A Rapid Method for Determination of Resveratrol in Wines by HPLC-MS

Rapid, Highly-Sensitive and Ecologically Greener Reversed-Phase/Normal-Phase HPTLC Technique with Univariate Calibration for the Determination of Trans-Resveratrol

The rapid, highly-sensitive and ecologically greener reversed-phase (RP)/normal-phase (NP) high-performance thin-layer chromatography (HPTLC) densitometric technique has been developed and validated for the determination of trans-resveratrol (TRV). The reversed-phase HPTLC-based analysis of TRV was performed using ethanol–water (65:35, v v−1) combination as the greener mobile phase, while, the normal-phase HPTLC-based estimation of TRV was performed using chloroform–methanol (85:15, v v−1) combination as the routine mobile phase. The TRV detection was carried out at 302 nm for RP/NP densitometric assay. The linearity was recorded as 10–1200 and 30–400 ng band−1 for RP and NP HPTLC techniques, respectively. The RP densitometric assay was observed as highly-sensitive, accurate, precise and robust for TRV detection in comparison with the NP densitometric assay. The contents of TRV in commercial formulation were recorded as 101.21% utilizing the RP densitometric assay, while, the contents of TRV in commercial formulation were found to be 91.64% utilizing the NP densitometric assay. The greener profile of RP/NP technique was obtained using the analytical GREEnness (AGREE) approach. The AGREE scales for RP and NP densitometric assays were estimated 0.75 and 0.48, respectively. The recorded AGREE scale for the RP densitometric assay indicated that this technique was highly green/the ecologically greener compared to the NP densitometric assay. After successful optimization of analytical conditions, validation parameters, AGREE scale and chromatography performance, the RP densitometric assay with univariate calibration was found to be better than the NP densitometric assay for the analysis of TRV.

Evolution of phenolic profile of white wines treated with enzymes

The aim of this study is to monitor the evolution of the principal phenolic compounds throughout the fermentation stage of white wines treated with different enzymes. The effect of five commercial enzymes on the evolution of the phenolic profile during the alcoholic fermentation of white wines obtained from Fetească regală and Sauvignon blanc varieties was evaluated. Physicochemical properties of resulted wine samples have been analyzed according to OIV standards and regulations. The evolution of the principal phenolic compounds was carried out using HPLC method. Enzymatic treatments did not significantly affect the physicochemical composition of the obtained wines. The analyzed samples showed different variations on the phenolic compound content, depending on the type of added enzyme and grape variety. The statistical analysis confirms that enzymes significantly contributed to the enrichment of the wines with phenolic compounds, especially with p-coumaric, gentisic, caftaric, and protocatechuic acids.

Development of HPLC method for determination of phenolic compounds on a core shell column by direct injection of wine samples

Phenolic compounds are frequently present in various natural products, and they can have different beneficial biological potentials. The most widely used method for determination of individual phenolic compounds is high-performance liquid chromatography (HPLC). In this paper, a method for simultaneous determination of 16 phenolic compounds (gallic acid, p-hydroxybenzoic acid, catechin, syringic acid, trans-cinnamic acid, hesperetin, naringenin, vanillic acid, benzoic acid, coumaric acid, resveratrol, chlorogenic acid, caffeic acid, rutin, quercetin, and kaempferol) on a core–shell column was developed. The separation method conducted on a standard ODS (250 mm) column was transferred to Poroshell column and optimized using non-ultra-high-performance liquid chromatography (UHPLC) apparatus. Phenolic compounds were separated fast and efficiently during 30-min analysis, and validation parameters were determined. The developed method was successfully applied on the analysis of phenolic content after direct injection of red wines from three different grape varieties.

