Analysis of the effects of different protease types on volatile compounds and oxidative properties of blackthroat seaperch ( Doederleinia berycoides ) liver oil

Abstract This study evaluated the effects of different proteases on the extraction, flavor profile, and oxidative stability of blackthroat seaperch (Doederleinia berycoides) liver oil obtained by aqueous enzymatic extraction. Trypsin-assisted extraction yielded oil with the greatest oxidative stability. Combined analysis by gas chromatography-ion mobility spectrometry and gas chromatography-mass spectrometry identified aldehydes as the characteristic volatile compounds in the liver oil. The relative odor activity value analysis identified (E)-2-nonenal, furaneol, benzeneacetaldehyde and 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one as the key volatile compounds. Differences in oxidative stability and thermal behavior were observed among the extraction methods, with the antioxidant capacity of blackthroat seaperch liver oil following the order of pepsin (PS) > alkaline protease > trypsin (TS) > neutral protease extraction methods. Differential scanning calorimetry analysis revealed that PS melting and cooling profiles enhanced flavor release and persistence, while TS and PS exhibited ω-3 fatty acid pyrolysis. These findings demonstrate the importance of enzyme selection for liver oil flavor and stability and support the valorization of blackthroat seaperch by-products.