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.