Effect of the ratio of SPOMFs to solvent (w/v)
Subsequently, the effects of the ratio of SPOMFs to solvent (w/v) on
purity (% palmitoleic acid relative to total fatty acid) and yield of
palmitoleic acid were investigated, and the results are shown in Figure
2b. When crystallization was carried out at -20 °C, our preliminary
study showed that SPOMFs: methanol ratios from 1:3 to 1:6 were
inappropriate, because the solution froze too quickly to allow
monitoring. Therefore, the SPOMF to methanol ratios were set at 1:9,
1:12, 1:15 and 1:18 (w/v), and the methanolic SPOMF solutions were
stored at -20 °C for 12 h.
At shown in Figure 2b, when the ratio of SPOMFs to methanol (w/v) was
changed from 1:9 to 1:15, the purity of the palmitoleic acid solution
increased from 36.32% to 40.43%. This is due to the effective
crystallization of the saturated fatty acid at high volume use of the
methanol (Shahidi, 2016). However, as the SPOMFs to methanol ratio
changed beyond 1:15, the proportion
of palmitoleic acid in solution decreased, indicating solubilization of
the saturated fatty acids due to the high solvent volume.
In terms of yield, no significant difference was found between SPOMFs to
methanol ratios of 1:12 and 1:15. Considering both purity and yield of
palmitoleic acid, an SPOMFs to methanol ratio of 1:15 (w/v) gave the
best result. Hence, an SPOMF to methanol ratio of 1:15 (w/v) was used
for further crystallization studies. Under these conditions, a solution
with 40.43% palmitoleic acid was obtained, that translates to an
88.47% palmitoleic acid yield.