Antioxidant activity of lees cell surface during sparkling wine sur lie aging Joan J. Gallardo-Chacón a,b,c , Stefania Vichi a, ⁎, Pilar Urpí d , Elvira López-Tamames a , Susana Buxaderas a a Departament de Nutrició i Bromatologia, Xarxa de Referència en Tecnologia dels Aliments (XaRTA), Facultat de Farmàcia, Universitat de Barcelona, Avda Joan XXIII, s/n, E-08028, Barcelona, Spain b CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain c Centre de Recerca en Enginyeria Biomedica (CREB), Universitat Politècnica de Catalunya, c/ Pau Gargallo 5, E-08028, Barcelona, Spain d Freixenet S.A. c/ Joan Sala, 2, E-08770, Sant Sadurní d’ Anoia, Barcelona, Spain abstract article info Article history: Received 1 March 2010 Received in revised form 9 July 2010 Accepted 17 July 2010 Keywords: Aging Sparkling wine Yeast lees Cell surface Antioxidant DPPH/FRAP Given the importance of the interactions between wine and lees cell surface during sparkling wine aging, and in view of recent results proving the antioxidant potential of yeast cell wall biomolecules, the antioxidant capacity of lees cell surface was investigated to establish its possible role in the antioxidative effect of lees. The surface antioxidant activity of lees from wines with different aging periods was determined on the whole cell by two widely used methods (DPPH and FRAP assays), obtaining maximum values of 24.5 μmol Trolox/g cells (fresh weight) by the DPPH assay, and 21.3 μmol Trolox/g cells (fresh weight) by the FRAP assay. Lees surface antioxidant activity was influenced by base wine characteristics and inversely related to sur lie aging period. Conversely, the percentage depletion of lees surface antioxidant activity during aging was mainly determined by the length of aging, regardless of wine characteristics. To examine the influence of cell wall thiol groups and adsorbed polyphenols on lees' protective effect, their presence on cell surfaces was assessed. They accounted for 25 ± 11% and 54±7% of the antioxidant activity measured by DPPH, respectively, and 0.3 ± 0.1% and 39 ± 8% measured by FRAP, respectively. Only a part of the remnant antioxidant activity of lees surface measured by FRAP could be theoretically explained by the presence of cell wall mannans. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Sparkling wines obtained by the méthode traditionnelle are characterized by two successive fermentation processes. Yeasts for second fermentation are selected on the basis of some desirable technological attributes such as pressure tolerance, alcohol resistance, capability for growing at low temperature, low production of SO 2 and off-flavors, and flocculating ability (Suárez-Lepe, 1997; Zoecklein, 2002). Once the second fermentation has finished, cell viability decreases more than 90% in one month (Hidalgo et al., 2004) and a degradation process known as autolysis takes place (Leroy et al., 1990). Lees from the second fermentation then remain in contact with the wine during a process called sur lie aging (Moreno-Arribas and Polo, 2005) which lasts at least 9–12 months. The results of this practice have recently been reviewed (Caridi, 2006; Fornairon- Bonnefond et al., 2002; Pérez-Serradilla and Luque de Castro, 2008), and have indicated an increase in product structure, richness and roundness. In particular, contact with yeast lees seems to protect wine from oxidation, contributing to the prevention of browning (Caridi, 2006; Pérez-Serradilla and Luque de Castro, 2008; Palomero et al., 2009) and the development of oxidation-related volatiles (Cullere et al., 2007). Model phenolic solutions (López-Toledano et al., 2002) and sparkling wine (Bosch-Fusté et al., 2009) subjected to different accelerated oxidation tests showed a significantly lower degree of oxidative alteration when assayed in the presence of yeasts. The prevention of wine browning could be an indirect effect of the absorption of colored compounds by lees (López-Toledano et al., 2002; Razmkhab et al., 2002), but this resistance could also be ascribed to yeast-promoted protection. The protective effect of lees could be largely due to the release of intracellular compounds to the wine (Pinheiro et al., 2002; Santiago and Mori, 1993; Demasi et al., 2001), as well as to membrane lipids, which consume oxygen during wine aging, thus preventing wine oxidation (Salmon et al., 2000). Recent studies that evaluated the antioxidant activity of different cell wall fractions of spent brewer's yeast (Saccharomyces cerevisiae), proved the significant antioxidant activity for wall proteins and glucans (Jaehrig et al., 2007, 2008). The cell wall makes up between 25 and 50% of cell volume (Lipke and Ovalle, 1998) and consists of an inner three-dimensional network of ramified glucans and outer layer of mannoproteins (Kath and Kulicke, 1999; Gemmill and Trimble, 1999). The antioxidant activity of these wall biomolecules could also occur during sur lie aging contributing to prevent oxidation, and these interactions deserve to be clarified. The studies on spent brewer's yeast have demonstrated that much of yeast wall activity depends on International Journal of Food Microbiology 143 (2010) 48–53 ⁎ Corresponding author. Tel.: + 34 93 4024508; fax: + 34 93 4035931. E-mail address: stefaniavichi@ub.edu (S. Vichi). 0168-1605/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2010.07.027 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro