Ana Barros

Natural Bioactive Compounds from Winery By-Products as Health Promoters: A Review

The relevance of food composition for human health has increased consumers’ interest in the consumption of fruits and vegetables, as well as foods enriched in bioactive compounds and nutraceuticals. This fact has led to a growing attention of suppliers on reuse of agro-industrial wastes rich in healthy plant ingredients. On this matter, grape has been pointed out as a rich source of bioactive compounds. Currently, up to 210 million tons of grapes (Vitis vinifera L.) are produced annually, being the 15% of the produced grapes addressed to the wine-making industry. This socio-economic activity generates a large amount of solid waste (up to 30%, w/w of the material used). Winery wastes include biodegradable solids namely stems, skins, and seeds. Bioactive compounds from winery by-products have disclosed interesting health promoting activities both in vitro and in vivo. This is a comprehensive review on the phytochemicals present in winery by-products, extraction techniques, industrial uses, and biological activities demonstrated by their bioactive compounds concerning potential for human health.

Effect of cooking on total vitamin C contents and antioxidant activity of sweet chestnuts (Castanea sativa Mill.)

In this work the total vitamin C contents (ascorbic acid+dehydroascorbic acid) and antioxidant activity of raw and cooked chestnuts was evaluated. The vitamin C contents of raw chestnuts varied significantly between the different cultivars (cv) studied and it varied from 400mg/kg dry weight (cv Lada) to 693mg/kg dry weight (cv Martaínha). The different cultivars behave differently during the cooking process concerning the loss of vitamin C. A significant decrease in the vitamin C content of the chestnuts was observed, 25-54% for the boiling process and 2-77% for the roasting process. Boiled and roasted chestnuts can be good sources of vitamin C since it may represent 22.4%, 16.2%, 26.8% and 19.4%, respectively, of the recommended dietary intake for an adult man and woman. The cooking process significantly changed the antioxidant activity of the chestnuts. A difference was observed between the cultivars during the cooking processes, concerning the antioxidant activity. For the raw chestnuts the variation in vitamin C content of the chestnuts explains 99% of the antioxidant activity variation but for the roasted and boiled chestnuts this percentage significantly decreases to 51% and 88%, respectively. Although a high antioxidant activity is still present in the cooked chestnuts, the cause for this antioxidant activity is less dependent on the vitamin C content of the chestnuts, probably due to the conversion of ascorbic acid to dehydroascorbic acid. The increase in gallic acid during the cooking process, presumably transferred from the peels to the fruit, also contributes to the high antioxidant activity observed for the cooked chestnuts.

Discrimination and characterisation of extra virgin olive oils from three cultivars in different maturation stages using Fourier transform infrared spectroscopy in tandem with chemometrics.

A methodology based on Fourier transform infrared (FTIR) spectroscopy, combined with multivariate analysis methods, was applied in order to monitor extra virgin olive oils produced from three distinct cultivars on different maturation stages. For the first time, this kind of methodology is used for the simultaneous discrimination of the maturation stage, and different cultivars. Principal component analysis and discriminant analysis were utilised to create a model for the discrimination of olive oil samples. Partial least squares regression was employed to design calibration models for the determination of chemical parameters. The performance of these models was based on the multiple coefficient of determination (R(2)), the root mean square error of calibration (RMSEC) and root mean square error of cross validation (RMSECV). The prediction models for the chemical parameters resulted in a R(2) ranged from 0.93 to 0.99, a RMSEC ranged from 1% to 4% and a RMSECV from 2% to 5%. It has been shown that this kind of approach allows to distinguish the different cultivars, and to clearly discern the different maturation stages, in each one of these distinct cultivars. Furthermore, the results demonstrated that FTIR spectroscopy in tandem with chemometric techniques allows the creation of viable and accurate models, suitable for correlating the data collected by FTIR spectroscopy, with the chemical composition of the EVOOs, obtained by standard methods.

One-pot synthesis of 2-(2-hydroxyaryl)quinolines: reductive coupling reactions of 2′-hydroxy-2-nitrochalcones

Abstract A one-pot synthesis of novel 2-(2-hydroxyaryl)quinolines have been developed from the intramolecular reductive coupling reactions of 2′-hydroxy-2-nitrochalcones, induced by stannous chloride in acidic medium (HCl/AcOH). In some cases these transformations can be performed with ammonium formate/Pd–C in methanol.

Evaluation of chemical and phenotypic changes in Blanqueta, Cobrançosa, and Galega during olive fruits ripening

Olea europaea L. presents a huge number of cultivars that differ in terms of end-use, and consequently in their chemical composition. The use of different phenotypic (fruit dimension, shape, and color) and chemical parameters (phenolic compounds, flavonoids, and antioxidant activity) during olive fruit maturation in three olive cultivars (Blanqueta, Cobrançosa, and Galega), grown in the Protected Denomination Region of Trás-os-Montes, revealed clear differences among the cultivars, indicating that they behave differently during the maturation process, Galega being the first to reach full maturity. All colorimetric parameters (L*, b*, C*, and H*) decreased with maturity. Galega cultivar presented the highest phenolic content in all the maturation stages analyzed (128.25–175.46 mg GAE g−1). Also, this cultivar presented the highest antioxidant activity in semi-green stage fruits (231.72 μmol Trolox g−1). The flavonoid content increased in all cultivars from the green drupe to black stage, with differential behavior between the cultivars within maturation stages. Moreover, a high correlation was found between the phenolic compounds content and the antioxidant activity levels.

