Optimization of fish gelatin drying processes and characterization of its properties

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 \textdegreeC for 12.35 h. Infrared radiation at 70 \textdegreeC for 2.0 h and convective drying at 70 \textdegreeC 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 authors are thankful for the Coordination for the Improvement of Higher Education Personnel (CAPES), the Provost’s Office of Research and Graduate Studies (PROPESP) of UFPA and at National Council for Scientific and Technological Development (CNPq), case 469101/2014-8. Enrique Pino-Hernández acknowledges the European Social Fund (call NORTE-69-2015-15) by the financial support provided through fellowship NORTE-08-5369-FSE-000036.info:eu-repo/semantics/publishedVersio

Characterization and Evaluation of Filmogenic, Polymeric, and Biofilm Suspension Properties of Cassava Starch Base (Manihot esculenta Crantz) Plasticized with Polyols / Caracterização e Avaliação das Propriedades Filmogénicas, Poliméricas e de Suspensão de Biofilme da Base de Amido de Mandioca (Manihot esculenta Crantz) Plastificado com Polióis

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. Keywords: Biofilms, starch, polyols, gelatinization, crystallinity. RESUMOEste estudo investigou o processo de gelatinização de suspensões poliméricas de amido de mandioca (Manihot esculenta Crantz) plastificado com glicerol ou etileno glicol e utilizado na produção de biofilme. A microscopia eletrônica de varredura confirmou que o amido, usado como matéria-prima para suspensões, consiste em torrões formadores de grânulos e agregados granulares. Parâmetros físicos como viscosidade, densidade e temperatura podem ser avaliados e utilizados para caracterizar e identificar com precisão o ponto de gelatinização do amido poliol plastificado. Ao atingir o ponto de gelatinização, as suspensões foram submetidas a retrogradação e tiveram uma viscosidade cinética de 19 a 23,508 mPa · s para a suspensão de amido-glicerol e 13,56 a 16,12 mPa · s para a suspensão de amido-etileno-glicol. No entanto, a densidade das suspensões diminuiu ligeiramente durante esse processo, variando de 1,01 a 0,98 g / cm3. O biofilme de amido-glicerol era mais maleável e resistente, enquanto o biofilme de amido-etileno-glicol era inflexível e quebradiço. O uso de diferentes polióis facilitou a modificação da capacidade de solubilização dos biofilmes. O biofilme de amido-glicerol apresentou um valor de solubilidade três vezes maior que o do biofilme de amido-etileno-glicol. 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.