Work Package 4 – Fruit Quality for Point of Sale (PoS) – develops and validates methodologies for testing variety-specific post-harvest properties. The findings improve the decision-making basis for choosing suitable varieties (specifically for the chosen sales channel) and enable variety-adapted post-harvest handling. WP4 focuses on cherries and plums, which need to ‘catch up’ with the other fruit varieties.
The post-harvest behaviour (quality development) of the fruits is tested under various storage conditions. The parameters to be tested – varieties, production sytem, storage – are determined based on the experience of previous projects and in cooperation with implementation partners Tobi Seeobst and fenaco. The consumer test determines acceptance and willingness to pay for different qualities at the PoS, in order to evaluate the tested post-harvest processes in economic terms.
Storage test with cherries and plums
Urgent action is required for stone fruit in particular, since the quality of the fruits at the PoS is increasingly coming under fire. There are various underlying causes, since not only the choice of variety, but also the time of harvesting and the post-harvest treatment can significantly affect fruit quality. Post-harvest processes have become more complex and retail structures larger and increasingly automated in recent years. Significant innovations include the calibration of cherries and the short-term storage of some stone fruit. Yet the current state of knowledge regarding variety-specific storage and processing properties is often insufficient to make optimal use of these developments.
WP4 thus focusses on the post-harvest quality of stone fruit. At Agroscope in Wädenswil the post-harvest behaviour of selected cherry and plum varieties is tested annually under two different storage conditions (cold storage and controlled atmosphere) and evaluated by measuring quality parameters. The quality measurements taken during harvesting are repeated at the end of the storage period, which lasts from two to four weeks. In addition, after removal from cold storage, some fruits are re-stored at room temperature to simulate the shelf life. After three days of re-storage, these fruits also undergo quality testing. Standard test devices are used, such as penetrometers for measuring fruit firmness and refractometers for determining the sugar content of the fruits. But innovative, non-destructive measurement tools are also being tested: the ColourPin for the colour tone of the fruit skin, the SCiO NIR spectrometer for the sugar content and the DA-Meter® to determine the chlorophyll content of the fruit, and by implication its ripeness.
The measurement data from the tests provide information about the storage potential of the varieties and contribute to optimising variety-specific storage conditions. In addition, the protocol for evaluating the post-harvest properties of plums and cherries is continuously refined to enable post-harvest data to be integrated into the variety testing process in future.
Cooperation with Tobi Seeobst and fenaco
The post-harvest treatments to be tested and quality parameters to be analysed were defined and the varieties then selected in consultation with project partners Tobi Seeobst and fenaco. Both project partners also provide data on fruit quality and shelf life from the practice. This data set enables cross-site evaluation and comparison with the results from the storage trial. Instructions relating to the shelf life, storage conditions and handling can be communicated farmers based on the findings. Close cooperation with retailers ensures that the research is practically relevant.
Consumer test 2023
A broad-based consumer test with plums and cherries is planned for the third year of the project. A small preliminary test with plums has already been conducted in 2022, in which fruit specimens were tasted by the Agroscope sensory panel. Selected quality parameters such firmness, sugar content and acidity were also measured. The aim was to determine how the fruit characteristics influence consumer acceptance and willingness to purchase. The results of the preliminary test informed the design of the consumer test planned for 2023.
