The interrelation effect of slaughtering, drying, and defatting methods of BSFL on the oxidative quality of the derived fat was studied. Blanching and freezing were compared as slaughtering methods, followed by oven or freeze-drying for drying and mechanical pressing or SFE for defatting. The oxidative state and stability of the extracted fat and defatted meals were monitored immediately after their production, using peroxide value (PV) and Rancimat test, and over 24 weeks of storage. Slaughtering and drying methods had an independent effect on PV, with freezing and freeze-drying being the best methods. Mechanical pressing and SFE were comparable and superior to conventional hexane defatting. Interactions were observed between slaughtering and defatting, drying and defatting, and between all three factors. Generally, freeze-drying combined with any of the slaughtering and defatting methods resulted in the lowest PVs, with mechanical pressing being preferred. Freeze-drying plus mechanical pressing also produced the most stable fats during storage according to the evolution of PV, while the combination of blanching and SFE produced the least stable. A significant correlation was found between the PV at 24 weeks and the antioxidant activity of the fats. Contrary to storage assays, in accelerated Rancimat assays, freeze-dried samples were the least stable, which was partially attributed to the significant correlation with the acid values of the samples. Defatted meals followed a similar pattern to the extracted fat, except for worse oxidation for SFE defatting. Therefore, the different processing methods of slaughtering, drying, and defatting of BSFL differently affect lipid oxidation, with interactions between such successive steps.

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.

The interrelated effect of different slaughtering, drying and defatting methods of black soldier fly larvae (BSFL) on the lipid composition and properties of the fat was studied. Blanching and freezing were compared as slaughtering methods, oven or freeze-drying as drying methods, and mechanical pressing or supercritical fluid extraction (SFE) as defatting methods.

Lauric acid is present in various vegetable fats and has been shown to be beneficial for human health and well-being. The interest in the properties of this fatty acid has led to an increase in the production and consumption of oils rich in lauric acid, primarily coconut oil. Despite being less known, there is an atypical animal source of lauric acid that can be considered more sustainable and that has levels of this fatty acid comparable to coconut oil, as the case of the larvae of the edible insect black soldier fly (Hermetia illucens) is. Due to the fact that some of the bioactive properties of lauric acid are linked to its free form, and also to facilitate subsequent concentration processes, the release of the fatty acid from the triacylglycerols present in fats becomes necessary. In this study, chemical and enzymatic hydrolysis for transforming both lauric acid-rich fats into a product rich in free fatty acids (FFA) were investigated. Different variables were studied, such as reaction time and the amount of catalyst used, resulting in maximum conversions to FFA in the case of chemical hydrolysis in just 20 min for both fats. Furthermore, the efficiency of the lipase Eversa® Transform 2.0 in generating a lauric acid-rich product from both oils was demonstrated, but in this case, a longer time was needed. The products obtained through both types of hydrolysis contained high percentages of free lauric acid, also exhibiting high stability against oxidation. This makes H. illucens larvae fat a comparable and alternative source to coconut oil to produce lauric-acid rich products useful for different applications.

In this study, the antibacterial effect of fats derived from black soldier fly larvae (BSFL) were evaluated against various antibiotic-resistant strains of Campylobacter jejuni and Campylobacter coli . BSFL fats with different free fatty acids (FFAs) contents were obtained based on the larvae’s processing conditions. Initially, antibiotic susceptibility testing revealed that all Campylobacter strains were resistant to at least one antibiotic, with two strains classified as multidrug-resistant. The antibacterial activity of the BSFL fats was directly correlated with their FFAs content. Fats obtained through freeze-drying and defatting via supercritical fluid extraction (SFE) exhibited the strongest antibacterial effects against Campylobacter spp., reducing bacterial growth by 4.1 to 5.6 log CFU/mL in C. jejuni and demonstrating bactericidal activity (reducing bacterial growth >6 log CFU/mL) against all C. coli strains. An analysis of the individual contributions of FFAs in BSFL fat revealed that lauric and linoleic acids were bactericidal (reducing bacterial growth >8 log CFU/mL), completely inhibiting the growth of C. jejuni and C. coli strains, while myristic, palmitic, and oleic acids showed no effect on Campylobacter growth. These findings suggest that BSFL fat, which has been shown to enhance broiler growth, could also serve as an effective strategy to combat Campylobacter spp. contamination in the food chain.

In the present study, different methodologies with potential scalability and environmental friendliness, such as winterization, supercritical fluid extraction, and multistage distillation, were evaluated for lauric acid concentration. In all cases, to facilitate fractionation, the transformation of triacylglycerols into free fatty acids or fatty acid ethyl esters was required as a previous step. For the winterization experimental assays, the amount and type of solvent was studied, resulting in a product containing ~65% lauric acid with a recovery of ~81% using a 1:10 oil-to-solvent ratio with hexane. On the other hand, the experimental extraction with supercritical carbon dioxide in a counter current packed column at 55 °C, 115 bar, and 70 g CO₂/min, resulted in a product composed of ~80% lauric acid as ethyl ester with a recovery of ~85%. Finally, flash and multistage distillation were analysed using process simulation (Aspen Plus V14), demonstrating that this methodology can achieve 80% recovery with high purity (lauric acid: 96.7%; ethyl laurate: 97.4%), but a high vacuum is required to prevent thermal degradation of the product (lauric acid: 0.2 mbar; ethyl laurate: 1.1 mbar). Overall, the employed methodologies proved highly efficient in concentrating lauric acid, yielding a product of commercial interest and high added value.