Uso potencial de taninos como antimicrobianos naturales

Abstract

[ES] En el presente estudio, se han evaluado las propiedades antimicrobianas de tres taninos comerciales extraídos de uva blanca, tinta y de madera de roble. Para ello, se caracterizaron los taninos disponibles según su cantidad de taninos condensados y taninos totales mediante los métodos HCl-Vainillina y de Folin-Ciocalteau, respectivamente. A continuación, se evaluaron las concentraciones mínimas inhibitorias de cada tanino para las bacterias Escherichia Coli y Listeria innocua mediante el método MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide). También se evaluaron las concentraciones mínimas inhibitorias de los taninos para los hongos Aspergillus niger y Botrytis cinerea mediante recuentos en placa. Por último, se realizó una aplicación de los taninos en diferentes alimentos (salmón y naranja) para evaluar su posible potencial como antimicrobiano en alimentos. Los resultados mostraron que el tanino de uva blanca presentó el mayor contenido en taninos totales, del orden de 82,491 ± 4,749 (mg fenoles GAE/ g de tanino comercial) y el tanino de uva tinta, el que mayor tanino condensados presentó, en torno a 10,767 ± 0,063 g tanino condensado CE/g de tanino comercial) Todos los taninos en estudio presentaron actividad antibacteriana y antifúngica in-vitro, siendo mayor para el tanino Wh, extraído de uva blanca. Para este tanino, se obtuvieron MIC¿s de 12,5; 6,0; 5,0 y 2,0 mg tanino/ml de medio de cultivo para E.Coli, L.monocitogenes, Aspergillus niger y Botrytis cinérea, respectivamente.

[EN] In the present study, the antimicrobial properties of three commercial tannins extracted from white and red grapes and oak wood were evaluated. Firstable, tannins were characterized in terms of quantity of condensed and total tannin contents, by using HCl-Vainillin and Folin-Ciocalteau methods, respectively. Secondly, the minimum inhibitory concentration (MIC) of tannins against two bacteria, Escherichia coli and Listeria innocua bacteries, by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) method was evaluated. Also, the minimum inhibitory concentration of tannins against two fungus, Aspergillus niger and Botrytis cinerea, by using the plate count method, was evaluated. Finally, a practical application of the tannins to different foodstuff (oranges and salmon) was carried out to evaluate their potential antimicrobial activity in order to contribute to food preservation. The results showed that white grape tannins on trial had the major amount of total tannins, on the order of 82,491 ± 4,749 (mg phenols GAE/ g commercial tannin) and red grape tannin, the one with most condensed tannins, around 10,767 ± 0,063 (g condensed tannins CE/g commercial tannin). All tannins on study had antimicrobial activity, being highest for Wh tannin, extracted form white grape. For this tannin, MIC¿s obtained were 12,5; 6,0; 5,0 y 2,0 mg tannin/ml broth culture for E.Coli, L.monocitogenes, Aspergillus niger and Botrytis cinérea, respectively.