Effect of liquid smoking on lipid hydrolysis and oxidation reactions during in vitro gastrointestinal digestion of European sea bass

- The effect of smoking fish on reactions occurring during digestion was studied.
- Smoking did not influence lipolysis, although it markedly delayed lipid oxidation.
- Smoke-derived compounds also protected BHT present in fish meat against oxidation.
- Liquid smoke composition influenced fish lipid oxidation extent during digestion.
- The bioaccessibility of smoke phenolic compounds was evidenced for the first time.

The effect of smoking using liquid smoke flavourings on the hydrolysis and oxidation of European sea bass lipids during in vitro digestion was investigated. The techniques used were 1H NMR and SPME-GC/MS. The former proved that liquid smoking does not influence the extent of lipolysis, but prevents those lipid oxidation reactions that occur during in vitro digestion of unsmoked samples, giving rise to cis,trans-conjugated dienes associated with hydroperoxy/hydroxy groups. SPME-GC/MS corroborated the results obtained by 1H NMR in relation to the antioxidant effect of smoking under gastrointestinal conditions. Smoked sea bass digests showed lower abundances of volatile oxidation markers derived from omega-3 and omega-6 lipids than unsmoked ones. Moreover, the lowest values were found in the digests of sea bass samples smoked with the flavouring showing the highest phenolic content. For the first time, the bioaccessibility of smoke flavouring components was evidenced, some of them well-known for displaying antioxidant activity.

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