Antioxidant Edible Films Based on Pear Juice and Pregelatinized Cassava Starch: Effect of the Carbohydrate Profile at Different Degrees of Pear Ripeness.

Edible films based on fruit and vegetable purees combined with different food-grade biopolymeric binding agents (e.g., pectin, gelatin, starch, sodium alginate) are recognized as interesting packaging materials that benefit from the physical, mechanical, and barrier properties of biopolymers as well as the sensory and nutritional properties of purees. In the current contribution, edible antioxidant films based on pear juice and pregelatinized cassava starch were developed. In particular, the suitability of using pregelatinized cassava starch for the non-thermal production of these novel edible films was evaluated. In addition, the effects on the films' properties derived from the use of pear juice instead of the complete puree, from the content of juice used, and from the carbohydrate composition associated with the ripening of pears were all studied. The produced films were characterized in terms of their total polyphenol content, water sensitivity, and water barrier, optical, mechanical and antioxidant properties. Results showed that the use of pear juice leads to films with enhanced transparency compared with puree-based films, and that juice concentration and carbohydrate composition associated with the degree of fruit ripeness strongly govern the films' properties. Furthermore, the addition of pregelatinized cassava starch at room temperature discloses a significant and favorable impact on the cohesiveness, lightness, water resistance, and adhesiveness of the pear-juice-based films, which is mainly attributed to the effective interactions established between the starch macromolecules and the juice components.

Inactivation kinetics of horseradish peroxidase (HRP) by hydrogen peroxide.

In recent years, the peroxidase enzymes have generated wide interest in several industrial processes, such as wastewater treatments, food processing, pharmaceuticals, and the production of fine chemicals. However, the low stability of the peroxidases in the presence of hydrogen peroxide (H2O2) has limited its commercial use. In the present work, the effect of H2O2 on the inactivation of horseradish peroxidase (HRP) was evaluated. Three states of HRP (E0, E2, and E3) were identified. While in the absence of H2O2, the resting state E0 was observed, in the presence of low and high concentrations of H2O2, E2, and E3 were found, respectively. The results showed that HRP catalyzed the H2O2 decomposition, forming the species Ex, which was catalytically inactive. Results suggest that this loss of enzymatic activity is an intrinsic characteristic of the studied HRP. A model from a modified version of the Dunford mechanism of peroxidases was developed, which was validated against experimental data and findings reported by the literature.

Exploring the Potential of Wild Andean Blueberries for Powdered Juice Production through Spray Drying.

The Andean blueberry (Vaccinium meridionale Sw) is an underutilized wild fruit native to South America. It is known for its antioxidant properties and potential health benefits. In this study, Andean blueberry juice powders were produced via spray drying, using maltodextrin (MD), gum Arabic (GA) or a combination of both (MD:GA) as wall materials. The spray-dried juices were analyzed for the recovery percentage of total polyphenols and monomeric anthocyanins, as well as for their physicochemical and technological properties. Results showed that the type of carrier agent used caused statistically significant differences in the bioactive content and the antioxidant activity of the powders (p < 0.05). It was found that the MD samples has the highest monomeric anthocyanins content (0.88 ± 0.02 mg cyanidin 3-glucoside equivalents/g) and the highest anthocyanins recovery (96.3 ± 1.7%), while the MD:GA powders showed the highest values of total polyphenol content (5.70 ± 0.09 mg gallic acid equivalents/g), DPPH scavenging capacity (2.49 ± 0.02 mg gallic acid equivalents/g) and phenolics recovery (87.2 ± 1.1%). Furthermore, all the spray-dried powders exhibited low moisture content (<5.5%) and water activity (<0.40), as well as high solubility in water (>94%) and good flowability. Future prospects include evaluating the stability of the Andean blueberry juice powders during storage and exploring the formulation of new foods and beverages that incorporate these spray-dried powders.

