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The DMACA–HCl Protocol and the Threshold Proanthocyanidin Content for Bloat Safety in Forage Legumes
Author(s) -
Li YuGuang,
Tanner Greg,
Larkin Phil
Publication year - 1996
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/(sici)1097-0010(199601)70:1<89::aid-jsfa470>3.0.co;2-n
Subject(s) - proanthocyanidin , forage , legume , red clover , dry matter , condensed tannin , chemistry , biology , fabaceae , food science , botany , horticulture , polyphenol , biochemistry , antioxidant
A protocol using HCl‐acidified 4‐dimethylaminocinnamaldehyde (DMACA) was developed for screening proanthocyanidins (PA) in plants. Individual PA‐containing cells could be observed following staining of decolourised leaves with DMACA. The quantitative assay using DMACA‐HCl to detect soluble PA and butanol–HCl to detect insoluble PA could detect PA content lower than 0·4 mg g −1 dry matter (DM). The DMACA–HCl protocol is recommended for PA detection in low‐PA plants because of its higher sensitivity than vanillin–acid protocols. Twenty‐two forage legume species, most of which had been reported free of leaf PA but bloat‐safe, were re‐examined using the DMACA–HCl protocol. PA‐positive cells were observed in leaves of 15 species. Measurable amounts of PA were detected in leaves of seven species, with the PA content ranging from 0·6 to 11 mg g −1 DM. White clover ( Trifolium repens L), red clover ( T pratense L) and lucerne ( Medicago sativa L) were also found to have PA‐positive leaf trichomes. By analysis of these data and the literature, the threshold PA content for bloat safety in forage legumes was estimated to be 1–5 mg PA g −1 DM.