Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
FIGURE 17.2 Schematic representation of the hydrophylic and hydrophobic regions of CDs.
The darker regions represent the more hydrophilic and the lighter regions the more hydrophobic
regions.
For a long time, only three parent major CDs (α-, β-, and γ-CD) were known
and well characterized. In the 1990s, a series of larger CDs was isolated. For example,
the nine-membered δ-CD was chromatographically isolated from the commercially
available CD-conversion mixture. It is more readily water soluble than β-CD, but
less water soluble than α- and γ-CD. In acids it is the least stable among the CDs
known; the rate of acid-catalyzed hydrolysis increases in the order α-CD < β-CD <
γ-CD < δ-CD.
Larger CDs have irregular cylindrical structures. They are like collapsed cylinders,
and their real cavity is even smaller than that in γ-CD. The driving force of
the complex formation, the substitution of high-enthalpy water molecules in the CD
cavity, is weaker in larger CDs. Therefore, their utilization as inclusion complexing
agents will probably remain restricted.
17.2.2 PRODUCTION 10,11
The cyclodextrin glucosyl transferase enzyme (CGT-ase) is produced by a large
number of microorganisms, for example, Bacillus macerans, Klebsiella oxytoca,