Abstract:
Tannin has gained wider acceptance as a dietary supplement in contemporary animal
nutrition investigations because of its potential to reduce enteric methane emission. However, a major
drawback to dietary tannin intake is the bitter taste and instability in the gastrointestinal tract (GIT).
The utilization of fats as coating materials will ensure appropriate masking of the tannin’s aversive
taste and its delivery to the target site. The aims of this study were to encapsulate mimosa tannin with
palm oil or sunflower oil, and to assess the microcapsules in terms of encapsulation efficiency, morphology,
density, and in vitro release of tannin in media simulating the rumen (pH 5.6), abomasum
(pH 2.9) and small intestine (pH 7.4). The microencapsulation of mimosa tannin in palm or sunflower
oils was accomplished using a double emulsion technique. The results revealed that encapsulated
mimosa tannins in palm oil (EMTP) and sunflower oil (EMTS) had high yields (59% vs. 58%) and
encapsulation efficiencies (70% vs. 68%), respectively. Compared to unencapsulated mimosa tannin
(UMT), the morphology showed that the encapsulated tannins were smaller in size and spherical in
shape. The UMT had (p < 0.01) higher particle density (1.44 g/cm3) compared to 1.22 g/cm3 and
1.21 g/cm3 for the EMTS and EMTP, respectively. The proportion of tannins released by the UMT
after 24 h in the rumen (94%), abomasum (92%) and small intestine (96%) simulated buffers, reduced
(p < 0.01) to 24%, 21% and 19% for the EMTS and 18%, 20% and 16% for the EMTP in similar media
and timeframe. The release kinetics for the encapsulated tannins was slow and steady, thus, best
fitted by the Higuchi model while the UMT dissolved quickly, hence, only fitted to a First order
model. Sequential tannin release also indicated that the EMTS and EMTP were stable across the GIT.
It was concluded that the microencapsulation of mimosa tannin in palm or sunflower oils stabilized
tannins release in the GIT simulated buffers with the potential to modify rumen fermentation. Further
studies should be conducted on the palm and sunflower oils microcapsules’ lipid stability, fatty acid transfer rate in the GIT and antioxidant properties of the encapsulated tannins.
