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Small deformation viscoelastic and thermal behaviours of pomegranate seed pips CMC gels

Savadkoohi, Sobhan, Farahnaky, Asgar
Journal of food science and technology 2015 v.52 no.7 pp. 4186-4195
carboxymethylcellulose, cellulose, deformation, differential scanning calorimetry, gels, pomegranates, scanning electron microscopy, sodium hydroxide, thermal properties, thermogravimetry, viscoelasticity, viscosity, weight loss
The current investigation presents an exploration in phase behaviour of carboxymethyl cellulose (CMC) produced from pomegranate seed pips compared to low and high viscosity CMCs (LMCMC and HMCMC) primarily at low solid concentrations. Cellulose was extracted with 10 % NaOH at 35 °C for 22 h from pomegranate seed pips and converted to CMC by etherification process. Thermomechanical analysis and micro-imaging were carried out using small deformation dynamic oscillation in shear, modulated differential scanning calorimetry (MDSC) and scanning electron microscopy (SEM). The results emphasize the importance of molecular interaction and the degree of substitution in produced CMC. Thermal gravimetric analysis (TGA) thermograms showed an initial weight loss in pomegranate seed pips CMC (PSCMC) sample, which we attribute to presence of amount of moisture in sample powder. MDSC analysis of PSCMC showed five different peaks at 84, 104, 173, 307 and 361 °C. Moreover, G’ and G” changes were found to be dependent on both concentration and frequency. The results of frequency sweep and tan δ indicate that PSCMC solutions can be classified as weak gels.