A study of the antioxidant capacity of oak wood used in wine ageing and the correlation with polyphenol composition

The antioxidant capacity of oak wood used in the ageing of wine was studied by four different methods: measurement of scavenging capacity against a given radical (ABTS, DPPH), oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP). Although, the four methods tested gave comparable results for the antioxidant capacity measured in oak wood extracts, the ORAC method gave results with some differences from the other methods. Non-toasted oak wood samples displayed more antioxidant power than toasted ones due to differences in the polyphenol compositon. A correlation analysis revealed that ellagitannins were the compounds mainly responsible for the antioxidant capacity of oak wood. Some phenolic acids, mainly gallic acid, also showed a significant correlation with antioxidant capacity

Degradation of pesticides by the ligninolytic enzyme Laccase : optimisation of in vitro conditions, immobilisation and screening for natural mediators

Pesticides are widely used in many industries but the majority reaches non-target organisms or locations through point or diffuse sources. Understanding conditions for their degradation is therefore important. The degradation of glyphosate, its metabolite AMPA and isoproturon using the ligninolytic enzyme laccase was studied. Optimisation of in vitro conditions were tested with findings indicating that factors such as altering pH and the concentrations of both manganese and redox mediators can impact degradation giving insight into optimal conditions. A method of encapsulation was used showing it is possible to immobilise laccase suggesting a possibility of its suitability as a co-formulation agent in pesticide applications. The immobilised laccase was applied in a laboratory scale experiment to investigate degradation of glyphosate and AMPA in soil and sand. The findings showed an apparent ability of the encapsulated laccase to be liberated and have an effect on glyphosate degradation, although much work still remains in this area. In the final part of this project ligninolytic substrates were screened for natural and easily extractable mediators. Extracts were used to check enzymatic activity and degradation potential. Candidates that showed promising results included extracts from hemp and wheat

Escobajos de la vid como fuente de compuestos fenólicos con propiedades antioxidantes

Winemaking industry generates considerable amounts of bunch stems that are usually wasted despite their potential value as source of bioactive compounds. Phenolic profiles and antioxidant capacity (AC) of bunch stem extracts from eight grape varieties of Vitis vinifera L. were determined. Sixteen phenolic compounds (PC) were quantified by high performance-liquid chromatography-diode array detection (HPLC-DAD). The maximum concentrations corresponded to the flavanols (+)-catechin (6462 μg g-1 DW) and procyanidin B1 (1987 μg g-1 DW), followed by the hydroxycinnamic acid caftaric acid (2967 μg g-1 DW). Naringin, myricetin and OH-tyrosol were identified for the first time in grape bunch stems. Total phenolic content (TPC) of extracts, assessed as gallic acid equivalents (GAE), ranged between 47 and 125 mg GAE g-1 DW. The AC of extracts was appraised by ORAC, ABTS and DPPH assays, with a good correlation between TPC and AC when measured by ABTS and DPPH (r ≥ 0.92), while for ORAC the correlation was lower (r ≤ 0.41). Samples of cv. Malbec, the most representative variety of Argentina, presented the highest contents in PC, particularly flavanols. The results showed that grape bunch stems may be an inexpensive, sustainable and high value source of bioactive compounds as functional ingredients.La industria vitivinícola genera cantidades considerables de escobajo que generalmente se desperdician a pesar de su valor potencial como fuente de compuestos bioactivos. En este trabajo se determinaron los perfiles fenólicos y capacidad antioxidantes (CA) de extractos de escobajo de ocho variedades diferentes de Vitis vinífera L. Se cuantificaron 16 compuestos fenólicos (PC) utilizando cromatografía líquida de alta resolución acoplada a detector de arreglo de diodos (HPLC-DAD). Las concentraciones más elevadas obtenidas correspondieron a los flavanoles (+)-catequina (6462 μg g-1 peso seco) y procianidina B1 (1987 μg g-1 peso seco), seguido del ácido caftárico (2967 μg g-1 peso seco). La naringenina, miricetina y OH-tirosol fueron identificados por primera vez en escobajos. El contenido total de compuestos fenólicos (TPC) de los extractos determinado con equivalentes de ácido gálico (GAE) presentó valores entre 47 y 125 mg GAE g-1 peso seco. La CA de los extractos fue determinada mediante las técnicas ORAC, ABTS y DPPH, evidenciando una buena correlación entre TPC y la CA medida mediante ABTS y DPPH (r ≥ 0,92), mientras que para ORAC la correlación fue más baja (r ≤ 0,41). La muestra de variedad más representativa de Argentina, cv. Malbec, presentó los mayores niveles de PC, particularmente flavanoles. Los resultados evidencian que los escobajos pueden ser una fuente económica, sostenible y de alto valor de compuestos bioactivos para su utilización como ingredientes funcionales.Fil: Ferreyra, Susana Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Bottini, Ambrosio Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentina. Universidad "Juan Agustín Maza"; ArgentinaFil: Fontana, Ariel Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin

