Physico-chemical Properties Gelatin from Bone of Pangasius sutchi Extracted with Citrus Fruits

This research was extracted gelatin from the bones of Pangasius catfish without any chemical interventions. This research is expected to substitute unsafe chemicals and reduce fishery and agriculture waste with respect to sustainable, eco-friendly, and environmental concerns. This research was done by three steps, i.e., gelatin extraction (pre-treatment and main extraction), gelatin identification, and physicochemical analysis for the selected treatment. The pre-treatment used four types of Citrus fruits marked as Citrus A, B, C, and D for 24, 36, 48, and 56 hours. Then continued with the main extraction on the water at 45, 55, 65, and 75 oC for 5 h. As a result, through Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE) molecular weight identification, the gelatin was successfully extracted using Citrus C D. The fish gelatin contains 1.61-3.83 g/100 g protein and 0.67-1.69 g/100g hydroxyproline. The gelatin yield was 6.26%, the gel strength of 451 g, the hardness of 10.33 N, the cohesiveness of 0.95, springiness of 1.46 mm, gumminess of 9.81 N, and chewiness of 14.32 N. Viscosity and pH of gelatin solution which obtained were 3.17 cP and 4.42 respectively. The proximate characteristics are moisture 8.81%, ash 1.12%, crude protein 58.47%, and fat 4.13%.

Pangas pond culture in Bangladesh.

Culture of indigenous pangas (Pangasius pangasius) started in 1945 in Khulna region and was dependent on natural fish fry. Exotic Thai pangas (Pangasius hypophthalmus, previously Pangasius sutchi) was introduced to Bangladesh in 1990 from Thailand by the Department of Fisheries. Induced breeding of Thai pangas was introduced by the Bangladesh Fisheries Research Institute in 1993. Pangas is omnivorous. It can tolerate a wide range of physico-chemical parameters. The survival rate of Thai pangas is 85-95% with a production rate of 20-30 t ha-1 yr-1. Both mono and polyculture are practiced in Bangladesh. Recently, cage culture of pangas has been introduced.

Radical-Scavenging Activity of Fish Gelatin Hydrolysates from Bone of Pangasius catfish (Pangasius sutchi) by Microbial Proteases Hydrolysis

The gelatin extracted from the bone of Indonesian Pangasius sutchi was hydrolyzed using two proteases, namely protease Lactobacillus plantarum S31, which isolating from bekasam (an Indonesian fermented fish product) and flavourzyme (a commercial enzyme from Aspergillus oryzase). The concentrations of enzymes for hydrolysis were 1% and 6% based on enzyme/substrate [E/S] ratio. The bioactivity of the hydrolysates as an antioxidant was measured based on their capacity to inhibit 1,1-diphenyl-2-picylhydrazyl (DPPH). The ascorbic acid or vitamin C in the range 50–150 ppm was used as positive controls. The result showed that the bioactivities of all hydrolysates were increased compared to gelatin before hydrolysis. The hydrolysates have a percent of inhibition range that higher than the ascorbic acid. The hydrolysates of gelatin derived from the bone of Pangasius sutchi would be a potential source as raw material for bioactive peptides production with antioxidant activity.

Effect of Pre-Treatment on Physical Properties and Sensory Attributes of Gelatin Extracted from Sutchi Catfish (Pangasius sutchi) Skin

This study was conducted to evaluate the effect of pre-treatment on fishy flavor and odor removal of gelatin extracted from sutchi catfish (Pangasius sutchi) skin. Pre-treatment of the skin involved soaking at 4°C in distilled water (GC), lime followed by tamarind (GLT) or salt followed by activated carbon (GSC) prior to extraction in warm distilled water (50°C) for 12 hrs. Yield, physical properties and sensory were determined. Results showed that GLT produced highest yield (19.72%) compared to GSC (15.01%) and GC (15.81%). Although, GLT exhibited lowest gel strength (282.29g), viscoelasticity (14.1ºC) and setting point (10.46ºC) compared to other pre-treatments, fishy flavor and odor of the gelatin were almost absent obtaining the score of 1.68 and 1.74, respectively. These values were below those of reference which are 1.87 (fishy flavor) and 2.71 (fishy odor) denoting from ‘absent to weak’. Since fishy flavor and odor were almost absent, soaking sutchi catfish skin in lime followed by tamarind could be a good method to obtain gelatin with the desired sensory attributes.