PCMs and ice slurries: Broccoli preservation with ice slurry

Preserving the quality of extremely perishable vegetables such as broccoli is dependent on rapid and thorough cooling immediately after harvest and maintaining at a low temperature during storage or processing. The lower the storage temperature is, the longer the shelf life will be. The advantage of using ice is that it can remove heat rapidly when first applied to produce; ice particles can fill air voids and have close contact with produce so that it can continue to absorb heat as it melts during produce cooling and processing. In the first continuous-flow ice slurry systems developed in 2000, ice slurry was made from crushed ice mixed with water which could liquid-ice 180 to 210 boxes of broccoli per hour. During the 7th IIR Conference on Phase-Change Materials and Slurries in September 2006 in Dinan, France, engineers from Sunwell presented the results of experiments led on the DeepchillTM ice slurry system which is composed of fine ice crystals ranging from 250 to 500 ìm in diameter with no sharp and irregular edges, and thus causes no mechanical damage to produce. Ice slurry was automatically charged in the cartons containing broccoli either by a forced flowing flow or an immersion method. The results showed that ice could fully fill the air voids in cartons by forced flowing but it could only partially fill the air voids in immersion tests. Icing distribution was affected by immersion height and duration.