LC-MS-based detection of silkworm pupae in feed with and without prior immunoaffinity enrichment

Due to their advantageous nutrient composition and high feed conversion efficiency, insects may be an alternative protein source for human and animal nutrition. Recently authorised for feeding purposes in the European Union, silkworm pupae are vastly and cheaply available by-products from sericulture that have been successfully replacing fish meal in aquaculture feed. In order to enable silkworm detection by official control, we firstly identified potential, easily detectable peptide targets from dried silkworm pupae subjected to a standard mass spectrometry (MS)-based bottom-up proteomic workflow. Secondly, a targeted method with an optional immunoaffinity enrichment (IAE) step was developed. Method validation provided a highly reproducible limit of detection of 0.05% (w/w) silkworm pupae in various feeds (aquaculture, poultry, pig) that proved independent from the experimenter and whether IAE was included in sample preparation or not. Furthermore, the method’s specificity and robustness were assessed.