Effect of various extraction systems on the antioxidant activity kinetic and color of extracts from purple corn

The purpose of this study was to investigate the effect of extraction systems on the anthocyanin index, antioxidant kinetics (DPPH-radical scavenging capacity) and color of purple corn (Zea mays) seeds. The factors studied were: extraction system (methanol, 100%, 80%, 60%, 40, 20% v/v) using hydrochloric acid as a means of acidifying. Tristimulus colorimetry was applied to evaluate quantitatively and qualitatively the process. The estimated effect and ANOVA parameters were calculated. The anthocyanins index in different extraction systems was between 1.09 to 2.87 mg/g. The highest anthocyanin index was obtained at an extraction system of 100% methanol. To determine their radical scavenging capacity, the second-order rate constant for the oxidation of these extraction systems measured by the DPPH (1,1-diphenyl-2-picrylhydrazyl radical) method, ranged from 1.19x10-2 to 1.27x10-2 (mg/mL)-1(s-1). The greatest second-order rate constant was obtained at an extraction system of 60% methanol. Regarding the simple regressions analysis the anthocyanin index showed a better relationship with CIELAB parameters: (L*; r =-0.928, p < 0.05), (a*; r = 0.982, p < 0.01), (b*; r = 0.927, p < 0.05), (C*ab; r = 0.9793, p < 0.01) and (hab; r = -0.936, p < 0.05). However, the correlation existing between color parameters and the second-order rate constant did not show a good relationship. When multiple linear regression analysis were applied considering the angular coordinates (L*, C*ab, hab) as independent variable values, a R2 nearing 1 was obtained for anthocyanins index. While a value of R2 = 0.63 was obtained for the second-order rate constant

Aplicación de técnicas de imagen para la evaluación de la madurez fenólica de semillas de uva

Quality of wine depends fundamentally on the condition of the components of grapes at the moment of harvest. In this respect, their seeds directly affect to structure, astringency, stability, and indirectly to colour of wine. In this work, the grape seeds have been evaluated by techniques of image analysis. In all cases, the methodology was developed trying to entail the minimum sample preparation and maximum quickness of the method, and as far as possible, substitute the chemical analysis that usually involves long and tedious processes that hamper monitoring of ripening in a rapid way. The proposed methodology for measuring and evaluating colour and near infrared spectrum has yielded satisfactory results for estimating the ripening of grape seeds, and it has been useful for establishing stages of ripeness from their optical features.La calidad del vino depende en gran medida del estado en que se encuentren los diferentes componentes de la uva en el momento de la recolección y, en este sentido, las semillas afectan directamente a su astringencia, así como a la estructura y estabilidad del color del vino. En el presente trabajo se han evaluado semillas de uva de diferentes variedades aplicando distintas técnicas de análisis de imagen. En todos los casos se han desarrollado metodologías que implican la mínima preparación de muestra y la máxima rapidez del método, con el objeto de poder sustituir, en la medida de la posible, el análisis químico, que suele suponer largos y tediosos procesos que impiden un seguimiento rápido de la maduración. La metodología propuesta para la medición y evaluación del color y el espectro infrarrojo cercano ha dado resultados satisfactorios en la estimación del estado de madurez de las semillas de uva, y ha sido útil para establecer etapas de maduración a partir de sus propiedades ópticas.Ministerio de Economía y Competitividad AGL2008-05569-C02-02, AGL2011-30254-C02-02 y AGL2014-58486-C2-2-

Application of tristimulus colorimetry in the stability assessment of anthocyanin-rich extracts from Colombian tropical fruits

El uso de la colorimetría triestímulo permitió evaluar la estabilidad del color de los extractos enriquecidos en antocianinas (AREs) de cuatro frutas tropicales Colombianas: motilón, coral, uva de árbol y mora pequeña, a diferentes valores de pH y durante un periodo de almacenamiento de un mes. Se encontró que el color de todos los extractos variaba con el pH y fue estable a pH ácido. El extracto más estable fue de la uva de árbol (M. cauliflora) debido a las menores variaciones en el croma.The use of tristimulus colorimetry allowed evaluating the color stability of anthocyanin-rich extracts (AREs) of four Colombian tropical fruits: motilón, coral, uva de árbol and mora pequeña, at different pH values and through one month of storage. The color of all extracts changed with pH and was stable at acid pH. Uva de árbol (M. cauliflora) extract was the more stable due to fewer variations in chroma

Impact of alternative protein fining agents on the phenolic composition and color of Syrah red wines from warm climate

Currently, the wine industry has an increasing interest in developing alternative solutions to traditional animal proteins fining agents. In this study, the impact of different protein fining agents on the turbidity, phenolic composition and color of 2-month and 12-month Syrah red wines was assessed. Wines fined with egg albumin and plant-based proteins from potato, pea, and grape seed as recent alternative, were compared to unfined control wines. Changes on turbidity, phenolic composition and color (by Differential Colorimetry) showed that animal and plant proteins differed in their clarifying efficiency and ability to interact with colorless phenolics and anthocyanins, depending on the age of wine, with important consequences on color quality and stability. Plant proteins showed lower effectiveness to reduce wine turbidity than egg albumin but modified in different way the phenolic composition, inducing lower color differences with respect to control wine and similar stability, especially potato and grape seed proteins. © 2020 Elsevier LtdMinisterio de Economía y Competitividad (MINECO). España AGL2017-84793-C

Revalorization of Colombian purple corn Zea mays L. by-products using two-step column chromatography

