The present study describes using molecularly imprinted polymer (MIP) technology for determination of patulin (PAT) and 5-hydroxymethylfurfural (5-HMF) in beverages by ultra-high performance liquid chromatography coupled to photodiode array (UPLC-PDA). PAT (4-hydroxy-4H-furo[3,2-c]pyran-2(6H)-one) is a mycotoxin produced by Penicillium fungi and Penicillium expansum is probably the most commonly encountered species that infects apples during their growth, harvest, storage or processing. The occurrence of PAT as a natural contaminant of apples is a worldwide problem. 5-HMF (also known as 5-(hydroxymethyl) furan-2-carbaldehyde), is formed in the Maillard reaction as well as during caramelisation. It is a good storage time-temperature marker and flavour indicator, especially in beverages such as wine, beer, but also cider and apple juice which may contain PAT. PAT and 5-HMF were separated within 2 min using a Luna Omega C18 column and the PDA detector wavelength was set to 276 nm. The validation parameters of the analytical method such as linearity, limit of detection, limit of quantification, accuracy and precision were tested. The calibration curves were linear at least in the range 50-1000 ng/ml with a good linearity (R2>0.999) for both analytes, the limit of detection and the limit of quantification for PAT and 5-HMF were in the range 4.9-6.6 and 16.1-21.8 μg/l, respectively. The recoveries of the selected analyte were in the range 61.9-109.0% with a precision of <8.2% (relative standard deviation (RSD)) for PAT and in the range 50.8-98.0% with a precision of <10.0% (RSD) for 5-HMF. The validated procedure was successfully applied for the analysis of PAT and 5-HMF in beverages from retail shops.

ProfilproanthokyanidinůvpivuajehosurovináchKlíčová slova : proanthokyanidiny,pivo,slad,chmel,vysokoúčinná kapalinováchromatografie,hmotnostníspektrometriesvysokým rozlišením ■ ■ 1 ÚVOD Polyfenoly, sekundární metabolity produkované zejména rostlinami, jsou velkou a různorodou skupinou sloučenin, která obsahuje přes 8000 dosud popsaných sloučenin. (Haslam et al., 1994). Proanthokyanidiny, známé také jako kondenzované taniny neboli třísloviny, jsou v přírodě po ligninu druhou nejrozšířenější skupinou polyfenolů (Lazarus et al., 1999). Molekuly flavan-3-olů: páry isomerů katechinu a epikatechinu, gallokatechinu a epigallokatechinu, afzelechinu a epiafzelechinu (viz obr.1) tvoří základní stavební jednotku kondenzovaných proanthokyanidinů. Tyto flavan-3-ol jednotky mají typickou C6-C3-C6 flavanoidní strukturu, která je tvořena třemi kruhy, dvěma aromatickými kruhy (kruhy A a C) a heterocyklickým kruhem B (Predy et al., 2009 Polyphenols, secondary metabolites produced mostly by plants, are a large and diverse group of compounds, which contains over 8000 previously described compounds. (Haslam et al. 1994). Proanthocyanidins, also known as condensed tannins or tannins, are the second most common group of polyphenols in the nature of after lignin (Lazarus et al., 1999). Molecules of flavan-3-ols, pairs of isomers of catechin and epicatechin, epigallocatechin and gallocatechin, and afzelechin and epiafzelechin (see Fig. 1) are the basic structural units of condensed proanthocyanidins. The flavan-3-ol units are typically C6-C3-C6 flavanoid structures which are formed by three rings, the two aromatic rings (rings A and C) and a heterocyclic ring B (Predy et al., 2009). Condensation of these simple catechins yields proanthocyanidins as dimeric, oligomeric or polymeric compounds. The diversity of the various structures of proanthocyanidins is given by the variability of monomeric units, i.e. the number of hydroxyl groups on both of the aromatic rings A and C and the stereochemistry at the asymmetric carbon C3 on ring B. The variability is also contributed by a specific type of an interflavonoid bond, wherein the self--condensation of the monomeric units of catechins can occur either between the carbon C4 of the higher flavonoid unit and C8 carbon (link 4→8) or 6 (4→6 linkage) of the lower flavonoid unit (type B), or the type A wherein the bond is formed via an ether bridge between Přítomnost proanthokyanidinů, látek patřících do široké skupiny polyfenolů, je v pivu obecně spíše nežádoucí a to vzhledem k jejich tendenci tvořit komplexy s proteiny, a tím zhoršovat jeho koloidní stabilitu. Na druhé straně, jsou tyto látky prospěšné díky schopnosti vázat volné radikály a tím zlepšovat senzorickou stabilitu piva. Znalost profilu jednotlivých proanthokyanidinů v pivu a surovinách a jejich individuálního chování během celého technologického procesu by mohla napomoci při řešení úkolů spojených se zlepšováním senzorické i koloidní stability piva. Proto byla vypracována nová metoda pro stanovení proanthokyanidinů pomocí kapalinové...

The present study aimed to apply a multi-residue method for the screening and quantification of pesticide residues in ciders, low alcoholic beverages made by fermentation of apple juice. Twenty bottled craft cider samples purchased from the Czech market were analysed for pesticide residues. The residues of pesticides were extracted from samples using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure in combination with additional solid-phase extraction (SPE) sample clean-up to achieve the lowest detection limit possible. In this study, targeted screening of pesticide residues in the samples was performed with the Q-Orbitrap mass spectrometry instrument. We identified 18 pesticides in cider samples analysed by screening method using an accurate-mass database of about 500 pesticide compounds, including their retention times, empirical formulas, and characteristic fragments. Additionally, liquid chromatography with high-resolution tandem mass spectrometer (LC-HRMS/MS) was used for re-analysis of positive findings of pesticides in samples and allowed to quantify compounds of interest at 0.2 µg•L -1 concentration level. The monitoring scheme was applied to the set of craft ciders, and the results revealed the presence of pesticide residues in most of the samples at trace levels ranging from 0.5 to 5 µg•L -1 and rarely at a level higher than 10 µg•L -1 .