Effect Of Ultra-high Pressure And Enzymatic Treatment On The Structure And Immunoreactivity Of Bitter Apricot Kernel Protein

Bitter apricot?Armeniaca sibirica?kernel contains various bioactive components and nutrients and can be used as value added food ingredients.However,the bitter apricot kernel is one of the food allergens and may cause severe allergic symptoms to people who are allergic to this food.In this work,the effect of ultra-high pressure on the structure,immunoreactivity and degradulation of RBL-2H3 cell were studied,and investigated the effect of enzymatic treatment on immunoreactivity of apricot kernel milk Based on which we can further find a best method of developing hypoallergenic apricot kernel product in the future.Amandin,the main allergen of apricot kernel,was isolated and purified by the Superdex200pg chromatography.Mass spectrometry analysis is consistent with the results of amandin monomer in the NCBI database,and the molecular weight was 226 kDa.The high titer rabbit polyclonal anti-amandin antibodies was prepared to detect the immunoreactivity of amandin with or without ultra-high pressure processing.The immunoreactivity of amandin decreased by27.26%at 500 MPa for 900 s.The RBL-2H3 cell model was established to assess the potential allergenicity in vitro.The change of biologically active medium(?-HEX,histamine,TNF-?,IL-6,Ca²⁺)released during the degranulation processing were detected.The result showed that ultra-high pressure processing of amandin did not influence the proliferation of RBL-2H3 cells.Compared to untreated amandin,the level of RBL-2H3 cells degranulation simulated by treated amandin was reduced.The level of?-HEX,TNF-?,IL-6,and histamine by RBL-2H3 cells stimulated by amandin treated by ultra-high pressure were reduced,which means the ability of recruit granulocyte pro-inflammatory factor decreased.The concentration of amandin could not significantly affect the release of pro-inflammatory factor in RBL-2H3 cells.Ultra-high pressure processing did not significantly change the SDS-PAGE results.However,the tertiary structure was unfolded,and the hydrophobic group was exposed,which lead to the increase of fluorescence intensity and surface hydrophobicity.The immunoreactivity of apricot kernel protein isolates reduced by 74.31%after ultra-high pressure processing.The optimal ultra-high pressure processing condition was 500 MPa for 900 s.The effect of enzymatic treatment on the immunoreactivity of apricot milk was studied,and it was shown that both papain and Neutrase can effectively degrade the allergenic protein in almond milk,thereby reducing the immunoreactivity of almond milk.The immunoreactivity of apricot milk treated by papain and Neutrase were reduced by 79.08%and 78.19%,respectively.The optimal enzyme content of papain and Neutrase were 250 U/g and 1.5 mL/g,and the reaction were hydrolyzed at 50?for 60 min.Since apricot milk treated by papain had better sensory evaluation,further research found that the polypeptide fragments of amandin hydrolyzed by papain had 6 linear epitopes,and the reduction rate of linear epitopes was57.14%.All the above results demonstrated that enzymatic treatment and ultra-high pressure processing can effectively reduce the immunoreactivity of bitter apricot kernel allergens.The potential triggering ananphylaxis of allergenic protein treated by ultra-high pressure were decreased,due to the clear structure alteration of it.The conformational epitopes were destroyed,which caused the decrease of sensitization capacity and immunoreactivity.The linear epitopes of amandin were destroyed by papain,lead to the decrease of of apricot kernel milk immunoreactivity.