Postharvest Biology and Technology 39 (2006) 69–74 Cell wall physicochemical aspects of peach fruit related to internal breakdown symptoms G.A. Manganaris a,b , M. Vasilakakis a , Gr. Diamantidis a , I. Mignani b,∗ a School of Agriculture, Aristotle University, 541 24, Thessaloniki, Greece b Department of Plant Production, Di.Pro.Ve. Sez. Coltivazioni Arboree, Facolt` a di Agraria, Universit` a degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy Received 14 May 2005; accepted 22 August 2005 Abstract The aim of this study was to dissect the physicochemical aspects of cell wall components in relation to chilling injury symptoms, expressed as flesh browning and postulated as internal breakdown in the present study, in a non-melting peach cultivar (Prunus persica L. Batsch, cv. Andross) during ripening after 4 weeks cold storage at 5 ◦ C. Uronic acids, neutral sugars and cellulose contents were assayed in order to determine the correlation between them and flesh browning. Cation distribution in cell wall material and activities of pectin-modifying enzymes were also monitored. Uronic acid content was higher in both water-soluble and -insoluble pectin fractions in sound peach fruit compared to fruit with internal breakdown symptoms. The chilling-injured fruit were characterized by 26% higher content in total neutral sugars compared to sound fruit, which was mainly attributed to increased galactose, arabinose and glucose contents, whereas tissue derived from sound fruit had a 27% higher cellulose content compared to chilling-injured tissue. Decreased activities of both polygalacturonase and pectin methyl esterase, accompanied by decreased levels of cation binding in the cell walls, primarily of calcium, were recorded in the brown-fleshed tissue. Since the examined tissues originated from fruit subjected to common storage treatments, differences reported here are related to the development of internal breakdown symptoms. © 2005 Elsevier B.V. All rights reserved. Keywords: Peach; Storage; Flesh browning; Pectin; Cell wall; Chilling injury 1. Introduction During cold storage of peach fruit, important biochem- ical, physiological and textural changes occur, which are mainly related to alterations of cell wall composition and structure, mostly due to enzymatic modifications of the pectic molecules (Brummell et al., 2004). However, extended cold storage periods lead to physiological disorders and abnormal fruit ripening, reducing consumer acceptance and limiting the fruit’s potential postharvest market life (Crisosto et al., 1999). Peach and nectarine cultivars develop chilling injury (CI) symptoms during prolonged low temperature storage (Zhou et al., 2000a; Crisosto and Labavitch, 2002; Brummell et al., 2004). Chilling-damaged peach fruit may develop flesh ∗ Corresponding author. Tel.: +39 02 58356561; fax: +39 02 58356553. E-mail address: ilaria.mignani@unimi.it (I. Mignani). woolliness that leads to a dry, grainy sand-like texture (Zhou et al., 2000a,b) and flesh browning (FB), failing to ripen prop- erly during prolonged cold storage and/or after holding at room temperature (Crisosto and Labavitch, 2002; Brummell et al., 2004). Browning in this case starts from the flesh near the skin and develops towards the core of the fruit (Fig. 1), and usually appears during the most advanced stages of CI in peach fruit (Crisosto et al., 1999; Crisosto and Labavitch, 2002; Brummell et al., 2004). On the other hand, internal discoloration of peach tissue, evident as flesh browning reported in the present study, is different from that accompanying woolliness and is charac- terized by discontinuity and no dry texture (Fig. 2). Flesh browning may extend to the rest of the fruit, with a zone of about 1 cm below the skin remaining unaffected and simi- lar symptoms, referred to as core breakdown, have been also reported in pear fruit (Larrigaudi` ere et al., 2004). These symp- 0925-5214/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.postharvbio.2005.08.003