S23 - Session O1 - Apples cold storage under high relative humidity with HDCOLD refrigeration technology

Authors: Kévin Vidot *, Valérie Lemetter, Benoît Duparc, Christophe Despierres

Fresh products are particularly sensitive to hydric stress even during storage in cold room. For long period storage, the hydric stress induces several products disorders leading to food loss. In contrast with conventional cold system, the refrigeration technology HDCOLD was developed to reduce hydric stress on fresh products during storage in cold room. The HDCOLD offers a natural high relative humidity ( > 95% RH) atmosphere without any water supply and without the use of humidifier. Moreover, the HDCOLD doesn't require energy-consuming cyclic defrost. The study aimed to identify the benefit of a such innovative postharvest technology to reduce apples quality loss during cold storage. Five cultivars of apple, 'Gala' ( Malus domestica cv Gala), 'Chantecler' ( Malus domestica cv Borkh Chantecler), 'Golden' ( Malus domestica cv Golden delicious), 'Granny' ( Malus domestica cv Granny Smith), 'Story' ( Malus domestica cv Story Inored c.o.v), were freshly harvested by a producer from South of France. The ripening stages at harvest were optimal following Starch-Iodine index, measured between 6 to 9 for 'Gala', 'Chantecler' and 'Golden', at 5 for 'Granny' and at 9 for 'Story'. Apples were stored at 1°C for 'Gala', 'Golden' and 'Granny' and at 2°C for 'Chantecler' and 'Story'. A part of the apples was stored in a cold room equipped with the HDCOLD refrigeration system with regulated relative humidity set at 98%RH , and the other part was stored in cold room equipped with a standard refrigeration system with unregulated relative humidity measured between 80-90%RH (defined as the control sample). The quality of both apples samples was studied through the weight loss, fungal aspect, and the organoleptic properties using Near-IR analysis. A study of the energetic consumption of the HDCOLD technology was also achieved. Results showed a better preservation of the apples stored in the cold chamber equipped with HDCOLD refrigeration system, with significant improvement of weight loss, firmness, skin colour change and physiological disorders (shrivel, senescent scald & breakdown) compare to conventional refrigeration system. The difference in weight loss after 6 month of cold storage were 4.2%, 4%, 1.2%, 1.7% and 6%, respectively for 'Gala', 'Chantecler', 'Golden', 'Granny' and 'Story'. In another hand, the HDCOLD was found to be 6 times more energy efficient. Thus, at the beginning of the post-harvest chain, a performant refrigeration system such as the HDCOLD is essential to better preserved fresh products during storage in cold room. Afterward, the combination of complementary existing techniques would be interesting aimed to extend fresh product storage. In further study, the benefits of HDCOLD system will be experimented on others fresh products as root-vegetables, flowers, apple plants, vine graft, exotic fruit.