GB805220A - Improvements in or relating to the manufacture of foam-generating substances - Google Patents

Abstract

A foam-generating substance comprises an aqueous solution of the hydrolytic degradation products of a protein and a substance capable of yielding sulphite ions in aqueous solution to inhibit, or reduce the tendency of, the formation of a precipitate when an aqueous solution of the substance is maintained at a high atmopheric temperature or stored for a prolonged period. The protein, e.g. soya bean protein, casein, fish waste, keratin, horn or hoof meal, may be in a fine state of division, e.g. 16 mesh or less, and may be hydrolysed in an aqueous solution or suspension of ammonia, or an alkaline earth metal or alkali metal hydroxide or oxide, e.g. caustic soda, magnesium oxide and hydroxide. in a concentration from 0.1 to 0.5 grams sodium hydroxide (or its equivalent in other alkalies) per gram of protein. The sulphite ions, which may be present within the range introduced by the addition of 0.04 to 0.07 gram anhydrous sodium sulphite per gram nitrogen in the hydrolysate, may be provided by addition of a sulphite, bisulphite or hydrosulphite, e.g. of an alkali metal, alkaline earth metal or ammonia, to the hydrolysate, which may then be filtered and from which undesirable gases may be expelled, prior to neutralization by the use of, at least in part, an aliphatic monocarboxylic acid such as a fatty acid which may contain not more than six carbon atoms, e.g. formic, acetic and propionic acid. A foam-stabilizing agent, e.g. ferrous or copper salts such as the sulphate and chloride, may be added to the hydrolysate after the addition of the sulphite ions, the addition, together with that of an alkali to maintain a constant pH, are led in below the surface of the hydrolysate.