Scientia Horticulturae 180 (2014) 1–5 Contents lists available at ScienceDirect Scientia Horticulturae journal h om epage: www.elsevier.com/locate/scihorti Review Pectin role in woolliness development in peaches and nectarines: A review Goran Fruk a,∗ , Zlatko Cmelik a , Tomislav Jemric a , Janez Hribar b , Rajko Vidrih b a University of Zagreb Faculty of Agriculture, Department of Pomology, Svetosimunska cesta 25, HR – 10 000 Zagreb, Croatia b University of Ljubljana Biotechnical Faculty, Department of Food Science and Technology, Jamnikarjeva 101, SI – 1000 Ljubljana, Slovenia a r t i c l e i n f o Article history: Received 25 July 2014 Received in revised form 20 September 2014 Accepted 24 September 2014 Keywords: Peach and nectarine Ethylene Chilling injury Pectin Cell anatomy Temperature a b s t r a c t One of the main problems during peach and nectarine cold storage is the associated chilling injuries, which can include woolliness, mealiness, leatheriness, flesh browning, internal reddening, and flesh or pit cavities. Woolliness is one form of chilling injury. It manifests as a lack of juiciness and a dry ‘woolly’ texture of the fruit flesh. Its occurrence is correlated with pectin metabolism and is controlled directly or indirectly by the pectolytic enzymes (i.e., polygalacturonase, pectin esterase, cellulase, lipoxygenase). Chilling injury to these fruit also results in changes in the fruit physiology and cell anatomy. A reduction in woolliness is possible with post-harvest treatments, such as with heat (which must be carried out carefully), calcium, ethylene (blocking or producing), nitrogen monoxide, or a controlled atmosphere. This paper focuses only on woolliness and factors affecting its occurrence. In this paper the role of pectin metabolism, temperature and postharvest treatments on occurrence of woolliness is discussed. The role of some enzymes, such as pectin esterase, and postharvest treatment with 1-MCP still remain unclear and further research is needed to elucidate physiological mechanisms that lead to development of woolliness. © 2014 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. The development of woolliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. The role of temperature in the development of woolliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4. Cell anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 5. Pectin metabolism in peaches and nectarines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6. Other metabolic processes and woolliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7. Harvest date and maturity stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 8. Post-harvest treatments to alleviate woolliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 9. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction During cold storage of peaches (Prunus persica Batsch.) and nec- tarines (P. persica var. nectarina Ait.), one of the main problems is chilling injuries, which are a collective term for the physiological ∗ Corresponding author. Tel.: +385 1 239 3842; fax: +385 1 239 3630. E-mail address: gfruk@agr.hr (G. Fruk). disorders that can occur during such fruit storage. Chilling injuries develop during ripening on 20 ◦ C (shelf life) after fruit is stored at 2.2–7.6 ◦ C for at least 2 weeks or at 0 ◦ C for 3 weeks or more (Lill et al., 1989; Lurie and Crisosto, 2005). Furthermore, chilling injuries are an internal disorder, and are therefore not generally noticed until the fruit reaches customers. With peaches and nectarines, chilling injuries can include woolliness, mealiness, leatheriness, flesh browning, internal reddening, and flesh or pit cavities (Lurie and Crisosto, 2005). Woolliness manifests as a lack of juiciness and a dry ‘woolly’ texture of the fruit flesh (Zhou et al., 2000a), and it http://dx.doi.org/10.1016/j.scienta.2014.09.042 0304-4238/© 2014 Elsevier B.V. All rights reserved.