The artificial digestion method underestimates the viability of Anisakis simplex (s.l.) L3 present in processed fish products

This work studied the performance of the artificial digestion method in terms of recovery andviability ofAnisakis simplexthird-stage larvae (L3) when previous treatments given to the in-fectedfish muscle may accidentally render viable larvae. For that: a) hake mince was spikedwith 10 L3/75g mince, frozen at−10,−15,−20, and−30 °C and immediately thawed, orstored for 12 or 24 h, and subjected to pepsin digestion; b) the mince was spiked under thesame conditions, frozen at the above temperatures and thawed immediately. After manual re-covery, L3 were assessed for viability, used to spike again the mincedfish and subjected topepsin digestion; c) the mince was spiked with 10 L3 which were: i) living (i.e. chilled), ii)freeze-surviving (live L3 had been previously recovered after freezing at−10 °C), or iii) dead(frozen at−30 °C or−80 °C), and then subjected to pepsin digestion. Results showed thatthe artificial digestion method kills a significant number of larvae that may have survivedfreezing and thus may underestimate the number of viable larvae in a given batch. The methodmay also underestimate the infection level offish batches containing dead larvae. It is sug-gested to take these limitations into account when designing digestion protocols for specificapplications, especially when there is a risk of insufficiently treated or cookedfish batches orready-to-eat foods.

This work has beenfinanced by the European Union's Seventh Framework Programme for Research, Technological Develop-ment and Demonstration under Grant Agreement 312068, EU PARASITE and Spanish ANIRISK (AGL2015-68248-C2-1-R) MINECO/FEDER.

Peer reviewed