Fruit colour, size and temperature effects on the shelf life of sweet cherry

The island state of Tasmania, Australia enjoys a cool, maritime climate well suited for production of quality cherries that mature over the mid-December to late-February period. The cherry industry in Tasmania has increased from boutique status, producing 200 tonnes in the late 1990s, to ca. 3000 tonnes in the 2008-2009 season. Significant new plantings underpin forecasts of production increasing to 8000 tonnes in the 2012-2013 season and industry are looking to increasingly utilise sea freight for export markets. The broad objective of our work is to investigate pre- and post-harvest management practices that may prolong the shelf life of sweet cherries. Further, the long term goal of this work is to identify characteristics of fruit at harvest that relate to shelf life and, therefore suitability for sea freight.

This work has demonstrated the critical impact of temperature on quality of sweet cherry fruit, with storage temperatures of 0 and 5°C reducing the rate of weight loss and retarding colour change. Water loss was greater in stemmed fruit and the higher weight loss in fruit stored at 20°C was associated with greater shrivelling of the pedicel. Stem removal had no effect on any of the fruit quality attributes measured in this work. Cherries harvested ripe (C7) had the highest sugar levels and same firmness as intermediate maturity fruit (C6). Pre-ripe fruit (C5) was firmer but had undesirable low sugar levels. Fruit from all colour categories lost weight at a consistent rate during storage. Larger fruit were higher in sugar content and firmer than smaller fruit. The lower temperatures retarded colour change. Weight loss and fruit acidity levels during storage were not affected by fruit size. This work indicates that fruit should be picked at optimum maturity for consumer acceptance and stored at 0°C.