GB479233A - Improvements in or relating to the storage of foodstuffs - Google Patents

Abstract

479,233. Preserving food. PIQUE, J. J. Dec. 18, 1936, No. 34847. [Class 49] In cold-storing meat, eggs, vegetables and other foodstuffs, the humidity of the atmosphere in the storage chamber is maintained during the cooling of the materials down to storage temperature at a value substantially equal to the vapour pressure of the moisture in the food and the raising of the temperature of the materials preparatory to removal from the storage chamber is effected by circulating through the chamber a warming atmosphere, the humidity of which is kept at about saturation point while, the atmosphere is gradually raised to the dew point of the outside atmosphere. In one form, eggs are packed in containers 1 which are of material non-absorbent of water vapour and introduced into a chamber 2 which is spaced on all sides from an outer chamber 3 by an air jacket 4. The chamber 2 is of metal or other non- absorbent material and has a gas-tight door 5. The chamber 3 has a heat-insulated door 6. Cold air is first circulated by a fan 8 through an air jacket 4, a duct 10, a cooler 7 and duct 9 back to the jacket. Carbon dioxide alone or mixed with nitrogen and /or substances having a preservative effect is introduced from cylinders 18, a storage tank 19 &c., through a humidifier 20, and if desired a cooler, pipes 21 and apertured ducts 14 into the chamber 2 until the appropriate amosphere is obtained. The atmosphere is then circulated by a fan 12 from the chamber through a duct 14, a cooler 11, a humidifier 15 which may consist of wicks or cascades over which water or a salt solution is circulated by a pump and through a duct 13 back to the chamber 2. The ducts 13, 14 have dampers 13a, 14a. The temperature and humidity are preferably maintained automatically, e.g. by thermostats and humidifiers, at the desired values, the eggs being kept at 32-34‹ F., the vapour pressure of eggs being about 97À5, of beef 99, and of apples 98À5 to 99À4 according to the variety. When the desired storage temperature is reached, e.g. 32-30‹ F. for eggs, and no heat is given off by the foodstuff no further extraction of heat is required, the low temperature in the jacket 4 being maintained by cooler 7. At the end of the storage period, cooler 7 is rendered inoperative and heaters 17, 24 operative, or instead of or in addition to these, hot water, steam, &c. may be circulated through the pipes in coolers 7, 11 and the temperatures in jacket 4 and chamber 2 are gradually raised to at least as high as the dew point of the outside atmosphere, the humidifier 15 keeping the atmosphere in chamber 2 at saturation point. The pump 23 withdraws gas from the chamber 2, air being admitted through the valve 25 during this step. The pressure in chambers 2, 3 may be kept sufficiently high to ensure leakage takes place outwards. When the preserving gas is reasonably cheap, the jacket 4 may be filled with it, the chamber 3 being gas-tight, the air in the chamber being exhausted through pipes 22, 27 and the gas introduced through pipe 21. Devices may be employed to absorb or neutralize noxious gases. In a modification, Figs. 3, 4 (not shown), the jacket 4 is filled with the preserving gas and a cooler, a heater and a humidifier are arranged together in the chamber, and delivery ducts provided, with means whereby the gas is circulated during the preliminary cooling through the storage chamber and the jacket, but during the storage period through the jacket only.