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Keywords:

  • α-amylase;
  • antigenic determinants;
  • baker's asthma;
  • bread

Background

The enzyme α-amylase from Aspergillus oryzae used in bakeries to improve the bread quality has been identified as an inhalative allergen in baker's asthma. It is doubtful whether this enzyme can induce allergic sensitization in regular bread consumers.

Objective

To find out whether fungal α-amylase in bread and rolls retains its antibody-binding capacity and allergenicity after the baking procedure.

Methods

Rabbit antibodies directed to fungal α-amylase were used for the development of a two-site enzyme-linked immunosorbent assay (ELISA). This assay was used to analyse different fractions of bread and rolls baked with the usual amounts of α-amylase in comparison with control products without added enzyme. Competitive experiments between bakers' sera containing specific immunoglobulin (Ig) E to α-amylase and the rabbit antibodies were performed. Additionally, specific IgE binding to fungal α-amylase was inhibited by native or heated α-amylase.

Results

With the highly specific two-site ELISA for native α-amylase in the crust of bread bottom and sides, 2.3–7 ng antigenic α-amylase per gram crust were measured. No α-amylase could be detected in the crumb fractions. Rabbit antibodies to native α-amylase completely inhibited human IgE binding to α-amylase allergen disks.

Conclusion

The results prove residual antibody-binding capacity of α-amylase in bread crusts and in the crust of some rolls. In comparison with the content of α-amylase in dough, between 0.1 and 20% of the antibody-binding capacity remained.