Supercritical-CO2 for defatting and production of bioactive extracts from black soldier fly (Hermetia illucens) larvae

Abstract

Edible insects are gaining attention as a source of bioactive compounds of great interest for health. To produce bioactive extracts from insects with a high concentration of bioactive compounds, defatting seems to be relevant for those fat-rich forms of insects as larvae. Supercritical fluid extraction (SFE) might be useful for both the defatting and subsequent extraction of the defatted sample to obtain bioactive extracts from edible insects. Different samples of black soldier fly (Hermetia illucens) larvae were defatted using SFE as an alternative to conventional defatting methods, and the optimal defatted flour was sequentially extracted by SFE employing different levels of ethanol as co-solvent. The resulting extracts were characterised by GC-MS-FID and their bioactivity was then assayed in terms of their antioxidant and pancreatic lipase inhibitory activities. The maximum fat yield by SFE (around 43%) was achieved at 450 bar, 60 °C and 100 g/min of CO2 flow, not being significantly different from conventional defatting with hexane. Extraction yield of SFE extracts increased along with the proportion of co-solvent. The composition of the extracts widely varied depending on the insect sample and the amount of co-solvent used, free amino acids and fatty acids being the two major chemical families among the different extracts. In terms of their bioactivity, a lipase inhibitory activity closer to 50% was exhibited by most extracts, which was favoured by the amount of co-solvent in one of the insect samples. Regardless of the significant differences observed between the insect samples, the exhibited DPPH radical inhibitory activity was weak. It is concluded that SFE is an interesting alternative to the conventional defatting of H. illucens, as well as an integrative and sequential process that allows producing bioactive extracts from this insect, especially towards the inhibition of the pancreatic lipase.

The Interaction of Slaughtering, Drying, and Defatting Methods Differently Affects Oxidative Quality of the Fat from Black Soldier Fly (Hermetia illucens) Larvae

“…Supercritical CO 2 defatting was performed using supercritical CO 2 extraction equipment (Model Thar SF2000, Thar Technology, Pittsburgh, PA, USA) and following the optimized conditions previously performed by Cantero-Bahillo et al (2022) [11]. Prior to extraction, 500 g of dried larvae were ground in a knife mill (Grindomix GM 200, Retsch GmbH, Haan, Germany).…”

“…The defatting was performed at 450 bars, 60 • C, and CO 2 flows of 130 g/min for 240 min. For comparative purposes with the traditional method of defatting by solvents, hexane was also used, according to Cantero-Bahillo et al (2022) [11]. Thus, 2 g of ground sample were homogenized with hexane at a ratio of sample to solvent of 1:5 (w/v) in an Ultraturrax (Ultra-turrax T18 basic, IKA, Staufen, Germany) (11,000 rpm) for 5 min.…”

“…Finally, defatting is also a common step for the use of edible insects to produce high-protein products, which is currently the primary purpose and interest in using edible insects. Thus, defatting is almost mandatory for insects with high lipid content, such as those consumed in the larval stage, like BSF, which can have lipid contents up to 40% [11]. Lipids dilute protein concentration and, in the case of feed, may hinder manufacturing technology, impact palatability, and affect productive yields and lipid composition of animals.…”

“…However, no conclusive results have been reached regarding the impact of the drying methods on lipid oxidation, likely due to the dependence on the slaughtering method used. Finally, concerning defatting, mechanical pressing or solvent extraction are the most popular methods, but other advanced and sustainable technologies are emerging, such as lipid extraction by supercritical fluids (SFE-CO 2 ) [11]. However, despite the relevance that this final step of insect meal processing might also have on lipid oxidation, this has not been fully explored, likely because the insect meal quality is the main aim after the defatting step.…”

Effects of a Mealworm (Tenebrio molitor) Extract on Metabolic Syndrome-Related Pathologies: In Vitro Insulin Sensitivity, Inflammatory Response, Hypolipidemic Activity and Oxidative Stress

“…Therefore, it remains of interest to explore how other presentations of mealworm, such as extracts, can modulate different metabolic syndrome-related pathologies. In this sense, we previously demonstrated the antioxidant and pancreatic-lipase inhibitory activities of non-protein extracts obtained under advanced extraction technologies from different species of edible insects, including T. molitor [ 16 , 17 , 18 ]. Recently, Ham et al [ 19 ] tested the effect of a mealworm fermentation extract in diet-induced obese mice and found improvements in reducing obesity, steatosis and whole-body glucose homeostasis.…”