Practical physiological chemistry : a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . rdinary starch is in-soluble in cold water, but if boiled with water the cell walls areruptured and starch paste results. Starch is acted upon by diastatic enzymes, e. g., ptyalin anda my I opsin, with the formation of soluble starch, erythro-dextrin, achroo-dextrin, malto-dextrin, maltose, iso-maltoseand dextrose (see Salivary Digestion, page 34). Maltose isthe principal end-product of this enzyme action. Upon boil-ing a starch solution with a dil
Practical physiological chemistry : a book designed for use in courses in practical physiological chemistry in schools of medicine and of science . rdinary starch is in-soluble in cold water, but if boiled with water the cell walls areruptured and starch paste results. Starch is acted upon by diastatic enzymes, e. g., ptyalin anda my I opsin, with the formation of soluble starch, erythro-dextrin, achroo-dextrin, malto-dextrin, maltose, iso-maltoseand dextrose (see Salivary Digestion, page 34). Maltose isthe principal end-product of this enzyme action. Upon boil-ing a starch solution with a dilute mineral acid a series ofsimilar bodies is formed, but under these conditions dextroseis the principal end-product. Experiments on Starch. 1. Preparation of Potato Starch.—Pare a raw potato,comminute it upon a fine grater, mix with water, and whipup the pulped material vigorously before straining it throughcheese cloth or gauze to remove the coarse particles. Thestarch rapidly settles to the bottom and can be washed by re-peated decantation. Allow the compact mass of starch todrain thoroughly and spread it out on a watch glass to dry in. Pea. Wheat. Starch Granules from Various Sources. (LefFmann and Ream.) 24 PHYSIOLOGICAL CHEMISTRY. the air. If so desired this preparation may be used in the ex-periments which follow. 2. Microscopical Examination.—Examine microscopic-ally the granules of the various starches submitted and comparethem with those shown in Figs. 7-17, page 23. 3. Solubility.—Try the solubility of one form of starch ineach of the ordinary solvents (see page 4). If uncertainregarding the solubility in any reagent, filter and test the fil-trate with iodine solution as given under 5 below. The pro-duction of a blue color would indicate that the starch had beendissolved by the solvent. 4. Iodine Test.—Place a few granules of starch in one ofthe depressions of a porcelain test-tablet and treat with a dropof a dilute solution of iodine in potassium iodide. Th
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