Fish industry residues are used due to their easy transformation into several products and because they have nutrients with high biological value, being rich in proteins and fatty acids, the work was to study the use of the skin of Amazonian fish for gelatin extraction. The gelatin extraction process from the skin of kumakuma (Brachyplatystoma filamentosum) and gilthead bream (Brachyplathystoma rousseauxii) with sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) was optimized and the product was characterized through analyses of yield, gel strength, color, viscosity, amino acid profile, scanning electron microscopy, melting point, foaming capacity, and emulsifying capacity. The optimized conditions established in the process from the skin of kumakuma (Brachyplatystoma filamentosum) with NaOH were 6 h extraction at 58 °C, with yield and gel strength at 19.7% and 244.3 g, respectively. The metod with (Ca(OH)2 the optimized conditions were defined over ten days of pre-treatment at 50 °C. This condition resulted in desirability of 0.965 and yield and gel strength values of 20.24% and 221 g, respectively. Glycine was the main amino acid both in the fish skin (23.77%) and in the gelatin obtained (NaOH - 23,39% e Ca(OH)2 - 24,97%). Pre-treatment with sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) was used and the gelatin the skin of gilthead bream (Brachyplathystoma rousseauxii) with 64 ° C and 6 h extraction. The pretreatment with Ca (OH)2 was for 12 days and 64 °C extraction for 6 hours. When the characteristics of the gelatins obtained were compared, the one that used NaOH had greater (p < 0.05) technological potential due to higher yield, greater amount of imino acids, and better properties (gel strength, viscosity, melting point, emulsifying power). However, the gelatin extracted with Ca(OH)2 had weak gels and lower melting point, which is appropriate for refrigerated products that require low gelling temperatures. It is concluded that the two gelatins obtained can be used in several applications in products according with the characteristic desired.
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