198
into the technology. Under these circumstances, also branched cyclodextrins of high
aqueous solubility were produced from wheat starch substrate. In these branched
cyclodextrins, glucosyl and maltosyl side chains were attached to glucopyranosyl
units of the parent cyclodextrin via alpha-1,6 linkages. Compared with other starch
sources, wheat starch produced the highest (35–40%) degree of conversion.
The conversion mixture obtained by processing pre-hydrolyzed starch using any
cyclodextrin glucosyltransferase enzyme always contains negligible amounts of
higher degree of oligomerization (9, 10, 11, and 12) cyclodextrins, so called largering cyclodextrins, moreover a series of branched cyclodextrins besides the three
major (native) cyclodextrins. The solubilities of branched cyclodextrins in water,
even in aqueous 80% ethanol or in aqueous 50% solutions of methanol, formaldehyde, and ethylene glycol, are extremely high in comparison with their parent
cyclodextrins. Their ratio depends on the conversion time and the applied enzyme
and can be strongly influenced by the reaction conditions, especially on the chemical nature of specific precipitating complexant. According to Chinoin developers,
the ratio to beta-cyclodextrin can be enhanced if wheat starch and trichloroethylene
or toluene is used as raw material and precipitating agent, respectively. From the
crystallization mother liquors of wheat starch-based beta-cyclodextrin technology,
the glucosyl beta-cyclodextrin content was recoverable at 50 °C, by the means of
chromatography on Amberlite cation exchange resin (Seres et al. 1989). At that
time, however, both branched cyclodextrins and large-ring cyclodextrins were considered scientific curiosities only.
Application of an immobilized cyclodextrin glucosyltransferase made possible a
continuous process in a stirred reactor connected with a laboratory-sized hollow
fiber membrane-equipped diafiltration cassette. Low molecular weight components,
cyclodextrins, and maltooligosaccharides squeezed through the membrane, whereas
unreacted amylose and amylopectin degradation products were recirculated. With
continuous input of corn starch hydrolysate, benzyl alcohol was added into the reaction vessel containing cyclodextrin glucosyltransferase beads. This system was
operated in steady state, for months in laboratory size; it has not been scaled up due
to the lack of a suitable industrial filtration device.
Because of limited scale-up capacity, Chinoin Pharmaceutical and Chemical
Works Co. Ltd. initiated negotiations with Győri Szeszipari Vállalat (Győr Distillery,
Hungary) in 1985, to adopt the beta-cyclodextrin technology and scale up it in the
future to 100 tons/year capacity. The original toluene-based beta-cyclodextrin technology, used in Chinoin earlier, was transformed into a large-scale manufacturing
pathway in the Győr Distillery. The industrial production in 20 m
3
volume fermentors was continued over 2 years in 1987–1989 period, to produce approximately
20 tons of beta-cyclodextrin.
As a factory product subjected to Hungarian food manufacturing law, permanent
problem was to reduce the toxic toluene residual solvent in the high capacity manufacturing. According to Hungarian dietary regulation, the allowable limit of toluene
was 1 ppm at that time. Moreover, it was a purchaser demand to get a toluene-free
product, which is utilizable safely in dietary or pharmaceutical products. To resolve
this problem, a new toluene-free conversion technology was elaborated at Chinoin
É. Fenyvesi et al.
into the technology. Under these circumstances, also branched cyclodextrins of high
aqueous solubility were produced from wheat starch substrate. In these branched
cyclodextrins, glucosyl and maltosyl side chains were attached to glucopyranosyl
units of the parent cyclodextrin via alpha-1,6 linkages. Compared with other starch
sources, wheat starch produced the highest (35–40%) degree of conversion.
The conversion mixture obtained by processing pre-hydrolyzed starch using any
cyclodextrin glucosyltransferase enzyme always contains negligible amounts of
higher degree of oligomerization (9, 10, 11, and 12) cyclodextrins, so called largering cyclodextrins, moreover a series of branched cyclodextrins besides the three
major (native) cyclodextrins. The solubilities of branched cyclodextrins in water,
even in aqueous 80% ethanol or in aqueous 50% solutions of methanol, formaldehyde, and ethylene glycol, are extremely high in comparison with their parent
cyclodextrins. Their ratio depends on the conversion time and the applied enzyme
and can be strongly influenced by the reaction conditions, especially on the chemical nature of specific precipitating complexant. According to Chinoin developers,
the ratio to beta-cyclodextrin can be enhanced if wheat starch and trichloroethylene
or toluene is used as raw material and precipitating agent, respectively. From the
crystallization mother liquors of wheat starch-based beta-cyclodextrin technology,
the glucosyl beta-cyclodextrin content was recoverable at 50 °C, by the means of
chromatography on Amberlite cation exchange resin (Seres et al. 1989). At that
time, however, both branched cyclodextrins and large-ring cyclodextrins were considered scientific curiosities only.
Application of an immobilized cyclodextrin glucosyltransferase made possible a
continuous process in a stirred reactor connected with a laboratory-sized hollow
fiber membrane-equipped diafiltration cassette. Low molecular weight components,
cyclodextrins, and maltooligosaccharides squeezed through the membrane, whereas
unreacted amylose and amylopectin degradation products were recirculated. With
continuous input of corn starch hydrolysate, benzyl alcohol was added into the reaction vessel containing cyclodextrin glucosyltransferase beads. This system was
operated in steady state, for months in laboratory size; it has not been scaled up due
to the lack of a suitable industrial filtration device.
Because of limited scale-up capacity, Chinoin Pharmaceutical and Chemical
Works Co. Ltd. initiated negotiations with Győri Szeszipari Vállalat (Győr Distillery,
Hungary) in 1985, to adopt the beta-cyclodextrin technology and scale up it in the
future to 100 tons/year capacity. The original toluene-based beta-cyclodextrin technology, used in Chinoin earlier, was transformed into a large-scale manufacturing
pathway in the Győr Distillery. The industrial production in 20 m
3
volume fermentors was continued over 2 years in 1987–1989 period, to produce approximately
20 tons of beta-cyclodextrin.
As a factory product subjected to Hungarian food manufacturing law, permanent
problem was to reduce the toxic toluene residual solvent in the high capacity manufacturing. According to Hungarian dietary regulation, the allowable limit of toluene
was 1 ppm at that time. Moreover, it was a purchaser demand to get a toluene-free
product, which is utilizable safely in dietary or pharmaceutical products. To resolve
this problem, a new toluene-free conversion technology was elaborated at Chinoin
É. Fenyvesi et al.