Freezing Technology

8.3.8 Toxic metals

 Toxic metals like Cd, Hg, Se, Pb etc. above normal level affect the safety and marketability of foods. Many countries have standards. Older ones have higher levels than younger ones of the same species. Presence of cadmium in cephalopods exported from India is reported. Control by minimizing pollution & environmental monitoring

Organochlorine pesticides & polychlorinated biphenyls

• OCP & PCBs now common is all environments

Important compounds of concern are

• DDT and its derivatives
• Aldrin and Dieldrin
• Benzene hexachloride
• Polychlorinated biphenyl

It pose special problems in the environment because they are

• Extremely persistent
• They are lipophilic is nature
• Filter feeders like oysters, mussels & clams accumulate these compounds

Permitted levels in seafood

Compounds	Max. residue limit (mg/kg)
DDT and its derivatives	5
Dieldrin	3
PCB	2
Mercury	0.5
Cadmium	3-Crustacean; 4- mollusc
Lead	1-5-crustacean; 1-7 bivalves

Control

• Prevention of contamination and Environmental monitoring