Determination of amino acids in tea leaves and beverages using capillary electrophoresis with light-emitting diode-induced fluorescence detection

Sequential determination of tannin and total amino acid contents in tea for taste assessment by a fluorescent flow-injection analytical system

“…Signal outputs of the four representative amino acids were examined; approximately 70.5% of signal response was associated with the umamirelated amino acids, theanine (58.4%) and glutamate (12.1%). This experimental result for response percentage is similar to that obtained by a previous study of green tea (Lee et al, 1996) and a recent report regarding Taiwan red tea (Hsieh & Chen, 2007). Therefore, the proposed amines determination based on OPA-fluorescent was considered as an indicator of umami in tea infusions during the taste assessment.…”

Study of the naphthalene-2,3-dicarboxaldehyde pre-column derivatization of biogenic mono- and diamines in mixture and fluorescence−HPLC determination

“…Compared with the products formed by derivatization with OPA, the NDA/CN derivatives exhibit improved chemical stability, excitation maxima (420 and 440 nm) in the visible region, efficient chemiluminescence by the peroxyoxalate method and enhanced fluorescence quantum efficiency [41]. NDA has been used for the derivatization of amino acids and peptides [41][42][43][44][45], catecholamines [46][47][48][49], aliphatic amines [50], heterocyclic amines [51,52], aliphatic diamines [53], drugs [54][55][56] and lipids [57]. The main features of these methods are summarized in Electronic supplementary material (ESM) Table S1.…”

Chemical characterization of liquid residues from aqueous enzymatic extraction of soybean oil

“…The amino acids derivatization was carried out using a modified procedure based on that described in Hsieh and Chen (2007).…”