Efecto de un pretratamiento alcalino-térmico y de irradiación con electrones acelerados en la obtención enzimática de queratina hidrolizada.

Abstract

Around 90 % of feathers correspond to keratin, a protein that, in water-soluble form, has many applications. In this study, an enzymatic process was established to obtain hydrolyzed keratin from chicken feathers; also, the effect of two types of pretreatments on the amount of the recovered protein was studied. The feathers were washed, dried, ground, and irradiated with a dose of 25 kGy. The feather meal was immersed in a 0.5 M NaOH solution and autoclaved for 2 min, at 95 °C. After centrifuging, the protein in the supernatant was quantified through the Biuret method, and the solid fraction was used in the hydrolysis with alcalase, trypsin, or bromelain. The enzyme that allowed the recovery of the highest amount of protein was selected for the evaluation of the effect of the pretreatments, which consisted of the hydrolysis with the chosen enzyme from feather meal without any pretreatment (SIN), with irradiation only (IR), with the alkaline-thermal pretreatment only (AT), and with both processes (IRAT). Finally, Raman analyzes were done on the irradiated and non-irradiated feather meals, and on the aqueous sample corresponding to the best treatment. The highest amount of protein (p ≤ 0.05) was achieved with alcalase, and the lowest values were obtained with bromelain. The global yield of the IRAT treatment followed by the enzymatic hydrolysis was 90.71 %. In the Raman spectra, bands corresponding to characteristic groups of the keratin structure were observed in both feather meals and in the soluble protein sample.