From vegetable food waste to earthworms as novel food/feed: nutritional characteristics

From vegetable food waste to earthworms as novel food/feed: nutritional characteristics D. Tedesco1, A. Tava2 and J.Parisi1 1Department of Health, Animal Science and Food Safety, University of Milan, Via Celoria 10, 20133, Milano,Italy, 2Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria, viale Piacenza 29, 26900 Lodi, Earthworms grown on fruit and vegetable waste can be a future alternative and sustainable food/feed source, contributing to waste disposal efficiency, responding to global food demand and reducing greenhouse gases (GHG) emission. As a part of studies on the feasibility to transform vegetable food wastes in this novel protein source, we evaluated the nutritional characteristic of earthworms (Eisenia foetida) reared on food vegetable waste from different rearing cycle. The focus was to evaluate the protein and fat content and the amino acids and fatty acids profile. Briefly, approximately 800 earthworms were separated from each substrate, washed in running controlled water to remove dirt from the body surface, kept in saline solution at room temperature changing the solution until the digestive system was clean, and then freeze – dried for further analyses. Samples of earthworms were analyzed for crude protein (CP) and total amino acids content, determined by the High Performance Liquid Chromatography (HPLC) analysis. Amino acids were quanti.ed according to calibration curves made with pure reference compounds, using the internal standard method. The ether extract was evaluated by solvent extraction, fatty acids profile was determined using reference fatty acid methyl esters (FAME) by gaschromatography flame ionization detector (GC/FID) analysis. The CP content ranged from 64.4% to 67.15% of the dry matter. The earthworm samples contain all the essential amino acids, with high lysine, threonine and arginine level. Total fats were quantified from 9.3% to 10.84% dry weight, while the fatty acids composition revealed a great amount of polyunsaturated fatty acids (PUFA), quantified from 40.32% to 43.91% of the total. Among PUFA, the .3 and .6 series were steadily well represented, ranged from 7.5% to 8.22% of the total amount. From these results, earthworms reared on vegetable food waste, showed an attractive nutritional profile for food/feed applications.