Figure 13. Scanning electron microscope images of C2C12 cells
on cellulose acetate (CA) nanofibers (A, C, E) after 14, 21, and 28 days
of cell culture, respectively, and cellulose acetate nanofibers with
annatto extract (CA@A) (B, D, F) after 14, 21, and 28 days of cell
culture, respectively. Scale bars indicate 50 µm.
After 14 days of culture, cells completely covered the CA@A scaffold,
while few cells were visible in the CA matrix (Figure 13). By 21 days,
the CA scaffold was also entirely covered with cells. Figure 13 suggests
that both the CA and CA@A nanofiber substrates can sustain long-term
culture of C2C12 cells, up to 28 days. According to Choi et al. [49]
and Post et al. [2], production of muscle cells in meat cultivation
requires numerous muscle precursor cells, and consequently in
vitro expansion of cells is a critical step for such applications. This
present study suggests that annatto extract is useful in promoting rapid
proliferation and coverage during the initial days of culture, providing
sufficient quantities of muscle cells and thus permitting large-scale
application for meat production. In addition, as already mentioned,
annatto extract can be an important factor for the long-term
preservation of the culture, avoiding unwanted contamination during the
process. Future studies can be carried out to confirm the protective
action of annatto extract as a meat preserver.