Light microscopy with differential staining techniques for the characterisation and discrimination of insects versus marine arthropods processed animal proteins

Abstract

The aim of this study was to evaluate the use of light microscopy with differential staining techniques for the discrimination of insect material from marine arthropods - classified as fishmeal. Specifically, three samples of single-species insect material, Hermetia illucens (HI), Bombyx mori (BM) and Tenebrio molitor (TM), and two samples of marine arthropods, shrimp material and krill, were analysed and compared after staining by two reagents to enhance fragment identification. Alizarin Red (AR) and Chlorazol Black (CB), which react respectively with calcium salts and chitin, were tested for their potential efficacy in distinguishing between insect and marine materials. Results indicated that AR failed to stain HI, BM and TM materials. By contrast, the three insect species materials tested were stained by CB. When shrimp fragments and krill were considered, AR and CB stained marine materials reddish-pink and light blue to black, respectively. By combining these results, it can be suggested that CB staining may efficiently be used to mark insect materials; AR does stain shrimp fragments but does not stain the tested insect material, indicating a possible approach for discriminating between insects and marine arthropods. However, since the present study was performed on pure materials and a small set of samples, possible implementation of this technique still needs to be confirmed in complex matrices such as compound feed.

Review: Insects and former foodstuffs for upgrading food waste biomasses/streams to feed ingredients for farm animals

“…Traceability implies that the ingredients of all products can be traced throughout the entire manufacturing process so that if any safety problem arises, its source can be located and the problem can be resolved. These good practice systems at all levels of the feed/food chain should enable all food and feed ingredients to be traced along with the presence of undesirable substances (European Commission, 2017;van Raamsdonk et al, 2017;Ottoboni et al, 2017b).…”

Bridging legal requirements and analytical methods: a review of monitoring opportunities of animal proteins in feed

“…Some results for DNA based detection or identification of insects have been published (see overviews in Ottoboni et al (2017) and van Raamsdonk et al (2017b)). A general test for the detection of the presence of insects based on the gene coding for 18S RNA showed a positive signal for wheat and tomato as well (Debode et al 2017).…”

“…Insects share the existence of a chitin based exoskeleton with the other arthropods, most notably krill. A proof of concept was provided for specific microscopic staining procedures to detect chitin fragments, and to discriminate between the krill and insect version of chitin (Ottoboni et al 2017). The use of Tetramethylbenzidine for the detection of blood products and the Alizarin staining for colouring of bone fragments, as part of Regulation (EC) 152/2009, appeared to be not particularly specific (van Raamsdonk et al 2011(van Raamsdonk et al , 2017a.…”

Insect and fish by-products as sustainable alternatives to conventional animal proteins in animal nutrition

“…A complete overview of the feed ban in the EU is reported in Thus far, the research carried out to evaluate the effects of dietary inclusion of insect-derived PAPs or dried larvae on in vivo performance, health status, and food product quality of fish and terrestrial monogastric species (poultry, swine) is promising. However, as for the other feed ingredients, well-defined protocols and controls of insect material productive chain must be implemented and regulated to protect animal and human safety (Ottoboni et al 2017b;van Raamsdonk et al 2017;Veys and Baeten 2018).…”