NIR SPECTRA IN RELATION TO VISCOELASTIC PROPERTIES OF MIXTURES OF NA-KAPPA-CARRAGEENAN, LOCUST BEAN GUM AND CASEIN

Near-infrared spectral data were correlated with the viscoelastic prop erty storage modulus, G', for mixtures of five biopolymers using multi variate analysis. Gels containing Na-kappa-carrageenan (0.5-1.0%) mixe d with locust bean gums with two different mannose to galactose ratios , alpha-casein and/or kappa-casein (0-0.5%, polymer concentration) in 0.25 M NaCl were studied. Forty-two experiments based on a multivariat e, central composite circumscribed design (CCC) were performed. Partia l least square (PLS) regression was used to find a model relation betw een NIR transmittance spectra, recorded at 15 degrees C in the wavelen gth interval 40-2500 nm, and the G' for the biopolymer gels at 15 degr ees C. Depending on sample composition, the G' varies between 0 and 35 00 Pa. Cross-validation using a designed data set led to a model based on 11 principal components with a correlation coefficient of 0.85 and a root mean square error of prediction of 540 Pa. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.