Se prohibe la reproduccion total o parcial de este libro asi como su tratamiento o distribucion i... more Se prohibe la reproduccion total o parcial de este libro asi como su tratamiento o distribucion informatica de alguna forma o por cualquier medio, ya sea electronico, magnetico, mecanico, fotocopia, registro u otros metodos, sin el permiso previo y por escrito del Departamento de Quimica de la Facultad de Ciencias de la Universidad de Los Andes, Merida, Venezuela.
Pterygium is a corneal alteration that can cause visual impairment, which has been traditionally ... more Pterygium is a corneal alteration that can cause visual impairment, which has been traditionally treated with the sap of Sedum dendroideum D.C. The pharmacological effect of a dichloromethane extract of S. dendroideum was demonstrated and implemented in a pterygium model on the healing process of corneal damage caused by phorbol esters. In mice of the ICR strain, a corneal lesion was caused by intravitreal injection of tetradecanoylphorbol acetate (TPA). The evolution of the corneal scarring process was monitored with vehicle, dexamethasone, and dichloromethane extract of S. dendroideum treatments by daily ophthalmic administration for fifteen days. The lesions were evaluated in situ with highlighted images of fluorescence of the lesions. Following treatment levels in eyeballs of IL-1α, TNF-α, and IL-10 cytokines were measured. The effective dose of TPA to produce a pterygium-like lesion was determined. The follow-up of the evolution of the scarring process allowed us to define that...
The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determin... more The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determined. The hydrolysates were produced by treatment of a nontoxic genotype with the digestive enzymes pepsin and pancreatin and then were characterized by fast protein liquid chromatography and reverse phase chromatography. Peptidic fractions with higher radical scavenging activity were analysed by matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant activity was determined by measuring inhibition of the oxidative degradation ofβ-carotene and by measuring the reactive oxygen species (ROS) in Caco-2 cell cultures. Cu2+and Fe2+chelating activities were also determined. The hydrolysates inhibited the degradation ofβ-carotene and the formation of ROS in Caco-2 cells. The lower molecular weight peptidic fractions from FPLC had stronger antioxidant activity in cell cultures compared with the hydrolysates, which correlated with a higher content in antioxidant and chelating...
The objective of this study was to produce and characterize gelatin foamed films using extrusion.... more The objective of this study was to produce and characterize gelatin foamed films using extrusion. Three “optimum” formulations containing tannic acid, nanoclays (Cloisite Na+), glycerol, water, and gelatin, as well as three “controls” without tannic acid and nanoclays were prepared by calendering. Furthermore, the three “optimum” formulations were produced by extrusion film blowing only, since no stable processing conditions could be obtained for the controls. A complete set of sample characterization was performed, including morphological, mechanical, physical, and thermal properties. The results showed that besides the processing method, the thickness was also controlled by the glycerol and water content, leading to density slightly above unity, with higher values for the optimum materials. The calendered films from the optimum formulations showed overall a higher number of cells and cell density than the controls. Higher elastic moduli and tensile strengths were obtained for the ...
Composite flours containing 5%, 10%, 15%, and 20% of chia seed flour and corn were used for torti... more Composite flours containing 5%, 10%, 15%, and 20% of chia seed flour and corn were used for tortilla formulations. The effects of chia powders supplementation on the physicochemical and sensorial characteristics as well as starch digestibility of the tortillas were evaluated. Nutritionally, all chia tortillas had significantly higher levels (P < 0.001) of protein, lipids, and total dietary fibre than the control. The reduced enzymatic starch hydrolysis rate and predicted glycemic index recorded for the chia seed-added tortilla indicated slow digestion features. Sensory evaluation did not show significant (P > 0.05) differences in the attributes among tortillas. Owing to the increase in the total dietary fibre, lower digestion, and predicted glycemic index values, chia seed-added tortilla can be considered as a nutraceutical food. Therefore, the newly developed tortilla supplemented with chia seed flour could represent a valuable staple in improving the nutritional value of the...
The aim of this work was to study the degree of hydrolysis and changes in the apparent viscosity ... more The aim of this work was to study the degree of hydrolysis and changes in the apparent viscosity of casein suspensions as a result of various enzymes addition. Suspensions with 3, 12 and 15 g/100 mL of casein, at pH 5.2, 6.0 and 6.5 were prepared in buffer solutions. Previous ...
