Decolourising isinglass derived from aqua-farmed sturgeon by sonication

Isinglass derived from the swim bladder of wild-caught sturgeon has been used extensively in conservation as an adhesive and consolidant. It is favoured for its durability, clarity and mild preparation. Overfishing of wild sturgeon has led to a dramatic population decline, with international trade restrictions being placed on sturgeon and their body parts. As such conservators have turned to sustainably aqua-farmed sturgeon for their isinglass needs. These farmed fish produce a notably more coloured swim bladder, which is possibly due to increased fat levels which produce yellow-brown isinglass. Sonication of aqua-farm derived swim bladder pieces in a range of common studio solvents was explored and found to show good potential as a method of quickly reducing yellow colouration. The difference in colour between lenses was quantified using Commission Internationale de L’Éclairage L*a*b* (CIELAB) ΔE*ab values.