Multi-objective optimization of storage temperature of apple to minimise energy use

Low temperature storage is widely employed to increase the storage life of apples. However, the use of refrigeration accounts for up to 15% of the global use of electricity. Increasing the storage temperature by 1°C can significantly reduce the total cost of electricity during apple storage. In this study, a multi-objective optimization approach is used to suggest new storage temperature of apple, taking into consideration the cost of electricity and the quality of the apple at the end of storage. Energy use was calculated using vapor pressure compression cycle models. Apple firmness was selected as the most important quality indicator for apple grading. The quality of the apple at the end of storage was converted to money value in €, based on the current grading system of apples in Belgium. Firmness was calculated using the firmness model developed by Gwanpua et al. (2012).The objective was to optimize storage temperature by minimizing the electricity usage, while minimizing quality losses (i.e. by maximizing the money value of the apple at the end of storage). This was done for different storage duration, and also for cool rooms with different storage capacity. New storage temperatures of apple, that will reduce the use of energy, were suggested.