Antioxidant and antimicrobial effects of grape pomace extracts

The use of antioxidants and antibacterials in food industry has become increasingly necessary to ensure the high quality of food. Grape pomace is the main by-product of winemaking industry that concentrates bioactive metabolites with more studied antioxidant activity and possible antibacterial activity. The grape pomace contains fragmented skin, broken cells, pulp remains, stalks and seeds with high amount of phenolic compounds due to their poor extraction during the winemaking process. Anthocyanins, catechins, flavonol glycosides, phenolic acids, alcohols and stilbenes have been identified among the compounds present in grape pomace. In this study, antibacterial activity against different pathogens (Escherichia coli ATCC 25922, Candida albicansATCC 90028, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923) was evaluated and the relation with polyphenols content and antioxidant activity of grape pomace from selected grapes from Iaşi vineyard was studied. The grape pomace samples were obtained after the fermentation process from the 2017 harvest of Sauvignon Blanc, Traminer, Busuioacă de Bohotin, Cabernet Sauvignon, Merlot, Fetească Neagră and Fetească Regală grape varieties. The antioxidant properties were evaluated using the DPPH method, FRAP assay and Folin Ciocalteu method. The content of resveratrol was quantified using an HPLC method. Samples with antioxidant activity showed the highest phenolics content. This study reveals that grape pomace is a potential source of natural antioxidant agents. The pomace extracts were tested to establish the effects on Gram-positive and Gram-negative bacteria. The analysed samples exhibited insignificant antibacterial activity and the method requires optimization. Grape marc represents an important source of resveratrol and other bioactive compounds that could be a valuable source of antioxidants for further utilization in food and pharmaceutical industry.

Biogenic amines and other polar compounds in long aged oxidized Vernaccia di Oristano white wines

Oxidized white wines are produced by techniques that provide a barrel ageing which can range from a few years to some decades. This step, characterized by the metabolic activity of peculiar strains of Saccharomyces cerevisiae yeast, can affect the chemical composition of these wines and the production of unwanted substances such as biogenic amines. In this study, Vernaccia di Oristano wines from different vintages have been analysed for the first time regarding the content of biogenic amines and amino acids (by HPLC-FLD), and polar compounds (by HPLC-DAD and LC-MS). Furthermore, colour and technological parameters (contents of alcohol, reducing sugars, total and volatile acidities, pH and organic acids) of the wines were also evaluated. Older samples showed dark shades, which may have derived from polyphenols' oxidation while ageing. Some typical ageing products, such as 5-(hydroxymethyl)furfural and hydroxycinnamic acid derivatives were found in larger quantities in these samples, as well as the purinic compound xanthine, which was also detected in relevant concentrations. Additionally, as expected, the average of the main biogenic amines quantified in Vernaccia di Oristano was higher compared to non-oxidized white wines, especially in the older samples. Thus, though this content does not exceed values which spoil the quality of the wine, the monitoring of the winemaking conditions is suggested, to further limit the presence of these undesirable compounds.

Development and validation of a HPLC method using a monolithic column for quantification of trans-resveratrol in lipid nanoparticles for intestinal permeability studies

The development of nanodelivery systems that protect trans-resveratrol is extremely important to preserve its bioactive properties in the development of further applications as nutraceuticals to supplement foods and beverages. In this work, a validated HPLC method was developed for the quantification of trans-resveratrol in lipid nanoparticles for application in studies of in vitro intestinal permeability. The chromatographic separation was achieved in a C18 monolithic column connected to a fluorometric detector (330/374 nm), by isocratic elution consisting of 2% acetic acid/acetonitrile (80:20). Two calibration ranges were established (0.020-0.200 and 0.200-2.00 μmol L(-1)), and low quantification limits (2-6 nmol L(-1), 23-69 pg) were achieved. Stability studies showed that trans-resveratrol is stable for 24 h at 4 °C, and storage at room temperature and freeze-thaw cycles are not recommended. The proposed method was applied to in vitro intestinal permeability studies, in which values between 0.05 ± 0.01 and 1.8 ± 0.3 μmol L(-1) were found.

Development and validation of an analytical method for the determination of trans- and cis-resveratrol in wine: analysis of its contents in 186 Portuguese red wines

A simple procedure based on solid-phase extraction and high performance liquid chromatography coupled to diode array detector has been developed and validated for the qualitative and quantitative analysis of cis- and trans-resveratrol in wines. The method was linear from 0.025 (lower limit of quantitation, LLOQ) to 15 μg/mL for trans-resveratrol and from 0.023 (LLOQ) to 0.92 μg/mL for cis-resveratrol, with correlation coefficients higher than 0.99 for both isomers. Intra- and interday precision and accuracy were in conformity with the criteria normally accepted in method validation, that is, CVs inferior to 15% and mean relative errors within a ±14% interval. The extraction presented mean efficiencies close to 100% for both analytes. The validated methodology was applied to 186 Portuguese red wines from different regions, grape varieties and vintage. The results obtained showed that the content of trans-resveratrol in red wines ranged from 0.05 to 10.9 μg/mL, while the concentrations of cis-resveratrol ranged from 0.04 to 8.71 μg/mL.