Efficient use of agricultural waste to naturally fortify Tenebrio molitor mealworms and evaluation of their nutraceutical properties

Circular economy principles aim to maintain resources in the economic circle. Accordingly, the use of agricultural waste and its transformation into novel products is a smart approach that creates benefits for the environment, industries and consumers. Herein, we conjugated the principles of circular economy with the search for novel sustainable functional foods, transforming agricultural food chain by-products into feed supplements for Tenebrio molitor larvae (TML) feeding. Accordingly, tomato peels and seeds (TPS) stemming from the tomato sauce production, as well as olive (Olea europaea) and mastic (Pistacia lentiscus) leaves (OEL and PLL) from pruning were finely pulverised and used as feed supplements. All the diet supplements efficiently supported larval growth, offering optimal values of larvae mean body weight and survival rate. Interestingly, both total phenol content and antioxidant activities increased compared to the control, thanks to the accumulation of active compounds with hydrophilic or lipophilic characteristics. In addition, the fatty acids composition was determined, revealing a beneficial reduction of omega-6 (n-6)/omega-3 (n-3) ratio. Taken together, our results strongly support TPS, OEL and PLL use as smart breeding supplements, able to increase the antioxidant activity and ameliorate fatty acid profile of TML with important applications in human and animal nutrition.