Modulating the Fatty Acid Profiles of Hermetia illucens Larvae Fats by Dietary Enrichment with Different Oilseeds: A Sustainable Way for Future Use in Feed and Food

SIMPLE SUMMARY: Most of the vegetable oils represent a suitable source of unsaturated fatty acids and bioactive compounds, which can be the key to solving different nutritional limitations. The fatty acid profile of Hermetia illucens larvae fats can be modulated through dietary enrichment as a result of adding vegetable oils to the rearing substrate. Therefore, the present research analyzes the effects of a 10% addition of vegetable oils from five dietary fat sources in larvae diets on the productive performances and fatty acid profiles of H. illucens. Oil inclusion in the larval diet improved (p < 0.05) the weight of larvae, prepupae, pupae, and imago without influencing (p > 0.05) the egg clutch weight and the number of eggs in the clutch. In addition, the larvae FA profile was enhanced in unsaturated fatty acids (p < 0.001), especially in long-chain polyunsaturated fatty acids from the omega-3 series, when the linseed oil, hempseed oil, and rapeseed oil were used in larvae diets. ABSTRACT: Edible insects such as the black soldier fly Hermetia illucens L. represent a potential and sustainable source of nutrients for food and feed due to their valuable nutritional composition, which can be modulated through dietary enrichment. The high content of saturated fatty acid (FA) of Hermetia illucens larvae fats can be modulated through dietary enrichment as a result of adding vegetable oils in the rearing substrate. Therefore, the present research aims to highlight the effects of a 10% addition of vegetable oils from five dietary fat sources (linseed oil, soybean oil, sunflower oil, rapeseed oil, and hempseed oil) on the growth, development, reproductive performance, and the fat and fatty acids profile of H. illucens. Oil inclusion in the larval diet improved (p < 0.05) the weight of larvae, prepupae, pupae, and imago without influencing (p > 0.05) the egg clutch weight and the number of eggs in the clutch. In addition, the larvae fatty acid profile was different (p < 0.001) according to the oil type, because the unsaturated FAs (UFA) increased from 11.23 to 48.74% of FAME, as well as according to the larvae age, because the saturated FAs decreased from 85.86 to 49.56% of FAME. Linseed oil inclusion led to the improvement of the FA profile at 10 days age of larvae, followed by hempseed and rapeseed oil. These three dietary treatments recorded the highest concentrations in UFA (29.94–48.74% of FAME), especially in polyunsaturated FA (18.91–37.22% of FAME) from the omega-3 series (3.19–15.55% of FAME) and the appropriate n–6/n–3 ratio. As a result, the degree of the lipid polyunsaturation index increased (17.76–41.44) and the value of the atherogenic (3.22–1.22) and thrombogenic (1.43–0.48) indices decreased. Based on the obtained results, it can be concluded that enriching the larval diet with these oils rich in UFA can modulate the larvae FA profile, making them suitable sources of quality fats for feed and indirectly for food.