Antioxidant properties of a tilapia (Oreochromis niloticus) diet with the inclusion of avocado by-product

Abstract

Since synthetic antioxidants have been questioned for their potential carcinogenic and teratogenic effects, interest has grown in aquaculture for alternatives of natural antioxidants used in diets. This study analyzed antioxidant properties of a diet for tilapia with the inclusion an avocado by-product (AP) paste. Avocado seed, skin and pulp, despite their proven antioxidant capacity, represent a great amount of waste in Mexico. We included four diets in this study: base diet 0 (BD), 10 (D10), 20 (D20) and 30 % (D30) of AP inclusion, and a commercial diet (CD) for comparison. The antioxidant activity was assessed by free-radical techniques, such as 1,1-diphenyl-2-pricrylhydrazil (DPPH•), 2,2’-azino-bis (3-ethylben zthiazoline-6-sulfonic acid (ABTS•+), iron ion (Fe III) and concentration of total phenolic compounds (TPC). An increasing pattern was observed both in antioxidant activity and TPC as the level of AP inclusion increased. In some determinations, CD showed the highest levels, which were attributed to the synthetic antioxidants added and undeclared in these formulations. Therefore, AP was considered a good option for its inclusion in aquaculture diets because of its antioxidant properties and the added value granted with its use.