Microstructure and flow properties of lyophilized mango pulp with maltodextrin/Microestrutura e propriedades de escoamento da polpa liofilizada de manga com maltodextrina

The present study had as objective to determine the flow properties and behavior of lyophilized mango pulp powder as a function of different concentrations of maltodextrin. In the samples of the powders contain 5, 10 and 15% of maltodextrin the angle of effective internal friction, wall friction angle, flow index and bulk density were determined. The microstructure was evaluated by scanning electron microscopy. The freeze-dried samples are characterized as having an amorphous structure, and the drying aid used modified the surface of the particles. The flow index was 3.19, 4.28 and 4.53 for samples containing, respectively, 5, 10 and 15% maltodextrin. Increasing the concentration of maltodextrin in the mango pulp decreased the effective angles of internal friction and wall friction. The bulk density of the powders increased with increasing concentration of maltodextrin for the samples containing 5, 10 and 15% of the maltodextrin, being equal to 597.8, 689.8 and 691.3 kg [m.sup.-3], respectively. Thus, it was concluded that the addition of maltodextrin modified the shape of the particles, decreased segregation, affected the flow properties of the mango powders, facilitating flow and increasing their bulk density. Key words: powdered fruit, microscopy, flow index, powder rheology Objetivou-se com o trabalho determinar as propriedades e o comportamento do escoamento do po da polpa de manga liofilizada em funcao de diferentes concentracoes de maltodextrina. Nas amostras dos pos contendo 5, 10 e 15% de maltodextrina foram determinados o efetivo angulo de atrito interno, angulo de atrito com a parede, indice de fluxo e densidade consolidada. A microestrutura foi avaliada atraves de microscopia eletronica por varredura. As amostras liofilizadas se caracterizam como de estrutura amorfa, e o adjuvante de secagem utilizado modificou a superficie das particulas. Os indices de fluxo foram 3,19, 4,28 e 4,53 para as amostras contendo, respectivamente, 5, 10 e 15% de maltodextrina. O aumento da concentracao de maltodextrina na polpa de manga diminuiu os angulos de atrito interno e atrito com parede. Ja para a densidade aparente dos pos houve uma elevacao em seus valores com o aumento da concentracao de maltodextrina, sendo observados valores de 597,8, 689,8 e 691,3 kg [m.sup.-3] para as amostras contendo 5, 10 e 15% de maltodextrina, respectivamente. Dessa forma, concluiu-se que a adicao da maltodextrina modificou a forma das particulas, diminuiu a segregacao, afetou as