Analysis of drying kinetic of brewer ́s spent grains: effect of the temperature on the physical properties and the content of bioactive compounds / Análisis de la cinética de secado del bagazo residual de malta: efecto de la temperatura sobre las propiedades físicas y el contenido de compuestos bioactivos

Background: Brewer ́s spent grain (BSG) is a biomass by-product generated in large volumes during industrial beer production. BSG has become a growing environmental problem, as most breweries discard it inappropriately, negatively impacting the environment. Alternatives for the exploitation of this by-product have consisted of elaborating food supplements for farm animals, obtaining biofuels, developing adsorbents, and obtaining substances for the food industry. However, the high moisture content in BSG (approximately 70%), poses a significant challenge in exploring various reuse alternatives. Therefore, the implementation of a pre-drying process becomes essential. Objective: This study aimed to analyze the BSG drying kinetics at different temperatures and the effect of the drying temperature on the physical properties and the content of bioactive compounds. Methods: BSG samples were dried at different temperatures (50, 60, 70, 80, 90, and 105°C) and analyzed for their moisture ratio, water activity, total polyphenol content (TPC), and DPPH (1,1-diphenyl-2-picrylhydrazil) radical scavenging activity. Also, four kinetics models were fitted to the drying data. Results:It was determined that the effective diffusivity was between 5.23x10

Antecedentes: El Bagazo residual de malta (BSG por sus siglas en inglés) es un subproducto biomásico generado en grandes volúmenes durante la producción industrial de cerveza. El BSG se ha convertido en un creciente problema para el medio ambiente, debido a que la mayoría de las cervecerías descartan inapropiadamente este residuo generando un impacto negativo al ambiente. Las alternativas para el aprovechamiento de este subproducto han consistido especialmente en la elaboración de suplementos alimenticios para animales de granja, obtención de biocombustibles, desarrollo de adsorbentes y obtención de productos para la industria alimentaria. Sin embargo, el alto contenido de humedad (~70%) del BSG representa un reto para el desarrollo de diferentes alternativas de reutilización, por lo que se hace necesario un proceso de secado previo. Objetivos: En este estudio se analizó la cinética de secado del BSG a diferentes temperaturas y el efecto de la temperatura de secado sobre sus propiedades físicas y contenido de compuestos bioactivos. Métodos: Las muestras de BSG fueron secadas a diferentes temperaturas (50, 60, 70, 80, 90 y 105°C) y analizadas en términos de razón de humedad, actividad acuosa, contenido de polifenoles totales (TPC) y actividad secuestradora del radical DPPH. Además, se ajustaron 4 modelos cinéticos a los datos de secado. Resultados: Se determinó que la difusividad efectiva del BSG varió entre 5.23x10

Improvement of the Polyhydroxyalkanoates Recovery from Mixed Microbial Cultures Using Sodium Hypochlorite Pre-Treatment Coupled with Solvent Extraction.

The use of mixed microbial cultures (MMC) and organic wastes and wastewaters as feed sources is considered an appealing approach to reduce the current polyhydroxyalkanoates (PHAs) production costs. However, this method entails an additional hurdle to the PHAs downstream processing (recovery and purification). In the current work, the effect of a sodium hypochlorite (NaClO) pre-treatment coupled with dimethyl carbonate (DMC) or chloroform (CF) as extraction solvents on the PHAs recovery efficiency (RE) from MMC was evaluated. MMC were harvested from a sequencing batch reactor (SBR) fed with a synthetic prefermented olive mill wastewaster. Two different carbon-sources (acetic acid and acetic/propionic acids) were employed during the batch accumulation of polyhydroxybutyrate (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from MMC. Obtained PHAs were characterized by 1H and 13C nuclear magnetic resonance, gel-permeation chromatography, differential scanning calorimetry, and thermal gravimetric analysis. The results showed that when a NaClO pre-treatment is not added, the use of DMC allows to obtain higher RE of both biopolymers (PHB and PHBV), in comparison with CF. In contrast, the use of CF as extraction solvent required a pre-treatment step to improve the PHB and PHBV recovery. In all cases, RE values were higher for PHBV than for PHB.

Improvement of the Ultrasound-Assisted Extraction of Polyphenols from Welsh Onion (Allium fistulosum) Leaves Using Response Surface Methodology.

Welsh onion (Allium fistulosum) leaves contain several bioactive compounds that can be extracted and used to develop new value-added products (e.g., functional foods and dietary supplements). In the current work, optimal ultrasound-assisted extraction (UAE) conditions to obtain extracts with high polyphenols content and DPPH (1,1-diphenyl-2-picrylhydrazil) scavenging activity were identified using response surface methodology. A complete 3k factorial design was used to evaluate the effect of different variables of the UAE (extraction temperature, time, and ethanol concentration) on the polyphenols content and the DPPH scavenging activity of the extracts. The best conditions for UAE to reach both the highest values of total polyphenols content (51.78 mg GAE/100 g) and DPPH scavenging activity (34.07 mg Trolox equivalents/100 g) were an extraction temperature of 60 °C, time of 10 min, and ethanol concentration of 70% v/v. The antioxidant activity of the extracts obtained at the optimal conditions was also evaluated by 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays obtaining values of 155.51 ± 2.80 µM Trolox/100 g and 1300.21 ± 65.55 µM Trolox/100 g, respectively. Moreover, these extracts were characterized by UHPLC-ESI+-Orbitrap-MS analysis finding that cyanidin (6.0 mg/kg) was the phenolic compound found in the highest amount followed by quercetin-3-glucoside (4.4 mg/kg).

