Effects of coating concentration, ripening stage, water status and fruit temperature on pear susceptibility to friction discolouration

Pear fruit (Pyrus communis L.) cv. 'Duyenne du Comice' were treated at harvest with different concentrations of a carnauba-based wax emulsion and assessed for susceptibility to friction discolouration (FD) after different periods in cold storage. Susceptibility to FD was low at harvest but increased with storage, especially between 1 and 2 months storage. Concomitantly, higher coating concentrations were required to reduced FD with prolonged storage; coating concentrations of 20 and 40% were necessary to reduce FD for fruit damaged after 1 and 2 months storage, respectively. Increasing coating concentration reduced internal O-2 partial pressure and reduced water loss. The lower internal O-2 level in coated fruit was associated with delayed ripening and reduced fruit susceptibility to FD. Reduced water loss preserved the integrity of skin and reduced susceptibility to FD. Higher levels of FD were observed at temperatures lower or higher than 10-20 degreesC. The physical protection provided by skin coatings in combination with their effects on fruit physiology, presents a useful opportunity to reduce FD after cold storage, if adopted in conjunction with adequate temperature and humidity control during storage and post-storage handling of the fruit. (C) 2001 Elsevier Science B.V. All rights reserved.