Fungal contamination, mycotoxins, histamine, and allergen-related immunoreactivity in edible insects and insect-fortified complementary foods.

Abstract

Introduction: Edible insects are consumed by over 3,000 ethnic groups, with 2,205 species documented as food in 128 countries, yet evidence on fungal contamination, mycotoxins and allergen-related risks remains limited. This study assessed these hazards in edible insects and insect-fortified complementary foods for infant and young child nutrition.

Methods: Fungal contamination in 11 edible-insect products, seven food ingredients, seven insect-enriched formulations and five commercial complementary flours was assessed by culture and internal transcribed spacer sequencing. Fungal isolation comprised 1,080 inoculated culture observations across three independent batches per material type, from which 798 fungal isolates were recovered. Endpoint PCR assessed aflatoxin- and fumonisin-biosynthesis markers in Aspergillus flavus-like and Fusarium-like morphotypes. Mycotoxins in five complementary-food formulations were quantified by LC-MS/MS over three months, while histamine concentrations and lysozyme- and crustacean-reactive signals were measured in edible-insect preparations by enzyme-linked immunosorbent assays.

Results: Aspergillus accounted for 70.7% of isolates from insect products. Penicillium and Fusarium were detected in all 11 and eight insect products, respectively. Among 44 A. flavus-like morphotypes, aflD and aflQ were detected in 32 and 23, respectively; among 22 Fusarium-like morphotypes, VERTF and FUM1 were detected in 10 and 19, respectively. Marker detection did not establish gene expression or mycotoxin production. Six of 23 mycotoxins were detected: 3-acetyldeoxynivalenol, aflatoxin G1, sterigmatocystin, and fumonisins B1, B2 and B3. Only aflatoxin G1 and fumonisin B1 were quantified, at 4.20 µg/kg and 20.31-86.88 µg/kg, respectively; all other confirmed detections were below quantification limits. Quantifiable fumonisin B1 occurred at later storage points and peaked after three months, although patterns were not uniformly monotonic across formulations. The aflatoxin G1 point estimate was below the Kenyan total-aflatoxin maximum, and the European Union maize-based infant-food fumonisin value was used only for context; neither comparison established compliance or safety. Quantifiable histamine concentrations ranged from 3,108 to 30,232 µg/kg; three preparations were < 2,500 µg/kg and one was > 40,000 µg/kg. Lysozyme-reactive signals were < 25 µg/kg in all 17 preparations. Crustacean-reactive signals were > 400 µg/kg in 16 preparations, while the remaining result was 382 µg/kg.

Discussion: These findings support fungal-contamination prevention, controlled storage and assessment of potential allergen cross-reactivity in edible insects.