Seventeen different free amino acids were detected in suan-cai during
natural fermentation; the total concentration of free amino acids
showed a small peak in the mid-fermentation stage, increasing from
217.51 mg/L after 0 d fermentation to 675.88 mg/L in the midfermentation
stage. In the late fermentation stage, the overall concentration
of free amino acids had decreased slightly to 659.46 mg/L.