Propolis from native Stingless Bees: ultrasound-assisted extraction / Propóleos de abejas nativas sin aguijón: extracción asistida por ultrasonido

BACKGROUND: Propolis has been considered a highly valuable material due to its therapeutic properties. However, in Colombia, the commercialization of propolis is limited not only by low production but also by the little knowledge about its efficient extraction. Therefore, finding an optimal and economical extraction method to obtain propolis is a necessity for beekeepers that would open new possibilities for industrial use and, therefore, for the market. OBJECTIVES:The objective of this study was to evaluate a conventional and ultrasound-assisted extraction method, seeking to obtain the highest yield and a high amount of content of bioactive compounds in propolis extracts. METHODS: The extraction was carried out for three crude propolis from different types of bees: Tetragoniscaangustula or Angelita (ANG), Meliponaeburnea or Melipona(MEL), and Scaptotrigonaspp (SCT). The extracts were characterized by color, pH, visual appearance, solid content, antioxidant capacity, total polyphenol content, and bacterial inhibition capacity. RESULTS: The highest extraction performance was obtained when the ultrasound-assisted method was used, especially for the ANG extract, which in addition to presenting inhibition for gram-negative (E. coli) and gram-positive (S. Aureus) bacteria, had the best antioxidant activity with a value of 545 mg GAE / 100 g of sample and total polyphenol content of 1,884 mg GAE / 100 g of sample. CONCLUSIONS: Ultrasound-assisted extraction can be considered a low-cost alternative to increase the extraction performance of crude propolis, together with its total polyphenol content and antioxidant capacity, without altering its physical properties

ANTECEDENTES: El propóleos ha sido considerado un material de alto valor por sus propiedades terapéuticas. Sin embargo, en Colombia la comercialización de propóleos está limitada no solo por la baja producción sino también por el incipiente conocimiento sobre la extracción eficiente de este. Por ello, encontrar un método de extracción óptimo y económico para la obtención de propóleos es una necesidad para los apicultores que abriría nuevas posibilidades para el uso industrial y por tanto para el mercado. OBJETIVOS: El objetivo de este estudio fue evaluar un método de extracción convencional y asistido por ultrasonido (US) buscando el mayor rendimiento y alto contenido de compuestos bioactivos en extractos de propóleos. MÉTODOS: La extracción se realizó para tres propóleos crudos de diferentes tipos de abejas Tetragonisca angustula o Angelita(ANG), Melipona eburnea o Melipona (MEL) y Scaptotrigona spp (SCT). Todos los extractos se caracterizaron por su color, pH, apariencia visual, contenido de sólidos, capacidad antioxidante, contenido total de polifenoles y capacidad de inhibición bacteriana. RESULTADOS: El mayor rendimiento de extracción se obtuvo cuando se usó el método asistido por ultrasonido y específicamente para el extracto ANG, que además de presentar inhibición para bacterias gram negativas (E. coli) y gram positivas (S. Aureus), tuvo la mejor actividad antioxidante con un valor de 545 mg GAE / 100 g de muestra y contenido total de polifenoles de 1884 mg GAE / 100 g de muestra. CONCLUSIONES: La extracción asistida por ultrasonido puede considerarse una alternativa de bajo costo para aumentar el rendimiento de extracción del propóleos crudo, así como su contenido total de polifenoles y capacidad antioxidante sin alterar sus propiedades físicas

Single and Combined Effect of Mild-Heat Treatment and Alginate Coatings on Quality Preservation of Minimally Processed Bunching Green Onions.

Bunching green onion is an Allium species that has been widely used in food flavorings and seasonings. This vegetable experiences a rapid loss of quality during storage due to physiological changes and microbial spoilage. In the current work, the single and combined effect of mild-heat treatment (55 °C for 60 s) and alginate edible coatings on the quality preservation of minimally processed bunching green onions was studied. Control and treated samples were stored at 4 °C for 15 days and examined periodically in terms of their respiration rate, weight loss, pH, soluble solids content, firmness, total polyphenol content, antioxidant activity, microbial count, decay ratio, and overall visual quality. The results showed that the combination of mild heat and alginate edible coatings was the most effective approach to slow down the respiration rate and the incidence of decay in the minimally processed bunching green onions. In addition, the treatments with alginate coating alone or combined with mild-heat treatment showed the best performance for maintaining the overall visual quality of the products during the storage.

