# Physicochemical and Functional Properties of Skipjack Tuna (Katsuwonus pelamis) Bone Gelatin Extracted at Different Temperatures

## TL;DR

This study examines how different extraction temperatures affect the quality of gelatin from skipjack tuna bones, finding that lower temperatures produce better gelatin for food and medicine.

## Contribution

The study provides new insights into the optimal extraction temperature for high-quality gelatin from skipjack tuna bones.

## Key findings

- Gelatin extracted at 80 °C had the highest gel strength and antioxidant activity.
- Higher extraction temperatures increased yield but reduced gel strength and stability.
- Lower extraction temperatures produced smoother and tighter gelatin microstructures.

## Abstract

In this study, we produced gelatin from Skipjack tuna (Katsuwonus pelamis) bone. We used three heating levels to obtain the gelatin (80 °C, 90 °C, 100 °C), and its physicochemical and gel characteristics were thoroughly examined. The results revealed that the extraction temperature significantly affected the yield, gel strength, amino acid composition, antioxidant activity, and microstructure of the gelatin. Gelatin obtained at 80 °C yielded 6.53% with peak gel strength (59.72 ± 4.67 g), whereas the gelatin extracted at 100 °C had the highest yield (23.24%) but the lowest gel strength (13.71 ± 3.78 g). Fourier transform infrared (FTIR) scans of gelatin derived at different temperature levels showed subtle changes in the amide region, but all the samples presented the characteristic absorption peaks of gelatin. An amino acid analysis showed high glycine (18.51%) and proline (13.45%) contents in the gelatin. Antioxidant tests revealed that gelatin obtained at 80 °C displayed the greatest scavenging effects on DPPH, hydroxyl, and ABTS radicals. Scanning electron microscopy (SEM) revealed that the gelatin made with lower temperatures showed a smoother and tighter microstructure. Rheological analyses revealed that higher extraction temperatures resulted in lower gel temperatures and melting temperatures and weaker gel network stability. The results of this study suggest that lower extraction temperatures are more suitable for the preparation of high-quality skipjack tuna bone gelatin, which gives scientific support for its application in food and medicine.