Results and discussion
The goal of this study was to enrich palmitoleic acid. As shown in Table 2, palmitic acid is the most abundant saturated fatty acid in the SPOMFs, accounting for 33.59% of total fatty acids, followed by oleic acid (32.16%), and palmitoleic acid (27.17%).
First, the optimal temperature for low-temperature crystallization was evaluated, and then solvent type, substrate ratio of SPOMFs to solvent (w/v) and crystallization time during the first crystallization stage were optimized to improve the results of crystallization. Some residual saturated fatty acids still remained in the collected liquid fraction 1, thus a secondary crystallization was performed at -40 °C to remove these, and this resulted in the liquid fraction 2. Then, the liquid fraction 2 was subject to molecular distillation to yield a concentrated palmitoleic acid final product.