Electrospun Ultrafine Cationic Cellulose Fibers Produced from Sugarcane Bagasse for Potential Textile Applications.

Sugarcane bagasse (SCB) is an abundant by-product of sugar refining that can be utilized as a raw material for cellulose isolation for several industrial applications. Electrospinning has garnered attention in recent years because it allows the preparation of cellulosic materials with unique properties. In this study, cellulose was isolated from sugarcane bagasse and acetylated to fabricate fine acetate cellulose fibers through electrospinning. Subsequently, the electrospun fibers were deacetylated and cationized in order to produce functionalized materials with potential textile applications. The functional fibers were colored with an anionic dye (vinyl sulfone) with and without the presence of salt and were evaluated according to dye fixation, color attributes, morphological characteristics, and thermal stability. Cationic cellulose fibers that were dyed without added salt were found to be brighter and demonstrated better color fixation than those with added salt. In addition, morphological analysis performed using scanning electron microscopy demonstrated that cationized fibers dyed without added salt were better preserved at this stage. The cationic fiber also evidenced a high-temperature resistance, exhibiting a degradation temperature above 236 °C. The results suggest that cellulose fibers dyed in this manner can potentially be considered for use in textile applications due to their suitable dye fixation and tunable porosity (i.e., breathability).

Feasibility of Using Carvacrol/Starch Edible Coatings to Improve the Quality of Paipa Cheese.

Paipa cheese is the only Colombian semi-ripened cheese with protected geographical indication. In the current work, the effect of applying starch coatings carrying carvacrol on Paipa cheeses was analyzed. Coatings were prepared based on blends of potato starch (2 g/100 g), carvacrol (0.1 g/100 g), polysorbate 80, glycerol, and water and applied to the cheese's surface by brushing. Uncoated cheeses were also analyzed for comparison. Moreover, films were prepared and characterized in terms of their moisture content, water vapor permeability, mechanical properties, transparency, water solubility, swelling (%), and antioxidant activity. Carvacrol/starch films showed a slight decrease in their water solubility and Young's modulus, while not significant changes were observed in water vapor permeability, moisture content, transparency, and swelling behavior, in comparison with the starch films. After application on the Paipa cheeses, the carvacrol/starch coatings enhanced the brightness of the cheeses without causing significant changes in water activity, moisture content, color attributes, and mesophilic aerobic bacteria and molds/yeasts count. Moreover, edible coatings have a significant effect on the hardness, the gumminess, the springiness, and the chewiness of the Paipa cheese. Coated cheeses were better preserved at day 60 of storage because they did not show changes in their lightness, hardness, and springiness.

Epoxidised sesame oil as a biobased coupling agent and plasticiser in polylactic acid/thermoplastic yam starch blends.

This work aims to improve the physicochemical properties of polylactic acid (PLA) and thermoplastic yam starch (TPS) blends using epoxidised sesame oil (ESO). We used epoxidised sesame oil from two Colombian Caribbean crops: Dioscorea rotundata and Sesamum indicum, with an oil substitution of 58.4 %. Films were obtained through extrusion and compression moulding processes. Moisture content, solubility, contact angle, and mechanical, barrier, and structural properties were determined using optical and scanning electron microscopy, infrared Fourier transform spectroscopy. Thermal analyses were also performed using thermogravimetry and differential scanning calorimetry techniques. The results suggest that the PLA and TPS interactions can be improved with the addition of ESO as coupling agent, enhancing the interfacial adhesion between the polymers, and favouring the smoothness of the film surface. Furthermore, the ESO addition led to increased thermal stability while restricting molecular mobility, indicating a coupling agent effect. In conclusion, the use of epoxidised oil for preparing films based on high PLA content and TPS allows obtaining enhanced interfacial adhesion. Considering the above, the developed materials have potential application in semi-rigid food packaging.

New Freeze-Dried Andean Blueberry Juice Powders for Potential Application as Functional Food Ingredients: Effect of Maltodextrin on Bioactive and Morphological Features.

