Subheading 151560 covers fats and oils produced by microbial fermentation (e.g., from algae or fungi) rather than extracted from plant seeds or animal tissue. Classification here requires that the oil be 'fixed'—meaning non-volatile—and not chemically modified. Novel microbial oils used as food ingredients may also require FDA pre-market review, so importers should confirm regulatory status before entry.

Castor oil falls under subheading 151530 regardless of its intended end-use, as the HTS classification is based on the product's nature, not its application. However, food-grade castor oil must meet FDA purity standards, while industrial-grade material does not. Importers should declare the correct end-use and ensure the product specification matches the intended application to avoid admissibility issues.