GB651861A - Method of treating fish - Google Patents

Abstract

651,861. Food for animals &c. DEHYDRATING PROCESS CO. Dec. 24. 1947. No. 34198. Convention date, Jan. 2. [Class 5(ii)] in a method of reducing fish matter to a liquid state (referred to as " liquefied fish "), suitable for mixing with cattle or poultry feeds, any or all of the components of the fish are subjected to contact with an acid, e.g. H 2 SO 4 , HO<SP>2</SP> or H 3 PO 4 , and simultaneously to an atmosphere of steam at elevated temperature, to develop a pH of approximately 2.8-3.7 and pressure-temperature conditions of approximately 50 pounds per square inch and 300‹F or the equivalent and continuing these conditions until the charge is reduced substantially completely to a particle size below approximately 50 microns. The charge may then be evaporated in vacuo to at least 40 per cent solids content. As shown, the fish material is fed into a hopper 7 at one end of a screw conveyer 8 mounted in a closed cylindrical chamber 9 into which steam is led via jets 15 from a steam line 13 and becomes slightly precooked during its passage through the chamber to a disintegrator 16 where it is broken into pieces to pass a inch mesh screen. The pulp then falls into a surge chamber 17 from which it is pumped via a mixing chamber 19 in which the acid may be mixed into a series of digesters 24 (one only shown). The acid may be added earlier. e.g. before the pre-cooking stage, which itself and the disintegrating stage may be omitted especially with small fish. The digester is provided with agitating blades 30, 31 and steam inlet 34. The acidified charge is stirred and brought up to 300‹F or about 50 pounds per square inch, and these conditions are maintained for 3-4 hours. The " liquefied material " is then passed out of the digester through valves 38, strainer 39, and pumped to the first (42) of a series of multiple effect evaporators where the charge is progressively evaporated and is finally withdrawn and pumped to an independent vacuum evaporator 76 where the charge is brought to the required consistency &c. and is then discharged to storage tanks 92.