GB701631A - Improvements in or relating to a process of deodorizing a glyceride oil and the products resulting therefrom - Google Patents

Abstract

<PICT:0701631/III/1> <PICT:0701631/III/2> Edible glyceride oils are deodorized by treating a shallow body of the oil with steam at a temperature which is raised in stages to 500-600 DEG F. and under a pressure not above 5mm. of mercury while withdrawing steam and other vapours from above the oil during each deodorization stage. The term "steam" includes any gas which is inert to the oil, such as carbon dioxide. In the continuous apparatus shown in Fig. 9, the oil is passed in succession through a heater 19, a deodorizing chamber 14, a second heater 21, a second deodorizing chamber 16, a third heater 22 and a third deodorizing chamber 17, the third heater raising the temperature of the oil to 500-600 DEG F. Each deodorizing chamber comprises, as shown in Fig. 2, a cylinder 63 containing a shallow layer of oil fed from pipe 62 and a screen 67 above the layer of oil. Steam <PICT:0701631/III/3> <PICT:0701631/III/4> is passed through the oil from a perforated pipe 66, and vapours are withdrawn through vents 64 fitted with baffles 681 to a vacuum manifold 115, Fig. 9. The oil from the final deodorizing chamber 17 is passed to a tank 92b, wherein it is partly cooled, and then to a tank 92g, wherein it is further cooled, the oil in each of these cooling stages being treated with steam under high vacuum and the vapours from each tank being passed to the vacuum manifold 115. Finally, the oil is discharged through a cooler 18. The vapours withdrawn from the chambers 14, 16, 17 and tanks 92b and 92g into the vacuum manifold 115 are condensed in a system comprising vacuum boosters 24, 26, Fig. 1, and jet condensers 27, 28, 29 arranged in series, residual gases from the condenser 29 being discharged by means of jet ejectors 126, 127. Condensates from condenser 27 is withdrawn by pump 132 through a pipe 133 in which a constant liquid level is maintained by a float-controlled valve 134 in the pipe 136 which supplies water to the condensers. Condensate from condenser 28 is returned by pipe 143 to the condenser 27. Condensate from condenser 29 is discharged through pipe 152. The condensates from condensers 27, 28, which contain vitamins, tocopherol, sterols and fatty acids, are collected in a settling tank 38, from which the supernatant layer is withdrawn to a tank 147. Condensate from the vacuum manifold 115, which may have a cooling jacket 168, is also collected in tank 38. Fig. 7 shows an apparatus for the treatment of a single batch of oil. The oil is supplied through a pipe 189 to a vessel 182 having a screen 183 above the surface of the oil and a heating coil 184 immersed in the oil. External heating units 186 may also be provided. Steam is supplied through a pipe 187 having a perforated end 188, and vapours are withdrawn through a duct 192 and trap 193 connected at 24 to a vacuum condensation system similar to that described above. The oil is discharged through a pipe 191 and tank 199. In a typical method of operation, oil preheated to 410 DEG F. is fed through pipe 189 to form a shallow body (less than 20 inches deep) in the vessel 182, and the temperature is then raised to 420 DEG F., held at this point for about 5 minutes raised rapidly to 480-500 DEG F., held again for about 5 minutes, and raised again to 540-580 DEG F., where it is held again for about 5 minutes. The oil is then rapidly cooled while the passage of steam through the oil is continued. The process is particularly applicable to soya-bean oil, but other oils which may be treated are cottonseed, corn, peanut, sunflower-seed, rapeseed and sesame-seed oils, and fish or fish-liver oils. The oil may have been preliminary refined, e.g. with alkali and (or) an adsorbent, and may have been hydrogenated. After the deodorization treatment, the cooled oil may be filtered. Specifications 589,534, 701,632 and 701,633 are referred to.