Detection of selected heavy metals and micronutrients in edible insect and their dependency on the feed using XRF spectrometry

Abstract

Edible insect can be a valuable source of nutrients, but also a potential source of heavy metals. Quick detection of over-limit heavy metals concentration could be a key to processing and quick distribution of edible insect products. The aim of this work was to evaluate the feed-dependent content of heavy metals in the mealworm and superworm using the X-ray fluorescence spectrometry as an easy, cheap and a timeless screening method for evaluating the content of heavy metals and microelements. Using a handheld analyser the content of Cd, Pb, Cu and Zn were detected. Both analysed species proved dependency of metal content on a feed. Detected level of Cu in mealworm was between 571 mg.kg-1 and 1768 mg.kg-1 and in superworm from 571 mg.kg-1 to 1768 mg.kg-1 based on the feed. The content of Zn was similar, between 725 mg.kg-1 and 1437 mg.kg-1 in mealworm and 555-1482 mg.kg-1 in superworm. The level of Pb was below the detection limit in all samples, thus from this point of view this food seems to be safe. On the contrary, the content of Cd in the dry matter samples was above the food limit –147 mg.kg-1 to 230 mg.kg-1. From this point of view, the samples were evaluated as unsuitable for consuming.

Edible insect can be a valuable source of nutrients, but also a potential source of heavy metals. Quick detection of over-limit heavy metals concentration could be a key to processing and quick distribution of edible insect products. The aim of this work was to evaluate the feed-dependent content of heavy metals in the mealworm and superworm using the X-ray fluorescence spectrometry as an easy, cheap and a timeless screening method for evaluating the content of heavy metals and microelements. Using a handheld analyser the content of Cd, Pb, Cu and Zn were detected. Both analysed species proved dependency of metal content on a feed. Detected level of Cu in mealworm was between 571 mg.kg-1 and 1768 mg.kg-1 and in superworm from 571 mg.kg-1 to 1768 mg.kg-1 based on the feed. The content of Zn was similar, between 725 mg.kg-1 and 1437 mg.kg-1 in mealworm and 555-1482 mg.kg-1 in superworm. The level of Pb was below the detection limit in all samples, thus from this point of view this food seems to be safe. On the contrary, the content of Cd in the dry matter samples was above the food limit –147 mg.kg-1 to 230 mg.kg-1. From this point of view, the samples were evaluated as unsuitable for consuming.