Role of cell wall deconstructing enzymes in the proanthocyanidin–cell wall adsorption–desorption phenomena Liliana del Rocío Castro-López a , Encarna Gómez-Plaza b,⇑ , Ana Ortega-Regules a , Daniel Lozada a , Ana Belén Bautista-Ortín b a Universidad de las Americas Puebla, Departamento de Ciencias de la Salud, Sta. Catarina Mártir, 72810 Cholula, Puebla, Mexico b Universidad de Murcia, Departamento de Tecnología de Alimentos, Nutrición y Bromatología, Facultad de Veterinaria, Campus de Espinardo, 30071 Murcia, Spain article info Article history: Received 5 July 2015 Received in revised form 16 September 2015 Accepted 22 September 2015 Available online 25 September 2015 Keywords: Proanthocyanidin Tannins Cell wall Polysaccharides Phloroglucinolysis Size exclusion chromatography abstract The transference of proanthocyanidins from grapes to wine is quite low. This could be due, among other causes, to proanthocyanidins being bound to grape cell wall polysaccharides, which are present in high concentrations in the must. Therefore, the effective extraction of proanthocyanidins from grapes will depend on the ability to disrupt these associations, and, in this respect, enzymes that degrade these polysaccharides could play an important role. The main objective of this work was to test the behavior of proanthocyanidin–cell wall interactions when commercial maceration enzymes are present in the solution. The results showed that cell wall polysaccharides adsorbed a high amount of proanthocyanidins and only a limited quantity of proanthocyanidins could be desorbed from the cell walls after washing with a model solution. The presence of enzymes in the solution reduced the proanthocyanidin–cell wall interaction, probably through the elimination of pectins from the cell wall network. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Proanthocyanidins (commonly called tannins by winemakers) are one of the main determinants of red wine quality. Some sen- sory attributes such as color, body and astringency are directly associated with the qualitative and quantitative composition of wine proanthocyanidins (PAs). In the grape, they are located in the skin and seeds and are transferred to the must/wine during the maceration step of winemaking. However, previous studies have shown that the quantities found in wines are frequently lower than expected (Adams & Scholz, 2007; Busse-Valverde, Bautista-Ortín, Gómez-Plaza, Fernández-Fernández, & Gil-Muñoz, 2012; Busse-Valverde et al., 2010), which may not only be related to the fact that PAs are not extensively extracted from the skin and seeds but also to the finding that a substantial proportion of them are adsorbed by the skin and pulp cell walls (CWs) in suspension in the must after crushing the grapes and that finally precipitates during settling (Bindon, Smith, Holt, & Kennedy, 2010). The existence of interactions between proanthocyanidins and cell wall material, more precisely with the polysaccharides that are the main components of the cell walls, has been demonstrated and investigated by several research groups (Cai, Gaffney, Lilley, & Haslam, 1989; McManus et al., 1985; Riou, Vernhet, & Doco, 2002) as has the possible enological implications such interactions may have (Bautista-Ortin, Cano-Lechuga, Ruiz-García, & Gómez-Plaza, 2014; Bindon, Smith, Holt, et al., 2010; Le Bourvellec, Bouchet, & Renard, 2005). Therefore, the effective extraction of proantho- cyanidins from grapes will depend on having enough knowledge of the nature of these interactions and on the ability to disrupt or manage these associations. As regards the nature of these asso- ciations it has been found that electrostatic or ionic interactions do not appear to play any part in the association between proantho- cyanidins and cell-wall material, rather the adsorption mechanism seems to involve the establishment of weak interactions, more pre- cisely hydrogen bonds and hydrophobic interactions (Le Bourvellec, Le Quere, & Renard, 2007). Studies have pointed to an increase in association with increasing ionic strength, suggesting the presence of hydrophobic interactions, and a notable decrease with increasing temperature, indicating hydrogen bonding (Le Bourvellec, Guyot, & Renard, 2004). Renard, Baron, Guyot, and Drilleau (2001) also demonstrated that washing the proantho- cyanidins + CW complexes with 8 M urea, a chaotropic reagent, or an acetone:water 60:40 solution, resulted in total re- extraction of the procyanidins, while washing with buffer led only to partial re-extraction and adding NaCl actually decreased this http://dx.doi.org/10.1016/j.foodchem.2015.09.080 0308-8146/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: encarna.gomez@um.es (E. Gómez-Plaza). Food Chemistry 196 (2016) 526–532 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem