Frente al constante aumento de la temperatura a nivel global y al progresivo avance del cambio climático, se ha hecho cada vez más común en el mundo vitivinícola la producción de vinos con un nivel de grado alcohólico más elevado. Esto se debe a la constante alza en los niveles de azúcar en la uva, al momento de la cosecha, materia prima de la elaboración del vino. Este estudio buscó evidenciar los resultados de los parámetros químicos y sensoriales de dos tratamientos de adición de agua creciente al mosto de uva, con el fin de disminuir los sólidos solubles de éste, mediante una dilución y así obtener una menor graduación alcohólica en el posterior vino. Para la realización de este estudio, se utilizaron mostos de uva, provenientes de un cv. Chardonnay, del valle de Curicó. Se llevaron a cabo 2 tratamientos con la adición de 5% y 10% de agua, además del tratamiento control, el cual no tuvo adición de agua. Los resultados reflejaron una disminución el grado alcohólico en ambos tratamientos. Sin embargo, el tratamiento donde se añadió un 5% dio como resultado vinos con menores cambios en sus atributos sensoriales y componentes químicos, tales como, fenoles de bajo peso molecular, compuestos volátiles y polisacáridos. En cambio, en el tratamiento con un 10% de adición de agua se observaron como resultado vinos con una mayor disminución de su grado alcohólico (-12,4%). No obstante, se evidenció, una significativa alteración de sus atributos sensoriales, específicamente en los atributos de carácter gustativo como la untuosidad y persistencia, los vinos generados de este tratamiento presentaron menor complejidad y preferencia de parte los consumidores. Estos resultados indican la posibilidad de reducir el grado alcohólico en vinos mediante una adición controlada de agua en el mosto, no obstante, algunos atributos sensoriales y químicos podrían verse alterados levemente. Esta práctica podría ser una buena alternativa de adaptación frente al escenario climático que enfrenta la vitivinicultura hoy en día, siempre y cuando se tenga en cuenta el impacto que podría producir en el vino resultante. | Faced with the constant increase in global temperature and the progressive advance of climate change, the production of wines with a higher alcoholic level has become increasingly common in the wine world. This is due to the constant rise in sugar levels in grape at the time of harvest, raw material of wine processing. This study sought to demonstrate the results of the chemical and sensory parameters of two treatments of increasing water addition to the grape must, in order to decrease the soluble solids of it, by a dilution and thus obtain a lower alcoholic gradation in the subsequent wine. For this study, were used grape musts from a cv. Chardonnay, in the Curicó valley. Two treatments were carried out with the addition of 5% and 10% water, in addition to the control treatment, which had no addition of water. The results reflected a decrease in the alcohol level in both treatments. However, the treatment where 5% was added resulted in wines with lesser changes in their sensory attributes and chemical components, such as, low molecular weight phenols, volatile compounds and polysaccharides. In contrast, in the treatment with a 10% addition of water were observed as a result wines with a greater decrease in their alcoholic degree (-12.4%). however, a significant alteration of their sensory attributes was shown, specifically in the attributes of a tasty character such as unctuosity and persistence, the wines generated by this treatment presented less complexity and preference on the part of consumers. These results indicate the possibility of reducing the alcoholic degree in wines by controlled addition of water to the must, however, some sensory and chemical attributes may be slightly altered. This practice could be a good alternative to adapting to the climate scenario facing wine-growing today, provided that the impact it could have on the resulting wine is taken into account. | Versión original del autor

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.