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Antioxidant and antihypertensive properties from muscle hydrolysates of farm rainbow trout
1 , 2 , 2 , 3 , 2 , 4 , * 2
1  Departamento de Biotecnología. Universidad Autónoma Metropolitana, Unidad Iztapalapa. División de Ciencias Biológicas y de la Salud. Av. San Rafael Atlixco 186 CP. 09340, Ciudad de México, México. Área Académica de Química. Universidad Autónoma del Estad
2  Área Académica de Química. Universidad Autónoma del Estado de Hidalgo. Ciudad del Conocimiento. Carretera Pachuca-Tulancingo km 4.5 Colonia Carboneras. CP. 42184. Mineral de la Reforma, Hidalgo, México.
3  División de Ciencias y Medio Ambiente. Universidad Intercultural del Estado de Hidalgo. Carretera Tenango a San Bartolo km 2.5. CP. 43480. El Desdaví, Tenango de Doria, Hidalgo, México.
4  Área Académica de Ingeniería de Alimentos. Instituto Tecnológico de Xalapa. 5ta sección de la Reserva Territorial, Colonia Santa Bárbara. CP. 91096. Xalapa de Enríquez, Veracruz, México.
Academic Editor: Arun Bhunia

Abstract:

Aquaculture is an economic activity with worldwide production of 82.1 million tons. A high potential of bioactive peptides from fish sources has been demonstrated but rainbow trout research is scarce and focused mainly on by-products. Thus, the present work aimed to obtain bioactive protein fractions through the enzymatic hydrolysis from the protein muscle of farm rainbow trout. Muscle fillets of trout at the commercial stage (250-300 g) from a local farm were homogenized in a food processor to obtain a uniform paste, which was used for protein content determination by Kjeldahl method. Afterward, trout paste was ultra-frozen at -70°C and freeze-dried at -43°C and 286X10-3 mbar. A lyophilized sample was used to perform suspensions at 5% (p/v) in Tris-HCl buffer (pH= 9), which were hydrolyzed with alcalase, having a mass ratio of 100:10 (soluble protein: enzyme). Enzymatic hydrolysis was carried out at 55°C and sampled at 0, 1, and 2 h, ending it through a boiling water bath for 10 min to inactivate the enzyme. Then, samples were centrifugated and supernatants were used for in vitro determinations of hydrolysis degree, antioxidant capacity, and antihypertensive bioactivity. All last tests were realized by spectrophotometric methodologies, measuring the amine-TNBS complex at 340 nm, DPPH remanent at 515 nm, TPTZ-Fe2+ complex at 595 nm, and hippuric acid presence to determine ACE inhibition at 228 nm. Trout muscle paste exhibited 17.87±0.31% of protein content. The maximum hydrolysis degree was equivalent to 32.64±0.37 mM of glycine. The best time for scavenging and ferric reducing power was at 2 h with 3.69±0.09 µM and 33.98±0.75 mM of Trolox and Fe2+ equivalent, respectively. At the same time, ACE inhibition was only 2.14±0.04%, having the best inhibition (56.43±2.05%) at 1 h. Results showed that antioxidant properties increased with higher hydrolysis time, but antihypertensive bioactivity could be lost.

Keywords: rainbow trout; hydrolysates; antioxidant; antihypertensive
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