These researchers compared the two most common tannin-precipitation assays: the methyl cellulose precipitation and the bovine serum albumin precipitation assays. They compared them for repeatability, time efficiency, throughput, and ease. Although their results are inconclusive, the questions they raise and the data they produced are certainly thought-provoking.
For the complete article, please see http://pubs.acs.org/cgi-bin/abstract.cgi/jafcau/2008/56/i14/abs/jf8008266.html