Deliverable D7.4 Report on parasite antigen elimination or inactivation methods in fishery products

PARASITE: Parasite Risk Assessment with Integrated Tools in EU Fish Production Value Chains Collaborative Project Targeted to a Special Group (Such as SMEs) GA 312068 (01/02/2013-1/01/2016).The objective of this task was to design strategies to reduce the allergens that in processed products produced from fish infected with Anisakis L3. Two different processes were selected: a) the surimi and production of kamaboko type gels, and b) conditions used in the canning processing. In surimi, the effects of factors such as removal of antigens by washing, the addition of cryoprotectants, salting, heating, and frozen storage were analysed. In the canning processing different heating regimes used in the canning industry were studied. The washing operation of fish muscle is one of the key steps in the production of surimi. The aim of this first part of the study was to assess in parasitized minced fish the effect of the washing steps on the allergen removal of Anisakis simplex and on protein yield during surimi processing. Experimentally infected hake (Merluccius merluccius) (50 Anisakis simplex s.s L3 larvae per 100 g of muscle) underwent three successive washing steps with water, phosphate buffer (20 mM), sodium bicarbonate (60 mM), or sodium hypochlorite (0.27 mM) (4 kg muscle, 1:4 w/v for each solution) that rendered an intermediate product named “raw surimi”. Total protein concentration and A. simplex antigens and allergens were evaluated in each waste fraction. The highest removal of Ani s 4 and A. simplex antigens was achieved by using phosphate buffer, together with a good protein yield in the raw surimi. Decrease of the concentration of allergens and antigens as a function of the washing steps rendered a linear trend (R2=0.95 and 0.98 for Ani s 4 and A. simplex antigens respectively). Results suggested that the conditions for an optimal removal of Anisakis allergens can be established and calculated as a function of the washing steps. Despite the fact that washing of muscle in surimi processing significantly reduced the allergen concentration, raw surimi still have residual antigens and allergens that are carried on in the subsequent steps. In order to know if additional factors related to surimi production could have an effect, the second objective of this work was to determine if the cryoprotectant blends added in the subsequent steps modified the antigens and allergen recognition. Surimi is usually commercialized frozen stored and therefore the effect of frozen storage was also assessed. Two cryoprotectant blends were added to each of the four raw surimi described in the previous paragraph: 4% sucrose+4% sorbitol and 4% sucrose+4% sorbitol+0.2% sodium pyrophosphate, thus making a total of eight combinations (four raw surimi x two cryoprotectant blends). Antigen and allergen recognition was analyzed in surimi that had been chilled (5°C), or frozen stored (-20°C) for 90 or 180 days. Ani s 4 and Anisakis simplex antigens were quantified by immunodetection (Dot blot). No significant differences (p