Effects of Industrial Processing on the Immunogenicity of Commonly Ingested Fish Species

Abstract

Background: Food-processing techniques may induce changes in fish protein immunogenicity. Allergens from >100 fish species have been identified, but little is known on the effects of processing on fish protein immunogenicity. Methods: IgE binding of sera of patients allergic to fresh and processed (smoked, salted/sugar-cured, canned, lye-treated and fermented) cod, haddock, salmon, trout, tuna, mackerel and herring and of hydrolysates based on salmon and whiting was investigated using immunoblot and inhibition ELISA. Results: Parvalbumin oligomers were identified using monoclonal and polyclonal antibodies. IgE binding was seen in most sera at 12–14 kDa (parvalbumin), and at 17–60 kDa for all fish except tuna. Changes in IgE binding appeared to reflect altered parvalbumin monomers and oligomers. Smoked haddock, salmon and mackerel had increased IgE binding and novel bands at 30 kDa. Chemically processed cod, salmon, trout and pickled herring had reduced or abolished IgE binding. The serum of 1 subject, however, had increased IgE binding to these products and also inhibition of binding by both fish hydrolysates to their constituent fish species. Conclusion: Process-induced changes in fish protein immunogenicity were more dependent on process rather than species, although individual responses varied. Changes in the allergenicity of a product may depend on the net effect of processing on parvalbumin oligomerization patterns, which may also vary in different species. Chemical processes generally caused loss in IgE-binding activity, though sensitization may occur to modified or degraded rather than intact peptides as shown by increased binding by chemically processed fish and hydrolysates in 1 subject. The clinical significance of these findings remains to be established.

Identification of Parvalbumin and Two New Thermolabile Major Allergens of Thunnus tonggol Using a Proteomics Approach

“…The raw extract contains 26 protein fractions, generally similar to the protein profile of raw yellowtail tuna [28,33], whereas the boiled extract has only 9 protein bands, probably due to denaturation of thermolabile proteins of 16-25 and 40-90 kDa. This protein pattern is also in accordance with other studies which reported thermolabile proteins between 20-100 [40] and 40-90 kDa [41] in multiple fish species.…”

“…Studies on tuna allergens have been conducted on several species of tuna such as Thunnus albacares/ yellowtail tuna [28,32,33], Thunnus alalunga/ albacore [16,32], Thunnus obesus /bigeye tuna [29,30] and Thunnus thynnus /bluefin tuna [31], while some other studies did not mentioned the tuna species [34]. To the best of our knowledge, there is only one short report on T. tonggol [35].…”

Important Variations in Parvalbumin Content in Common Fish Species: A Factor Possibly Contributing to Variable Allergenicity

“…In this study, we included such treated food samples from pickled, canned and smoked fish and could quantify significantly lower parvalbumin levels. The solubility of parvalbumins in processed food may also be reduced by interaction with other matrix ingredients and formation of high-molecular-weight complexes [21]. In contrast, parvalbumin contents in extracts prepared from cooked fish fillets were only up to 25% lower than in raw fish.…”

Untitled

“…The various treatments often, but not consistently, reduced IgE-binding, whereas some treatments and some sera also showed increased IgE-binding (Sletten et al, 2010).…”

“…The latter were shown to contain peptides with lower molecular weight than the former and to be less antigenic . Furthermore, chemically hydrolysed salmon had a reduced or abolished IgEbinding capacity (Sletten et al, 2010). The clinical significance of these findings has to be established.…”