Effect of high temperature and 1-MCP application or dynamic controlled atmosphere on energy savings during apple storage

Abstract

The aim of this work was to evaluate the energy saving benefits that new storage strategies such as ULO storage + 1-MCP at higher temperatures and DCA may have when compared to standard ULO. The experiment was carried out in three storage rooms (11 tons each) under ULO conditions (1.0 kPa O2 + 2.5 kPa CO2) at 1°C or ULO at 5°C plus 1-MCP or DCA controlled by chlorophyll fluorescence (~0.7 kPa O2+ 1.5 kPa CO2) at 1°C. The apple cultivars ‘Golden Delicious’, ‘Jonagold’ and ‘Pinova’ were stored for 7 months and the energy consumption for each of the three rooms calculated from the refrigeration compressors, ventilation fans, defrosting and CO2 scrubber machinery run-times. Energy use was reduced by 20% in DCA and 70% in ULO + 1-MCP at 5°C when compared to ULO at 1°C. Apples stored at 5°C showed a lower weight loss when compared to 1°C. Despite a higher storage temperature, 1-MCP treated ‘Jonagold’ at 5°C were firmer than fruit under either ULO or DCA at 1°C without 1-MCP. The firmness of ‘Golden Delicious’ and ‘Pinova’ did not differ between treatments. The incidence of fungal rots was slightly increased under ULO + 1-MCP at 5°C for ‘Jonagold’, but strongly reduced for ‘Pinova’. There were no treatment differences in rot incidence for ‘Golden Delicious’. Sensorial analyses conducted after storage plus 7 days shelf-life at 20°C rated the texture of ‘Jonagold’ higher for ULO at 5°C + 1-MCP than for ULO at 1°C without 1-MCP and accordingly, purchase preferences were higher for ‘Jonagold’ under ULO at 5°C + 1-MCP. ‘Pinova’ texture was rated best after DCA at 1°C. There were no differences in the texture preferences between ULO at 5°C + 1-MCP or ULO at 1°C without 1-MCP or any differences in taste preferences between the storage treatments for either ‘Jonagold’ or ‘Pinova’.