Influence of sweeteners on the viscoelasticity of hydrocolloids gelled systems

The influence of sucrose at relatively low concentrations (10 and 20%, w/w) and of aspartame (0.08 and 0.16%, w/w) on the viscoelastic properties of three hydrocolloids gelled systems-kappa-carrageenan, gellan gum, and kappa-carrageenan/locust bean gum (LBG)-at two gum concentrations (0.3 and 1.2%, w/w) have been studied by oscillatory rheological methods. Both storage and loss moduli values increased in the order: kappa-carrageenan < kappa-carrageenan/LBG < gellan in both soft (0.3%) and hard (1.2%) gels. In soft kappa-carrageenan gels, addition of 10% sucrose slightly increased G' and G" values. In contrast, both in soft gellan gum gels and in soft kappa-carrageenan/LBG mixed gels, the same addition of sucrose resulted in a small decrease in the values of both moduli. Addition of sucrose at 20% showed different effects depending on hydrocolloids: in soft kappa-carrageenan gels it produced a further increase in G', in soft gellan gels, it produced a further slight decrease in both moduli and in soft kappa-carrageenan/LBG mixed gels no change in any modulus was detected. In hard kappa-carrageenan gels, no alteration of the moduli values was observed on adding sucrose. In hard gellan gels, G' and G" values increased on adding 20% sucrose. In hard kappa-carrageenan/LBG mixed gels, the decrease in the moduli values was more pronounced on adding the higher sucrose concentration. In the case of aspartame addition, no important change in the viscoelastic properties of any system was observed. Both in kappa-carrageenan and in kappa-carrageenan/LBG mixed gels, tan delta values in soft gels were somewhat lower than those in hard gels, indicating a slightly more elastic behaviour of the former ones. (C) 2003 Elsevier Ltd. All rights reserved.