Colombian purple corn Zea mays L. by-products have been chemically characterized. To achieve this, after Amberlite XAD-7 purification and Sephadex LH-20 fractionation, the accurate anthocyanin and flavonol profile using UHPL-DAD-ESI-MS, total monomeric anthocyanin (TMA), polyphenols using Folin-Ciocalteau reduction capacity (FCRC), and antioxidant activity (DPPH and TEAC) of each fraction were performed. Cob and leaves illustrated a more complete flavonoid profile and a higher content of anthocyanins and flavonols, strongly related to the highest reducing power and radical scavenging activity compared to grains. Furthermore, the most antioxidant fractions corresponded to the higher molecular weight compounds. The cob and leaves were enriched in cyanidin-3-O-glucoside, cyanidin-3-O-malonyl-hexoside, and peonidin-3-O-glucoside, peonidin-3-O-(6′'-malonyl-glucoside). The purification and fractionation allowed us to establish the chemical and antioxidant characterization, and the resulting revalorization, of purple corn by-products for the first time, and to have available pure fractions of Zea mays L. for a wide diversity of industries

Application of multivariate statistical analyses to the study of factors affecting white wine volatile composition

The influence of different storage conditions on the volatile composition of young white wine was evaluated during 1 year of storage. The wine was bottled and stored under different conditions of temperature, position and illumination. During storage, a significant increase in total content esters (mainly due to the increase in ethyl butyrate, ethyl acetate and diethyl succinate) and total content acids was detected. Also total content alcohols and carbonyl compounds decreased during storage. Storage time, temperature and illumination have a significant effect on esters content, whereas carbonyl compounds are affected by temperature, and alcohols content is affected by illumination. Stepwise linear discriminant analysis was applied to the experimental data. The results showed that the samples were well classified as a function of storage temperature. On the other hand, a certain trend was observed when the wine samples were classified according to storage time. The samples corresponding to two and four months of storage were well differentiated from the rest

Aplicación de la nefelometría espectral a la medida simultánea del color y la turbidez en aceites de oliva obtenidos por distinto grado de clarificación

Se ha estudiado la utilidad de la nefelometría espectral en la medida simultánea del color y turbidez en aceites de oliva virgen extra. Se han considerado 25 aceites, cada uno de ellos con 6 niveles de turbidez diferente, sobre los que se han realizado medidas nefelométricas y gonioespectrofotométricas (0º, 30º, 60º y 90º). Los resultados ponen de manifiesto dificultades en las medidas por transmisión a ángulos superiores a 30º. Se concluye que existe una fuerte dependencia entre la turbidez y la variación de claridad L*10 entre 0º y 30º, que no pudo ser confirmada para el ángulo de tono hab,10 ni para el croma C*ab,10.Consejería de Innovación, Ciencia y Empresa de la Junta de Andalucía: proyectos IAC07-I-1664 y P06-AGR-01744Ministerio de Educación y Ciencia (España): Proyecto FIS2007-6426

Effect of time and storage conditions on major volatile compounds of zalema white wine

Changes in quality attributes during bottled storage of white wine were studied. Different storage conditions, temperature, bottle position and exposure to light were studied over 1 year and their effects on major volatile compounds were evaluated. Ethyl lactate and diethyl succinate contents increased after 12 months of storage, whereas isoamyl acetate decreased over this period. The analysis of variance revealed that the temperature had a statistically significant effect on most volatile compounds studied. Multivariate statistical techniques (specifically principal component analysis and linear discriminant analysis) confirmed that temperature is the most important factor, so the samples were distributed into two groups according to storage temperature. A rough differentiation among wines according to the length of storage was also obtained using linear discriminant analysis

Proteomic and computational characterisation of 11S globulins from grape seed flour by-product and its interaction with malvidin 3-glucoside by molecular docking

Grape seed flour by-product (GSBP) is an economic and renewable source of proteins, increasingly being explored due to interesting technological application such as colour protection in rich-anthocyanins beverages. Globulin-like proteins from GSBP were characterised by proteomic and computational studies. MALDI TOF/TOF analysis revealed the presence of two 11S globulins (acid and basic), whose 3D structures have been elucidated for the first time in Vitis vinifera L. grape seeds by using homology models and molecular dynamics. The secondary structure showed 11 α-helices and 25 β-sheets for acid and 12 α-helices and 24 β-sheets for basic 11S globulins. Molecular docking results indicate that both grape seed 11S globulins could establish different types of non-covalent interactions (π-π) with malvidin 3-O-glucoside (wine anthocyanin), which suggest a possible colour protection similar to that occurring in copigmentation phenomenon. These findings provide valuable information of globulin family proteins that could be relevant in food industry applications.España Ministerio de Economía y Competitividad (Project AGL2017- 84793-C2 and FPI grant PRE2018-087184)Programa Operativo FEDER 2014-2020/Consejería de Economía y Conocimiento de la Junta de Andalucía (Project US-1261752

Impact of a post-fermentative maceration with overripe seeds on the color stability of red wines

With the purpose of modulating the copigmentation equilibria of red wines, an environmentally sustainable process was performed based on post-fermentative addition of overripe seeds (OS). Simple (SW) and double (DW) addition were performed to produce different enrichment of phenolics from seeds, hence different copigmentation/polymerization ratios. The determination of the phenolic composition showed different global increases in OS-macerates wines (catechin, epicatechin, gallic acid and procyanidins B1 and B2). The double post-maceration (DW) was more effective than the simple post-maceration addition to improve the phenolic structure of wines. The application of Differential Tristimulus Colorimetry could assess the effects of this practice on the color characteristics and stability of wines. Results highlighted that both simple and double assays underwent colorimetric improvements against the control wines (CW, no seeds addition). DW led to the highest chromatic stability, showing lower lightness, higher chroma values and bluish hues than CW. This color difference was visually detectable. © 2018 Elsevier LtdMinisterio de Economía y Competitividad (MINECO). España AGL2014-58486-C2-2-