Mineral analysis reveals extreme manganese concentrations in wild harvested and commercially available edible termites

Rudi L Verspoor,Kathryn Powell,Maud Langton,Gregory D D Hurst,Rousseau Djouaka,Murielle Soglo,Razack Adeoti,Rosana Moriana,Catherine L Parr,Rikard Landberg,Matthew Osborne,Sam Edwards,Rikard Fristedt

doi:10.1038/s41598-020-63157-7

Abstract

Termites are widely used as a food resource, particularly in Africa and Asia. Markets for insects as food are also expanding worldwide. To inform the development of insect-based foods, we analysed selected minerals (Fe-Mn-Zn-Cu-Mg) in wild-harvested and commercially available termites. Mineral values were compared to selected commercially available insects. Alate termites, of the genera Macrotermes and Odontotermes, showed remarkably high manganese (Mn) content (292–515 mg/100 gdw), roughly 50–100 times the concentrations detected in other insects. Other mineral elements occur at moderate concentrations in all insects examined. On further examination, the Mn is located primarily in the abdomens of the Macrotermes subhyalinus; with scanning electron microscopy revealing small spherical structures highly enriched for Mn. We identify the fungus comb, of Macrotermes subhyanus, as a potential biological source of the high Mn concentrations. Consuming even small quantities of termite alates could exceed current upper recommended intakes for Mn in both adults and children. Given the widespread use of termites as food, a better understanding the sources, distribution and bio-availability of these high Mn concentrations in termite alates is needed.

Highlights

Termites are widely used as a food resource, in Africa and Asia
Marketing and export of edible insects can provide an important source of revenue (e.g.3) and the use of insects as food is expanding into countries beyond those where use is traditional
To establish if the Mn was anatomically localised and could be reduced by processing we examined whether heads and bodies of M. subhylanus differed in Mn content

Summary

Introduction

Termites are widely used as a food resource, in Africa and Asia. Markets for insects as food are expanding worldwide. Novel edible insects are reaching new markets, bringing unique obstacles for value chain regulation; for example accurate identification of species. Specific factors, such as wild harvesting and rural processing bring additional difficulties when trying to establish and maintain the quality of insect foods[6,7]; for example, the accumulation of heavy metals[8,9]. The extent and source of variations in mineral content within and between species remains largely unknown This knowledge gap is important, as nutritional information underpins food safety standards and is vital for decision making when novel foods are entering markets, for example in the European Union[10]. Establishing consistent estimates of mineral concentrations in alates is critical when assessing their potential benefit and informing their potential marketability[20,21]

Methods

Results

Discussion

Conclusion