Andean blueberry (Vaccinium meridionale Swartz) fruits are an underutilized source of anthocyanins and other valuable bioactive phytochemicals. The purpose of this work was to obtain Andean blueberry juice powders via freeze-drying processing and evaluate the effect of maltodextrin as a drying aid on their physicochemical, technological, microstructural, and bioactive characteristics. Andean blueberry juices were mixed with variable proportions of maltodextrin (20-50%); freeze-dried; and characterized in terms of their tristimulus color, Fourier transform infrared spectra (FTIR), moisture content, water activity, morphology, water solubility, flow properties, total polyphenols and anthocyanins content, and DPPH•-scavenging capacity. The powders obtained presented suitable characteristics in terms of their water activity (<0.5), solubility (>90%), and bioactive compound recovery (>70% for total phenolics, and >60% for total monomeric anthocyanins), with antioxidant activities up to 4 mg equivalent of gallic acid/g of dry matter. Although an increased content of maltodextrin resulted in lower concentrations of phytochemicals, as expected, it also favored an increased % recovery (over 90% of total phenolics at the highest maltodextrin proportion) and improved their flow properties. Freeze-dried juice powders are a potential alternative for the stabilization and value addition of this fruit as a new source of functionality for processed foods.

Improvement of Andean Blueberries Postharvest Preservation Using Carvacrol/Alginate-Edible Coatings.

Edible coatings are attractive strategies for blueberries postharvest preservation. In this work, carvacrol/alginate coatings were developed for application on Andean blueberries. Coating formulations were prepared based on blends of sodium alginate (2% w/v), carvacrol (0%, 0.03%, 0.06% or 0.09%), glycerol, and water and applied to the fruits by dip-coating. Then, the fruits were immersed in a calcium batch to induce a crosslink reaction. Changes in the physicochemical and microbiological characteristics of the blueberries were monitored during 21 days of storage at 4 °C. Coated blueberries were better preserved throughout the 21 days of storage because of their lower respiration rate and water loss, in comparison with the uncoated ones. Besides, the coatings enhanced the appearance and the gloss of the fruits. Control fruits showed a significant decrease in the firmness, while, in the coated fruits, this critical postharvest quality was preserved during the entire storage. Coating formulations with 0.09% of carvacrol was the most effective in preventing mesophilic aerobic bacteria and molds/yeasts growth on the fruits during the storage. Edible carvacrol/alginate coatings can be considered as a useful alternative to complement the benefits of refrigerated storage by delaying post-harvest spoilage of Andean blueberries.

Alginate-Edible Coatings for Application on Wild Andean Blueberries (Vaccinium meridionale Swartz): Effect of the Addition of Nanofibrils Isolated from Cocoa By-Products.

Edible coatings and films are appealing strategies for the postharvest management of blueberries. In the current work, alginate and alginate/cellulose nanofibril (CNF) edible coatings crosslinked with calcium chloride were developed for application on Andean blueberry (a promissory wild blueberry). Cocoa by-products were valorized through the isolation of their CNFs, and these were incorporated in the edible coatings. Edible coating formulations were based on blends of alginate (2% w/v), CNFs (0%, 0.1%, or 0.3%), glycerol, and water. In addition, stand-alone films were prepared, and their light and water vapor barrier properties were studied before applying the coating on the fruit surface. The results show that the addition of CNFs caused a significant decrease in the transparency and the water vapor permeability of the alginate films. After applying on the Andean blueberry fruits, the alginate and alginate/CNF coatings enhanced the appearance and the firmness of the fruits. Moreover, they significantly reduced the respiration rate and the water loss of the Andean blueberries throughout the 21 days of refrigerated storage. Alginate and alginate/CNFs coatings may be considered a useful alternative for the delay of the postharvest deterioration of Andean blueberries.

Characterization of Starches Isolated from Colombian Native Potatoes and Their Application as Novel Edible Coatings for Wild Andean Blueberries (Vaccinium meridionale Swartz).

Andean blueberry is a promissory fruit native to South America. The current work aimed to characterize starches isolated from Colombian native potatoes and to evaluate the effect of the application of starch edible coatings on the changes in the physicochemical quality parameters of the Andean blueberry during storage. Starches were isolated from three different potatoes varieties (pacha negra, mora, and alcarrosa) and characterized. Then, starch-based coatings were applied to Andean blueberries, and the changes in their quality parameters were monitored during 12 days of storage. Despite the phenotypical differences in the starch sources used, starches were similar in terms of their granule morphology, amylose content (~19%), crystallinity degree (~46%), and thermal properties. Coatings were able to reduce the gaseous exchange of the fruit, and, thus, the respiration rate of all coated blueberries was ~27% lower compared to the uncoated fruits (p < 0.05) at the end of the storage. While the application of starch coatings did not prevent water loss, all samples reached water loss of up 20%. Besides, the coated fruits showed soluble solids contents ~14% higher compared to the control one, as well as better bright and firmness. The new edible coatings can help add value to the Andean blueberry.

