engleski

Survival of Anisakis spp. larvae directly exposed to different solutions used for fish marination

Many studies showed that the prevalence and the intensity of the infection with Anisakis larvae in fish vary with species, fishing area and season. The traditional fish dishes in Mediterranean countries are lightly preserved and usually non-thermally processed, and as such create an important public health problem concerning anisakidosis. Croatian seafood products such as dry salted and marinated anchovies and sardines are exported in EU and wildly consumed as delicacy in many Mediterranean countries. As an important tourist destination Croatian traditional food may present a source of human Anisakis spp. disease to both, local population and foreign visitors. Although the European Union and Croatian regulations require freezing the fishery products intended for raw consumption (minimum 24 hours on -20 °C), domestically prepared traditional marinades are usually prepared without any thermal processing, because the textural changes during freezing may affect adversely the taste, colour and appearance of marinated fillets. Inactivation of Anisakis spp. larvae by chemical treatments was observed in some studies. L3 larvae showed high sensitivity to salt content under certain conditions. Synergic effect of organic acids and salts on larvae mortality rate is considered a time function entirely dependent on acid and salt concentration in the fish muscle. Different brines and marinade baths may successfully kill Anisakis larvae over time. However, if larvae penetrates the muscle before it is killed, allergic risk from dead nematodes consumption is present since the allergens from Anisakis spp. larva retain their allergenicity even after the fish had being processed. In order to observe the resistance of Anisakis larvae in different solutions, live L3 larvae were exposed directly to different solutions of NaCl (5, 10, 15, 20 and 35 g/100 mL) ; sugar solution (10 and 20 g/100 mL) ; fresh lemon juice, solutions of lemon juice and acetic acid (0.5, 1 and 1.5 % vol/vol) ; alcoholic, wine and apple vinegar. The survival of the larvae was microscopically monitored over time. The larvae were inspected for spontaneous and stimulated movements ; those that showed no movement were considered and counted as dead. L3 larvae exposed directly to different NaCl solution survived from 2.7 (35 g/L) to 10.4 (5 g/L) days. Larvae exposed to sugar and lemon juice solutions survived up to 270 and 180 days, respectively. In vinegar water solutions with ratio 1:1, the larvae survived up to 52 days, and in pure vinegar up to 18 days, regarding the vinegar type. In addition, the survival of live larvae, inserted into anchovy fillets was investigated during the preparation of traditional “carpaccio” marinade, made from brined anchovy fillets marinated in lemon juice and olive oil. The larvae survived 74 days, thus the combination of brining and marinating reduced the time of Anisakis spp. larvae survival for 106 days. Although the larvae survived the direct exposure to different marinating solutions, the infectivity of L3 larvae after these treatments remains to be determined.

Anisakis; Marination baths; Brines; Fish marinades

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