E. GENERAL LECTURES - MOISTURE IN VEGETABLE STORAGE
Refrigerated storage are used for these purposes in a greater extent from year to year. International and national recommendations for optimal storage conditions are to be found in handbooks (Kurki 1966, Phillips and Armstrong 1967, Lutz and Hardenburg 1968). It is difficult to get and to maintain the recommended relative humidity of 90–95% in the types of refrigerated storage which are mostly used at present, namely in the storage where the evaporator with forced air is inside the room. And even if the recommended moisture level is maintained, water is lost through evaporation. Shriveling and drying of vegetables occur.
At the Department of Horticulture at Piikkiö preliminary research with the refrigerated storage of vegetables begun in 1963. Already after the first season it became obvious that the moisture content of refrigerated vegetable storages is one of the main questions in the long term as well as in the short term storage of fresh vegetables. A long term in Finland means a storage time of seven months for rootcrops, five to six months for cabbage and leek, and a year for onions.
To solve the problems of moisture in vegetable storage a series of small scale trials was set up in separate storage rooms of 4.3 m3, where the temperature was automatically regulated in the range of 0.5°C. Moisture levels were maintained with humidifiers, regulated automatically within a range of 1%-unit. These two moisture levels were maintained at temperatures of 0–1°C, 4–5°C, and for leek also -1°C where the relative humidity of 80% was held. The air was kept fresh with ventilation when needed.
Experiments were made with carrots, celeriac, cabbage, leek, celery and lettuce. Experimental amounts for rootcrops and leek 3 kg, for cabbage and celery 5 kg and 0.5 kg for lettuce, all with 5 replications. Products were precooled immediately after harvest and placed in the storages within a day. Lots were analysed and discarded every two months except for lettuce and celery, which were analysed each week. Results presented here are of the storage season 1966–1967.
The best storing result for carrot was obtained in the conditions of 0–1°C and R=97–99% (table 1). The total loss after eight months of storage, beginning in October, was after trimming 16% from the initial