Re-extraction, Recovery, and Characteristics of Skin Gelatin from Farmed Giant Catfish

This study was aimed to investigate the re-extraction process for gelatin recovery from the skin of farmed giant catfish. The first extraction was done by incubating the acid-treated fish skin at 45 A degrees C for 12 h. The remnant was re-extracted at temperatures of 60-90 A degrees C for 1-12 h. The gelatin yield of the first extraction was 10.14%, while the re-extraction at high temperature provided higher recovery (19.5%). Low band intensity of alpha(1) and alpha(2) chains of gelatin was observed when it was re-extracted at high temperature for a longer time. The absorption bands of amide I and II from both extracted gelatins were similar. Low-transition temperature with high transition enthalpy of gelatin extracted at 90 A degrees C was observed. The obtained results suggested that the re-extraction process could be applied as a supplemental step for other sources to obtain high recovery with the desired properties.