Ultrasonic Treatment Combining With Glycosylation Reduces The Allergenicity Of Ginkgo Seed Protein

Ginkgo seed has rich nutrients and high price of nutrition.Ginkgo seed protein(GSP),which is one of the main active ingredients in GSP,not only has excellent foaming and emulsifying properties,but also has high bioactive and potential economic value.However,the allergenicity of GSP limits its application.Ultrasound is an emerging physical processing that effectively alters protein conformational epitopes.Glycosylation could alter the linear epitope of the protein while minimizing disruption of protein activity.Therefore,this paper attempts to use ultrasonic to reduce the allergenicity of GSP,and to study the stability of the effect;The effect of ultrasonic treatment combining with glycosylation(UTCG)was studied to reduce the allergenicity of GSP.The changes in structure caused by UTCG were analyzed to explore the relationship between structure changes and sensitization changes of GSP.The main contents and results are as follows:(1)Study about the effect of ultrasonic treatment on the allergenicity of GSP.GSP which had been prepared was detected by SDS-PAGE electrophoresis to study molecular weight distribution.Mice were immunizated with GSP to obtain antibody serum,and indirect ELISA was established assay for determination the contrent of IgE and IgG.The different conditions of ultrasonic treatment on reducing the allergenicity of GSP were studied to determine better condition,and the effects of ultrasonic and heat treatment on structure were also reasearched.After using better ultrasound condition to treat GSP,the changes of both allergenicity and antigenicity within 36 h were studied to research the stablity of reducing-allergencity effect.The results showed that the molecular weight of GSP was mainly concentrated at 25~50 kDa.GSP could increase the content of IgG and IgE in mice serum,and the titer of serum IgE was 1:6400.When GSP was treated with 20/60 kHz multi-frequency ultrasound at the condition of 70 oC for 40 min,GSP has the greatest decline in allergenicity,which reducing 40.1%,and its antigenicity also significantly decreased by 47%,without causing denaturation and precipitation during processing.Ultrasonic and heat treatment were consistent with the trend of changing the ultraviolet absorbing group,the fluorescent emitting group,the surface hydrophobic group and the secondary structure on GSP,but ultrasonic treatment at 70 °C could induce the ?-folding of GSP significantly lower than the heat treatment at the same temperature.Antigenicity and allergenicity of GSP respectively increased by 14.4% and 20%,within 36 h storaged after ultrasonic treatment.Therefore,the effect of ultrasonic treatment on reducing allergy of GSP was unstable.(2)The effect of UTCG on the allergenicity and antigenicity of GSP.Using allergenicity as an indicator and considering the degree of grafting and browning to optimize the parameters of UTCG.Under the optimal treatment conditions,the antigenic changes of GSP were detected.The results showed that the optimal pH value,the ratio of GSP to glucose,reaction time and temperature were 8.0,1:3,50 min and 70 oC,respectively.UTCG could maximumly reduce the allergenicity of GSP,which reduced to 34.2%,and ensured that GSP has a higher degree of grafting without brownnig.The antigenicity of GSP decreased significantly by 60.4% under this treatment condition.(3)Compration of the effects about ultrasonic and UTCG on protein structure.After treatment with UTCG,GSP allergenicity and antigenicity were decteted during 36 h.The changes of free amino group content,ultraviolet absorption spectrum,endogenous fluorescence spectrum,surface hydrophobicity and circular dichroism spectrum of GSP were examined under different treatmental conditions.The results showed that the allergenicity and antigenicity of GSP was maintained within 36 h.Ultrasonic treatment could increase the free amino content of GSP,while UTCG could significantly reduce the content.Compared with ultrasonic treatment,UTCG could produce more ultraviolet absorption,fluorescent emission groups,including tyrosine,phenylalanine and hydroxymethylfurfural,and also expose more hydrophobic groups.Circular dichroism results showd an increase in a-helix,a decrease in b-folding and random curl after ultrasonic treatment,but UTCG could enhance this change.In addition,there was no significant difference in the structure of GSP between 0 h and 36 h after treatment with UTCG.Therefore,UTCG caused an irreversible and stable change in the structure of GSP,so resulted in irreversibly reducing the allergenicity of GSP.