Potato starch-based biocomposites with enhanced thermal, mechanical and barrier properties comprising water-resistant electrospun poly (vinyl alcohol) fibers and yerba mate extract.

Water-resistant electrospun poly(vinyl alcohol) (PVA) mats and a yerba mate extract (YM) were incorporated together within potato starch (PS) matrices to prepare biocomposites (PS-YM/PVA/PS-YM). The thermal, mechanical and barrier properties of the PS-YM/PVA/PS-YM systems were compared with biocomposites without YM (PS/PVA/PS) and, with potato starch films without (PS) and with (PS-YM) the YM extract. Scanning electron microscopy analysis showed that the electrospun mats were fully incorporated into the biocomposites and that the PS/PVA interlayer adhesion was only slightly affected by the addition of the extract. Infrared spectra analysis confirmed that this behavior was due to the lower amount of hydroxyl groups available in the biocomposites. As compared with the other systems, the PS-YM/PVA/PS-YM biocomposites exhibited better light- and water vapor barrier properties. Moreover, the presence of the electrospun PVA core layer and the YM extract caused an increase of around 60% in the elastic modulus of these materials.

A simple green route to obtain poly(vinyl alcohol) electrospun mats with improved water stability for use as potential carriers of drugs.

Poly(vinyl alcohol) (PVA) is a hydrophilic, biocompatible and nontoxic polymer. However, because of its low water-resistance, some applications for PVA-based materials are limited (e.g., drug delivery systems and wound dressings). In the current work, PVA mats containing tetracycline hydrochloride (TC) were successfully developed by electrospinning. In order to improve the water stability of the systems, the cross-linking of the PVA matrix was induced by citric acid (CA) addition together with heating treatments (150°C or 190°C for 3min). TC presence led to a strong increase in the electrical conductivity of the blends and as a result, fibers with about 44% lower diameter (270nm) than that of the corresponding unloaded mats (485nm) were obtained. Laser scanning confocal microscopy images indicated that TC was well distributed along the PVA nanofibers. The mats were evaluated by FTIR, which revealed chemical interactions between PVA hydroxyl groups and CA carboxylic ones. The treatment at 150°C for 3min proved to be the more suitable for the preparation of TC-containing mats with improved water resistance, maintaining the TC antimicrobial activity against both Escherichia coli and Staphylococcus aureus almost unaltered. These mats showed a burst release of TC, giving around 95% of the drug within the first hour of immersion in water.

Release of yerba mate antioxidants from corn starch-alginate capsules as affected by structure.

Encapsulation of yerba mate (Ilex paraguariensis) extract in a proper matrix enhances the possible applications of this natural antioxidant in food systems. To start, calcium alginate capsules were used as carriers of yerba mate extract and a filler material (corn starch at 2%) was added to the alginate matrix to improve the structural properties and to modulate the release of the active compounds. Next, kinetics and swelling mechanisms involved in the release of yerba mate polyphenols in simulated digestive fluids were analyzed. A lower rate of release was obtained with calcium alginate-starch capsules as compared to control ones, which was attributed to the lower porosity of filled capsules. The release profiles of both systems were satisfactorily fitted with semi-empirical models, which indicated that a combined mechanism of polymer-chain relaxation and diffusion was taking place.

Effect of starch filler on calcium-alginate hydrogels loaded with yerba mate antioxidants.

A liquid extract of yerba mate (Ilex paraguariensis), with antioxidant properties was encapsulated in calcium-alginate hydrogels containing corn starch as filler at different concentrations. Hydrogel beads were characterized for morphological and size aspects, encapsulation efficiency, Fourier Transform Infrared Spectrometry (FT-IR) and thermal behavior. Addition of starch improved the encapsulation efficiency from 55 to 65%. In vitro release of polyphenols was analyzed in model gastric and intestinal media. The recovery of encapsulated polyphenols occurred mainly in the simulated gastric fluid (85%). Kinetics and release mechanism were satisfactorily fitted to semi-empirical models. The incorporation of starch filler (2 g/100 mL) in calcium alginate hydrogels modified the release profile of polyphenols in acidic medium. In calcium alginate beads, a release mechanism combining erosion and diffusion was observed. Whereas, for polyphenols release of starch loaded beads, only diffusion was relevant.