SUPERHEATED STEAM-DRYING OF MATE LEAVES AND EFFECT OF DRYING CONDITIONS ON THE PHENOL CONTENT

Authors

  • EVERTON FERNANDO ZANOELO,

    Corresponding author
    1. Department of Chemical Engineering
      Federal University of Paraná
      Polytechnic Center, Jardim das Américas 81530-900
      Curitiba, Paraná, Brazil
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  • LÚCIO CARDOZO-FILHO,

    1. Department of Chemical Engineering
      State University of Maringá, Av. Colombo, 5790, 87020-900
      Maringá, Paraná, Brazil
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  • EUCLIDES LARA CARDOZO-JÚNIOR

    1. Department of Pharmacy
      Universidade Paranaense
      Av. Parigot de Souza, 3636, Jardim Prada, 85903-170
      Toledo, Paraná, Brazil
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TEL: +55 41 3361-3202; FAX: +55 41 3361-3674; EMAIL: everton.zanoelo@ufpr.br

ABSTRACT

Four drying experiments of mate leaves (Ilex paraguariensis St. Hilaire) were carried out in a packed bed superheated steam dryer by varying outlet steam temperature from 120 to 140C and equivalent particle diameter from 4.7 × 10−3 to 6.95 × 10−3 m. The influence of these variables on the drying coefficient calculated by assuming a simplified drying kinetic model was investigated. A classical statistical approach revealed the significant effect of both factors on this parameter. Two additional drying runs were performed at identical conditions with conventional hot air and low pressure superheated steam, respectively. The influence of drying atmosphere on the total content of phenols was evaluated. A conventional process of extraction by using an aqueous methanol solution was adopted. Analyses for total phenols were performed by spectrophotometry at 715 nm by applying Folin-Denis assay. The leaves dried with superheated steam had approximately 47% higher retention of these compounds.

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