Abstract: To efficiently select microbial strains capable of biotransforming cinnamaldehyde into cinnamyl alcohol, a new method for the rapid determination of cinnamyl alcohol, cinnamaldehyde and cinnamic acid in the biotransformation products of cinnamaldehyde was established using multi-order derivative ultraviolet (UV) spectrometry. Based on their second (for cinnamaldehyde and cinnamic acid) or third (for cinnamyl alcohol) order derivative UV absorption spectra, 320, 306 and 256 nm were selected as suitable wavelengths for determination of cinnamaldehyde, cinnamic acid and cinnamyl alcohol, respectively. Good linearity was observed in the concentration range of 0.52–9.27, 0.51–9.24 and 0.55–5.47 mg/L for the three compounds, respectively. Their average recoveries were 103.3%, 104.1% and 98.0% with relative standard deviations (RSDs) of 4.1%, 2.1% and 3.5% (n = 3), respectively. The measurement could be carried out on samples after dilution without extraction or separation, which could be used for rapid screening for strains capable of biotransforming cinnamaldehyde into cinnamyl alcohol.

Key words: multi-order derivative ultraviolet spectrometry, cinnamaldehyde, cinnamyl alcohol, cinnamic acid, biotransformation