Towards Functional Insect Feeds: Agri-Food By-Products Enriched with Post-Distillation Residues of Medicinal Aromatic Plants in Tenebrio molitor (Coleoptera: Tenebrionidae) Breeding.

Stefanos S Andreadis,Eleftheria Rizou,Eirini Sarrou,Nikos Krigas,Efthimia Antonopoulou,Vassilia Stefanou,Maria Mastoraki,Sofia Tzentilasvili,Stavros Chatzifotis,Nikolas Panteli

doi:10.3390/antiox11010068

Abstract

Sustainability, circular economy and alternative production systems are urgent imperatives for humanity and animal husbandry. Unless wasted, agri-food by-products can offer a promising source of high value. We evaluated the effect of rice bran (RB), corncob (CC), potato peels (PP), solid biogas residues (BR), and olive-oil processing residuals (OR), as alternative substrates to wheat bran (WB as control), on the growth and nutritional value of Tenebrio molitor during its breeding for animal feeds and/or human consumption. Innovation-wise, we further investigated the substrate supplementation (0, 10, 20%) with post-distillation residues of Mediterranean aromatic-medicinal plants (MAPs: lavender, Greek oregano, rosemary, olive; 1:1:1:1 ratio). Tenebrio molitor larvae (TML) were reared in all the studied substrates, and TML and diets’ proximate and fatty acid compositions as well as total phenol and flavonoid content and antioxidant potential were assessed using standard procedures. After statistical analysis of correlations, we observed that CC promoted oviposition and progeny survival; larval weight and dry matter were positively affected mainly by dietary energy and fat content; number of TML and/or larval weight increased using 10% MAPs inclusion in WB, RB and OR or RB, OR, BR and PP, respectively, which did not affect protein content; TML fatty acid composition decreased the content of saturated ones and increased that of mono-unsaturated ones; MAPs residues had an apparent favorable impact on total phenolic content and antioxidant activity of each substrate, with RB displaying the highest capacity and content. These findings indicate that alternative substrates can be exploited and their enrichment with natural phenolics is able to influence T. molitor growth, offering highly beneficial and nutritional value.

Highlights

IntroductionThe rapid increase in demand for animal protein is driven by the continuous increase of world population, forcing consecutively the expansion of livestock industry [1]
In the frame of sustainability, agri-food by-products can be exploited by the feed industry as natural sources of functional ingredients for animal feeds or human consumption due to their high nutritional value and rich content of bioactive compounds with beneficial properties
With limited research on this subject to date, the study investigated, for the first-time, alternative substitutes of wheat bran in Tenebrio molitor breeding such as rice bran, corn cob, potato peels, solid biogas residues, and olive-oil processing residuals. These were investigated in respect to growth, nutritional value and beneficial content during T. molitor breeding, which is an economically important insect officially able to be exploited for animal feeds and/or human consumption

Summary

Introduction

The rapid increase in demand for animal protein is driven by the continuous increase of world population, forcing consecutively the expansion of livestock industry [1]. Livestock production is regarded as one of the major detrimental sectors of rural development in environmental terms, contributing to ecosystem degradation and disruption of biodiversity conservation [2]. Deforestation, landscape conversion to cropland, degradation and desertification of grasslands and pasture areas as well as water resource depletion are an immense reflection of livestock extensive requirements in arable land and fresh water [2,3].

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