Effect of pretreatment conditions and bleaching on physico-chemical and functional properties of gelatin prepared from cuttlefish skin

Gelatin was extracted from the skin of cuttlefish Sepia pharaonis after pretreatment with sodium hydroxide (NaOH) and bleaching with hydrogen peroxide (H2O2) for varying durations. The extracted gelatin was lyophilised and quality characteristics were assessed. There was a significant increase (15.5-17.1%) in the yield of gelatin extracted from skin treated with 5% H2O2 for 24 h when compared to control samples. Viscosity of the gelatin samples were in the range of 3.76-6.54 cP which can be considered to be in the mid-range since viscosities for commercial gelatin have been reported to be in the range 2.0-7.0 cP. Bleaching the skin with H2O2 significantly improved the bloom strength of extracted gelatin. Maximum bloom strength was obtained for gelatin extracted from skin bleached for 48 h (133-140 g) whereas it was only in the range of 22-28 g for gelatin from unbleached skins. Gelatin from treated skin samples had significantly higher L* values in the range of 90.4-92.8 than control samples indicating superior white colour. Functional properties viz., foaming and fat binding properties were also significantly improved by bleaching. Gelatin extracted from the ventral skin of cuttlefish after bleaching with H2O2 exhibited characterestics of Type B gelatin with desirable functional properties suitable for commercial utilisation. The skin of cuttlefish, which is considered to be an environmental hazard as a processing waste has the potential to yield good quality gelatin.