Estimate of chitin in raw whole insects

Abstract

Insects contain significant amounts of fiber as measured by crude fiber, acid detergent fiber (ADF) or neutral detergent fiber (NDF). It has always been assumed that the fiber in insects represents chitin based on the structural similarity between cellulose and chitin and the fact that the ADF fraction from insects contains nitrogen. In this study, a number of insect species that are raised commercially as food for insectivores were analyzed for moisture, crude protein (nitrogen x 6.25), fat, ash, NDF, ADF, and amino acids. Additionally, the ADF fraction was analyzed for nitrogen and amino acids to determine if proteins might be present in the ADF fraction. The ADF fraction contained a significant amount of amino acids accounting for 9.3-32.7% of the ADF (by weight). The presence of amino acids in the ADF fraction means that using ADF to estimate insect chitin results in an overestimation of insect chitin content. Using ADF adjusted for its amino acid content, the estimated chitin content of these insect species ranged from 2.7-49.8 mg/kg (as is) and 11.6-137.2 mg/kg (dry matter basis). Additionally, these data suggest that for the species measured here the amount of chitin nitrogen is quite small (as a % of total nitrogen) and that crude protein (nitrogen x 6.25) provides a reasonable estimate of the true protein for most species of insects. Zoo Biol 0:1-11, 2007. (c) 2007 Wiley-Liss, Inc.

Effect of Tenebrio molitor larvae meal on growth performance, in vivo nutrients digestibility, somatic and marketable indexes of gilthead sea bream (Sparus aurata)

“…In cuticle, chitin is linked to protein, reducing the apparent and true digestibility of nitrogen. It also has to be considered that the insect meal protein is reported (Bovera et al, 2016) to have a low content in essential aminoacids (methionine, cystine, lysine, tryptophan) and that the cuticle proteins present an aminoacid composition different from that of the whole insects (Finke, 2007). Based on these considerations, and considering that dietary protein fraction is the most important factor affecting fish growth (Garcia De La Serrana et al, 2012), the hypothesis is that the amount of essential aminoacids available for digestion was sufficient to sustain fish growth, also in the case of the TM50 diet.…”

Improvement of techno-functional properties of edible insect protein from migratory locust by enzymatic hydrolysis

“…The higher amount of crude protein in MLPF can be ascribed to the partial removal of fat during flour production resulting in a considerable lower crude fat content. Data concerning the chitin or fibre content of migratory locusts are not available, but the chemical characterisation of other species from the same order (Orthoptera) revealed total dietary fiber contents between 10-16% db [5,48,49].…”

A Comprehensive Look at the Possibilities of Edible Insects as Food in Europe – A Review

“…Some authors suggest the fi ber in insects represents chitin because chitin (linear polymer of b-(1-4) N-acetyl-D-glucosamine units) is similar structurally to cellulose (linear polymer of b-(1-4)-D-glucopyranose units) and because the ADF (acid detergent fi ber) fraction has been shown to contain nitrogen [Barker et al, 1998;Finke, 2002]. Finke [2007] states that the fi ber content of insects (measured as ADF) consists not only of chitin but also of signifi cant amounts of amino acids that are likely to represent cuticular proteins. Insects with ''harder'' cuticles do not seem to contain signifi cantly more chitin than softer bodied insects but rather their ADF fraction seems to contain a much higher proportion of amino acids than softer bodied insects.…”