Ability of black soldier fly larvae to bioaccumulate tocopherols from different substrates and measurement of larval tocopherol bioavailability in vitro

Edible insects are an emerging approach to provide sustainable proteins in feed. Black soldier fly larvae (BSFL) can also bioaccumulate micronutrients from various substrates. The purpose of this study was to assess whether BSFL can bioaccumulate significant concentrations of bioavailable α and ɣ-tocopherol (TOC) from vitamin E (VE) rich substrates. BSFL were reared on VE rich substrates, e.g. wheat germ oil, bran, etc. α and γ-tocopherol were quantified in larvae and substrates by HPLC. VE bioaccessibility was estimated using an in vitro model of digestion. Uptake efficiency of micellarized VE by intestinal cell was estimated using Caco-2 cells. BSFL were at least as rich in α-TOC, but not ɣ-TOC, as their rearing substrates. VE bioaccessibility was almost always significantly lower in BSFL than in corresponding substrates. Conversely, VE uptake efficiency was either not significantly different or significantly higher in BSFLs than in substrates. Thus, VE enrichment of BSFL from VE rich substrates, in particular co-products such as brans and oil cakes, could be an innovative way to recycle VE and to provide significant amounts of sustainable VE in farm animal feed.