Abstract
Salmon skin is a byproduct from the fish processing industry that can be used as a potential source of collagen. Due to the presence of other constituents, pretreatment of the skin is required prior to the preparation of the acid-soluble collagen (ASC) solution and film. This study aimed to investigate the effects of ultrasonication amplitudes (50% and 70%) and times (5, 10, and 15 min) on the properties and characteristics of ASC solutions and films. The ASC solutions had higher elastic behavior when ultrasonication at a lower amplitude and a shorter time was used. Films from solutions ultrasonicated at 50% amplitude had a higher thickness, tensile strength, elongation at break, and water vapor barrier property than films from solutions ultrasonicated at 70% amplitude, regardless of the ultrasonication time used. A longer ultrasonication time decreased the L* value but increased the transparency value. The FTIR spectra indicated that structural modifications were affected by the ultrasonication conditions used. The SEM images showed a continuous surface for all the films. Higher amplitudes and longer times reduced the thermal stability and crystallinity, respectively, as determined by differential scanning calorimetry and thermogravimetric analysis as well as X-ray diffraction. Therefore, ultrasonication at 50% amplitude for 10 min was suitable for producing films with satisfactory mechanical and water vapor barrier properties.