Author
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Rendleman Jr, Jacob |
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Submitted to: Applied Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/2/1996 Publication Date: N/A Citation: N/A Interpretive Summary: New and expanded markets are needed to utilize surplus starch produced in the U.S. Cyclodextrins, which are made by the action of an enzyme on solubilized starch (maltodextrin), can fulfill the role of an agrochemical that would benefit both farmer and industry. Cyclodextrins are being used increasingly by agricultural, pharmaceutical, cosmetic, fragrance, and food industries. However, because of high production costs, a need has existed for research that will provide greater knowledge of factors that govern yields of these compounds. A potentially important factor ignored by earlier workers was temperature. Almost all conversion of starch into cyclodextrins had been conducted at 40-60 C; virtually none at 25 C or below. The author has conducted conversion reactions over the range of 5-25 C and, under appropriate conditions, observed substantial improvements in yield over those yields obtained at higher temperatures. In low temperature studies he found a relationship between the molecular size and shape of an alcohol or hydrocarbon and the ability of such compounds to enhance the production of cyclodextrins from starch. The simple sugar maltose was found to be convertible into cyclodextrin in good yield at low temperatures, an accomplishment not possible at more commonly employed high temperatures. This information should be useful to cyclodextrin manufacturers concerned with reducing production costs, lowering the cost to consumers, and, ultimately, creating a greater demand for corn products in the marketplace. Technical Abstract: At 5-25 C, in the presence of appropriate complexants, maltose, maltotriose, and maltohexaose were converted by Bacillus macerans cyclodextrin glucanotransferase (EC 2.4.1.19) into beta-cyclodextrin (beta-CD, cyclomaltoheptaose) in yields as high as 34, 49, and 66%, respectively. In the absence of complexant, yields of CD were extremely low (<2% overall); however, they were greatly enhanced by the presence of certain complexants (cyclononanone, cyclodecanone, and cycloundecanone) known to be highly selective for beta-CD. Many complexants that enhance CD production from starch or maltodextrin failed to enhance CD production from maltose. An investigation of the influence of molecular size and geometry of alkyl alcohols and aliphatic hydrocarbons on CD production from maltodextrin at low temperature revealed that all C2-C14 alcohols and all C3-C15 hydrocarbons enhance overall CD yield. While all of the hydrocarbons were highly selective for beta-CD, selectivity of the alcohols varied according to chain length and degree of branching, with no alcohol enhancing the yield of gamma-CD. Straight-chain alcohols with 8 or fewer carbon atoms strongly favored beta-CD production; those with more than 8 carbon atoms favored alpha-CD production. Highest yields of alpha-CD (49-53%) were with C9-C12 1-alkanols. With the exception of n-butane, the use of which provided beta-CD yields as high as 59%, use of branched hydrocarbons and branched alcohols resulted in beta-CD yields (58-64%) higher than those obtained with the corresponding unbranched compounds. |
