DNA metabarcoding for food authentication: identification of freshwater, marine, and terrestrial gastropods in commercial food products.

Food fraud through species substitution has been reported for edible gastropods, particularly in processed products where morphological identification is not feasible. DNA-based methods have been used to identify gastropod species in food products, but are largely limited to targeted analyses. To address this limitation, we applied, for the first time, an untargeted DNA metabarcoding approach to detect and identify gastropod species in processed foods. Mitochondrial 16S rDNA fragments of approximately 150 bp were analyzed. In 17 of 18 reference samples, taxa were resolved to genus or species level, in agreement with Codex Alimentarius Austriacus guidelines, facilitated by a curated reference database that enables assignments across freshwater, marine, and terrestrial gastropods. Thirteen DNA extract mixtures were analyzed for method validation, yielding few false-negative results for minor components. These likely resulted from primer-template mismatches causing amplification bias. Analysis of 20 commercial food products revealed seven mislabeled samples. The approach is compatible with established in-house metabarcoding assays targeting other animal species and consequently complements broad application across various taxa. This qualitative screening tool is suitable for routine food authentication, supporting supply chain transparency and regulatory monitoring.