Preliminary assessment of the utilization of durian peel liquid smoke as a natural preservative for mackerel

Background: Durian peel is a type of biomass waste that contains cellulose, hemicelluloses, and lignin. The pyrolysis of these compounds results in production of liquid smoke which can be used as a natural preservative to replace current synthetic preservatives. This research assessed the ability of liquid smoke produced during pyrolysis of durian peel to preserve fish. Methods: Dry durian peel waste underwent batch reactor pyrolysis at 340°C and 380°C, resulting in production of liquid smoke (grade 3), charcoal, and tar. This liquid smoke was then distilled at 190°C to produce grade 1 liquid smoke, which was used to preserve mackerel. The preservation process was conducted by soaking the mackerel samples in liquid smoke at 0.5, 1, 2, and 3% concentration levels followed by observations every 6 hours. Tests to determine the total volatile base nitrogen (TVB-N) content, antibacterial quality of the liquid smoke and organoleptic quality of the fish were conducted in order to assess the preservation properties of the liquid smoke. Results: Tests on the antibacterial effects showed that the liquid smoke inhibited the growth of Escherichia coli and Staphylococcus aureus on fish even at low concentrations. At 54 hours, the TVB-N values remained below 30 mg nitrogen/g, indicating that the fish was still safe for human consumption. Results from the organoleptic tests showed that the concentration of liquid smoke influenced the preservation effects. Conclusions: At a concentration of 2–3%, the fish samples possessed acceptable flavor, taste, color and texture for up to 48 hours of soaking. However, the best conditions were obtained with a 3% concentration of liquid smoke (produced with 340°C pyrolysis), as the fish was still considered acceptable for up to 42 hours.