Effect of Moisture and Oil Content in the Supercritical CO2 Defatting of Hermetia illucens Larvae

The supercritical defatting of H. illucens was scaled up at 450 bar and 60 °C from a 270 cm³ extraction cell to a vessel five times larger. Then, eight different H. illucens larvae batches, with variable content of oil (16.80-29.17% w/w) and moisture (4.45-15.95% w/w) were defatted. The effect of these parameters on yield and oil composition was analyzed. The presence of moisture in the larvae batch, in the range of the values studied, had no negative effect on the oil recovery efficiency, which was mainly determined by the initial content of oil in the larvae samples. Furthermore, no differences were determined in the fatty acid profile of the oils recovered, which were rich in saturated fatty acids, mainly lauric acid (ca. 50% w/w). Minor lipids, such as squalene and phytosterols, were determined in all the oil samples. The moisture content in the oils extracted was in the range of 0.118-1.706% w/w. Therefore, some samples exceeded the limits recommended for volatile matter in edible fats and oils (0.2%, including moisture). Yet, concerning the oil peroxide index, values were much lower than those corresponding to the oil extracted using hexane.

Proximate, Physicochemical, Techno-Functional and Antioxidant Properties of Three Edible Insect (Gonimbrasia belina, Hermetia illucens and Macrotermes subhylanus) Flours

In this study, edible insect flours from Gonimbrasia belina (Mashonzha), Hermetia illucens (black soldier fly larvae) and Macrotermes subhylanus (Madzhulu) were prepared and assessed in terms of proximal, physicochemical, techno-functional and antioxidant properties. The crude protein of the edible insect flours varied between 34.90−52.74%. The crude fat of the insect flours differed significantly (p < 0.05), with H. illucens (27.93%) having the highest crude fat. G. belina was lighter (L*) and yellower (+b*) compared to H. illucens and M. subhylanus, and there was no significant difference (p > 0.05) in the redness (+a*) of the edible insect flours. There were no significant differences (p > 0.05) in foam capacity and foam stability of all three edible insect flours. Moreover, the antioxidant activity against the DPPH radical was low for H. illucens (3.63%), with M. subhylanus (55.37%) exhibiting the highest DPPH radical. Principal component analysis (PCA) was applied to the techno-functional properties and antioxidant indices of the edible insect flours. PC1 accounted for 51.39% of the total variability, while component 2 accounted for 24.71%. In terms of PC1, the FS, OBC and FC were responsible for the major differences in the edible insect flours. The findings revealed that edible insect flours are a good source of antioxidants and can be used as an alternative protein source and a potential novel food additive due to their techno-functional qualities.

Fatty Acids-Enriched Fractions of Hermetia illucens (Black Soldier Fly) Larvae Fat Can Combat MDR Pathogenic Fish Bacteria Aeromonas spp

Aeromonas spp. cause many diseases in aquaculture habitats. Hermetia illucens (Hi) larvae were used as feed-in aquacultures and in eradicating pathogenic fish bacteria. In the present study, we applied consecutive extractions of the same biomass of BSFL fat using the acidic water–methanol solution. The major constituents of the sequential extracts (SEs) were free fatty acids (FFAs), and fatty acids derivatives as identified by gas chromatography spectrometry (GC-MS). Our improved procedure enabled gradual enrichment in the unsaturated fatty acids (USFAs) content in our SEs. The present study aimed to compare the composition and antimicrobial properties of SEs. Among actual fish pathogens, A. hydrophila and A. salmonicida demonstrated multiple drug resistance (MDR) against different recommended standard antibiotics: A. salmonicida was resistant to six, while A. hydrophila was resistant to four antibiotics from ten used in the present study. For the first time, we demonstrated the high dose-dependent antibacterial activity of each SE against Aeromonas spp., especially MDR A. salmonicida. The bacteriostatic and bactericidal (MIC/MBC) activity of SEs was significantly enhanced through the sequential extractions. The third sequential extract (AWME3) possessed the highest activity against Aeromonas spp.: inhibition zone diameters were in the range (21.47 ± 0.14–20.83 ± 0.22 mm) at a concentration of 40 mg/mL, MIC values ranged between 0.09 and 0.38 mg/mL for A. hydrophila and A. salmonicida, respectively. AWME3 MBC values recorded 0.19 and 0.38 mg/mL, while MIC₅₀ values were 0.065 ± 0.004 and 0.22 ± 0.005 mg/mL against A. hydrophila and A. salmonicida, respectively. Thus, the larvae fat from Hermitia illucens may serve as an excellent reservoir of bioactive molecules with good capacity to eradicate the multidrug-resistant bacteria, having promising potential for practical application in the aquaculture field.