Efeito do sorbitol em relaxação estrutural de filmes de gelatina em estado vítreo

The objective of this work was to study the effect of sorbitol on the kinetic of enthalpy relaxation of gelatin films stored at temperatures below the glass transition temperature (Tg). Bovine gelatin and sorbitol films were prepared by cold casting method. Sorbitol was added at weight fraction (Qs) of 0.0, 0.06 and 0.10. Films were equilibrated in environment of 44% relative humidity using a saturated salt solution of potassium carbonate, giving a moisture weight fraction in samples (Qw) of 0.18, 0.16 and 0.18 respectively. Enthalpy relaxation (∆H) was measured by differential scanning calorimetry (DSC). Tg values of the samples tested were observed at 48ºC (Qs=0.0), 35ºC (Qs=0.06) and 30ºC (Qs=0.10). After the thermal history deletion (30ºC above Tg, 15 minutes), samples were annealed from 2 to 80 hours at 10ºC below Tgonset. The addition of sorbitol showed a significant reduction (p<0.05) in structural relaxation kinetic. The linearization of relaxation enthalpy (∆H) versus log of annealing time showed a reduction of the slope in samples plasticized with sorbitol. The reduction in structural relaxation kinetic could be related to the effect of molecular packing by the presence of polyol in polymer matrix as has been recently reported by Positron Annihilation Spectroscopy (PALS).O objetivo deste estudo foi avaliar o efeito do sorbitol sobre a cinética da relaxação estrutural de películas de gelatina armazenadas a temperatura inferior a temperatura de transição vítrea (Tg). Filmes de gelatina bovina e sorbitol foram preparados por moldagem a frio. O sorbitol foi adicionado em fracções de peso (QS), de 0,0, 0,06 e 0,10. Os filmes foram acondicionados em atmosfera de humidade relativa constante (44%), utilizando uma solução saturada de carbonato de potássio, obtendo-se de frações de teor de humidade de peso (Qw) de 0,18, 0,16 e 0,18, respectivamente. A entalpia de relaxação (DH) foi determinada por Calorimetria Diferencial de Varrimento (DSC). As amostras usadas neste estudo apresentaram valores de Tg de 48°C (Qs = 0,0), 35ºC (Qs = 0,06) e 30ºC (Qs = 0,10). Após eliminar historial térmico (30°C a Tg, 15 minutos), as amostras foram armazenadas isotermicamente a 10°C sob Tgonset entre 2 e 80 horas. A adição de sorbitol produziu uma redução significativa (p <0,05) na cinética da relaxação estrutural. A linearização do valor de entalpia de relaxação (DH) versus o logaritmo do tempo de armazenamento apresentou uma redução do declive nas amostras plastificados com sorbitol. A redução da cinética de relaxamento poderia estar relacionada com o efeito de empaquetamiento molecular associado à presença de polióis em matrizes em estado vítreo recentemente relatado pela espectroscopia de positroês (PALS).El objetivo de este trabajo fue evaluar el efecto del sorbitol sobre la cinética de relajación estructural de películas de gelatina almacenadas bajo la temperatura de transición vítrea (Tg). Películas de gelatina de bovino y sorbitol fueron preparadas mediante casting en frío. El sorbitol fue agregado en fracciones en peso (Qs) de 0,0, 0,06 y 0,10. Las películas fueron acondicionadas en un ambiente de humedad relativa constante (44%) utilizando una solución saturada de carbonato de potasio, obteniéndose fracciones de contenido de humedad en peso (Qw) de 0,18, 0,16 y 0,18 respectivamente. La entalpía de relajación (∆H) fue determinada mediante Calorimetría Diferencial de Barrido (DSC). Las muestras utilizadas en este estudio presentaron valores de Tg de 48ºC (Qs=0,0), 35ºC (Qs=0,06) y 30ºC (Qs=0,10). Luego de eliminar el historial térmico (30ºC sobre Tg, 15min), las muestras fueron almacenadas isotérmicamente a 10ºC bajo Tgonset entre 2 y 80 horas. La adición de sorbitol produjo una reducción significativa (p<0,05) en la cinética de relajación estructural. La linealización del valor de entalpía de relajación (∆H) en función del logaritmo del tiempo de almacenamiento mostró una reducción de la pendiente en las muestras plastificadas con sorbitol. La reducción en la cinética de relajación estaría relacionada con el efecto de empaquetamiento molecular asociado a la presencia de polioles en matrices en estado vítreo recientemente reportada mediante espectroscopía de positrones (PALS)

