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Hypoallergenic Approach of Major Allergen of Penaeus Vannmei and Its Evaluation System

Author: SunJiaYi
Tutor: WangXiChang
School: Shanghai Ocean University,
Course: Food Science and Engineering
Keywords: shrimp Tropomyosin hypoallergenic enzymolysis sensitizationanimal model
CLC: R593.1
Type: Master's thesis
Year: 2013
Downloads: 40
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Abstract

Recently, food allergy patients rose gradually worldwide. Food allergy has becomean important issue of food safety. Food and Agriculture Organization(FAO) haveconfirmed the8allergenic food. Crustacea of shrimp and crab are one of the allergenicfood. However, Crustaceans are in global consumption and production is the highestone of three big shrimp class. Also they are well received by consumers for high values.The pathogenesis of a food allergy at present is not entirely clear. There is no effectivemethod for the treatment of food allergy clinically. Allergic patients can only rely onfood to prevent allergic sensitization to avoid intake of purpose. Therefore, to reduce theallergenicity of food and to establish proper evaluation system are emergency to protectthe food allergy sufferers.The aim allergen Tropomyosin(Tm) of Penaeus vannamei were the object of thisstudy. Firstly, trypsin, bromelian, alcalase, ficin and-chymotrypsin were selected.Most of these enzymes are food grade. Biochemical method of enzymatic hydrolysis,physical method of ultrasonic method and physical method combining with biochemicalmethod were individually used to reduce shrimp major allergen tropomyosin.Enzymolysis condition of trypsin and bromelian were optimized. The reduction oftreated and untreated allergen were evaluated by SDS-PAGE. This study provided thebasis for allergen reduction method and choice of enzymes.In order to study the reduction of allergen Tm and to prepare the anti-Tm serum toevaluate the allergenicity, sensitization animal model based on BALB/c mice for havebeen established. The BALB/c mice were immunized by intraperitoneal injection ofimmunogens. They were immunized with emulsions prepared by mixing immunogenswith aluminum hydroxide adjuvant (v/v,3:1). Ovalbumin (OVA) as a commonsensitisation protein, tropomyosin as a major allergenic constituent of shrimp,tropomyosin by ficin enzymolysis(Tm-E), and a negative control of PBS were respectively applied as immunogens. Injection was repeated once every other week.Blood samples were collected at the fourth day after every exposure. Specifc IgE andIgG antibodies in antiserum were detected using enzyme-linked immunosorbent assay(ELISA). Sensitization animal model based on BALB/c mice for have been established.Whatsmore, allergenicity have been reduced when the allergen have been reduced.Based on Tm study, the treatment of shrimp products were further studied. Theprepared anti-Tm serum were used to evaluate the allergenicity of peeled prawns,butterfly shrimp and minced shrimp by enzymolysis. Production feasibility ofhypoallergenic shrimp products have been discussed combined with the existingproduction process. The results of this study were showed as follow.Optimized enzymolysis conditions of trypsin and bromelian were obtained byallergen reduction experiment. Allergen and allergenicity were declined of varyingdegrees by enzymolysis and ultrasound combining with enzymolysis treatment at thesame temperature(35℃).One approach of sensitization animal model for shrimp allergen tropomyosin hasbeen established successfully. ELISA results showed that OVA and Tm immunogensinduced vigorous IgE and IgG antibody responses at the35th day. In contrast, exposureto PBS failed to induce vigorous IgE and IgG production, with no detectable IgE andIgG. The specific IgE of Tm-E group was gradually increased at the21th and35th day,however, compared with the Tm group, it is decreased by22.17%and35.94%(P<0.01),respectively. The results showed that IgE sensitization animal model for shrimp allergentropomyosin has been established. It proved that ficin enzymolysis of Tm have theobviously effective in the animal model.Process of hypoallergenic shrimp products of peeled prawns, butterfly shrimpand minced shrimp have been discussed. Allergenicity of the butterfly shrimp andminced shrimp samples dealed with ultrasound combining with enzymolysis21.05%and33.33%, respectively. Allergenicity of the minced shrimp samples dealed withenzymolysis was reduced to30.70%. No significant difference (P>0.05) inallergenicity was appeared for the peeled prawn samples. This research showed thatcombining with ultrasound were useful to reduce the allergenicity of the butterflyshrimp and minced shrimp by enzymolysis. Application feasibility of hypoallergenicshrimp products have been studied. In conclusion, the aim allergen Tropomyosin(Tm) were the object of this study.Effective hypoallergenic treatments have been established by physical methodcombining with Biochemical method to reduce shrimp major allergen tropomyosin. Oneapproach of sensitization animal model for shrimp allergen tropomyosin has beenestablished. Evaluation of this method of reduction allergenicity have been discussedIn Vivo. Based on the evaluation In Vitro and In Vivo, application feasibility ofhypoallergenic shrimp products of peeled prawns, butterfly shrimp and mincedshrimp have been studied. Treatments of hypoallergenic shrimp products combinedwith the existing production process could reduce the allergenicity certainly. Thisstudy provides scientific theory basis for future production of hypoallergenic shrimpproducts and have the potential application values.

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