The electron donating capacity of biochar is dramatically underestimated

Biochars have gathered considerable interest for agronomic and engineering applications. In addition to their high sorption ability, biochars have been shown to accept or donate considerable amounts of electrons to/from their environment via abiotic or microbial processes. Here, we measured the electron accepting (EAC) and electron donating (EDC) capacities of wood-based biochars pyrolyzed at three different highest treatment temperatures (HTTs: 400, 500, 600 °C) via hydrodynamic electrochemical techniques using a rotating disc electrode. EACs and EDCs varied with HTT in accordance with a previous report with a maximal EAC at 500 °C (0.4 mmol(e−).gchar−1) and a large decrease of EDC with HTT. However, while we monitored similar EAC values than in the preceding study, we show that the EDCs have been underestimated by at least 1 order of magnitude, up to 7 mmol(e−).gchar−1 for a HTT of 400 °C. We attribute this existing underestimation to unnoticed slow kinetics of electron transfer from biochars to the dissolved redox mediators used in the monitoring. The EDC of other soil organic constituents such as humic substances may also have been underestimated. These results imply that the redox properties of biochars may have a much bigger impact on soil biogeochemical processes than previously conjectured

Assay of the antioxidant capacity of foods using an iron(II)-catalysed lipid peroxidation model for greater nutritional relevance

The formation of free radicals by the iron-catalysed Fenton reaction is a major cause of oxidative damage in the body. Here a common assay of antioxidant capacity, inhibition of the β-carotene-linoleic acid model of lipid peroxidation, has been modified by the addition of ferrous iron (final concentration 36 μmol/l), which makes the rate of oxidation of the lipids occur twenty-five times faster. Such an assay can simulate the oxidative damage to membrane lipids and low density lipoproteins occurring in the body in the presence of free iron. It thus may be nutritionally more relevant than traditional chemical assays of antioxidant capacity, as it measures pre-emptive antioxidant activity, i.e. activity which prevents free radicals being formed in the first place. Pre-empting their formation is likely to be more protective than scavenging of free radicals. The relative antioxidant activity of some food products found using this new assay was very different from that found using a radical-scavenging assay. Vitamin C, at 280 mg/l, was found to be sixty times better than blackcurrant puree in scavenging free radicals, but only one eighth as good as the blackcurrant puree in preventing iron-catalysed lipid peroxidation

Metal oxide nanoparticle based electrochemical sensor for total antioxidant capacity (TAC) detection in wine samples

A single-use electrochemical screen-printed electrode is reported based on biomimetic properties of nanoceria particles (CeNPs). The developed tool showed an easy approach compared to the classical spectrophotometric methods reported in literature in terms of ease of use, cost, portability, and unnecessary secondary reagents. The sensor allowed the detection of the total antioxidant capacity (TAC) in wine samples. The sensor has been optimized and characterized electrochemically and then tested with antioxidant compounds occurred in wine samples. The electrochemical CeNPs modified sensor has been used for detection of TAC in white and red commercial wines and the data compared to the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS)-based spectrophotometric method. Finally, the obtained results have demonstrated that the proposed sensor was suitable for the simple and quick evaluation of TAC in beverage samples

Phenolics extraction from sweet potato peels: modelling and optimization by response surface modelling and artificial neural network

