D2.282 - Impact of Polyethylene Terephthalate Microplastics on the Digestibility of Shrimp Allergen Tropomyosin

Microplastic pollution is an emerging environmental concern with potential human health implications. Seafood is particularly susceptible to plastic contamination, highlighting the need to investigate interactions between microplastics and food allergens. Microplastics may persist in the gastrointestinal tract (GIT) and interact with dietary proteins, potentially affecting their digestion. This is especially relevant for tropomyosin (TPM), the major shellfish allergen, whose digestive stability may influence allergen exposure.

Shrimp TPM was isolated and subjected to simulated gastrointestinal digestion using the INFOGEST 2.0 protocol in the presence or absence of high concentrations of polyethylene terephthalate (PET) microplastics (<80 µm). Digestion was performed through oral, gastric, and intestinal phases with sampling at defined time points. Whole shrimp (Litopenaeus vannamei) samples were digested under identical conditions, including enzyme-free controls. Protein concentrations were measured using BCA and Bradford assays. Protein degradation and persistence were analyzed by SDS-PAGE, Western blotting, and two-dimensional SDS-PAGE, while lipid degradation was assessed using Nile Red staining.

PET microplastics modulated shrimp protein digestion predominantly during the gastric phase. In purified TPM digests, PET microplastics accelerated the loss of intact TPM compared to controls. In whole shrimp digests, TPM was detectable during gastric digestion but largely absent after the intestinal phase. Two-dimensional SDS-PAGE of gastric digesta revealed reduced abundance of TPM-related protein spots (pI ~4, 27–39 kDa) and loss of more acidic TPM isoforms (pI <4, 25–35 kDa). Enhanced degradation of other major shrimp allergens, including sarcoplasmic calcium-binding protein and myosin light chain, was also observed. No substantial differences were detected during the intestinal phase.

PET microplastics transiently affect the gastric digestion of shrimp proteins by accelerating proteolysis, without persistent effects during intestinal digestion. Even under exaggerated exposure conditions, these findings suggest limited biological relevance of PET microplastics for the digestion of major shrimp allergens at environmentally realistic doses.