Recycling fish skin for utilization in food industry as an effective emulsifier and foam stabilizing agent

Background: Indian fish industry produces a staggering amount of waste every year part of which is dumped as landfill leading to pollution. Objective: This study aims to extract collagen from fish skin, a major component of this waste, hydrolyze it and use the hydrolysate as emulsifiers to increase the shelf life of food products. Materials and methods: Collagen was purified from the skin of Catfish, Mullet and Indian Salmon were characterized through infrared and diffraction studies. The samples were hydrolyzed enzymatically. The hydrolysates were assayed for emulsifying, foam stabilizing and hemolytic properties. Results: The samples displayed an electrophoretic and infrared spectral profile corresponding to that of collagen type I. X-ray diffraction patterns revealed the presence of triple helix and traces of phosphate. The hydrolysates (6 kDa) exhibited the highest emulsion at 2.74 ± 0.20 m2/g (for 57.00 ± 0.50 min) and foam stability in the range of 75-78%, respectively. The hydrolysates were able to stabilize drug and food formulations successfully and two of the samples exhibited less than 3% toxicity as determined through hemolytic assay. Conclusion: Collagen hydrolysates from fish skin, a common fish industry waste, were found to be bioactive and non-toxic making them suitable replacements for synthetic emulsifiers. © 2019 De Gruyter. All rights reserved.