Use of non-Saccharomyces wine yeasts as novel sources of mannoproteins in wine P. Domizio a, b, * , Y. Liu c , L.F. Bisson a , D. Barile c, d, ** a Department of Viticulture & Enology, University of California-Davis, Davis, CA 95616, USA b Dipartimento di Gestione dei Sistemi Agrari, Alimentari e Forestali (GESAAF), Università degli Studi di Firenze, 50144 Firenze, Italy c Department of Foods Science & Technology, University of California-Davis, Davis, CA 95616, USA d Foods for Health Institute, University of California-Davis, Davis, CA 95616, USA article info Article history: Received 12 February 2014 Received in revised form 22 March 2014 Accepted 14 April 2014 Available online 30 April 2014 Keywords: Wine Non-Saccharomyces Yeast Mannoprotein Polysaccharide N-glycan MALDI-TOF abstract Eight non-Saccharomyces wine strains, previously selected for their ability to modulate the final con- centrations of various volatile compounds and to persist with Saccharomyces cerevisiae in mixed inocula fermentations of grape juice, have been analyzed in the present work to test their ability to release mannoproteins. The eight strains were members of different genera originally isolated from grape: Hansensiaspora osmophila, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia fermentans, Saccharomycodes ludwigii, Starmerella bacillaris, Torulaspora delbrueckii and Zygosaccharomyces flor- entinus. A synthetic polysaccharide-free grape juice, was used to characterize the mannoproteins released during the alcoholic fermentation. Mannoproteins profiles were characterized by gel electro- phoresis and carbohydrate composition was analyzed both by HPLC and by mass spectrometry. The eight non-Saccharomyces yeasts demonstrated a higher capacity to release polysaccharides compared to S. cerevisiae. The proteins released by the eight yeast strains showed a wide variety of protein sizes, ranging from 25 kDa to greater than 250 kDa. The mass spectrometric profile of the N-glycans ranged from 1600 to 4000 Da and was characteristic for each strain. Detailed investigation of the degree of polymerization of released N-glycans revealed variable composition from 8 to 15 units of monosaccharides. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Mannoproteins are released from the yeast cell wall during the alcoholic fermentation and wine aging processes (Boivin et al., 1998; Charpentier and Feuillat, 1993; Charpentier et al., 2004a; Llaubères et al., 1987) and represent one of the major poly- saccharides found in wine. The mannoproteins have been recog- nized to have many positive enological properties such as improving mouth-feel and fullness (Vidal et al., 2004), decreasing astringency (Carvalho et al., 2006), adding complexity and aromatic persistence (Chalier et al., 2007), increasing sweetness and roundness (Guadalupe et al., 2007), and reducing protein and tartrate instability (Gonzalez-Ramos et al., 2008). Moreover, man- noproteins can stimulate malolactic fermentation by lactic acid bacteria (Guilloux-Benatier et al., 1995; Rosi et al., 2000), adsorb some toxic compounds possibly present in the wine such as ochratoxin A (Caridi, 2007; Moruno et al., 2005), and improve the foam quality of sparkling wines (Moreno-Arribas et al., 2000; Nunez et al., 2006). In order to increase the amount of mannoproteins released during the alcoholic fermentation, some researchers have devel- oped autolytic thermosensitive mutants (Giovani and Rosi, 2007) or genetically engineered wine yeast strains of Saccharomyces cer- evisiae (Brown et al., 2007; Gonzalez-Ramos and Gonzalez, 2006; Gonzalez-Ramos et al., 2008). However, these organisms are likely to be viewed as releasing components not normally present in wine. Recently, some authors (Comitini et al., 2011; Domizio et al., 2010, 2011; Gobbi et al., 2013; Romani et al., 2010) have shown that other non-Saccharomyces wine yeasts found in grape and wine making environments have a high capacity to release important * Corresponding author. Permanent address: Dipartimento di Gestione dei Sis- temi Agrari, Alimentari e Forestali (GESAAF), Università degli Studi di Firenze, Via Donizetti 6, 50144 Firenze, Italy. Tel.: þ39055 2755502. ** Corresponding author. Department of Food Science and Technology, University of California-Davis, One Shields Ave, Davis, CA 95616, USA. Tel.: þ1 530 752 0976. E-mail addresses: domizio@unifi.it (P. Domizio), dbarile@ucdavis.edu (D. Barile). Contents lists available at ScienceDirect Food Microbiology journal homepage: www.elsevier.com/locate/fm http://dx.doi.org/10.1016/j.fm.2014.04.005 0740-0020/Ó 2014 Elsevier Ltd. All rights reserved. Food Microbiology 43 (2014) 5e15