Elution was at 32 °C,
with a flow rate of 1 mL/min, using acetonitrile 80% as mobile phase.
Total and individual free amino acids were analyzed by a Biochrom 30
series Amino Acid Analyzer (Biochrom Ltd., Cambridge Science Park,
England) with a Na-cation-exchange column (20 by 0.46 cm internal
diameter) as described by Rizzello et al. (2010).