Journal of the Science of Food and Agriculture, 2015
Researches about the overall effect of the addition of plasticizers, cross-linking and strengthen... more Researches about the overall effect of the addition of plasticizers, cross-linking and strengthening agents in gelatin film-forming mixtures are very scarce. Also, there are not studies focused on the interactions among their individual components, and neither those showing which sort of effects they might cause altogether. The obtainment of a gelatin film from a composite consisting of tannic acid, bentonite, and glycerol were evaluated. Nine gelatin films were manufactured by the casting method, using these materials, following a 2(3) factorial design with five replicates on the central point. The interactions among gelatin, tannic acid, and bentonite, caused a decrease in hydrogen bonds, while the polar groups of the gelatin chains were less exposed to interactions with water molecules. There was an increase in temperature and enthalpy of gelatin denaturation, due to increasing tannic acid and bentonite concentration. Tactoids were found in the gelatin films, caused mainly by bentonite poly-dispersion. A synergistic effect among tannic acid, bentonite, and glycerol, which overall improved the measured gelatin film properties was found. The best film formulation was that with 40, 150 and 250 g kg(-1) gelatin of tannic acid, bentonite and glycerol respectively, displaying a tensile strength of 38 MPa, an elongation at break of 136%, a water vapor permeability of 1.28x10(-12) g (Pa s m)(-1) and solubility of 23.4%.
The objective of this work was to study, using a calorimetric method, the effect of the starch co... more The objective of this work was to study, using a calorimetric method, the effect of the starch concentration on the phase properties of cassava starch dispersions, prepared using a glycerol solution and pure glycerol. Starch dispersions (SD) were prepared with 10-70 g of starch.100 g –1 of SD using either a 20% glycerol solution (GS) or pure glycerol (PG). These dispersions were analyzed with a differential scanning calorimeter. The water activity of these samples was also determined at 25 °C. At low temperatures the glass transition (Tg) was well defined in samples prepared with 10-50% of starch, but was not so for SDs with 70% starch, for both glycerol solutions. For SD prepared with GS, an increase in starch concentration from 10 to 70% caused a reduction in Tg, but for SD with 10-50% starch and prepared with PG, the Tg remained constant, increasing slightly for samples with 70% starch. This behaviour agreed with that of the water activity, which increased when the starch concent...
Se prohibe la reproduccion total o parcial de este libro asi como su tratamiento o distribucion i... more Se prohibe la reproduccion total o parcial de este libro asi como su tratamiento o distribucion informatica de alguna forma o por cualquier medio, ya sea electronico, magnetico, mecanico, fotocopia, registro u otros metodos, sin el permiso previo y por escrito del Departamento de Quimica de la Facultad de Ciencias de la Universidad de Los Andes, Merida, Venezuela.
Pterygium is a corneal alteration that can cause visual impairment, which has been traditionally ... more Pterygium is a corneal alteration that can cause visual impairment, which has been traditionally treated with the sap of Sedum dendroideum D.C. The pharmacological effect of a dichloromethane extract of S. dendroideum was demonstrated and implemented in a pterygium model on the healing process of corneal damage caused by phorbol esters. In mice of the ICR strain, a corneal lesion was caused by intravitreal injection of tetradecanoylphorbol acetate (TPA). The evolution of the corneal scarring process was monitored with vehicle, dexamethasone, and dichloromethane extract of S. dendroideum treatments by daily ophthalmic administration for fifteen days. The lesions were evaluated in situ with highlighted images of fluorescence of the lesions. Following treatment levels in eyeballs of IL-1α, TNF-α, and IL-10 cytokines were measured. The effective dose of TPA to produce a pterygium-like lesion was determined. The follow-up of the evolution of the scarring process allowed us to define that...
The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determin... more The antioxidant and metal chelating activities inJ. curcasprotein hydrolysates have been determined. The hydrolysates were produced by treatment of a nontoxic genotype with the digestive enzymes pepsin and pancreatin and then were characterized by fast protein liquid chromatography and reverse phase chromatography. Peptidic fractions with higher radical scavenging activity were analysed by matrix-assisted laser desorption/ionization mass spectrometry. The antioxidant activity was determined by measuring inhibition of the oxidative degradation ofβ-carotene and by measuring the reactive oxygen species (ROS) in Caco-2 cell cultures. Cu2+and Fe2+chelating activities were also determined. The hydrolysates inhibited the degradation ofβ-carotene and the formation of ROS in Caco-2 cells. The lower molecular weight peptidic fractions from FPLC had stronger antioxidant activity in cell cultures compared with the hydrolysates, which correlated with a higher content in antioxidant and chelating...
