M. Castellari

Analysis of wine phenolics by high-performance liquid chromatography using a monolithic type column

A HPLC method involving direct injection was developed to determine phenolic compounds in wine. The separation was carried out on an RP C18 monolithic column using a binary gradient elution and diode array detection. In this way 17 monomeric compounds of different phenolic groups (hydroxybenzoic acids, hydroxycinnamic acids, hydroxycinnamyltartaric acids, flavanol, flavonol and stilbenes) could be separated and quantified in a single run and in a very short time.

AN IMPROVED HPLC METHOD FOR THE ANALYSIS OF ORGANIC ACIDS, CARBOHYDRATES, AND ALCOHOLS IN GRAPE MUSTS AND WINES

An improved high performance liquid chromatography (HPLC) method for the analysis of the main organic compounds in musts and wines is presented. A column packed with hydrogen sulfonated divinyl benzene-styrene copolymer and two detectors connected in series were used (UV at 210 nm and RI, respectively). The addition of acetonitrile (6%) to the mobile phase (0.045N H2SO4) allowed the simultaneous separation and quantification of several organic acids, glucose, fructose, glycerol, and ethanol. Direct injection and sample clean-up with a SAX cartridge was tested and compared. The SAX fractionation gave satisfactory results, however the direct injection of diluted wine (1:20) provided the best precision (CV ≤ 2.1%) and accuracy of analysis. Statistical analysis (paired t-test) disclosed significant differences only for glucose, fructose, α-ketoglutaric, and pyruvic acid. The role of column temperature for the analysis of vitamin C (ascorbic acid) was also investigated. Vitamin C underwent thermal degradation during analysis with column temperature ≥ 30°C.

Immunochemical Assays for Direct Sulfonamide Antibiotic Detection In Milk and Hair Samples Using Antibody Derivatized Magnetic Nanoparticles

Two direct enzyme-linked immunosorbent assays (ELISAs) have been developed for detection of sulfonamide antibiotic residues in milk samples. One of them is using magnetic nanoparticles (MNP) for target capture/enrichment (Ab-MNP-ELISA), and the second is performed using microtiter plates. Selective polyclonal antibodies, raised against 5-[6-(4-amino-benzenesulfonylamino)-pyridin-3-yl]-2-methyl-pentanoic acid (SA1), used in combination with an enzyme tracer prepared with the same hapten, has allowed us to reach a limit of detection (LOD) lower than 0.5 microg L(-1) for both ELISA formats. Sulfapyridine, sulfamethoxypyridazine, sulfathiazole, and sulfachloropyridazine are detected below the maximum residue limits established by the European Union for these antibiotics in milk (100 microg L(-1)). Matrix effects and accuracy studies performed with full-cream milk and hair extracts indicated a lack of interference from these sample matrices and very good recovery values, especially when using the Ab-MNP format. Milk samples and hair extracts can be measured without any previous treatment. The results demonstrate the high potential of these methods as screening tools for food safety and inspection controls.

Level of single bioactive phenolics in red wine as a function of the oxygen supplied during storage.

Abstract The influence of three levels of oxygen supply on the phenolic composition of Sangiovese wine was evaluated during 6 months of storage. Oxygenation reduced the total phenolics content and increased the concentration of red polymeric compounds. Saturation with oxygen every 30 days significantly improved the wine colour density as compared to the control. The individual behaviour of phenolic compounds such as (+) catechin, (−) epicatechin, quercetin, caffeic acid, and anthocyanins showed a significant depleting effect of oxygen on wine phenolic composition when wines were oxygenated every month. The supply of oxygen every 60 days limited the oxidation of low molecular weight phenolic compounds and slightly influenced the wine colour. This confirmed that oxygenation could improve the evolution of red wines during ageing, but its control is necessary to reduce detrimental effects upon single bioactive phenolic compounds.

Effects of high pressure processing on polyphenoloxidase enzyme activity of grape musts

Abstract The effects of high pressure processing (300, 600, 900 MPa for 2, 6 and 10min) on the activity of polyphenoloxidase (PPO) enzymes were evaluated in a synthetic must to which an enzymatic extract obtained from grapes had been added, and in a white grapes must. Despite the fact that the results vary as a function of the medium studied, it could be seen that the PPO typical of the musts could only be partly inactivated by high pressure treatment (300–600 MPa). On the other hand, at higher pressures (900 MPa), PPO enzymatic residual activity was clearly lower (1 to 16%) in both the synthetic and the white must.