Efeito do sorbitol em relaxação estrutural de filmes de gelatina em estado vítreo

The objective of this work was to study the effect of sorbitol on the kinetic of enthalpy relaxation of gelatin films stored at temperatures below the glass transition temperature (Tg). Bovine gelatin and sorbitol films were prepared by cold casting method. Sorbitol was added at weight fraction (Qs) of 0.0, 0.06 and 0.10. Films were equilibrated in environment of 44% relative humidity using a saturated salt solution of potassium carbonate, giving a moisture weight fraction in samples (Qw) of 0.18, 0.16 and 0.18 respectively. Enthalpy relaxation (∆H) was measured by differential scanning calorimetry (DSC). Tg values of the samples tested were observed at 48ºC (Qs=0.0), 35ºC (Qs=0.06) and 30ºC (Qs=0.10). After the thermal history deletion (30ºC above Tg, 15 minutes), samples were annealed from 2 to 80 hours at 10ºC below Tgonset. The addition of sorbitol showed a significant reduction (p<0.05) in structural relaxation kinetic. The linearization of relaxation enthalpy (∆H) versus log of annealing time showed a reduction of the slope in samples plasticized with sorbitol. The reduction in structural relaxation kinetic could be related to the effect of molecular packing by the presence of polyol in polymer matrix as has been recently reported by Positron Annihilation Spectroscopy (PALS).O objetivo deste estudo foi avaliar o efeito do sorbitol sobre a cinética da relaxação estrutural de películas de gelatina armazenadas a temperatura inferior a temperatura de transição vítrea (Tg). Filmes de gelatina bovina e sorbitol foram preparados por moldagem a frio. O sorbitol foi adicionado em fracções de peso (QS), de 0,0, 0,06 e 0,10. Os filmes foram acondicionados em atmosfera de humidade relativa constante (44%), utilizando uma solução saturada de carbonato de potássio, obtendo-se de frações de teor de humidade de peso (Qw) de 0,18, 0,16 e 0,18, respectivamente. A entalpia de relaxação (DH) foi determinada por Calorimetria Diferencial de Varrimento (DSC). As amostras usadas neste estudo apresentaram valores de Tg de 48°C (Qs = 0,0), 35ºC (Qs = 0,06) e 30ºC (Qs = 0,10). Após eliminar historial térmico (30°C a Tg, 15 minutos), as amostras foram armazenadas isotermicamente a 10°C sob Tgonset entre 2 e 80 horas. A adição de sorbitol produziu uma redução significativa (p <0,05) na cinética da relaxação estrutural. A linearização do valor de entalpia de relaxação (DH) versus o logaritmo do tempo de armazenamento apresentou uma redução do declive nas amostras plastificados com sorbitol. A redução da cinética de relaxamento poderia estar relacionada com o efeito de empaquetamiento molecular associado à presença de polióis em matrizes em estado vítreo recentemente relatado pela espectroscopia de positroês (PALS).El objetivo de este trabajo fue evaluar el efecto del sorbitol sobre la cinética de relajación estructural de películas de gelatina almacenadas bajo la temperatura de transición vítrea (Tg). Películas de gelatina de bovino y sorbitol fueron preparadas mediante casting en frío. El sorbitol fue agregado en fracciones en peso (Qs) de 0,0, 0,06 y 0,10. Las películas fueron acondicionadas en un ambiente de humedad relativa constante (44%) utilizando una solución saturada de carbonato de potasio, obteniéndose fracciones de contenido de humedad en peso (Qw) de 0,18, 0,16 y 0,18 respectivamente. La entalpía de relajación (∆H) fue determinada mediante Calorimetría Diferencial de Barrido (DSC). Las muestras utilizadas en este estudio presentaron valores de Tg de 48ºC (Qs=0,0), 35ºC (Qs=0,06) y 30ºC (Qs=0,10). Luego de eliminar el historial térmico (30ºC sobre Tg, 15min), las muestras fueron almacenadas isotérmicamente a 10ºC bajo Tgonset entre 2 y 80 horas. La adición de sorbitol produjo una reducción significativa (p<0,05) en la cinética de relajación estructural. La linealización del valor de entalpía de relajación (∆H) en función del logaritmo del tiempo de almacenamiento mostró una reducción de la pendiente en las muestras plastificadas con sorbitol. La reducción en la cinética de relajación estaría relacionada con el efecto de empaquetamiento molecular asociado a la presencia de polioles en matrices en estado vítreo recientemente reportada mediante espectroscopía de positrones (PALS)

