Abstract: Pacific cod head soups were prepared by various cooking methods, namely atmospheric pressure cooking (AP), high pressure cooking (HP), atmospheric pressure and high pressure cooking (AP-HP), and high pressure and atmospheric pressure cooking (HP-AP) and were evaluated for total solids content, color, sensory score, amino acid nitrogen content, protein content, nucleotide content, organic acid content, flavor characteristics (determined by electronic nose), taste characteristics (determined by electronic tongue) and volatile substances (determined by gas chromatography-mass spectrometry, GC-MS). Our aim was to investigate the effects of these four cooking methods on the flavor characteristics of cod head soup. The results showed that the total solids content and nucleotide content of cod head soup prepared by HP were significantly higher compared with those prepared by the other three cooking methods (P < 0.05), and the whiteness, amino acid nitrogen content, and protein content were also higher. The sensory score and organic acid content of cod head soup prepared by AP-HP was significantly higher than those of the other three groups (P < 0.05). The electronic tongue results showed that the AP group had a weaker umami taste than the other groups, whereas there was no significant difference in the other taste attributes evaluated. The electronic nose results showed that the odor characteristics of the HP and AP-HP groups were similar, but were significantly different from those of the HP-AP and AP groups, which may be due to significant differences in odor components including aromatic compounds, nitrogen oxides, ammonia, alkanes, methane, ethanol, etc.. In total 27, 25, 28 and 40 volatile compounds were identified in AP, HP, AP-HP and HP-AP soup samples. Collectively, these results indicated that high pressure cooking may be a more suitable method for processing cod head soup.

Key words: cod head soup; cooking methods; non-volatile compounds; flavor