Patent GB-483003-A (GB)
Title: Improvements in or relating to the protection of vegetable and animal goods during storage
IPC: A23L3/3445
Filed: 1936-10-02
Abstract: The second Provisional Specification describes the production of a complex cuprammonium compound by mixing a solution of about 60 gm. of hydrated copper sulphate in 500 ccs. of water with a solution of about 30 gm. of sodium hydroxide in 150 ccs. of water, the solutions being first heated to 55 DEG  C. and the black precipitate produced separated, washed, dried to a slightly moist condition on a water bath and mixed with about 30 gm. of pulverized ammonium carbonate, 100 ccs. of a 20 per cent solution of ammonia being added and the mixture slightly warmed and shaken well.  Specification 404,539, [Group VI], is referred to.ALSO:Vegetable and animal goods are protected against damage during storage by wrapping around or placing in association therewith paper, cardboard, fabric or like carrier which has been impregnated or coated with a substance adapted to evolve an alkaline gas, e.g. ammonia, under the conditions of use. The impregnating substance may be such as to give off the alkaline gas gradually and continuously, e.g. the ammonium salt of tartaric, salicylic, benzoic, lactic, formic, boric or carbonic acid.  The substance may, alternatively, be such that evolution of the gas occurs only when the carrier is subjected to the action of carbon dioxide evolved by the goods e.g. commercial cuprammonium or other complex compounds of metals with ammonia, these compounds, if insoluble or slightly soluble, being preferably formed in situ in the press or on the fibres of the paper &c. Paper may be impregnated by passing it through a solution of the substance which is heated, preferably to about 70 DEG  C., and kept saturated, the paper being dried by traversing through the air, or treating with a current of air, or both.  Where, in the case of foodstuffs, it is desired to repel flies and insects, the paper, &c., may be impregnated or coated with ammonium formate or lactate, or one side of the paper, &c., may be coated with a substance yielding an alkaline gas and the other side with a solution of formic or lactic acid, or these two classes of substances, may be applied to a common base, e.g. paper over adjacent areas.  To enable the efficiency of the preserving process to be checked, an unimpregnated edge of the paper may be provided with a series of sensitive indicators adapted to change colour in dependence upon the alkalinity of the air, e.g. by impregnating three small areas with respectively 0,4 per cent solutions of brom-cresol-purple and bromthymol blue and an 0,2 per cent solution of phenol red, all in isopropyl alcohol, and providing a colour chart by which, according to the colour of these indicators, the alkalinity of the air can be determined; this chart may be printed on the paper. To protect the treated paper &c. against damp or moisture, there is applied a coating or covering of a waterproof material, e.g. a waterproof varnish, a cellulose lacquer or a cellulose acetate film. The paper, waterproofed or not, may be perforated to facilitate evolution of the alkaline gas.  All or part of the paper or other carrier may be corrugated, cr<\>zeped, crinkled or folded to increase the area for dissemination of the gas or to concentrate the effect at a predetermined location.  The second Provisional Specification describes the production of a complex compound for use in impregnating or coating the paper &c. by mixing a solution of about 60 gm. of hydrated copper sulphate in 500 ccs. of water with a solution of about 30 gm. of sodium hydroxide in 150 ccs. of water, the solutions being first heated to 55 DEG  C.; the black precipitate produced is separated, washed, dried to a slightly moist condition on a water bath and mixed with about 30 gm. of pulverized, ammonium carbonate, 100 ccs. of a 20 per cent solution of ammonia being added and the mixture slightly warmed and shaken well.  Specification 404,539 is referred to.