Drum-drying of mango peel and characterization of different varieties

Abstract

Mango peel, a by-product of the mango pulp industry, is rich in nutrients but with high moisture content. Drying is indicated to stabilize the residue and use of a drum-dryer is a little studied alternative. The present study evaluated the application of this technology for mango peels, investigating the influence of process conditions. The potential of mango peels from Palmer, Haden, Keitt, and Espada Vermelha varieties was also assessed using physicochemical analyses. The results showed differences between the varieties: Palmer exhibited the lowest moisture content (73.97 g per 100 g); Keitt the highest reducing sugar content (25.06 g per 100 g d.b.); Haden the highest soluble dietary fiber content (20.85 g per 100 g d.b.); and Espada Vermelha the highest phenolic compound content (5462 mg GAE per 100 g d.b.). Palmer mango peels were dried, varying temperature (130.6/146.4 ºC) and residence time (14/28 s). The independent variables influenced mass flow rate, moisture content, and color parameter a*. The antioxidant capacity, phenolic compounds and total carotenoid content, in addition to other color parameters, were not affected. The best process conditions were determined at 138.4-146.4 ºC and 14-21 s. The flakes exhibited phenolic compound contents of 3200 mg GAE per 100 g d.b., and antioxidant capacity of 360 µmol TE g-1 d.b. The product can be used as an ingredient in food formulations.