Fish skin is a raw material used for gelatin production. It can satisfy consumers with specific socio-cultural and religious needs. Different technologies have been studied for drying gelatin. Therefore, it is relevant to understand the influence of drying conditions on the final product. This study aims to optimize drying methods such as convection hot air alone and combined with infrared radiation to obtain gelatin from acoupa weakfish skin by using composite central rotational designs 22 and 23 and response surface methodology. The gelatin obtained from the optimized conditions were characterized based on their physical, chemical, technological, and functional properties. The desirability function results show the convection hot air as the most effective method when conducted at 59.14 °C for 12.35 h. Infrared radiation at 70 °C for 2.0 h and convective drying at 70 °C for 3.5 h were the best condition of the combined process. The gelatins obtained had gel strength of 298.00 and 507.33 g and emulsion activity index of 82.46 and 62.77 m2/g in the combined and convective methods, respectively, and protein content above 90%. These results indicate that the processes studied can be used to produce gelatin with suitable technological and functional properties for several applications.
The objective of the present work is to evaluate the antioxidant activity in plants of the genus Croton, in addition to verifying which is the method or more employed. The study is a bibliographic review in the SciFinder database, which did not occur in the period from September to November 2019. 37 articles were selected for the development of the work. To select the forums needed to filter articles containing the keywords "croton" and "antioxidante" combined in languages and English and publication data between January 1959 and August 2019. Many plants of the genus Croton have relatively high antioxidant activity for reduction and prevention of damage caused by free radicals, among them can mention or extract ethanolic Croton cordiifolius, when compared with plants covered in this study, showing the highest IC50 value, being higher than 1000 mg/mL. The lowest value found was extracted for Croton hypoleucus with an IC50 of 0.63 mg/mL, the latter being the best value of the antioxidant activity found in this study. The antioxidant activity in plants of the genus Croton seems to be promising, since all vegetables use the same activity in high quantities. The most used method to determine antioxidant activity was the IC50 method.
Films and coatings based on natural polymers are used to conserve nutritional quality of fruits, vegetables and also delay their ripening. The purpose of this study was to develop films with starch extracted from Dioscorea altissima Lam. (dunguey) incorporated with silver nanoparticles for coating and preserving fruits. The films obtained by cast were characterized visually, by Scanning Electron Microscope, by Atomic Force Microscopy, by X-Ray Diffraction and by Fourier-Transform Infrared Spectroscopy. Antimicrobial activity and technological properties were also evaluated. The coating of camu-camu fruits [Myrciaria dubia (Kunth) McVaugh] was carried out by immersing them in the filmogenic solution, followed by their physicochemical and microbiological analysis. The films with silver nanoparticles showed transparency, flexibility, spherical clusters and a higher average roughness. A reduction in thickness, solubility and water vapor permeability was also observed. Antimicrobial action against Staphylococcus aureus and Escherichia coli was proved as well. The fruits coated with films exhibited delay in ripening, with maintenance of quality and longevity. Uncoated fruits showed greater wilting and wrinkling. The starch film incorporated with silver nanoparticles was effective for preserving camu-camu fruit.
This study investigated the gelatinization process of polymeric suspensions of cassava starch (Manihot esculenta Crantz) plasticized with glycerol or ethylene glycol and used for biofilm production. Scanning electron microscopy confirmed that the starch, used as raw material for suspensions, consists of granule-forming clods and granular aggregates. Physical parameters such as viscosity, density, and temperature can be evaluated and used to accurately characterize and identify the gelatinization point of the polyol-plasticized starch. Upon reaching the gelatinization point, the suspensions went underwent retrogradation and had a kinetic viscosity of 19 to 23.508 mPa•s for the starch-glycerol suspension and 13.56 to 16.12 mPa•s for the starch-ethylene glycol suspension. However, the density of the suspensions slightly decreased during this process, ranging from 1.01 to 0.98 g/cm3. The starch-glycerol biofilm was more malleable and resistant, while the starch-ethylene glycol biofilm was inflexible and brittle. The use of different polyols facilitated the modification of the solubilization capacity of the biofilms. The starch-glycerol biofilm had a solubility value three times higher than that of the starch-ethylene glycol biofilm.
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