Pilot‐scale supercritical CO₂ extraction of edible insect oil from Tenebrio molitor L. larvae – Influence of extraction conditions on kinetics, defatting performance and compositional properties

Abstract

In view of industrial fractionation processes for edible insects, supercritical CO2 extraction of Tenebrio molitor larval oil was studied. The influence of extraction parameters on defatting of larvae was investigated using a full factorial design. Furthermore, the effect of operating conditions on extraction kinetics, fatty acid composition, and acidity of mealworm oil was evaluated. Pressure, time, and their interaction showed the most significant effects on defatting. Maximal defatting (95%) was achieved at 400/250 bar, 45°C, and 105 min. Extraction kinetics revealed that incrementing pressure increased the solubility of mealworm oil in SC–CO2 enabling faster extraction. Extracted oils contained 72% unsaturated fatty acids, and oleic acid accounted for 42% of total FAME. Oil composition and acidity were found to be affected by extraction parameters showing the highest amount of low molecular and free fatty acids after slow extraction at 250 bar and 65°C. Use of selective extraction conditions enabled simple time‐dependent fractionation and deacidification yielding fractions with tailored fatty acid profiles or facilitating subsequent refining processes, respectively. Defatting performance and oil composition were not substantially different when using hexane as a solvent in comparison to SC–CO2. Mealworm larvae can be effectively defatted using SC–CO2 at high pressure and moderate temperature, yielding two valuable fractions: oil‐ and protein‐rich residue. Practical applications: Mealworm larvae are promising candidates for the inclusion of edible insects in the western food and feed industry due to modest breeding demands, existing rearing knowledge, and high contents of protein and fat. The development of fractionation processes for the production of standardized insect bulk materials and incorporation in feed or food in analogy to soy and other plant raw materials rich in fat and protein will help gain industrial applicability and enhance consumer acceptance. Depending on the processing approach, a defatting step is crucial prior to protein extraction. The results of this study indicate that SC–CO2 extraction is suitable for achieving a high yield of solvent‐free oil and a protein‐enriched, solvent‐free residue at low extraction temperatures. Both fractions can be further refined and purified in order to achieve valuable intermediates for food and feed applications. The SC–CO2 extraction of mealworms yielded highly unsaturated oil and a defatted residue containing protein and chitin. The operating parameters clearly affected the defatting performance and the extraction rate.

Effect of pre-treatment and drying method on physico-chemical properties and dry fractionation behaviour of mealworm larvae (Tenebrio molitor L.)

“…Chemical composition of larvae [6,12,13,35,41]. The large heterogeneity of nutrient composition-even in the same species and metamorphic stage-can be ascribed to different diet, instar, origin, season, and gut content [7].…”

“…Extraction parameters were chosen according to the study of Purschke et al [35] and set to 400 bar, 45 °C, and 20 kg of CO 2 /h. The extractor was charged with 250 g of dried larvae.…”

Edible Insects Processing: Traditional and Innovative Technologies

“…Purschke et al. () studied supercritical CO 2 extraction of edible insect oil from T. molitor L. larvae. The authors found that T. molitor oil composition and acidity was influenced by the extraction parameters.…”

“…Some changes in protein composition were also found as a decrease in low-molecular fractions (15 to 20 kDa) and an increase in high-molecular fractions (>60 kDa; Bußler et al, 2016). Purschke et al (2017) studied supercritical CO 2 extraction of edible insect oil from T. molitor L. larvae. The authors found that T. molitor oil composition and acidity was influenced by the extraction parameters.…”

“…Another area of interest consists of the development of functional ingredients for food, feed, pharmaceutical, and industrial applications. Ingredients of interest such as chitin (Song et al., ), oleic acid (Purschke, Stegmann, Schreiner, & Jäger, ; Sun et al., ), proteins (Bußler, Rumpold, Jander, Rawel, & Schlüter, ; Huang et al., ; Ndiritu, Kinyuru, Kenji, & Gichuhi, ), and bioactive peptides (Montowska, Kowalczewski, Rybicka, & Fornal, ; Nongonierma & FitzGerald, ; Zielińska, Karaś, & Jakubczyk, ) have been partially or totally extracted and purified. Nonetheless, scaling up these processes to the industrial level would still be too costly (Lamsal, Wang, Pinsirodom, & Dossey, ).…”