แปลบทความวิจัยTablet strength claimed as an important property of tablets depends
principally on the dominating bonding mechanism between the particles
and the surface area overwhich these bonds are active [22]. The relationship
of tensile strength and density with pressure for the three
different types of tablets prepared from powders of pitaya, guava and
their binary mixture are illustrated in Fig. 2.
With increasing pressure, the density of the tablets increased and
consequently porosity of the powder was decreased (Fig. 2a). This
trend was similar to the findings reported by Yusof et al. [23] on
Andrographis paniculata tablets. Among the three tablets, guava powder
showed the lowest density followed by mixed fruit powder and the
pitaya powder possessed the highest density. Hence, guava powder
was the lowest compressible powder, whereas pitaya powder was
highly compressible. Similar findings were reported by Yusof et al. [7]
on the compression of pitaya powder dried in mechanical driers. However,
mixing of the two powders improved compressibility significantly
compared to guava powder alone since stiffness of the pressure–density
curve of the mixed fruit tablet was in between pitaya and guava tablets.
Due to the low particle size of pitaya powder, it was able to accommodate
more inter-particle friction and thus exhibit the lower range of
density compared to guava and mixed fruit powders.
However, in spite of the larger size of the particles in themixed fruit
powder, the density–pressure curves were almost alike with guava
powder. This is attributed to the moisture content and agglomeration
of the mixed fruit powder during mixing. The blending of guava and
pitaya powders reduced the porosity by accommodating the lower
pitaya particles within the void of larger guava particles, thus resulting
in the mixed powder with higher porosity. The complex interaction of
moisture content, agglomeration and increased porosity of the mixed