Mineral spectrum in different body parts of five species of tuna consumed in Sri Lanka

The mineral spectrum of five species of tuna namely; Skipjack (Balaya, Katsuwonus pelamis), Yellow fin tuna (Kelawalla, Thunnus albacores), Bullet tuna (Ragoduwa, Auxis rochei), Frigate tuna (Alagoduwa, Auxis thazard) and Kawakawa (Atawalla, Euthynnus affinis) were detected in skin, red muscle, white muscle, head muscle and belly flap using an Atomic Absorption Spectrophotometer (GBC 932 plus). Both macro and micro elements were detected in all tunas studied. Accordingly from the recorded minerals K was the most abundant macro element as its mean concentration among the tunas studied ranged from 246.94±62.27 to 293.84±77.78 mg/100g and the highest K level among the different body parts, was recorded in the skin (p<0.05). The second most abundant macro element was Na and its mean concentration among all tunas varied from 135.19±41.04 to 155.47±38.92 mg/100g. The ratio between Na:Kwas 1:2 to 1:3. Skin was five times (103.36±67.43 - 512.72±88.23 mg/100g) as rich in Ca as other body parts (9.84±2.43 - 19.32±14.47 mg/100g) in tunas studied except yellow fin tuna (P<0.05). Mg concentration varied from 52.95±11.68 mg/100g to 79.66±15.02 mg/100g in all tunas studied and highest values were recorded in the skin samples except for skipjack tuna. Fe was the most abundant micro element (2.52±1.78 - 3.29±1.88 mg/100g) followed by Zn (1.03±0.53 mg/100g – 1.70±0.88 mg/100g). Red muscles of all tunas were significantly rich in Fe than the other body parts. The recorded mean values for Mn were always less than 0.2mg/100g. Cu, Ni and Cr were the other trace elements studied and those were recorded occasionally in trace amounts, and were well below the permissible limits.

Key words : Tuna; macro elements; micro elements

Vidyodaya Journal of Science Vol.14(2) 103-111