GB668288A - Improvements in or relating to processes and apparatus for the preparation of parboiled rice - Google Patents

Abstract

668,288. Treating grain. FERNANDES, March 13, 1950, No. 6278/50. Class 6(iii) 30531/48. Class 58. In a process for converting crude rice into parboiled rice, while conserving in the kernels the full vitamin contents originally present, the crude rice is first soaked by imparting thereto, while in a thinly-spread condition, a slowly progressing and rolling motion and supplying water to said kernels, at a temperature preferably between 75‹ and 95‹C so that it permeates the kernels gradually, whilst the quantity of water supplied is at most only in slight excess of the amount taken up by the kernels, whereby the minimum of vitamins are washed out of the kernels; whereafter the soaked rice is slowly conveyed in a thinly-spread condition and with a rolling motion through an open vessel supplied with steam at a uniform temperature not exceeding 100‹C, whereby the vitamins diffused in the kernels are fixed; and finally drying the parboiled rice at substantially atmospheric pressure and moderate constant temperature. As shown, the soaking, steaming and drying are carried out in three separate apparatus, each similar and comprising a horizontal rotatable drum 1 (perforated only for the drying process), having a helical conveying member 2 fixed to the wall and provided with conical nozzles 5, 6 at the ends, the former being rotatably supported by a hollow sheet metal cone 7 carrying a hopper 9. Through a perforated tube 11 extending axially through the drum water and steam may be passed for the steeping and steaming processes and hot air blown through by a fan for the drying process. In a modification (Fig. 4, not shown) of the apparatus for the soaking step, the discharge end of the drum is provided with an extension having a perforated wall and a conical nozzle end into which the conical nozzle 6 of the drum extends and is provided with a helical conveying member. A receptacle under the extension catches the draining from the soaked crude rice. In another modification, Fig. 5 (not shown), the hot steeping water from the receptacle which is provided with a steam inlet to maintain temperature is pumped back through the perforated tube 11.