Characteristics of Collagen Skin and Scales of Lattice Monocle Bream, Purple-Spotted Bigeye and Threadfin Bream as Gelatin Ingredients

Abstract

The by-product of the fish fillet industry for lattice monocle bream, purple-spotted bigeye and threadfin bream, are only used as an ingredient for animal feed although it can be used as a source of collagen and gelatin. The hydroxyproline content forming collagen along with the properties of collagen protein is not yet available, so research is done. This study was aimed to determine the selected skin type as a gelatin material by taking into account the characteristics of the skin and scales of lattice monocle bream, purple-spotted bigeye, threadfin bream, and hydroxyproline content as a collagen marker. The experimental design used at the deproteination stage used a Randomized Block Design (RBD) with three factors where the first factor was the type of fish consisting of three levels (lattice monocle bream, purple-spotted bigeye and threadfin bream), the second factor was the soaking time of NaOH 12 levels (2; 4; 6; 8; 10; 12; 14; 16; 18; 20; 22; 24) hours, the third factor of the skin type is three levels (skin, scales, scaly skin), The experimental design in this study was analyzed by statistic with ANOVA and Duncan’s advanced test. The results showed that the deproteinization optimization time of NaOH immersion started from 14-20 hours depending on the type of fish and the raw materials, effectively eliminated non-collagen proteins. The area of collagen tissue in histology test preparations was ±95.136,16 µm² highest in the scaly skin of the purple-spotted bigeye associated with the highest protein content in purple-spotted bigeye scaly skin of 21.20±0.18% (wet basis) 56.17±0.12% (dry basis). The skin type had a molecular weight in the range of 10 to 105 kDa. The raw material contains protein which is sarcoplasmic protein, myofibrils and collagen containing connective tissue, so the raw material can be used as a gelatin producer. The scaly skin of purple spotted bream has the highest hydroxyproline than other skin types of 0.0888 µg/µL, so it can be determined as the selected skin types.