GB750825A - Improvements in or relating to the extraction of animal glue - Google Patents

Abstract

Collagen-bearing animal tissues, e.g. cattle hide trimmings or bacon skins, are acidulated with a water-soluble acid, e.g. to a pH between 1.5 and 6.0, and glue is extracted by treating them with water kept at a non-acidic pH by contact with a water-insoluble basic compound which reacts with the acid to form an insoluble salt, the tissues being maintained internally at an acidic pH, e.g. below 6.5, during the extraction, which may be effected in four stages at temperatures of 65, 75, 85 and 100 DEG C. respectively. The water-soluble acid may be sulphuric, sulphurous, phosphoric, citric or oxalic acid. The water-insoluble basic compound may be dispersed in the water and may be an alkaline earth carbonate, e.g. calcium carbonate, or an oxide, e.g. aluminium oxide. The tissues may first be soaked in dilute hydrochloric, nitric or acetic acid, which must be replaced by an acid forming an insoluble salt with the water-insoluble basic compound, before glue is extracted. To facilitate extraction of glue, the tissues may be conditioned in a saturated lime solution, in hydrochloric acid at pH4 in the presence of sodium silicofluoride and native yeast cultures, or in an aqueous solution of sodium silico-fluoride in the presence of native yeasts and added cultures of Mycoderma and Torulopsis yeasts.