Control and reduction of free fatty acid concentration in oil recovered from fish silage prepared from sprat

Increases in the free fatty acid (FFA) content of oil recovered from sprat silage have been shown to be partially due to release of FFA from their water‐soluble salts on acidification and to the carry over of certain organic acid acidulants. Acid hydrolysis has been shown to be a significant contributor to oil degradation at low pH, but a heat‐labile catalyst active below pH 7.0 has been shown to be a contributor to FFA levels in the oil of sprat silage incubated for long periods of time. Preparation of silages using sulphuric‐formic acid mixtures and the use of a preheat treatment have been shown to reduce this activity.