Drum-drying of mango peel and characterization of different varieties/Secagem de cascas de manga em cilindro rotativo e caracterizacao de diferentes variedades

HIGHLIGHTS: The Palmer mango showed higher nutrient concentration, besides lower moisture content and reducing sugar content in peels. The drum-drying process influenced variables related to the drying efficiency and non-enzymatic browning of mango peels. The drum-drying process did not affect nutrient concentration and the yellow color of the mango peels. 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 [degrees]C) 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 [degrees]C and 14-21 s. The flakes exhibited phenolic compound contents of 3200 mg GAE per 100 g d.b., and antioxidant capacity of 360 (imol TE [g.sup.-1] d.b. The product can be used as an ingredient in food formulations. Keywords: byproduct, agro-industrial waste, antioxidant, phenolic compounds, physicochemical properties A casca da manga, um subproduto da industria de polpa, e rica em nutrientes, porem com alto teor de umidade. A secagem e indicada para estabilizar o residuo e o uso do drum-dryer e uma alternativa pouco estudada. O presente estudo avaliou a aplicacao da tecnologia para cascas de manga, investigando as condicoes de processo. O potencial das cascas das variedades Palmer, Haden, Keitt e Espada Vermelha tambem foi avaliado usando analises fisico-quimicas. Os resultados mostraram diferencas entre as variedades: a Palmer exibiu o menor teor de umidade (73,97 g por 100 g); a Keitt o maior teor de