polysaccharide, d-FucoPol, was evaluated, as well as its emulsion and film-forming capacity. d-FucoPol aqueous solutions maintained the shear thinning behaviour characteristic of FucoPol, but the apparent viscosity decreased significantly. ...
Polymers
This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromo... more This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromonas strains recently isolated from different marine environments in French Polynesia atolls. The films were transparent and resulted in small colour alterations when applied over a coloured surface (ΔEab below 12.6 in the five different colours tested). Moreover, scanning electron microscopy showed that the EPS films were dense and compact, with a smooth surface. High water vapour permeabilities were observed (2.7–6.1 × 10−11 mol m−1 s−1 Pa−1), which are characteristic of hydrophilic polysaccharide films. The films were also characterised in terms of barrier properties to oxygen and carbon dioxide. Interestingly, different behaviours in terms of their mechanical properties under tensile tests were observed: three of the EPS films were ductile with high elongation at break (ε) (35.6–47.0%), low tensile strength at break (Ꞇ) (4.55–11.7 MPa) and low Young’s modulus (εm) (10–93 MPa), whereas...
Coatings
In the last decades, the overuse of synthetic polymers in the packaging industry has become a ser... more In the last decades, the overuse of synthetic polymers in the packaging industry has become a serious global environmental problem due to their nonbiodegradability. To overcome this issue, attention has been driven to study alternative materials, namely the use of biodegradable biopolymers extracted from agro-industrial residues, as materials for food packages. In this work, the polysaccharide arabinoxylan, previously extracted from corn fibre by alkaline hydrolysis, was used to produce composite and multilayer films. The composite films were produced by casting an oil-in-water emulsion with different quantities of oleic acid, while the multilayer films (beeswax-arabinoxylan-beeswax) were manufactured by submerging the arabinoxylan films in a beeswax solution. Both film types, along with a film composed only of arabinoxylan, were characterised in terms of their antioxidant activity, optical and mechanical properties, surface hydrophobicity, and barrier properties against water vapou...
Membranes, 2021
Corn fiber from the corn starch industry is a by-product produced in large quantity that is mainl... more Corn fiber from the corn starch industry is a by-product produced in large quantity that is mainly used in animal feed formulations, though it is still rich in valuable components, such as arabinoxylans, with proven film-forming ability. During arabinoxylans’ recovery under alkaline extraction, a dark-colored biopolymer fraction is obtained. In this work, a purified arabinoxylan extract from corn fiber with an intense brownish color was decolorized using hydrogen peroxide as the decolorizing agent. Biodegradable films prepared by casting the decolorized extract exhibited a light-yellow color, considered more appealing, envisaging their application in food packaging. Films were prepared with glycerol as plasticizer and citric acid as cross-linker. Although the cross-linking reaction was not effective, films presented antioxidant activity, a water vapor permeability similar to that of non-decolorized films, and other polysaccharides’ and mechanical properties that enable their applica...
Fruit Juices, 2018
Abstract Enzymes are an integral component of modern fruit juice manufacturing, having several ad... more Abstract Enzymes are an integral component of modern fruit juice manufacturing, having several advantages from a commercial and environmental point of view. The enzymes used in the fruit juice industry are primarily mixtures of pectinolytic enzymes. These enzymes break down complex polysaccharides of fruit tissues into simpler molecules. Pectin degradation by enzyme action (enzyme-assisted extraction) leads to an increase in the yield of the extraction of juice from raw material, improves the production efficiency, reduces energy costs and waste, and generates visually attractive final products with improved quality. In this chapter, the discussion is focused on the enzyme-assisted extraction method of fruit juices, particularly in the occurrence and nature of pectic substances in fruits, chemistry of enzymes and their substrates, as well as their biotechnological applications for the processing of different fruits and their effects on the properties of the resulting fruit juices.
ACS Applied Bio Materials, 2021
Food Bioscience, 2021
Abstract Structured guava (SG) was produced by inducing gelation of guava pulp adding agar and ge... more Abstract Structured guava (SG) was produced by inducing gelation of guava pulp adding agar and gellan gum (GG). The rheological properties, as well as in vitro bioaccessibility of ascorbic acid (AA), total antioxidant activity (TAA) and total extractable polyphenols (TEP) were investigated. The results illustrated that the SG gel network made from agar and low acyl gellan (LAG) was completely developed at temperatures close to 20 °C. LA75/HA25 showed higher elastic behavior in time sweep. The AA analysis of the pulp and SG revealed that these compounds remained practically unchanged after gastrointestinal digestion in vitro (GID), with a higher bioaccessibility percentage. The average values of TAA and TEP of the structured products were close to those of the guava pulp, with no interference from the use of agar and GG. The Optimized Descriptive Profile showed that the hydrocolloid used influenced the sensory attributes of the SG, changing the texture and appearance.
Membranes, 2020
Corn fiber, a by-product of the starch industry, is presently incorporated in animal feed. Howeve... more Corn fiber, a by-product of the starch industry, is presently incorporated in animal feed. However, it has arabinoxylans as added-value components (besides ferulic acid) that should be valorized. In this work, the raw material, a fraction enriched in arabinoxylans from corn fiber, previously produced by alkaline extraction from corn fiber and pre-concentrated by ultrafiltration, was further purified. The use of ultrafiltration operated in diafiltration mode (dia-ultrafiltration) was evaluated for the purification of the arabinoxylans fraction. The objective was to maximize the removal of the small contaminants from the fraction and to maximize the permeability and/or the permeate flux, by selecting the relevant operating conditions involved in this process. The removal of contaminants (%) was estimated when their apparent rejection stabilized. Edible films were produced, from the resultant purified arabinoxylans fraction, using glycerol as plasticizer (30% dry basis). Additionally, ...
International Journal of Polymeric Materials and Polymeric Biomaterials, 2019
Bioengineering, 2020
Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from ... more Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although th...
Journal of Food Engineering, 2018
International journal of biological macromolecules, Jan 5, 2017
The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobac... more The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7μm and presented thin walls (thickness from 222 to 1094nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products.
International Journal of Biological Macromolecules, 2016
Carbohydrate Polymers, 2016
International Journal of Polymeric Materials and Polymeric Biomaterials, 2016
ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical charac... more ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. GRAPHICAL ABSTRACT