Characterisation of peach juices obtained from cultivars Redhaven, Suncrest and Maria Marta grown in Italy

Abstract The compositions of three peach juices obtained from the cultivars Redhaven, Suncrest and Maria Marta, respectively, were studied. The fruits were grown in the Emilia-Romagna region (Italy). The juices were characterised by pH, CIE L *, a *, b * colour values, soluble solids, individual carbohydrates, organic acids, and phenolic compounds. Univariate analysis disclosed some significant differences among the compositions of the varietal peach juices. Principal component revealed clear group structures in the data matrix, the most relevant variables being glucose, fructose, sorbitol, malic acid, L * and b *-values. Suncrest peach juice was clearly distinguished from Redhaven and Maria Marta juices.

Analysis of eleven phenolic compounds including novel p-coumaroyl derivatives in lettuce (Lactuca sativa L.) by ultra-high-performance liquid chromatography with photodiode array and mass spectrometry detection.

INTRODUCTION Lettuce is a widely consumed vegetable and a good source of phenolic compounds. Several factors (genetic, agronomical and environmental) can influence the lettuce composition; their effects are not completely defined and more studies are needed on this topic. OBJECTIVE To develop an improved ultra-high-performance liquid chromatography (UHPLC) method to quantify the main target intact phenolic compounds in lettuce. METHODOLOGY UHPLC identification of the compounds was supported by PAD spectra and MS(n) analyses. Quantification was carried out by PAD, by creating matrix-matched calibration curves at the specific wavelength for each compound. RESULTS Sample pretreatment was simplified, with neither purification nor hydrolysis steps. Chromatographic conditions were chosen to minimise matrix interferences and to give a suitable separation of the major phenolic compounds within 27 min. The method allowed the quantification of 11 intact phenolic compounds in Romaine lettuces, including phenolic acids (caffeoyl and p-coumaroyl esters) and flavonoids (quercetin glycosides). Four p-coumaroyl esters were tentatively identified and quantified for the first time in lettuce. CONCLUSION The main intact phenolic compounds, including four novel p-coumaroyl esters, were simultaneously quantified in lettuce with optimal performances and a reduced total time of analysis. These findings make headway in the understanding of the lettuce phytochemicals with potential nutritional relevance.

Analysis of seven purines and pyrimidines in pork meat products by ultra high performance liquid chromatography–tandem mass spectrometry

An ultra high performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS) is proposed for the simultaneous quantification of inosine, adenosine, guanosine, uridine, hypoxanthine, xanthine and uric acid in pork meat, dry-cured and cooked ham. Samples were added with (15)N(2)-xanthine (internal standard) and extracted with boiling water for 30 min. Supernatants were washed with hexane, added with formic acid 10% in water, methanol:acetone (1:1, v/v), evaporated to dryness under N(2), and finally re-dissolved in water prior to injection. Chromatographic separation was carried out with a HSS T3 column with a total time of analysis of 15 min. Two specific transitions for each compound were used for identification and quantification (with matrix matched calibration curves). Linearity, limit of detection, repeatability and accuracy were evaluated. The method was used to quantify the seven purines and pyrimidines in 15 commercial samples.

Detection of tetracycline and oxytetracycline residues in pig and calf hair by ultra-high-performance liquid chromatography tandem mass spectrometry

An ultra-high-performance liquid chromatography tandem mass spectrometry method to detect residues of tetracycline (TC), epi-tetracycline (eTC) and oxytetracycline (OTC) in animal hair was developed. Hair samples were washed with water, extracted with NH(4)OH 0.1M, purified by SPE-C(18) cartridge and analyzed by tandem mass spectrometry (ESI(+), MRM mode) with satisfactory results. For the first time, accumulation of TC, eTC and OTC was confirmed in livestock hairs after a therapeutic treatment with TC and OTC, respectively. Administered drug residues were detectable in hair samples up to 2 months after the last treatment, providing a retrospective evidence of TC and OTC administration. Hair analysis seems to offer a wider window of detection than edible tissues.

Identification of 5-hydroxymethyl-2-furfural (5-HMF) in Cava sparkling wines by LC-DAD-MS/MS and NMR spectrometry.

The aim of this study was to elucidate the structure of a potential ageing marker for Cava sparkling wine. In order to clarify the structure of this compound, NMR spectroscopy and hyphenated UHPLC-DAD-MS/MS techniques were used. We identified the hitherto unknown compound as 5-hydroxymethyl-2-furfuraldehyde (5-HMF). This is the first time that this compound has been reported in sparkling wines. A survey, based on the analysis of 80 commercial sparkling wines, showed that 5-HMF is present between 0.25 and 12.81 mg/L, and is compared with those reported for other types of wine. Hypothetical origin of 5-HMF in Cava sparkling wine is discussed.