Determination of Some Chemical Components of Fermented Cordyceps Mycelia Using Near-Infrared Spectroscopy
he study evaluated the potential of using near-infrared spectroscopy (NIRS) to predict adenosine, moisture and total amino acid content of fermented mycelia of Paecilomyces hepialid, a derivative of Cordyceps sinensis. A total of 200 samples were collected and randomly divided for calibration (n=140) and prediction (n=60). Spectra were generated by a multi-purpose analyser (MPATM) Fourier transform NIRS system with recorded spectral range of 12500–4000 cm-1. Several spectral pretreatment techniques were adopted for spectral transformation. The transformed spectra in calibration set were subjected to a partial least squares (PLS) algorithm with leave-one-out cross- validation. Prediction results showed that the PLS models developed for the orthogonal signal correction (OSC)-transformed spectra achieved best performance with coefficient of determination (R2) of 0.996, 0.996 and 0.990 for adenosine, moisture and total amino acid contents, respectively. This experiment suggests that the NIR spectroscopy, if coupled with appropriate spectrum transformation, is a promising tool for rapid, nondestructive and accurate measurement of chemical components of natural and fermented mycelia of Cordyceps sinensis.
Key Words: Cordyceps sinensis, near-infrared spectroscopy, orthogonal signal correction, Paecilomyces hepialid, partial least squares regression
Abbreviations: AN – area normalization, BOC – baseline offset correction, LVs – latent variables, MSC – multiplicative scatter correction, NIRS – near-infrared spectroscopy, OSC – orthogonal signal correction, PLS – partial least squares regression, RMSEC – root-mean-square error of calibration, RMSEP – root-mean-square error of prediction, RPD – residual prediction deviation, SNV – standard normal variate
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