The flowability of five kinds of microencapsulation powders, with different β-carotene contents and by two alternative particle-forming technologies i.e. spray-drying and starch-catching beadlet technology, was measured. The actual flow properties of the five powders were compared based on bin-flow test, and three flow indexes (Hausner ratio, repose angle and flow index) were measured. It was found that the repose angle is the most suitable index to reflect the flowability of these powders for the particle properties would not be altered due to compaction or tapping during the measuring process. Particle size and particle size distribution play most important roles in the flowability of these granular materials, which was also influenced by other factors like shape, surface texture, surface roughness, etc. Microcapsules with wall material of gelatin and a layer of modified starch absorbed on the surface showed excellent flowabilities and good mechanical properties, and they are favorable for tabletting to supply β-carotene.
Carotenoids, such as /?-carotene, have long been
demonstrated to be capable of providing some medical
or health benefits, including the possible prevention or
treatment of skin cancer and cardiovascular disease
[ 1-41. Moreover, /?-carotene is still an important biological
compound for its provitamin A activity[5].
With the increasing knowledge of the positive
functions of /?-carotene, more and more people take
interest in some foods or pharmaceuticals containing
/?-carotene ingredients, such as beverages, baked
goods, oils, capsules and tablets. Usage of tablets
made of high-content p-carotene granule or powder to
provide this active material is very effective and conventional.
Besides high-content, some properties, such
as particle size, size distribution, surface texture, surface
energy, moisture content, flowability, compactibility,
morphology of the powder or granule, are also
very important for the formation and characterization
of the tablet. Among them, the flowability and compactibility
are two essential factors to ensure a successful
process for preparing tablets[6-81.
In recent years, there appeared some kinds of
,&carotene powdersheadlets in the market. These
products, contained different compositions or produced
by different particle-formed methods, were not
all fit for being compressed into a tablet. In this work,
the flowability of different microencapsulated powders
with high j?-carotene content is studied to make
sure which kind of /?-carotene microcapsules is suitable
for tabletting dosage. In detail, Hausner ratio,
flow index and repose angle of different /?-carotene
microcapsules are chosen as three flow indexes for
comparing with their actual-flow properties based on
bin-flow test, so as to find the most congruent flowindex to reflect its flowability. Furthermore, the reasons
for the discrepancies of flowability through different
indexes and factors influencing the p-carotene
microcapsule powders flowability are also discussed.
Hausner ratio and flow index, measuring particle
flowabilities indirectively, may be deceptive or misleading.
In the case of no compaction and tapping, that
is, no external forces are imposed to make particles
deformation during the process of manufacture, and
the repose angle is an instantaneous and easy way to
measure the particle flowability.
For spray-drying technology, when used gelatin
and sucrose as capsule wall material, the particles,
such as SD-lOG, SD-20G with large interparticle adhesion
forces will show low flowabilities. On the
other hand, when using modified starch as wall material,
no matter how good flow property the particles
have, because of the cracks, pores, dents in the outer
surface, and solid-bridge between particles, they are
not fit for compressing into tablets, too. When
starch-catching technology was applied, the microencapsulated
powder, for example, SC-1 OGS and
SC-20GS, with gelatin and sucrose as wall materials,
absorbed a layer modified starch on the outer surface
and showed perfect flowability and good mechanical
properties, seemingly suitable for producing tablet.
