Purification, characterization and immunoreactivity of tropomyosin, the allergen in Octopus fangsiao

• The major allergen tropomyosin (TM) of Octopus fangsiao was purified. The purified TM was treated with different food processing.
• The digestibility and allergenicity of the treated TM and the native TM were compared.
• The food processing for the degrading of allergenicity of octopus TM is proposed.

Octopus is one of the foods that can cause food allergies. In this study, tropomyosin (TM) – the primary allergen in octopus – was purified from Octopus fangsiao following different food processing treatments. The changes in the allergenicity and digestibility of different TM samples were estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunological experiments. The results showed that TM was resistant to pepsin but not to trypsin or α-chymotrypsin. Compared with crude TM, the TM treated by ultrasound-heat (UH) and ultraviolet radiation (UVR) showed no significant change in IgG/IgE-binding ability, except high pressure steaming (HP). And the resistance of the treated TM to digestive enzymes was reduced, with HP-treated TM showing the most significant change in stability. It was different that the resistance of TM to the digestive enzymes was increased after treatment with the Maillard reaction (MR); the IgG/IgE-binding activities of the MR products were almost completely eliminated. Thus, all of these results show that the immunoreactivity of octopus TM can be reduced by HP and MR treatment.