ISSN:
1573-1561
Keywords:
Tannins
;
antioxidants
;
extraction
;
protein precipitation
;
walnut
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The radial diffusion assay was applied to estimate the amount of total tannins in extracts from walnut plant materials. We found that the protein-precipitating activity of the tannin extracts were increased by 30–75 % when antioxidants (ascorbic acid or sodium metabisulfite, 5.5 mM) were added in extraction solvents (50% aqueous methanol). The extracts obtained with Na2S2O5 were much less brown than control. Moreover, two-dimensional thin-layer chromatography revealed some additional polyphenolic compounds in the extracts made with Na2S2O5. These results suggest that the amount of tannins and/or their protein-precipitating property may be strongly affected by oxidation events during extraction procedure. The addition of antioxidants in the extraction solvents is useful to limit this problem.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01395597
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