Testing the effects of drying methods on willow flavonoids, tannins, and salicylates

In this study, we compared the effects of several preservation methods on the secondary phenolics of the mature leaves of purple willow (Salix purpurea L., Salicaceae) with results obtained with fresh leaf analyses. Conventional freeze-drying, in which the leaves were first frozen with liquid nitrog...

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Bibliographic Details
Published in:Journal of chemical ecology 2001-04, Vol.27 (4), p.779-789
Main Authors: Julkunen-Tiitto, R, Sorsa, S
Format: Article
Language:English
Subjects:
ambient temperature
Biological and medical sciences
Chemical constitution
Desiccation
Flavonoids
Flavonoids - analysis
Flavonoids - chemistry
Flowers & plants
Freeze drying
Fundamental and applied biological sciences. Psychology
Furosemide - chemistry
heat
leaves
nitrogen
Phenology
Phenols
Plant Extracts - analysis
Plant physiology and development
Preservation, Biological - methods
salicylates
Salicylates - analysis
Salicylates - chemistry
Salix purpurea
Specimen Handling
tannins
Tannins - analysis
Tannins - chemistry
Vacuum drying
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Summary:In this study, we compared the effects of several preservation methods on the secondary phenolics of the mature leaves of purple willow (Salix purpurea L., Salicaceae) with results obtained with fresh leaf analyses. Conventional freeze-drying, in which the leaves were first frozen with liquid nitrogen and then placed in a freeze-dryer, produced substantial qualitative and quantitative changes in purple willow flavonoids and salicylates. Modified freeze-drying, in which leaves were put into a freeze-dryer without being prefrozen, gave concentrations that, for most secondary components, were comparable with those found in fresh leaves. Reducing the freeze-dryer chamber temperature hindered the decomposition of phenolics in prefrozen leaves and in leaves dried without prefreezing. Heat drying induced substantial changes in the composition of all phenolics, except for apigenin-7-glucoside. Vacuum drying at room temperature gave the highest concentrations for nearly all phenolics, while room-drying with desiccation gave results that were comparable with those obtained by fresh leaf analyses.
ISSN:0098-0331
1573-1561
DOI:10.1023/A:1010358120482