Evaluation and comparison of durability of polycyclic aromatic hydrocarbon compounds (PAHs) and its relation to the lipid content in smoked fishes, Silver carp (Hypophthalmichthys molitrix), Rutilus frisii kutum and Herring (Alosa caspia)

Cold smoking method is one of the commonest ways for fish smoking. It is done by the smoke that is the result of burning hard and soft woods is smoking rooms. Smoke includes a number of chemical constructs and its main part is poly aromatic hydrocarbons. More than one hundred kinds of these constructs are recognized in smoke that is produced from saturated hydrocarbons resulted from the solution of the woods Ligno cellulose in high temperature and lack of oxygen conditions. The high poisoning potentials and carcinogenic features sixteen constructs among them are proved and observed on humans. In this research, the PAH compounds were identified and observed in a three month period after smoking and during storing among three types of smoked fishes Silver carp and Caspian sea Sefid and herring. They are the most produced and consumed smoked fish in Iran. To find the relationship between the concentrations of PAH constructs and the amount of lipid in fish, first, the amount of lipid were determined separately in the skin and flesh of 30 samples of each type. The method used was Bligh and Dyer (1959). PAH compounds derivation were made for all skin and flesh samples smoked fish using organic solvents with Soxeleh and the derived samples were injected to gas chromatography (GC) by Hamilton injectors for determining their components quality and their quantity. The height of the used column was 25 meters and its diameter was 0.32 mm with the silica filler, nitrogen gas as carrier and flame ionization detector (FID) that are special for these constructs. For data analysis, Statistical tests were used by computer soft ware identified that the difference in the amount of lipid within the flesh and skin of each species and also among each other is significant. The largest amount was in Herrings flesh and skin, 18.74% in skin and 14.47% in flesh. The least amount in the skin 4.19% and the flesh 3.10% of Sefid. The amount in Silver carp was 13.28%in skin and 8.16% in flesh. The examination of the PAH compounds in smoked fish showed that is carcinogenic compounds; exist in these in these fish with different quantities in each. It seems that its amount is directly related to the amount of their lipid. The amount is different in flesh and skin. One of the most important reasons is the direct content of smoke and the concentration of lipid in tissues of all three types. The maintenance of the smoked fish for three months showed that most of PAH compounds were solved and their density decreased. The changes in density within time in different in each type and in flesh and skin. The amount of their receiving in human through the consumption of the smoked fish depends on the resulted density, the way and the amount of consumption and now we can determine and execute standards for the maximum dosage per day and per month regarding effective factors.

Labroidaes dimidiatus (Valenciennes, 1839)

Labroides dimidiatus, is one of several species of cleaner wrasses found on coral reefs from Eastern Africa and the Red Sea to French Polynesia, for the first time from Iran (Persian Gulf, Kish Island). Like other cleaner wrasses, it eats parasites and dead tissue off larger fishes’ skin in a mutualistic relationship that provides food and protection for the wrasse, and considerable health benefits for the other fishes. Some fish mimic cleaner wrasses. For example, a species of blenny called Aspidontus taeniatus has evolved the same behavior to tear small pieces of flesh from bigger fish. Cleaner wrasses are usually found at cleaning stations. Cleaning stations are occupied by different units of cleaner wrasses, such as a group of youths, a pair of adults, or a group of females accompanied by a dominant male. When visitors come near the cleaning stations, the cleaner wrasses greet the visitors by performing a dance-like motion in which they move their rear up and down. The visitors are referred to as "clients". Blue streak cleaner wrasses clean to consume ectoparasites on client fish for food. The bigger fish recognise them as cleaner fish because they have a lateral stripe along the length of their bodies and by their movement patterns.

Torpedo sinuspersici Olfers, 1831

Electric rays, thought to be the most primitive of the skates and rays, have stout tails but have rather expansive disc. This group is distinguished by the presence of powerful electric organs, derived from branchial muscles in head region. Torpedo sinuspersici found inshore in sandy bottoms, and well offshore from the surf zone down to 200 m. Also on or near coral reefs (like Kish Island in Persian Gulf). Common in shallow sandy areas. Occasionally hooked by anglers, more often seen by divers; can deliver a strong shock. Flesh is edible. T. sinuspersici can survive for hours after being stranded on the beach. Little is known of the life history of the Gulf torpedo. It is a sluggish predator of bony fishes. At night it actively hunts for food, sculling slowly through the water about a meter above the bottom; during the day it usually rests on the bottom and opportunistically ambushes unwary prey. It uses its broad pectoral fins to envelop the target fish before delivering an electric shock to stun it. Usually solitary, they may form groups during the mating season. Reproduction is a placental viviparous, with the developing embryos initially surviving on their yolk sacs, and then on enriched uterine fluid produced by the mother. Litters of 9-22 young are birthed in the summer. Newborns measure about 10 cm wide; males mature at a disc width of 39 cm and females at 45 cm.