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Relationship between condensed tannin structures and their ability to precipitate feed proteins in the rumen
Author(s) -
Lorenz Martin M,
Alkhafadji Loy,
Stringano Elisabetta,
Nilsson Staffan,
MuellerHarvey Irene,
Udén Peter
Publication year - 2013
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.6344
Subject(s) - solubility , tannin , rapeseed , chemistry , precipitation , proanthocyanidin , condensed tannin , rumen , food science , rubisco , biochemistry , pea protein , circular dichroism , chromatography , fermentation , organic chemistry , polyphenol , physics , enzyme , meteorology , antioxidant
BACKGROUND Tannins can bind to and precipitate protein by forming insoluble complexes resistant to fermentation and with a positive effect on protein utilisation by ruminants. Three protein types, Rubisco, rapeseed protein and bovine serum albumin (a single high‐molecular weight protein), were used to test the effects of increasing concentrations of structurally different condensed tannins on protein solubility/precipitation.RESULTS Protein type ( PT ) influenced solubility after addition of condensed tannins ( P < 0.001) in the order: Rubisco < rapeseed < BSA ( P < 0.05). The type of condensed tannin ( CT ) affected protein solubility ( P = 0.001) with a CT × PT interaction ( P = 0.001). Mean degree of polymerisation, proportions of cis ‐ versus trans ‐flavanol subunits or prodelphinidins versus procyanidins among CTs could not explain precipitation capacities. Increasing tannin concentration decreased protein solubility ( P < 0.001) with a PT × CT concentration interaction. The proportion of low‐molecular weight rapeseed proteins remaining in solution increased with CT concentration but not with Rubisco.CONCLUSIONS Results of this study suggest that PT and CT type are both of importance for protein precipitation but that the CT structures investigated did not allow identification of parameters that contribute most to precipitation. It is possible that the three‐dimensional structures of tannins and proteins may be more important factors in tannin–protein interactions. © 2013 Society of Chemical Industry