Natural food colorant from blackcurrant spray-dried powder obtained by enzymatic treatment: Characterization and acceptability

Blackcurrant juice extraction was optimized by enzymatic maceration. A Box–Behnken experimental design was used considering the effect of enzyme concentration, temperature, and treatment time over the total polyphenolic content (TPC), antioxidant capacity (AC), and juice yield. Under the obtained optimal conditions (200 ppm enzyme, 45°C and 60 min), a 2.4-fold increment for TPC, 2.8-fold for AC, and 2.7-fold for total monomeric anthocyanins (ACY) were observed, along with a 15% increase in juice yield. The juice was spray-dried and the powder was tested as an ingredient in a jelly dessert. An attractive color product was obtained, also containing blackcurrant bioactive compounds (0.56 ± 0.03 mg GA/g, 0.20 ± 0.02 mg cyd-3-glu/g and 0.16 ± 0.02 mg of GA/g for TPC, ACY, and AC, respectively). This jelly was stable regarding syneresis and antioxidant compounds for 15 days at 4°C. The developed blackcurrant powder could be useful as natural colorant and source of bioactive compounds for several food applications. Practical applications: An efficient extraction process of blackcurrant juice by enzymatic treatment of ground fruit was achieved. As a result of the process, it was possible to improve the extraction of bioactive compounds and also increasing antioxidant activity. A fruit juice powder was obtained from the enriched juice by spray-drying. The blackcurrant powder showed relatively good physical characteristics and potential functional properties. The use of this powder as a natural colorant in a jelly dessert showed promising results. The ingredient not only enriched the product with bioactive components, but also provided a stable and attractive color. Moreover, the gel properties were improved and the jelly showed very good acceptance in the consumer’s perception test. These results prove that this ingredient has good potential to be used as natural colorant and functional additive in food.Fil: Toscano Martínez, Hernando. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Gagneten, Maite. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; ArgentinaFil: Díaz Calderón, Paulo. Universidad de Los Andes, Chile; ChileFil: Enrione, Javier. Universidad de Los Andes, Chile; ChileFil: Salvatori, Daniela Marisol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Schebor, Carolina Claudia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Quimicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Quimicos.; ArgentinaFil: Leiva, Graciela Edith. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; Argentin

Rheological and Thermal Study about the Gelatinization of Different Starches (Potato, Wheat and Waxy) in Blend with Cellulose Nanocrystals

The goal of this work was to analyze the effect of CNCs on the gelatinization of different starches (potato, wheat and waxy maize) through the characterization of the rheological and thermal properties of starch–CNC blends. CNCs were blended with different starches, adding CNCs at concentrations of 0, 2, 6 and 10% w/w. Starch–CNC blends were processed by rapid visco-analysis (RVA) and cooled to 70 °C. Pasting parameters such as pasting temperature, peak, hold and breakdown viscosity were assessed. After RVA testing, starch–CNC blends were immediately analyzed by rotational and dynamic rheology at 70 °C. Gelatinization temperature and enthalpy were assessed by differential scanning calorimetry. Our results suggest that CNCs modify the starch gelatinization but that this behavior depends on the starch origin. In potato starch, CNCs promoted a less organized structure after gelatinization which would allow a higher interaction amylose–CNC. However, this behavior was not observed in wheat and waxy maize starch. Insights focusing on the role of CNC on gelatinization yielded relevant information for better understanding the structural changes that take place on starch during storage, which are closely related with starch retrogradation. This insight can be used as an input for the tailored design of novel materials oriented towards different technological applications