The objective of this study was to produce and characterize gelatin foamed films using extrusion.... more The objective of this study was to produce and characterize gelatin foamed films using extrusion. Three “optimum” formulations containing tannic acid, nanoclays (Cloisite Na+), glycerol, water, and gelatin, as well as three “controls” without tannic acid and nanoclays were prepared by calendering. Furthermore, the three “optimum” formulations were produced by extrusion film blowing only, since no stable processing conditions could be obtained for the controls. A complete set of sample characterization was performed, including morphological, mechanical, physical, and thermal properties. The results showed that besides the processing method, the thickness was also controlled by the glycerol and water content, leading to density slightly above unity, with higher values for the optimum materials. The calendered films from the optimum formulations showed overall a higher number of cells and cell density than the controls. Higher elastic moduli and tensile strengths were obtained for the ...
Composite flours containing 5%, 10%, 15%, and 20% of chia seed flour and corn were used for torti... more Composite flours containing 5%, 10%, 15%, and 20% of chia seed flour and corn were used for tortilla formulations. The effects of chia powders supplementation on the physicochemical and sensorial characteristics as well as starch digestibility of the tortillas were evaluated. Nutritionally, all chia tortillas had significantly higher levels (P < 0.001) of protein, lipids, and total dietary fibre than the control. The reduced enzymatic starch hydrolysis rate and predicted glycemic index recorded for the chia seed-added tortilla indicated slow digestion features. Sensory evaluation did not show significant (P > 0.05) differences in the attributes among tortillas. Owing to the increase in the total dietary fibre, lower digestion, and predicted glycemic index values, chia seed-added tortilla can be considered as a nutraceutical food. Therefore, the newly developed tortilla supplemented with chia seed flour could represent a valuable staple in improving the nutritional value of the...
The aim of this work was to study the degree of hydrolysis and changes in the apparent viscosity ... more The aim of this work was to study the degree of hydrolysis and changes in the apparent viscosity of casein suspensions as a result of various enzymes addition. Suspensions with 3, 12 and 15 g/100 mL of casein, at pH 5.2, 6.0 and 6.5 were prepared in buffer solutions. Previous ...
Journal of the Science of Food and Agriculture, 2015
Researches about the overall effect of the addition of plasticizers, cross-linking and strengthen... more Researches about the overall effect of the addition of plasticizers, cross-linking and strengthening agents in gelatin film-forming mixtures are very scarce. Also, there are not studies focused on the interactions among their individual components, and neither those showing which sort of effects they might cause altogether. The obtainment of a gelatin film from a composite consisting of tannic acid, bentonite, and glycerol were evaluated. Nine gelatin films were manufactured by the casting method, using these materials, following a 2(3) factorial design with five replicates on the central point. The interactions among gelatin, tannic acid, and bentonite, caused a decrease in hydrogen bonds, while the polar groups of the gelatin chains were less exposed to interactions with water molecules. There was an increase in temperature and enthalpy of gelatin denaturation, due to increasing tannic acid and bentonite concentration. Tactoids were found in the gelatin films, caused mainly by bentonite poly-dispersion. A synergistic effect among tannic acid, bentonite, and glycerol, which overall improved the measured gelatin film properties was found. The best film formulation was that with 40, 150 and 250 g kg(-1) gelatin of tannic acid, bentonite and glycerol respectively, displaying a tensile strength of 38 MPa, an elongation at break of 136%, a water vapor permeability of 1.28x10(-12) g (Pa s m)(-1) and solubility of 23.4%.
The objective of this work was to study, using a calorimetric method, the effect of the starch co... more The objective of this work was to study, using a calorimetric method, the effect of the starch concentration on the phase properties of cassava starch dispersions, prepared using a glycerol solution and pure glycerol. Starch dispersions (SD) were prepared with 10-70 g of starch.100 g –1 of SD using either a 20% glycerol solution (GS) or pure glycerol (PG). These dispersions were analyzed with a differential scanning calorimeter. The water activity of these samples was also determined at 25 °C. At low temperatures the glass transition (Tg) was well defined in samples prepared with 10-50% of starch, but was not so for SDs with 70% starch, for both glycerol solutions. For SD prepared with GS, an increase in starch concentration from 10 to 70% caused a reduction in Tg, but for SD with 10-50% starch and prepared with PG, the Tg remained constant, increasing slightly for samples with 70% starch. This behaviour agreed with that of the water activity, which increased when the starch concent...
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