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SUPERHEATED STEAM‐DRYING OF MATE LEAVES AND EFFECT OF DRYING CONDITIONS ON THE PHENOL CONTENT
Author(s) -
ZANOELO EVERTON FERNANDO,
CARDOZOFILHO LÚCIO,
CARDOZOJÚNIOR EUCLIDES LARA
Publication year - 2006
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/j.1745-4530.2006.00064.x
Subject(s) - superheated steam , chemistry , phenol , steam explosion , phenols , superheating , chromatography , methanol , extraction (chemistry) , pulp and paper industry , thermodynamics , organic chemistry , physics , engineering
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.