DMACA protocols

Unfortunately, there exist a variety of different protocols. None of these protocols is generally accepted as an universal method. The assay of Delcour and Janssens de Varebeke [148] has been adopted by the European Brewery Convention Analysis Committee as an official method, but a new protocol has recently been published for the analysis of beer [31]. To our knowledge, one of the most carefully optimized DMACA protocols at this time is the one of Li et al. [67] for the analysis of forage legumes. 

Fig. 3.7 Normal-phase-HPLC chromatograms of PA fractions generated by differential solvent extraction of crude GSE (protocol 1). (a) Fraction 1, (b) Fraction 2, (c) Fraction 3, (d) Fraction 4, (e) Fraction 5, and (f) Fraction 6. Compounds were detected with post-column deiivatization using DMACA...

Protocols use beer, barley and hops d for 0.1 % DMACA in 25 % concentrated hydrochloric acid in methanol 0.3 % DMACA in 25 % concentrated hydrochloric acid in methanol 147,148,291 3 ... 

The use of dimethylaminocinnamaldehyde (DMACA) as a reagent for the colorimetric determination of flavanols was first described by Thies and Fischer [146]. The first protocol was developed by Me Murrough and Me Dowell [147] for purified extracts of barley and hops (Humulus lupulus). The reaction scheme is the same as for the vanillin reaction. The reactivity of proanthocyanidins essentially again resides in the 5,7-hydroxylation of the aromatic A-ring, a single bond between C2 and C3 and the lack of a... 

---