Terahertz spectral markers of apparent amylose content in rice and corn starches
Han Guo1, Lin Wang2, Sihui Li3
1Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
Abstract:
Apparent amylose content (AAC) is a key parameter governing the functional and nutritional properties of starch, yet its conventional determination relies on labor-intensive and destructive wet-chemical methods. Here, terahertz (THz) spectral features were evaluated as markers for AAC in rice and corn starches. AAC was determined using the iodine colorimetric method, and calibration models were developed from mixtures of waxy starches and isolated amylose. Several characteristic peaks were examined, among which features near 9.0 THz showed the most consistent correlation with AAC, while the 10.5 THz feature exhibited secondary, more structure-dependent behavior. Validation using native starch samples demonstrated that the peak at 9.0 THz provided the best prediction performance. This enhanced sensitivity is likely associated with collective vibrational modes linked to starch molecular organization, particularly structural features related to α-(1 → 6) branching and chain length. These results demonstrate the potential of THz spectroscopy as a rapid, nondestructive, and structure-sensitive approach for AAC determination in starch.
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