Improved method for pasteurising or sterilising liquid and semi-liquid products

摘要

789,767. Sterilizing liquids. LAGUILHARRE, P. R. Nov. 28,1955 [Sept. 20, 1955; Nov. 3, 1955], No. 34077/55. Class 49. In continuously pasteurizing and sterilizing liquid and semi-liquid foods by injection of hot vapour such as steam, the hot food so injected is subjected to at least one expansion down to a pressure between that corresponding to the initial temperature of the food being pasteurized or sterilized and that corresponding to the pasteurizing or sterilizing temperature, the vapour evolved during the expansion is removed and compressed to a pressure at least as high as that corresponding to the pasteurizing or sterilizing temperature and is injected into the food, which is preferably in subdivided form. With the apparatus of Fig. 1, milk pumped at 15 ‹ C. to a preheater 1 is there heated to 100 ‹ C., is fed through an atomizing nozzle 7 into a sterilizing chamber 5 and is there rapidly heated to 140‹ C. by steam introduced by a pipe 13; milk sterilized in the chamber 5 is fed into an expansion chamber 10, the temperature being so decreased to 100‹ C., and the vapours evolved are withdrawn to a compressor 12, there compressed to 3 kg./sq. cm. above atmospheric pressure, i.e. are brought to a temperature greater than the sterilizing temperature, and are then introduced through a valve 14 and the pipe 13 into the chamber 5, whereby the pressure falls to 2.7 kg./sq. cm. above atmospheric, i.e. the temperature falls to the sterilizing temperature 140‹ C.; milk pumped from the expansion chamber 10 is cooled further at 18; the continuous operation is initiated by a preliminary admission of steam by a pipe 15. With the apparatus of Fig. 2, there are successive expansions in chambers 10 and 24, the vapours evolved in the chamber 24 being compressed at 29 and further compressed at 30, where also the vapours evolved in the chamber 10 are compressed, and the compressed vapours being introduced by way of a valve 14a into the sterilizing chamber 5. With the apparatus of Fig. 3, vapours evolved in a single expansion chamber 10a are fed by a pipe 31 to a compressor 32 to which is fed also milk preliminarily heated at 1, and the mixture is fed into a conduit 33 which constitutes the sterilizing chamber; with the apparatus of Fig. 4, vapours evolved in successive expansion chambers 10b and 24b are fed to compressors 38 and 39 to which is fed also milk preliminarily heated at 1, and the mixture is fed into a sterilizing conduit 41; with the apparatus of Fig. 5, vapours evolved in a single expansion chamber 10a are compressed in two stages in compressors 45 and 46 to which is fed also milk preliminarily heated at 1, and the mixture is fed into a sterilizing conduit 47.