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The technology of microencapsulation has developed for several
decades. Many industries have been concerned with
microencapsulated products. Development of the polymers for
microencapsulation classically emphasized the technology to make
materials durable and weatherable. During the 1970's a need
arose of biodegradable materials for drug, agricultural and
environment protection requirements. But the existing
biodegradable materials are too expensive for the agricultural
purpose. Furthermore, the chemical pesticides have brought many
serious damages to the environment, so the most important thing
to the agriculture is the introduction of the microbial
pesticides. In this research, we developed the techniques of
microencapsulating biologically antifungal antibiotic using the
biodegradable polymers as the coating materials by a simple
coacervation-phase separation procedure. The coating materials
are gluten and casein. The core materials are either the cell
powder containing the biologically antifungal antibiotic,
pyrrolnitrin, or the Microken powders adsorbing pyrrolnitrin.
The irregular microcapsules prepared in this research have a
particle size range between 5-80 , and a smooth surface after
hardening. In the degradation experiments of coating materials
we found that in twenty days the degradation of gluten particles
without hardening was 29.6﹪and with hardening 12.9﹪,whereas
the degradation of casein particles without hardening was 70.4﹪
and with hardening 38.2﹪. When the cell powders were capsulated
with gluten, six or more times delay in the release of
pyrrolnitrin was achieved and with casein had a five or more
times delay was observed. When the adsorbed Microken powders
were capsulated with gluten and casein and then hardened, the
delay of releasing pyrrolnitrin were respectively, 4.7 and 8
times in comparing with releasing non-encapsulated pyrrolnitrin.
Besides, the release rates of microcapsulates fit well the
first-order release model and the Higuchi model.
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