Hermetia illucens Larvae as a Living Bioreactor for Simultaneous Food by‐Products Recycling and Useful Oil Production

Abstract

The effects of feeds containing several food by‐products on the fatty acid compositions of Hermetia illucens larvae were studied. Coconut, tomato, apple, and viscera by‐products, as well as combinations of control feed containing carbohydrate‐rich additives were assayed. Final live weight (mg) and daily growth coefficient (%/day) ranged from 41 and 0.548 (tomato) to 93 and 1.292 (coconut), respectively. Oils containing lauric acid were obtained from larvae‐fed vegetable by‐products, especially those fed feed containing apple, coconut, and tomato (65.3, 54.4 and 52.3% of total fatty acids, respectively). Feed containing apple and a 1:1 (w/w) mix of control feed and apple by‐products yielded the highest proportion of fatty acids in the larvae (23.5 and 15.6 g fatty acids/100 g fresh larvae, respectively). The properties of biodiesel that could be produced from larvae fatty acids were calculated and the following values were obtained: cetane number (58.5–60.2), higher heating value (38.3–39.0 MJ·kg−1), density (0.869–0.873 g·cm−3), and induction period, an index of oxidation stability (8.4–150 hours). Such values were within the ranges specified by the ASTM D6751 and Europe EN 14214:2008 standards, while values for cold filter plugging point (−9.6 to 2.8 °C) were adequate for biodiesels intended for use in temperate climates. However, values for kinematic viscosity (2.93–3.58 mm2·s−1) were slightly below the requirements of EN 14214:2008 (3.5–5.0). Overall, larvae fed food by‐products produced lauric acid‐rich oils, and the calculated properties of the oils were largely suitable for biodiesel production.

Functional characterization of fatty acid synthase inHermetia illucens

“…In another Dipteran insect Hermetia illucens (Diptera: Stratiomyidae), acted as an organic waste recycler, lauric acid mostly accumulates to a surprising level (36%-60%)(Almeida et al, 2020), which is uncommon in other insects, such as flies, crickets, locusts, mealworms and superworms (Adámková et al, 2017; Cripps et al, 1986; Jayanegara et al, 2020; Suryati et al, 2023; Thompson, 1973; Verheyen et al, 2018). Meanwhile, fed with various common organic substrates with little LA, including chicken feed, manure, vegetables, fruits and cereal, BSF larvae showed a relative constant lipids profiles and relative high LA content (Almeida et al, 2020; Guil−Guerrero et al, 2020; Rodrigues et al, 2022). As a main component of coconut oil or palm kernel oil (Dayrit, 2015) appeared in a terrestrial insect with a relative high content, a DNL origin hypothesis was proposed and tested in different ways.…”

“…Meanwhile, fed with various common organic substrates with little LA, including chicken feed, manure, vegetables, fruits and cereal, BSF larvae showed a relative constant lipids profiles and relative high LA content (Almeida et al, 2020;Guil-Guerrero et al, 2020;Rodrigues et al, 2022). As a main component of coconut oil or palm kernel oil (Dayrit, 2015) appeared in a terrestrial insect with a relative high content, a DNL origin hypothesis was proposed and tested in different ways.…”