We divised a simplified analytical method based on fractional quantitative determination proposed by Patterson and co-workers. While using commercial decolorizing activated carbon, we established conditions for a carbon column which can be operated under pressure at room temperature and examined the accuracy of fractionation on this column. We then proposed GV (Glucose Value) and MV (Maltose Value) to be calculated from the amounts of glucose and maltose fractionated under the abovementioned conditions as indicators of the quality of starch syrups. (1) With the aid of a carbon column consisting of a mixture of 5 g of activated carbon and 5 g of celite (No. 535) as an adsorption layer, glucose was recovered in a fraction eluted with 150 ml of water and maltose in a fraction eluted with 200-250ml of 5 % ethanol. The reproducibility of this method was within ±0.5 . (2) The values of GV and MV were determined for a variety of starch syrups. Acid-hydrolyzed syrups and malt-hydrolyzed syrups gave roughly constant MV of 31.2 and 121.9 respectively on the average. On the other hand, GV increased in proportion to DE in the case of acid-hydrolyzed syrups but it remained in the range of 5-10 in the case of malt-hydrolyzed syrups.
The Zerban-Sattler modification of the Steinhoff method adopted in "Official Method of Analysis of the A. O. A. C." was adapted to microanalysis. Reagents (A) 40 g of CuSO4. 5H2O dissolved in water and made up to 1 liter. (B) 300 g of NaOAc. 3H2O dissolved in water and made up to 1 liter. (C) 200 g of KI dissolved in water and made up to 1 liter. (D) 6N-H2SO4. (E) 12g of KCNS dissolved in water and made up to 100 ml. (F) 1 % soluble starch. (G) 0.02N-Na2S2O3 standard solution. Procedure Introduce 2 ml of (A), 2 ml of (B) and 2 ml of a sugar solution containing 40-180mg of glucose in 100 ml into a glass-stoppered test tube which is 2.5 cm in diameter and 20 cm in length, stopper the test tube, and shake vigorously. Heat the test tube and the contents in briskly boiling water in a water bath for 25 minutes, and then cool in running tap water. Add 1 ml of (C) and 1 ml of (D), shake the mixture well, leave it standing for 3-4 minutes, and titrate with (G). When the solution has turned light yellow in color, add 2 ml of (E) and continue titrating . When the color has again turned light yellow, add 2-3 drops of (F) and titrate until the bluish violet color disappears while recording the total volume (a) in ml . Run a blank test and determine the volume of (G) consumed or (b) in ml . Calculate the amount of glucose (y in mg/100 ml) according to the following equation :y=25.27(b-a)+15.17 A comparison of this method with carbon column chromatography indicates that glucose determined by this method comes out 2-3% higher for acid-hydrolyzed syrups and 4-5 % higher for malt-hydrolyzed syrups ; however, this method is practical because of its simplicity in procedure and calculation .
Fractionation of maltooligosaccharides and isomaltooligosaccharides was carried out by the improved carbon column chromatography using a concentration gradient system of 3% n-butanol and 10% n-propanol . Excellent resolution of the oligosaccharides series was obtained. In the case of the maltooligosaccharides series, each oligosccharide was separated with wide window up to DP 12 and the similar results were obtained for the isomaltooligosaccharides up to DP 9 . Deactivation of carbon had strong influence on the resolution of oligosaccharides .
Gelatinization and retrogradation of starch were estimated by the iodine binding values (lab) which were determined by the amperometric titration with KIO3 of an acidified specimen in both solution and suspension as follows : Gelatinization degree(%)=Iab in suspension/Iab in solution×100 Retrogradation degree (%) = 100-gelatinization degree In the titration of the suspension, a specimen was homogenized with water in a glass homogenizer by hands and was added KCl, HCl and KI to the suitable conditions for the titration. The homogenization conditions did not effect on the determination of Tab when the suspension was apparently homogeneous. In the titration of the solution, the specimen was dissolved in 0, 5 N KOH, acidified with HCl and added KI to be the same composition as in the suspension. Before the determination, specimens were dehydrated well with ethanol, washed with ether and dried over CaCl2 in a vacuum desiccator. The estimation method is specific basically for amylose and, therefore, it is very useful for the analysis of gelatinization and retrogradation of starch. As applications, the retrogradation of potato amylose, amylopection and starch was characterized by the present method together with the glucoamylase digestion and x-ray diffraction procedures.
(1) Iodine affinity (I. A.) values of 7 starch samples (each sample treated with petroleum benzine, treated with methanol, and untreated) were measured by means of the automatic amperometric titration method in a team project . Amylose contents of these samples were calculated from the I . A. values of methanol-extracted samples, on the basis of a standard I. A, value (-19) of amylose : the results obtained were 23-25% for 3 ordinary cereal starches, 19-20% for 3 tuber or root starches and 3 % for waxy corn starch.(2) The 7 starch samples were divided by the type of titration curve into two groups : 4 cereal starches and 3 tuber or root starches. The samples of the latter group have a refracting point in the sharply ascending straight part of titration curve .(3) Since the slopes of the sharply ascending straight line of titration curves differed with starch samples, the slope was corrected in such a manner that the slope for sample solution became identical with the slope for the blank solution . The I. A. values after the correction were only 0.1-0.4 higher than the uncorrected values .