Sweet potato peels (SPP) are a major waste generated during root processing and currently have little commercial value. Phenolics with free radical scavenging activity from SPP may represent a possible added-value product for the food industry. The aqueous extraction of phenolics from SPP was studied using a Central Composite Design with solvent to solid ratio (30-60 mL g(-1)), time (30-90 min) and temperature (25-75 A degrees C) as independent variables. The comparison of response surface methodology (RSM) and artificial neural network (ANN) analysis on extraction modelling and optimising was performed. Temperature and solvent to solid ratio, alone and in interaction, presented a positive effect in TPC, ABTS and DPPH assays. Time was only significant for ABTS assay with a negative influence both as main effect and in interaction with other independent variables. RSM and ANN models predicted the same optimal extraction conditions as 60 mL g(-1) for solvent to solid ratio, 30 min for time and 75 A degrees C for temperature. The obtained responses in the optimized conditions were as follow: 11.87 +/- 0.69 mg GAE g(-1) DM for TPC, 12.91 +/- 0.42 mg TE g(-1) DM for ABTS assay and 46.35 +/- 3.08 mg TE g(-1) DM for DPPH assay. SPP presented similar optimum extraction conditions and phenolic content than peels of potato, tea fruit and bambangan. Predictive models and the optimized extraction conditions offers an opportunity for food processors to generate products with high potential health benefits

Effect of thermal treatment and storage on bioactive compounds, organic acids and antioxidant activity of baobab fruit (Adansonia digitata) pulp from Malawi

Bioactive compounds of baobab (Adansonia digitata) pulp from Malawi were investigated. The effect of thermal treatment and storage on selected quality attributes of the juice was also evaluated. Organic compounds were analysed by HPLC; total phenol content (TPC) and total antioxidant activity (FRAP, ABTS and DPPH) were measured by spectrophotometry. Malawi baobab pulp contains high levels of procyanidin B2 (533 ± 22.6 mg/100 g FW), vitamin C (AA + DHA) (466 ± 2.5 mg/100 g FW), gallic acid (68.5 ± 12.4 mg/100 g FW) and (−)-epicatechin (43.0 ± 3.0 mg/100 g FW) and showed a maximum TPC of 1.89 × 103 ± 1.61 mg GAE/100 g FW. The maximum antioxidant activity was 2.81 × 103 ± 92.8 mg TEAC/100 g FW for FRAP, 1.52 × 103 ± 17.1 mg TEAC/100 g FW for ABTS and 50.9 ± 0.43% DPPH for DPPH. Thermal pasteurisation (72 °C, 15 s) retained vitamin C which further showed extended half-life under refrigeration temperature (6 °C). Procyanidin B2, (−)-epicatechin, TPC and antioxidant activity fluctuated during storage. Antioxidant activity was significantly correlated (p ≤ 0.05) with bioactive compounds and TPC

Chemical–physical characteristics, polyphenolic content and total antioxidant activity of three Italian-grown pomegranate cultivars

Background In Mediterranean countries, there is an increasing demand for pomegranate fruits due to their antioxidant properties and nutritional values. The large diffusion of new genotypes and cultivars requires the knowledge of all fruit characteristics in connection with the cultivation area, to satisfy the market demand. This study seeks to determine the fruit quality attributes and nutraceutical values of three pomegranate cultivars (Wonderful, Acco and Kamel) grown in the Mediterranean climate. Methods The fruits were evaluated for their main physico-chemical traits (weight, volume, height, width, thickness, total arils number, total arils weight, juiciness, fruit index, peel index and total soluble solids content/titratable acidity ratio), bioactive compounds (total phenolic content and total anthocyanin content) and antioxidant activities (radical scavenging activity and ferric reducing power). Results: The data showed that Acco fruit is bigger, juicier and sweeter when compared with the cultivars Wonderful and Kamel. Wonderful is the smallest, least juicy and least sweet but the reddest among all the studied cultivars. Regarding the phenolic compounds and antioxidant activity (radical scavenging activity and ferric reducing power), cultivar Wonderful has the highest values and cultivar Acco contains the most anthocyanin content. Conclusions This study showed that pomegranate cultivars grown in the Mediterranean area exhibit an appreciable quality, but there are significant differences in quality properties of the arils and juice