Flavanol Content and Antioxidant Activity in Winery Byproducts ANA M. GONZA Ä LEZ-PARAMA Ä S,SARA ESTEBAN-RUANO, CELESTINO SANTOS-BUELGA,SONIA DE PASCUAL-TERESA, AND JULIA Ä N C. RIVAS-GONZALO* Universidad de Salamanca, A Ä rea de Nutricio ´n y Bromatologı ´a, Facultad de Farmacia, Campus Miguel de Unamuno, E-37007 Salamanca, Spain Proanthocyanidins, particularly those coming from wine and grape products, have became of interest to nutritionists. Particular attention is currently being paid to the exploitation of this kind of grape byproducts for obtaining bio-active phenolic compounds with potential application as food antioxidants and preventive agents against cancer and other diseases. In this work, the flavanol composition of various winery byproducts submitted to different degrees of industrial exploitation has been studied and their antioxidant activity determined using two different methods (TBARS and TEAC) to evaluate their interest as suitable sources for the preparation of flavanol-rich antioxidant extracts. All the byproducts studied were still good flavanol sources no matter their exploitation degree. An important conclusion was that dried grape seeds, obtained as an end byproduct after the color extraction and alcohol distillation of the wine pomace, still kept important flavanol concentrations and significant antioxidant activity, even if they were submitted to high temperatures. These byproducts can be considered a cheap source for the extraction of antioxidant flavanols, which can be used as dietary supplements or in the production of phytochemicals. KEYWORDS: Winery byproducts; flavanols; antioxidant activity; TEAC; TBARS INTRODUCTION Numerous studies indicate that oxidative stress is associated to the development of a great number of chronic ailments, such as arthritis, dementias, cardiovascular illnesses, and cancer, and that antioxidants in the diet can play an important role in the prevention of these illnesses (1). Thus, different epidemiological studies have demonstrated the association between a diet rich in polyphenols and the decrease in the risk of suffering certain diseases, especially cardiovascular ones and certain types of cancer (2-4). The phenolic compounds of wine, and particularly the flavanols (e.g., catechins, proanthocyanidins), have been the center of attention of recent studies since their relation to the beneficial effects attributed to a moderate consumption of wine was observed (5, 6). These compounds have their origin in the grape, and only a part is transferred to the must during the elaboration of the wine, which is why important quantities still remain in the grape pomace. For this reason, at present, a particular interest exists in the exploitation of this type of byproducts of the grape to obtain potentially bio-active phenolic compounds (7-9). In recent years, the use of grape seed extracts (GSE) has begun to become popular as a nutritional supplement that also has antioxidant activity. These extracts contain a heterogeneous mixture of monomers, oligomers, and polymers formed by subunits of flavan-3-ol (10, 11). With regard to their pharma- cological properties, these phenols have shown themselves active, in in vitro studies, against the oxidation of the low-density lipoproteins, at the same time as they appear to demonstrate antiulcer, anticarcinogenic, antimutagenic, and antiviral activity (12-15). Moreover, at present, there is a growing interest in the exploitation of the residues generated by the food industry. In particular, in the zones of grape and wine production, a great quantity of residues are generated whose storage, transformation, or elimination pose problems both in ecological and economic terms. For this reason, the recovery of the antioxidant com- pounds present in these byproducts could represent an interesting advance in the maintenance of the environmental equilibrium (16, 17). The objective of this work was to determine the flavanol composition and the antioxidant activity of byproducts of wine- making from different varieties of grapes. The samples were collected directly from cellars and also at different stages of a process of industrial exploitation of pomaces destined to the extraction of alcohol and anthocyanins from the byproducts, with the objective of testing how this process affected the composition of the pomaces and their corresponding seeds and evaluating the interest of these byproducts as possible sources for the preparation of flavanol-rich antioxidant extracts. * To whom correspondence should be addressed. Tel.: +34 923 294537. Fax: +34 923 294515. E-mail: jcrivas@usal.es. 234 J. Agric. Food Chem. 2004, 52, 234-238 10.1021/jf0348727 CCC: $27.50 © 2004 American Chemical Society Published on Web 12/31/2003