Water content quantification by FTIR in carboxymethyl cellulose food additive

Water content quantification of raw polysaccharide materials for food processing is generally performed by gravimetric analysis or titrimetric methods, which are time- and energy-consuming, non-eco-friendly and sample destructive. The present study develops and validates a new approach, based on the use of Fourier transform infrared (FTIR) spectroscopy, resulting in a model of the water content of carboxymethyl cellulose (CMC) polysaccharides. Samples of CMC were exposed to different relative humidity conditions. Water content was determined by standard gravimetric methods (OIV-Oeno 404–2010) and compared with the area of FTIR absorption in the range 3675–2980 cm−1, attributed to the stretching of OH groups. The strong correlation between gravimetric results and FTIR area (R2 = 0.88) showed no signs of bias across the water content range. A cross-validation technique to predict the water content by band area was assessed obtaining a general equation: y = 2.12 x + 2.80 with a high repetitively and good prediction of the tested models.