THERMAL-ANALYSIS OF THE WATER-UPTAKE BY HYDROCOLLOIDS

Water uptakes by the hydrocolloids gelatin, pectin and sodium carboxym ethylcellulose (NaCMC) and their mixtures, following storage at 20 deg rees C and 93% relative humidity (RH), were investigated using differe ntial scanning calorimetry. An increase in water uptake was observed f or each sample on storage. The majority of the moisture sorption occur red in the initial 2 h. Only non-freezable, bound water was present in gelatin, pectin and gelatin/pectin or NaCMC/pectin/gelatin mixtures d uring storage for 28 h. Loosely bound freezable and non-freezable, bou nd water were detected in NaCMC stored for 2 h. Water in mixtures of N aCMC/gelatin or NaCMC/pectin was predominately loosely bound freezable and non-freezable bound. The order of water uptake was C/pectin/gelat in<NaCMC/gelatin<NaCMC/pectin<NaCMC. (C) 1998 Elsevier Science B.V.