Estudio de la recuperación de compuestos bioactivos de salvado de trigo mediante extracción enzimática y con mezclas etanol-agua

Abstract

El salvado de trigo es un residuo valorizable debido a que presenta un alto contenido en compuestos fenólicos y una fracción proteica rica en albúminas, prolaminas y glutelinas. El objetivo del trabajo fue estudiar la recuperación de las fracciones polifenólica y proteica del salvado de trigo utilizando como agentes de extracción distintos biocatalizadores enzimáticos y diferentes mezclas etanol-agua, así como analizar el efecto de la temperatura y del contacto ultrasónico en su liberación a la fase extracto. Finalmente, se realizó un estudio comparativo de identificación y cuantificación de los principales tipos de compuestos polifenólicos extraídos y del perfil de aminoácidos de la fracción proteica recuperada en las diferentes condiciones de extracción utilizadas.

This final degree project shows the experimental results of the recovery of bioactive substances from wheat bran using enzyme biocatalysts and ethanol-water mixtures as extraction agents. Wheat bran (WB) was selected because it is an abundant by-product of wheat flour processing, containing 13-19% high quality proteins with a wide variety of biological functions and 4-8% polyphenolic compounds with antioxidant and anti-tumour activity. Ultrasound-assisted extraction and bath extraction were employed as the extraction techniques. The enzyme biocatalyst was cellulose and a binary mixture of xylanase (40%) and protease (60%). Ethanol-water solutions were mixtures from 0 wt.% to 100 wt.% ethanol. Different extraction tests were carried out in order to analyse the effect of extraction agent and extraction technique on the recovery degree of the polyphenolic and protein fractions from leaf WB, granulated WB and powdered WB. The extraction results were quite similar, with minor differences, for the three types of WB examined. A faster recovery of polyphenols was obtained by ultrasonic-assisted extraction, compared to bath extraction for all WB and extraction agents. The best recovery of the polyphenolic and protein fractions was obtained by using the xylanase-protease mixture. Gallic acid and ferulic acid have been identified as the main phenolic compounds in WB extracts, with the identification of vanillinic acid and syringic aldehyde in all extracts from powdered WB. In addition, the protein recovery was similar in the three WB types, with high proportion of essential amino acids. This amino acid results have confirmed the high food quality of recovered proteins. It can be concluded that the effect of cellulase enzyme and ethanol did not improve the recovery of the polyphenolic and protein fractions in either case. However, ethyl ferulate was the main polyphenolic compound in all ethanol-water WB extracts.