Pulsed ultraviolet light reduces immunoglobulin E binding to Atlantic white shrimp (Litopenaeus setiferus) extract

Abstract

Pulsed ultraviolet light (PUV), a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa), and to attenuate immunoglobulin E (IgE) binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus) extract was treated with PUV (3 pulses/s, 10 cm from light source) for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA) using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract.

Keywords: IgE antibodies; PUV; allergen; allergy; pulsed ultraviolet light; shrimp; tropomyosin.

Figure 1

An SDS-PAGE profile of shrimp extract treated with PUV at 0, 1, 2, 3, 4, 5, and 6 min. Molecular weight marker (M) is shown. The band corresponding to tropomyosin (36-kDa) is highlighted with an arrow.

Figure 2

Western blot analysis of shrimp extract samples treated with PUV at 0 (control), 1, 2, 3, 4, 5, and 6 min using pooled human plasma from 3 individuals containing IgE antibodies against shrimp. Tropomyosin bands (36-kDa) are highlighted within a box.

Figure 3

An SDS-PAGE profile of untreated (1), boiled (2), PUV-treated (3), and [boiled+PUV]-treated (4) shrimp extracts. Molecular weight marker is shown (M). An arrow highlights the bands corresponding to tropomyosin (36-kDa).

Figure 4

Western blots using (a) pooled human plasma containing IgE antibodies against shrimp and (b) monoclonal anti-tropomyosin antibody (IgG) to analyze untreated (1), boiled (2), PUV-treated (3) and [boiled+PUV]-treated (4) shrimp extracts. Tropomyosin (36-kDa) is highlighted using a box.

Figure 5

Dot blot analysis of untreated, boiled, PUV-treated, and [boiled+PUV]-treated shrimp extract using pooled human plasma containing IgE antibodies against shrimp.

Figure 6

Indirect ELISA illustrating changes in IgE binding compared to untreated, boiled, PUV-treated, and [boiled+PUV]-treated shrimp extracts using pooled human plasma containing IgE antibodies against shrimp. A = absorbance of the sample; A₀ = absorbance of untreated sample. Data are expressed as mean ±SEM (n = 5). Results are relative values, normalized to the untreated sample; untreated is standardized and set to 1. Values that are significantly different (S = 0.05) from the untreated sample are annotated as **.