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The condensed tannin content of vegetative Lotus pedunculatus , its regulation by fertiliser application, and effect upon protein solubility
Author(s) -
Barry Thomas N.,
Forss David A.
Publication year - 1983
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/jsfa.2740341004
Subject(s) - tannin , condensed tannin , lotus , chemistry , lotus effect , solubility , proanthocyanidin , food science , botany , polyphenol , biochemistry , biology , organic chemistry , raw material , antioxidant
The condensed tannin concentration in Lotus pedunculatus (cv. Grasslands ‘Maku’) was 8–11% DM when grown in acid soils without fertiliser application and 2–3% DM when grown in high fertility soils. Application of P & S fertiliser to the acid soils increased DM yield and reduced condensed tannin content to 4–5% DM, with over 88% of the variation in condensed tannin content being explained by variation in DM yield; it also increased plant total N concentration and halved the molar ratio of condensed tannin: protein (MR). Condensed tannins quantitatively precipitated soluble protein in lotus and also effectively precipitated protein in mixtures of lotus with white clover. The minimum concentration of condensed tannin necessary to precipitate protein was 2–4% DM, corresponding to MR values of 6–13. However, protein from such mixtures could be deaminated by fermentations with rumen fluid in vitro , but potentially soluble protein in pure lotus (MR 29) was protected from deamination by condensed tannins. A portion of lotus tannin could not be bound by plant constituents in finely ground fresh herbage and was designated ‘free’ tannin. This fraction was linearly related to total plant tannin content, was predicted to be zero at 1.8% DM total tannin, and increased at 0.15 units per unit increase in total tannin content above this figure. Maximum ‘free’ tannin comprised 17% of total condensed tannin. Effects of total and ‘free’ tannin content upon the intake and digestion of lotus by sheep are discussed.