Transforming Fish Waste into a Green Gold Treasure

Ever wondered what happens to the skin of yellowfin tuna after it's caught? Turns out, this seemingly useless waste could be a goldmine for gelatin production. Gelatin is a widely used ingredient in food, pharmaceuticals, and cosmetics, and fishes like tuna are packed with collagen, the main protein in gelatin. Enzymatic hydrolysis is an eco-friendly way to extract gelatin, but it’s pricey. So, scientists decided to boost its efficiency using ultrasound pre-treatment, which works by creating tiny bubbles (cavitation) that enhances the breakdown of collagen. In this study, researchers explored how different factors like ultrasound amplitude, pre-treatment duration, enzyme concentration, and hydrolysis duration affect the gelatin yield. They also aimed to find the best conditions for this process. The research follows three main steps: first, they screened the factors one at a time; then, they used a response surface methodology with a Box-Behnken design to optimize the extraction process; and finally, they characterized the gelatin.Preliminary screening showed that pre-treatment should last between 5 to 25 minutes, enzyme concentration should be between 1 to 3%, and hydrolysis should run for 1 to 5 hours. They then conducted 15 experiments focusing on yield, viscosity, and gel strength. The sweet spot for efficiency turned out to be 25 minutes of pre-treatment, 1% enzyme concentration, and a hydrolysis time of 2. 17 hours. This combination yielded a stunning 64. 08% of gelatin, with a viscosity of 9. 29 mPa·s and a bloom gel strength of 166. 28. The resulting gelatin was quite the all-rounder! It had good emulsifying properties with an Emulsifying Activity Index (EAI) of 50. 5 m²/g and Emulsifying Stability Index (ESI) of 23. 80 minutes. It also showed excellent water and oil retention, coming in at 192% and 406%, respectively. The antioxidant activity was 60. 16%, and the molecular weight ranged between 17-160 kDa. Amino acid-wise, it was rich in glycine (29. 26%) and proline (18. 26%), and had a high digestibility rate of 76. 95%. This method not only makes the gelatin extraction process more efficient but also aligns with sustainable practices. By making use of what would otherwise be waste, it supports a more eco-friendly industry.