Phosphoric acid
The liquid fish hydrolysate process minces the whole fish, then enzymatically digests, then grinds and liquifies the resulting product, known as gurry. Because it is a cold process, gurry putrefies more rapidly than fish emulsion and needs to be stabilized at a lower pH, requiring more acid. Researchers have tried formic acid, sulfuric acid, and others. Formic acid had phytotoxic effects on plants. Phosphoric acid is the preferred stabilizer.