1. Analysis of Polycyclic aromatic hydrocarbons to determine the best firewood for smoking
of fish
P.Anoja1*, S.S.K. Madage2 and R.G.S. Wijesekara1
1Department of Aquaculture and Fisheries, Faculty of Livestock, Fisheries and Nutrition,
Wayamba University of Sri Lanka, Makandura, Gonawila (NWP), Sri Lanka;
2Food Technology Section, Research and Development Division, Industrial Technology Institute,
363, Bauddhaloka Mawatha, Colombo 7, Sri Lanka.
*Corresponding author (email: anojalingam@gmail.com)
Firewood smoking is one of the traditional preservation techniques, still widely is being used in
processing of maldives’ fish, smoked dry fish, garcinia at very primitive level in various parts of
Sri Lanka. Modern food industry also use smoking processes to obtain desired flavors in certain
products like ham, bacon and sausage. Various types of firewood are being used to generate
smoke, which contains at least 100 Polycyclic Aromatic Hydrocarbons (PAH) and their alkylated
derivatives. US-EPA and EU listed 16 PAHs as hazardous compounds. Benzo[a]pyrene (Bap) is
regarded as a marker of the carcinogenic PAHs in smoke. The maximum acceptable content of
B(a)P in smoked food is 0.031µg/kg in EU.
This study investigated the PAHs content in smoke of selected fire woods aiming to find out
suitable fire woods for food smoking. Nine commonly use, wood variety such as coconut husk,
coconut fronds, palmyrah, cinnamon, mango, jack, margosa, portia and weera from northern and
southern parts of Sri Lanka were selected for the study. Initially they were dried to assure the
desired moisture content for burning. A solvent extraction method was adapted at ITI to separate
PAHs from smoke. The solvent mixture of acetonitrile, acetone and toluene with a ratio of 6:3:1
was used to trap PAHs within one hour time duration with two replicates. Then the extract was
concentrate up to 50 ml. PAHs analysis was performed by Agilent 1260 Infinity Quaternary
Gradient HPLC. The different PAHs were separated on an Agilent ZORBAX Eclipse PAH
column (4.6mm x 250mm x 5 µm) by gradient elution with a binary system of acetonitrile-
gradient water with subsequent fluorescence and UV detections set at appropriate excitation and
emission wavelengths.
According to the analysis, naphthalene, fluorene, phenanthrene, anthracene,
benzo(a)anthracene, benzo(a)pyrene and benzo(k)fluoranthene were identified. Among them
naphthalene was prominent to all selected woods. Particularly palmyrah, jack and weera have
considerable amounts, 198.89ppm, 67.37ppm, and 38.55ppm of naphthalene respectively.
According to the EU-EPA probable carcinogenic compounds such as benzo(a)anthracene
(1.55ppm), benzo(a)pyrene (1.18ppm) and benzo(k)fluoranthene (0.41ppm) were detected in
palmyrah smoke. In conclusion among the nine firewood tested, margosa, mango and portia can
be selected as the best fire woods for smoking of fish.
Key words: Carcinogenicity; Polycyclic aromatic hydrocarbons; Smoked fish; Wood smoke