Short wavelength Raman spectroscopy applied to the discrimination and characterization of three cultivars of extra virgin olive oils in different maturation stages.

Extra virgin olive oils produced from three cultivars on different maturation stages were characterized using Raman spectroscopy. Chemometric methods (principal component analysis, discriminant analysis, principal component regression and partial least squares regression) applied to Raman spectral data were utilized to evaluate and quantify the statistical differences between cultivars and their ripening process. The models for predicting the peroxide value and free acidity of olive oils showed good calibration and prediction values and presented high coefficients of determination (>0.933). Both the R(2), and the correlation equations between the measured chemical parameters, and the values predicted by each approach are presented; these comprehend both PCR and PLS, used to assess SNV normalized Raman data, as well as first and second derivative of the spectra. This study demonstrates that a combination of Raman spectroscopy with multivariate analysis methods can be useful to predict rapidly olive oil chemical characteristics during the maturation process.

A novel, direct, reagent-free method for the detection of beeswax adulteration by single-reflection attenuated total reflectance mid-infrared spectroscopy

In this work, a novel, direct, reagent-free method for the detection of beeswax adulteration by paraffin, microcrystalline wax, tallow and stearic acid using single-reflection attenuated total reflectance mid-infrared spectroscopy was developed. The use of the absorbance ratios of [Formula: see text] , [Formula: see text] and [Formula: see text] allows a minimum of 5% paraffin/microcrystalline wax and tallow adulteration and 0.5% stearic acid adulteration of beeswax to be detected. The upper and lower critical limits for beeswax authenticity were established from the analysis of virgin beeswax and were validated by independent analysis of real sheet and comb beeswax samples using high-temperature gas chromatography with flame-ionization detection. In addition to its simplicity with respect to sample handling, the amount of sample and the time needed are far less than those required in previously described methods, which are based on chemical analysis and chromatographic techniques. These advantages result in time and cost savings, an increase in the number of samples that can be analyzed, and, most importantly, the detection of the main beeswax adulterants using a single method.

Study of adulteration of extra virgin olive oil with peanut oil using FTIR spectroscopy and chemometrics

Abstract A methodology based on Fourier transform infrared spectroscopy with attenuated total reflectance sampling technique, combined with multivariate analysis, was developed to monitor adulteration of extra virgin olive oil (EVOO) with peanut oil (PEO). Principal components regression (PCR), partial least squares regression (PLS-R), and linear discriminant analysis (LDA) allowed quantification of percentage of adulteration based on spectral data of 192 samples. Wavenumbers associated with the biochemical differences among several types of edible oils were investigated by principal component analysis. Two sets of frequencies were selected in order to establish a robust regression model. Set A consisted on the frequency regions from 600 to 1,800 cm−1 and from 2,750 to 3,050 cm−1. Set B comprised 17 discrete peak absorbance frequencies for which the communality value was higher than 0.6. Analysis of an external set of 25 samples allowed the validation and evaluation of the predictability of the models. When using a specific set of discrete peak absorbance frequencies, the R2 coefficients for the prediction were 0.960 and 0.977, and the root mean square error (RMSE) were 1.49 and 1.05% V/V when using the PCR or PLS-R models, respectively. LDA was successful in the binary classification presence/absence of PEO in adulterated EVOO (with 5% V/V of less of PEO). LDA provided 92.3% correct classification for the calibration set and 88.3% correct classification when cross-validated. The lowest detectable concentration of PEO in EVOO was the lowest adulteration level studied, 0.5% V/V.

Grape stems as a source of bioactive compounds: application towards added-value commodities and significance for human health

Phenolic compounds occur in high concentration in grapes (Vitis vinifera L.) and grape’s by-products as secondary metabolites responsible for distinct functions linked to plants protection against biotic and abiotic environmental stress. Once integrated as an ingredient in added-value products, these compounds are responsible for the protective effect described regarding plant material extracts, which has become an increasingly important area of applied research. Grape stems constitute the less valorised residue from grapes derived from the winery industry. Moreover to their value as a source of bioactive (poly)phenols, this material could display an additional advantage due to their content in complex carbohydrates, which provide benefits through improving the digestive process as insoluble fibres that reduce the absorption of unhealthy fats and promote detoxification processes. However, the application of this material as a functional ingredient might entail the modification of the (poly)phenolic profile resulting from processing procedures. These microbiological derived compounds require a further evaluation concerning their biological activity and technological applications. The inclusion of intact (poly)phenolic extracts of grape-stems in cosmetic and pharmaceutical formulations may allow to evaluate directly the biological effect of these compounds in vivo. This is an overview of the compounds present in grape stems and their potential to exert valuable biological and technological applications through their integration in distinct added-value products as well as the impact of available processing alternatives.

Synthesis and structure elucidation of three series of nitro‐2‐styrylchromones using 1D and 2D NMR spectroscopy

2‐Styrylchromones, although scarce in nature, constitute a group of oxygen heterocyclic compounds which have shown significant biological activities. New nitro‐2‐styrylchromones have been synthesised by the Baker–Venkataraman method, and the structure elucidation was accomplished using extensive 1D (1H, 13C) and 2D NMR spectroscopic studies (COSY, HSQC and HMBC experiments). Copyright