ABSTRACT
An ultrahigh-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS/MS) method was developed for the simultaneous determination of nine target indoles in sparkling wines. The proposed method requires minimal sample pretreatment, and its performance parameters (accuracy, repeatability, LOD, and matrix effect) indicate that it is suitable for routine analysis. Four indoles were found at detectable levels in commercial Cava samples: 5-methoxytryptophol (5MTL), tryptophan (TRP), tryptophan ethyl ester (TEE), and N-acetylserotonin (NSER). Two of them, NSER and 5MTL, are reported here for the first time in sparkling wines, with values of 0.3-2 and 0.29-29.2 µg/L, respectively. In the same samples, the contents of melatonin (MEL), serotonin (SER), 5-hydroxytryptophan (5-OHTRP), 5-hydroxyindole-3-acetic acid (5OHIA), and 5-methoxy-3-indoleacetic acid (5MIA) were all below the corresponding limits of detection.
Subject(s)
Chromatography, High Pressure Liquid/methods , Indoles/analysis , Tandem Mass Spectrometry/methods , Wine/analysis , Food Analysis , Limit of Detection , Melatonin/analysis , Serotonin/analogs & derivatives , Serotonin/analysisABSTRACT
In this study the catabolites derived from RNA degradation were assessed in Cava sparkling wines as a consequence of lees autolysis. For this purpose, the changes in the content of adenosine, guanosine, inosine, uridine, hypoxanthine, xanthine, and uric acid were determined by UHPLC-MS/MS, in sparkling wines produced on industrial scale, and aged for 4 years. Uridine is the main nucleoside, and its content increases whenever lees cells are present (sur lie aging). Purines seem to have a fermentative origin, with xanthine the most abundant one. When RNA catabolite amounts in sparkling wines aged with or without lees are compared over time, it can be concluded that lees and their cell degradation play an important role in the evolution of Cava; when lees are removed, RNA catabolite amounts remain unchanged.
Subject(s)
Alcoholic Beverages/analysis , RNA, Fungal/analysis , Saccharomyces cerevisiae/metabolism , Alcoholic Beverages/microbiology , Fermentation , Food Microbiology , RNA, Fungal/metabolism , Saccharomyces cerevisiae/chemistry , Tandem Mass Spectrometry , Time Factors , Uridine/analysisABSTRACT
Ultrastructural changes of lees of three series of sparkling wines produced using the traditional method during long-term aging (4 years) were assessed by high-pressure freezing in combination with transmission electron microscopy. The stratified structure of the cell wall disappeared throughout aging. After 18 months, the microfibrous material of the cell wall appeared more diffuse and the amorphous midzone of the inner wall layer was progressively degraded. From 30 months onward, the cell wall consisted of a tangled structure of fibers. In spite of these changes, the cell wall of yeasts remained unbroken at 48 months of wine aging. Cell membrane breakage was observed for the first time in lees of Saccharomyces cerevisiae. An increase in the thickness of the periplasmic space owing to plasmolysis and of the number of cells with less cytoplasmic content was observed during aging. Morphological evidence of microautophagy was detected for the first time in S. cerevisiae in enological conditions.
