Aflatoxin Contamination Detected in Nutrient and Anti-Oxidant Rich Edible Stink Bug Stored in Recycled Grain Containers

Abstract

Recently, there has been multi-agency promotion of entomophagy as an environmentally-friendly source of food for the ever increasing human population especially in the developing countries. However, food quality and safety concerns must first be addressed in this context. We addressed these concerns in the present study using the edible stink bug Encosternum delegorguei, which is widely consumed in southern Africa. We analysed for mycotoxins, and health beneficials including antioxidants, amino acids and essential fatty acids using liquid chromatography coupled to quadrupole time of flight mass spectrometry (LC-Qtof-MS) and coupled gas chromatography (GC)-MS. We also performed proximate analysis to determine nutritional components. We identified the human carcinogen mycotoxin (aflatoxin B1) at low levels in edible stink bugs that were stored in traditonally woven wooden dung smeared baskets and gunny bags previously used to store cereals. However, it was absent in insects stored in clean zip lock bags. On the other hand, we identified 10 fatty acids, of which 7 are considered essential fatty acids for human nutrition and health; 4 flavonoids and 12 amino acids of which two are considered the most limiting amino acids in cereal based diets. The edible stink bug also contained high crude protein and fats but was a poor source of minerals, except for phosphorus which was found in relatively high levels. Our results show that the edible stink bug is a nutrient- and antioxidant-rich source of food and health benefits for human consumption. As such, use of better handling and storage methods can help eliminate contamination of the edible stink bug with the carcinogen aflatoxin and ensure its safety as human food.

Fig 1. Method of storage of processed insects a) traditionally wooven wooden baskets, b) used grain bags and c) clean zip lock bags.

Fig 2. Representative Extracted ion chromatograms for m/z 313.0737.

The retention time of aflatoxin B₁ is 2.20 min.

Fig 3. Representative total ion chromatogram showing fatty acid methyl esters (FAMEs) detected in processed and unprocessed E. delegorguei.

Peaks 1–10 indicate FAMEs shown in Table 1.

Fig 4. Representative total ion chromatogram showing flavonoids detected in samples of V. apiculata leaves and of E. delegorguei.

Peaks 1–4 indicate the flavonoids shown in Table 2.

Fig 5. Representative total ion chromatogram of the amino acid profile of unprocessed and processed insects.

Peaks 1–10 indicate amino acids shown in Table 5.