Fast and solvent-free determination of kappa and iota carrageenan in Kappaphycus alvarezii using ATR-FTIR spectroscopy and chemometrics

Determining kappa and iota carrageenan composition is essential for optimizing its functionality in food applications. Kappaphycus alvarezii is a major source of carrageenan, widely used as a gelling agent, thickener, and stabilizer. However, conventional carrageenan analysis requires time-consuming extraction and chemical treatments, limiting efficiency in quality control. This study proposes a rapid, solvent-free approach to quantify total carrageenan yield and its kappa and iota composition in different forms of raw macroalgae. Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy combined with Partial Least Squares (PLS) regression was employed to develop a predictive model for carrageenan determination. The model achieved high accuracy, with calibration, cross-validation, and prediction coefficients (R2) exceeding 0.9 within the 600–1100 cm−1 spectral range. Validation with real samples confirmed its reliability, making it a suitable tool for carrageenan quality assessment and industrial applications. © 2025 Elsevier Ltd