Katsuhiko Mikuni

Stabilization and Solubilization of Lipophilic Natural Colorants with Cyclodextrins

The paper provides data on the practical utilization of the benefits of the molecular encapsulation of natural colorants by cyclodextrins. Experimental results on the stability of cyclodextrin complexed curcumin, curcuma oleoresin, β-carotene and carotenoid oleoresins against light-, heat- and oxygen prove the benefits of molecular encapsulation of colorants. The parent β-cyclodextrin stabilized most effectively the curcumines, while the stability of carotenoids was most effectively achieved by α-cyclodextrin complexation. Methylated β-cyclodextrin was found to be the most potent solubilizing agent for both carotenoids and curcuminoids.

Purification of the glucoamylase components of Chalara paradoxa by affinity chromatography and chromatofusing

Abstract The six major glucoamylase components (A1–A6) in the culture filtrate of Chalara paradoxa , which had different isoelectric points, were isolated electrophoretically pure by affinity chromatography on α-CD(cyclomaltohexaose)-Sepharose 6B and positive pH-gradient chromatofocusing using CM-Sepharose CL-6B and Polybuffer 74. The isoelectric points were: A1, 3.80; A2, 3.75; A3, 3.70; A4, 3.65; A5, 3.60; and A6, 3.55, A1–A3 had molecular weights of 76,000, 77,000, 78,000, respectively, were most active at pH 5.0–6.0 and 50°, and were stable in the pH range 4.5–8.0 and up to 45°. Each of the purified glucoamylases A1–A3 attacked soluble starch to give β- d -glucose.

The structure of high molecular weight dextrins obtained from potato starch by treatment with Bacillus macerans enzyme

Abstract Bacillus macerans enzyme (BME)-derived high molecular weight dextrins, which are by-products in the course of the industrial production of cylodextrins, were isolated and their chemical structures were characterized. Dextrin I was obtained in a yield of about 24% from BME-hydrolyzate (a mixture of dextrin and cylodextrins, 50% each) of potato starch by fractionation with an ultrafiltrator having a membrane of cut-off molecular weight 2.0 × 104. Dextrin II was obtained in a yield of about 15% from BME-hydrolyzate (a mixture of dextrins and cyclodextrins, 70 : 30) of Dextrin I by the same method. Dextrin I and II consisted of dextrin having molecular weights over 20 × 106 and dextrins having molecular weights 4 × 103−1 × 105 in the ratio of 80 : 12 and 66: 15, respectively. The results of hydrolysis by β-amylase and methylation analysis indicated that the average, exterior and interior chain lenghts of the dextrins having molecular weights over 20 × 106 and 4 × 103−1 × 105 from Dextrin I were 16.5, 8.2 and 7.3, and 11.5, 6.9 and 3.6, respectively, than those from Dextrin II were 13.6, 4.7 and 9.9, and 10.4, 5.1 and 4.3, respectively.

Chemical characterization of dextrins obtained from potato starch by treatment with Bacillus macerans enzyme

Abstract Potato starch was degraded with Bacillus macerans enzyme (BME), and the degradation product (a mixture of dextrins and cyclodextrins, 56.4:43.6) was separated by gel chromatography on Bio-Gel P-10 and Sepharose CL-2B into four fractions, I-1 (mol wt > 20 × 106), I-2 (mol wt 2 × 104-1 × 105), II (mol wt 1.5 × 103-2 × 104) and III (mol wt