Use of distillery by-products as Tenebrio molitor mealworm feed supplement

Agricultural and industrial waste represent valuable starting materials to create novel products with economic value added. Winery industry represents an important economic sector in Italy, which produces tons of by-products every year. Global warming and the increasing demand for food and feed led us to analyse the nutraceutical properties of distillery by-products as possible supplements to feed Tenebrio molitor larvae (TML). Grape pomace (GP) and grape marcs (GM), grape skin pulp, grape seeds and winery waste sludge were analysed for their antioxidant activity and fatty acid (FA) profile. Even if subjected to multiple processing, by-products had an important content of antioxidant compounds, in particular polyphenols, flavonols, flavonoids and condensed tannins. Moreover, the high amount of polyunsaturated fatty acids and the low percentage of saturated fatty acids found make them useful feed supplements. Herein has been disclosed that their use as TML feed material was well tolerated over TML development, with a significant mean weight gain respect to control of about 25% and no effect on survival rate. Interestingly, total antioxidant activity and FA profile ameliorate significantly, suggesting that distillery by-products can be used to extend the shelf-life of TML and ameliorate their nutraceutical properties, with possible application in controlled dietary regimens. This work confirmed that by-products largely produced in Europe can be used as TML feed materials, simplifying waste management and reducing rearing costs.