Abstract
The changes of amino acid both in the calf skin and in lime solution in the proccess of liming were examined chiefly by paper chromatography The results are as follows:
(1) Amino acids, detected in the calf skin at the early stage of liming were of sixteen kinds, such as glycine, alanine, valine, leucine, serine, phenylalanine, cystine, thyrosine, histidine, threonine, arginine, lysine, aspartic acid, glutamic acid, proline and oxyproline. Three of these amino acids; cystine, threonine and histidine vanished after 10 or 15 days of liming, while thirteen other amino acids were detected even after the skin had been soaked for 20 days.
(2) By liming some sorts of amino acid of the calf skin were dissolved in lime solution. Most of these amino acids construct soluble protein, such as albumin, globulin, mucoid and so on.
Most of them are presumed to have been dissolved in lime solution by 10th day or so after soaking in lime solution, considering the rise and fall of the quantity of volatile ammonia in lime solution, and the kind of amino acids soluble in lime solution.
(3) Insoluble protein in the skin is also being resolved little by ltttle by saturated lime solution, and it is considered that the desoluble ammount of amino acid should increase if it was soaked in lime solution for a long time.
That is to say, the chief amino acids composing collagen, lysine, arginine, proline and oxyproline were surely detected after the skin was soaked for about 20 days.
(4) Gelatine can be obtained by heating collagen fibre together with water. In this case most important point for making fine quality of gelatine is that the collagen, not yet desolved and as pure as possible, should be used as materials.
Considering this experiments and results written in the preceding chapters, it is deducted that the skin should be soaked in lime solution for about 20 days at 18°C for the purpose of making gelatine from calf skin.