Characterization and Testing of a Novel Sprayable Crosslinked Edible Coating Based on Salmon Gelatin

The aim of this study was to develop and characterize a sprayable edible coating using salmon gelatin (SG) and its stabilization by photopolymerization using riboflavin (Rf). Suspensions of SG with Rf at pH values of 5.0 and 8.5 were exposed for 2 min to visible light (VL) and ultraviolet (UV) light and further characterized to determine structural changes of the different gelatin formulations. Rheology analysis showed that at pH 5, the loss modulus (G″) was higher that the storage modulus (G’) for crosslinked samples (VL and UV light). However, at pH 8.5 G’ values increased over G″, showing a strong crosslinking effect. Interestingly both moduli did not intersect at any point and their maximum values did not change upon cooling with respect to the gelatin suspension without light exposure, demonstrating that triple helix formation was not affected by the reaction. In fact, neither the gelation temperature nor the enthalpy values were significantly affected. Viscosity measurements confirmed the hydrogel formation using VL, showing higher viscosity values after exposure at increasing temperatures. Transmittance (T%) measurements showed an increase in T% in the suspensions after VL exposure, with only a 10% decrease compared to SG without riboflavin. For validation, the coating was sprayed in fresh salmon fillets, showing a 37% delay in spoilage and reduced weight loss. Therefore, photopolymerization of low viscosity gelatins would allow to manage viscoelasticity of the biomaterial stabilizing it as coating and preventing the deterioration of salmon fillets

Effect of adding curcumin on the properties of linseed oil organogels used as fat replacers in pâtés

Beeswax-based organogels were formulated with linseed oil and curcumin according to a statistical design to increase the oxidative stability of spreadable meat products (pate) where these organogels (OGCur) were incorporated as fat substitutes. The organogels obtained under optimal conditions (9.12% beeswax, 0.54% curcumin) showed a mechanical strength similar to pork backfat determined by back extrusion and high oil binding capacity (OBC; over 90%). The incorporation of curcumin at this concentration did not lead to any change in the arrangement of the crystal network, OBC, and mechanical, thermal, or rheological properties of the organogels. Beeswax organogels with and without curcumin, with a beta' orthorhombic subcell structure, showed a predominant elastic behavior and a melting event wider and shifted to lower temperatures than pure beeswax, suggesting a plasticizer effect of the oil in the wax crystals. The oxidative stability of the organogels under accelerated oxidation conditions increased due to the incorporation of curcumin. A decrease in the curcumin content was found from day 4 at 60 degrees C, together with a significantly lower formation of both peroxides and malonaldehyde. When pork backfat was partially or totally replaced by OGCur in pates, a noticeable protective effect of curcumin against lipid oxidation was found during chilled storage.ANID (Fondecyt Project), Chile 1180885 1171595 ANID (ANID/PIA/ACT), Chile 19214

Cold-adaptation of a methacrylamide gelatin towards the expansion of the biomaterial toolbox for specialized functionalities in tissue engineering

© 2019 Elsevier B.V.Tissue regeneration is witnessing a significant surge in advanced medicine. It requires the interaction of scaffolds with different cell types for efficient tissue formation post-implantation. The presence of tissue subtypes in more complex organs demands the co-existence of different biomaterials showing different hydrolysis rate for specialized cell-dependent remodeling. To expand the available toolbox of biomaterials with sufficient mechanical strength and variable rate of enzymatic degradation, a cold-adapted methacrylamide gelatin was developed from salmon skin. Compared with mammalian methacrylamide gelatin (GelMA), hydrogels derived from salmon GelMA displayed similar mechanical properties than the former. Nevertheless, salmon gelatin and salmon GelMA-derived hydrogels presented characteristics common of cold-adaptation, such as reduced activation energy for collagenase, increased enzymatic hydrolysis turnover of hydrogels, increased interconnected polypepti